6-Phenoxy-2-phenylbenzoxazoles, novel inhibitors of receptor for advanced glycation end products (RAGE)

Bioorganic & Medicinal Chemistry xxx (2015) xxx–xxx

Contents lists available at ScienceDirect

Bioorganic & Medicinal Chemistry journal homepage: www.elsevier.com/locate/bmc

6-Phenoxy-2-phenylbenzoxazoles, novel inhibitors of receptor for advanced glycation end products (RAGE) Kwanghyun Choi a,b, Kwang Su Lim a, Juhee Shin a, Seo Hee Kim a, Young-Ger Suh a, Hyun-Seok Hong b, Hee Kim b, Hee-Jin Ha b, Young-Ho Kim b, Jiyoun Lee c, Jeewoo Lee a,⇑ a b c

Laboratory of Medicinal Chemistry, Research Institute of Pharmaceutical Sciences, College of Pharmacy, Seoul National University, Seoul 151-742, South Korea Medifron DBT, Sandanro 349, Danwon-Gu, Ansan-City, Gyeonggi-Do 425-839, South Korea Department of Global Medical Science, Sungshin University, Seoul 142-732, South Korea

a r t i c l e

i n f o

Article history: Received 6 April 2015 Revised 12 May 2015 Accepted 13 May 2015 Available online xxxx Keywords: Receptor for advanced glycation end products, RAGE Alzheimer’s disease Amyloid b

a b s t r a c t Receptor for advanced glycation end products (RAGE) is known to be involved in the transportation of amyloid b (Ab) peptides and causes the accumulation of Ab in the brain. Moreover, recent studies suggest that the interactions between RAGE and Ab peptides may be the culprit behind Alzheimer’s disease (AD). Inhibitors of the RAGE–Ab interactions would not only prevent the accumulation of toxic Ab in the brain, and but also block the progress of AD, therefore, have the potential to provide a ‘disease-modifying therapy’. In this study, we have developed a series of 6-phenoxy-2-phenylbenzoxazole analogs as novel inhibitors of RAGE. Among these derivatives, we found several effective inhibitors that block the RAGE–Ab interactions without causing significant cellular toxicity. Further testing showed that compound 48 suppressed Ab induced toxicity in mouse hippocampal neuronal cells and reduced Ab levels in the brains of a transgenic mouse model of AD after oral administration. Ó 2015 Elsevier Ltd. All rights reserved.

1. Introduction Alzheimer’s disease (AD) is the most common cause of dementia, accounting for 50–75 percent of the cases worldwide.1 Although the cause and progression of AD are still not completely understood, amyloid b (Ab) plaques are considered to be one of the most important hall mark changes in the brains of AD patients.2 Ab plaques, known to cause neuronal damage and chronic inflammation, are derived from Ab peptides accumulated inside the brain. Ab peptides are mainly produced from proteolytic cleavage of amyloid precursor proteins (APPs), and the influx and clearance of Ab peptides inside the brain are regulated by the blood–brain barrier (BBB).3,4 According to the vascular hypothesis in AD pathogenesis, damaged brain vasculature leads to abnormal BBB permeation, which in turn accelerates the accumulation of Ab peptides in the brain.5 The elevated levels of Ab peptides promote a cascade of events that eventually lead to neuronal damage and dementia.6 The mechanisms underlying toxic Ab accumulation and AD pathogenesis remain unclear, however, Zlokovic and colleagues demonstrated that the receptor for advanced glycation end products (RAGE) plays a crucial role in the transportation of plasma-derived

⇑ Corresponding author. Tel.: +82 2 880 7846; fax: +82 2 888 0649. E-mail address: [email protected] (J. Lee).

Ab across the BBB, thus causes the accumulation of Ab in the brain.7,8 RAGE is a transmembrane receptor expressed on the surface of diverse cells including monocytes, neurons, and vascular endothelial cells.9,10 RAGE is known as a pattern recognition receptor, which binds to multiple ligands.11 There are several endogenous ligands including AGE (advanced glycation end products),9 S100 proteins,12 HMGB1 (high-mobility group box1; amphoterin),13 and Ab peptides.7,8 Interestingly, most of these ligands are linked to several chronic diseases such as cancer,14 diabetic nephropathy,15 atherosclerosis16 and AD.17 It is hypothesized that RAGE activates the nuclear factor kappa B (NF-jB) upon binding to these ligands and triggers inflammatory responses.18 Furthermore, prolonged exposure to high concentrations of the ligands results in a positive feedback cycle, which, in turn, leads to chronic inflammation.19 In addition to the significant role of RAGE in chronic inflammation, direct involvement of RAGE in AD has drawn much attention in hopes to find novel therapeutics. RAGE is overexpressed in AD induced animals and human AD patients, and it acts as major transporters of Ab peptides into the brain.7,8 Furthermore, the interactions between Ab peptides and RAGE induce oxidative stress and chronic inflammation in the brain, and accelerate neuronal damage and cognitive decline.18,20–22 It has been reported that anti-RAGE antibodies suppress detrimental effects of Ab peptides

http://dx.doi.org/10.1016/j.bmc.2015.05.022 0968-0896/Ó 2015 Elsevier Ltd. All rights reserved.

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K. Choi et al. / Bioorg. Med. Chem. xxx (2015) xxx–xxx

in transgenic mice models of AD, suggesting that RAGE is a promising therapeutic target for AD.23–25 Taken together, inhibitors of RAGE–Ab interactions would block the accumulation of toxic Ab in the brain, protect neurons from oxidative damage, and interfere with the progress of AD. Therefore, these inhibitors have the potential to provide a ‘disease-modifying therapy’, whereas most AD therapies developed to date are symptomatic treatments that can improve cognitive functions and memory. Initial efforts to develop therapies based on RAGE–Ab interactions were mostly focused on anti-RAGE antibodies and soluble RAGE proteins. However, recently, Zlokovic and colleagues reported a small molecule RAGE-specific inhibitor that reduced brain Ab level and Ab-induced cellular stress in an animal model of AD.26 In addition, a RAGE-specific inhibitor developed by TransTech Pharma, TTP-488, has reached phase 3 trial in patients with mild to moderate AD. Inspired by these approaches, we performed a pharmacophoric analysis based on the small molecule ligands that were reported previously.27–31 We established a hypothetical pharmacophore model, and identified the principal pharmacophores including an aryloxy group, a dialkylaminoalkyl group, and lipophilic substituents. On the basis of these findings, we designed a series of small molecule inhibitors of RAGE–Ab interactions as depicted in Figure 1. In this study, we synthesized a novel series of 6-phenoxy-2-phenylbenzoxazole analogues and evaluated their ability to block RAGE–Ab interactions in vitro and in vivo.

2-Phenylbenzoxazole core N

R1

O O

6-Phenoxy region

O

R2 Aminoalkyloxy region

Figure 1. Design of 6-phenoxy-2-phenylbenzoxazole analogues as RAGE inhibitors.

2. Results and discussion 2.1. Chemistry Syntheses of 6-phenoxy-2-(4-oxyphenyl)benzoxazole intermediates 6a–e were carried out by following the synthetic pathway described in Scheme 1. First, the biaryl ether fragments, 2a–e, were synthesized by alkylating various substituted phenols with 2-benzyloxy-4-fluoro-1-nitro-benzene 1. Debenzylation at the ortho-position was achieved in good yields (74–99%) by using trifluoroacetic acid. Subsequent reduction of nitro group with tin chloride and hydrochloric acid afforded compounds 4a–e. Condensation of compounds 4a–e with 4-formylphenyl acetate, followed by oxidation using DDQ successfully constructed the key benzoxazole fragments 5a–e in moderate to good yields (43–78%). Deacetylation of 5a–e with sodium hydroxide generated 6-phenoxy-2-(4-oxyphenyl)benzoxazole intermediates 6a–e. Syntheses of 6-(4-chlorophenoxy)-2-phenylbenzoxazole derivatives containing a piperidine (7–23) were performed by following the pathway described in Scheme 2. Mitsunobu reaction of 6a with Boc-protected piperidinyl alcohols afforded compound 7 and 8. After the Boc group was removed by using trifluoroacetic acid, the free amine nitrogen was substituted by using a base and alkyl halide or acyl halide to afford compounds 13, 15–17, 19, and 21–23. Compounds 14 and 20 were obtained via palladium-catalyzed cross coupling reactions with bromobenzene.

Compounds 12 and 18 were produced by amide reduction of compounds 17 and 23 respectively. Syntheses of 6-phenoxy-2-phenylbenzoxazole derivatives containing a flexible aminoalkyl chain (26–75) were carried out by following the pathway described in Scheme 3. The phenoxy group of 6a–e were alkylated with 1-bromo-2-chloroethane (n = 1) or 1bromo-3-chloropropane (n = 2) to generate compounds 24 and 25 respectively. Compounds 26–30 were prepared from compound 24a by addition of the corresponding amines, and compounds 31–75 were prepared from compounds 25a–e. More specifically, compounds 31–34, 37–61, and 64–75 were obtained via a simple substitution reaction with the corresponding amines. Compounds 35, 36, 62, and 63 were generated by deprotecting the Boc group from compounds 33, 34, 60, and 61 respectively. 2.2. Inhibition of the RAGE–Ab interaction To evaluate whether the synthesized inhibitors can effectively block the interactions between RAGE and Ab, we tested all compounds using fluorescence resonance energy transfer (FRET) assay along with MTT assay for cytotoxicity as presented in Table 1–3. For the FRET assay, we first incubated biotinylated human RAGE proteins and streptavidin–Cy3 conjugates, and then added Ab– FITC conjugates and each compound. Based on the FRET signals between RAGE–Cy3 and Ab–FITC in the presence of a vehicle control, the reduction of the FRET signals induced by each inhibitor was recorded and calculated as percent inhibition. Additionally, we assessed cytotoxicity of each compound by performing MTT assays using HT22 cells (mouse hippocampal neuronal cell line). Among the 4-chlorophenoxy benzoxazole derivatives, compounds with a longer and flexible spacer (compounds 26–52, Table 2) are likely to have higher activity compared to derivatives with a shorter and constrained spacer (compounds 7–23, Table 1). However, when we compared the compounds with the same Nalkyl groups, for example, compounds 27 to 37, 28 to 40, 29 to 48, no clear tendency was observed. Among the derivatives with various N-alkyl groups, compounds with morpholine (28 and 40) and piperazine groups (41–52) were more likely to be active than the rest of the analogues. Although, compounds with diethyl amine (26, 31, and 53) and Boc-protected pyrrolidine groups (33 and 34) appeared to inhibit FRET signals to some extent, all of these compounds demonstrated noticeable cytotoxicity. Within the group of compounds containing piperazine moiety, compounds with the N-alkylcarbamate group (44–48) mostly showed good inhibitory effects. On the other hand, the analogues containing an aromatic substituent on the N-alkyl group (14–16, 20–22, 30, 39, 49–52) were generally insoluble in water, therefore we were unable to measure any FRET signals from these compounds. When we replaced the 4-Cl group on the phenyl ring with various substituents (compounds 53–75, Table 3), we noticed that the 4-F and 4-CF3 containing derivatives appeared to show better solubility and higher activity compared to the 4-t-Bu substituted analogues, suggesting that these substituents may be the key pharmacophore for binding. Overall, we identified several highly active compounds showing inhibition values greater than 40%. On the basis of these measurements, we decided to exclude any compounds showing cytotoxicity greater than 20% for further testing, and selected 20 compounds (17, 19, 28–29, 36, 41, 46–48, 60–61, 65–68, 70–73, 75) exhibiting significant percent inhibition values (>20%) with low cytotoxicity (<20%) at the indicated concentrations. 2.3. Inhibition of the Ab induced cytotoxicity It has been reported that the RAGE–Ab interactions induce various inflammatory responses,32 and amplify Ab induced toxicity in

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NO2

NO2

a

F

O

OBn 1

R

OR

O

N R

R=4-Cl R=4-t-Bu R=4-F R=4-CF3 R=3-CF3

N

e

OAc

R

OH

O

O

OH

a b c d e

4

2 R = Bn 3 R=H

b

d

NH2

c

R

O

O

5

6

Scheme 1. Synthesis of 6-phenoxy-2-(4-oxyphenyl)benzoxazole intermediates. Reagents and conditions: (a) K2CO3, DMF, 140 °C, overnight; (b) CF3CO2H, CH2Cl2, rt, 5 h; (c) SnCl2–2H2O, concd HCl, 2-propanol, reflux, 2 h; (d) (i) 4-formylphenyl acetate, MeOH, 45 °C, 2 h, (ii) DDQ, CH2Cl2, rt, 30 min; (e) 2 N NaOH solution, MeOH, rt, 6 h.

Cl

N

a

Cl

N

O

O

O

O

N

n

O

Cl

c

O O

N Boc

7 n=0 8 n=1

6a

Cl

b

O

OH

n

N O

NH

O

O

N R

n

11-23

9 n=0 10 n=1

Scheme 2. Synthesis of compounds 7–23. Reagents and conditions: (a) Boc-4-hydroxypiperidine or N-Boc-4-piperidine–methanol, DIAD, PPh3, THF, rt, 48 h; (b) TFA, DCM, rt, 5 h; (c) see Section 4 for detailed procedures.

6

a

N R1

b

O O

O

n

24 n=1 25 n=2

Cl

N R1

O O

O

n

R2

26-75

Scheme 3. Synthesis of compounds 26–75. Reagents and conditions: (a) 1-bromo-3-chloropropane or 1-bromo-2-chloroethane, K2CO3, CH3CN, 60 °C, overnight; (b) amines, Na2CO3, KI, n-BuOH, 105 °C, 36 h.

neurons,33 therefore, we believe that RAGE inhibitors may have protective effects against Ab induced cytotoxicity. To investigate the protective effects of the selected compounds, we determined cell viability via MTT assay after incubating HT22 cells with 2 lM of aggregated Ab, and 10 lM of each compound for 18 h. Based on the cellular viability of Ab treated cells in the presence of a vehicle, we calculated percent inhibition values for each compound. Among the tested compounds, compounds 29, 47, 48, 67, and 75 significantly inhibited Ab induced cytotoxicity (>50%) compared to the vehicle control as described in Table 4. Notably, all five compounds contain a (4-alkoxycarbonylpiperazin-1-yl)alkyloxy side chain, indicating that this functional group is crucial for inhibiting the RAGE–Ab interactions in cells. These compounds also share a flexible chain between the phenylbenzoxazole core and the aminoalkyl moiety, which coincides with the same preference observed in the FRET assay. In addition, three out of these five compounds have a 4-Cl substituent on R1 position, suggesting a potentially favorable interaction around this region. Among these five analogues, compound 48 appeared to inhibit the RAGE–Ab interactions significantly in vitro, and also showed the greatest protective

effect in HT22 cells, therefore, we chose compound 48 for further testing in vivo. 2.4. Studies of the Ab-lowering effect in vivo To examine whether the selected compound 48 can block the transport of Ab in vivo, we tested this compound in a transgenic animal model of AD, APPsw/PS1 mice. There are two major species of Ab peptides in plasma, namely, Ab1–40, and Ab1–42. Generally, Ab1–40 is much more abundant in cells and tissues, which accounts for 90% of the secreted Ab peptides, however, Ab1–42 is thought to be more neurotoxic and prone to aggregation.34 Therefore, we decided to measure the levels of these two forms of Ab peptides in addition to the amount of amyloid plaques in tested mice. First, we administered compound 48 orally at 50 mg/kg every two days for 4 weeks, and determined the accumulation of Ab1–40, and Ab1–42 from the post-mortem brain homogenates by enzyme-linked immunosorbent assay (ELISA). As demonstrated in Figure 2a, compound 48 effectively reduced the brain levels of Ab1–40 without any noticeable side effects,

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Table 1 In vitro activity of compounds 7–23*

Cl

N O O

Compound

7

R

N

O

O

R Inhibition of FRET signals (%)

Cytotoxicity (%)

NA

NT

20.6

20.6

19.5

74.3

15.3

38.2

O 9

NH 11

N 12

N

13

N

12.7

86.5

14

N

ND

ND

15

N

ND

ND

ND

ND

20.0

NT

NA

NT

NA

29.0

2.1

4.1

N N

16

N

17

N O O

8

10

18

N

O

NH N

19

N

26.2

NT

20

N

ND

ND

ND

ND

5.1

82.4

NA

32.7

N 21

22

N

N

N O

23

N

Abbreviations. NA: not active, NT: not toxic, ND: not determined. * All measurements were performed in triplicate. FRET signals were collected in the presence of 40 nM of Ab42 and 4 lM of each compound after incubating for 1 h with RAGE–Cy3.

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K. Choi et al. / Bioorg. Med. Chem. xxx (2015) xxx–xxx Table 2 In vitro activity of compounds 26–52*

Cl

N O O

Compound

R

O

R Inhibition of FRET signals (%)

Cytotoxicity (%)

26

N

33.5

85.2

27

N

18.5

21.4

28

N

25.7

NT

O

24.6

NT

N

ND

ND

4.9

32.1

NA

NT

90.2

63.2

16.6

58.2

19.6

NT

29.9

NT

2.2

32.4

16.6

32.2

NA

NT

NA

NT

42.7

18.5

24.3

69.3

3.3

3.3

O

NA

NT

O

6.6

NT

O N 29

N O

N N

30

N 31

N

32

N

O 33

N

34

N

N H

35

N

NH2

36

N

NH2

N H

O

O

37

O

N

38

N

39

N 40 41 42

O N NH N N N

OH

N

43

N O 44

N N O

45

N N

(continued on next page)

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Table 2 (continued) Compound

R

Inhibition of FRET signals (%)

Cytotoxicity (%)

O

41.2

NT

O

25.9

NT

O

40.0

NT

NA

NT

25.1

25.1

ND

ND

ND

ND

O 46

N N O

47

N N O

48

N N

49

N N N

50

N

N

N F

N 51

N

N

N Cl

N 52

N

N

N Abbreviations. NA: not active, NT: not toxic, ND: not determined. * All measurements were performed in triplicate. FRET signals were collected in the presence of 40 nM of Ab42 and 4 lM of each compound after incubating for 1 h with RAGE–Cy3.

Table 3 In vitro activity of compounds 53-75*

N R1

O O

O Compound

R1

53

4-t-Bu

54

4-t-Bu

55

4-t-Bu

56

4-t-Bu

R2

R2 Inhibition of FRET signals (%)

Cytotoxicity (%)

NA

74.1

NA

49.4

NA

NT

ND

ND

O

ND

ND

N

ND

ND

NA

NT

N N

O N

N N O

57

4-t-Bu

N N

N 58

4-t-Bu

N N

59

4-t-Bu

N

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K. Choi et al. / Bioorg. Med. Chem. xxx (2015) xxx–xxx Table 3 (continued) Compound

R1

R2

Inhibition of FRET signals (%)

Cytotoxicity (%)

26.8

NT

61.6

8.2

NA

12.8

54.7

60.3

5.4

NT

30.3

NT

56.7

NT

21.0

15.2

34.9

NT

44.3

93.4

32.1

NT

27.8

7.9

24.1

NT

42.7

4.4

NA

NT

22.8

NT

O 60

4-t-Bu

N

N H

61

4-t-Bu

N

N H

62

4-t-Bu

N

NH2

63

4-t-Bu

N

NH2

64

4-F

65

4-F

66

4-F

67

4-F

O

O O

N N

O N

O N

O

N 68

4-CF3

69

4-CF3

70

4-CF3

71

4-CF3

N N

O N

O N

O

N 72

3-CF3

73

3-CF3

74

3-CF3

N N

O N

O 75

3-CF3

N

O

N Abbreviations. NA: not active, NT: not toxic, ND: not determined. * All measurements were performed in triplicate. FRET signals were collected in the presence of 40 nM of Ab42 and 4 lM of each compound after incubating for 1 h with RAGE–Cy3.

Table 4 Inhibition of Ab induced cytotoxicity* Compound

Inhibition of Ab induced cytotoxicity (%)

29 47 48 67 75

50.6 54.4 65 62.3 56.2

* All measurements were performed in triplicate. The cell viability was measured after incubating HT22 cells with 2 lM of aggregated Ab and 10 lM of each compound for 18 h.

suggesting that this compound blocked the transportation of plasma Ab1–40 into the brain. Compound 48 also appeared to reduce levels of Ab1–42, however, observed differences were within the error range (Fig. 2b). Additionally, we quantified the amount of amyloid plaque in the brains of transgenic mice by staining with Congo red. As shown in Figure 2c, compound 48 appeared to reduce amyloid deposits compared to a vehicle control, however, the average number of plaques was within the error range. We speculated that although compound 48 adequately blocked the transport of peripheral Ab1–40, which consist of a large fraction of circulating Ab peptides, it did not seem to affect the RAGE–Ab interactions inside the brain significantly.

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(a)

(c)

(b)

β

β

**

Figure 2. The brain levels of (a) human Ab1–40, (b) Ab1–42, and (c) amyloid plaques in APPsw/PS1 mice. The concentrations of Ab and the number of amyloid plaques per section are expressed as the means ± standard deviation. (Vehicle, n = 4; compound 48, n = 5 at 50 mg/kg).

3. Conclusion In this work, we have developed a series of 6-phenoxy-2phenylbenzoxazole derivatives as a potential AD therapeutics. We evaluated their ability to inhibit the RAGE–Ab interactions in vitro, and assessed their protective effects against Ab induced cytotoxicity. Structure–activity relationship analysis revealed that compounds with a (4-(alkoxycarbonyl)piperazin-1-yl)alkyloxy side chain inhibited the RAGE–Ab interactions significantly, and retained cellular viability against Ab induced toxicity. Based on these findings, we selected compound 48 as a promising candidate, and tested its efficacy in a transgenic mice model of AD. The results from in vivo study suggested that compound 48 appeared to block Ab transport across the BBB, resulting in the reduced levels of Ab1– 40 in the brain. Further structural optimization of the benzoxazole series is currently underway, and we believe that this study can provide valuable insights into RAGE as a promising target for disease-modifying AD therapy. 4. Experimental section 4.1. Chemistry All chemical reagents were commercially available. Flash column chromatography was performed using silica gel 60 (230– 400 mesh, Merck) with the indicated solvents. 1H NMR spectra were recorded on JEOL JNM-LA 300 and Bruker Avance 400 MHz FT-NMR spectrometers. Chemical shifts are reported in ppm units with Me4Si as a reference standard. Mass spectra were recorded on a VG Trio-2 GC–MS and a 6460 Triple Quad LC/MS. 4.1.1. General procedure for preparation of compounds 2a–2e A mixture of 2-benzyloxy-4-fluoro-1-nitro-benzene (1.0 equiv), alcohol (1.1 equiv) and potassium carbonate (1.5 equiv) in DMF was stirred for 14 h at 140 °C. The reaction mixture was evaporated under reduced pressure. The residue was dissolved in EtOAc, and washed with water and brine. The organic layer was dried over MgSO4, filtered and concentrated in vacuo. The resulting crude residue was purified by recrystallization in DCM/isopropyl alcohol system to yield the corresponding biaryl ether fragments 2a–2e. 4.1.1.1. 2-Benzyloxy-4-(4-chlorophenoxy)-1-nitro-benzene (2a). Compound 2a was synthesized with 4-chlorophenol by following Section 4.1.1. Yield 85%; 1H NMR (300 MHz, CDCl3) d 7.95 (d, 1H, J = 9.3 Hz), 7.41–7.31 (m, 7H), 6.95 (m, 2H), 6.62 (d, 1H, J = 2.7 Hz), 6.51 (dd, 1H, J = 9.0, 2.4 Hz), 5.16 (s, 2H).

4.1.1.2. 2-(Benzyloxy)-4-(4-tert-butylphenoxy)-1-nitrobenzene (2b). Compound 2b was synthesized with 4-tert-phenol by following the Section 4.1.1. Yield 58%; 1H NMR (300 MHz, CDCl3) d 7.95 (d, 1H, J = 9.2 Hz), 7.34–7.42 (m, 7H), 6.94 (d, 2H, J = 8.8 Hz), 6.65 (d, 2H, J = 2.4 Hz), 6.52–6.48 (m, 1H), 5.16 (s, 2H), 1.36 (s, 9H). 4.1.1.3. 2-Benzyloxy-4-(4-fluorophenoxy)-1-nitro-benzene (2c). Compound 2c was synthesized with 4-fluorophenol by following the Section 4.1.1. Yield 94%; 1H NMR (300 MHz, CDCl3) d 7.95 (d, 1H, J = 9.0 Hz), 7.41–7.32 (m, 5H), 7.12–7.05 (m, 2H), 7.02–6.96 (m, 2H), 6.60 (d, 1H, J = 2.4 Hz), 6.48 (dd, 1H, J = 9.0, 2.7 Hz), 5.16 (s, 2H). 4.1.1.4. 2-Benzyloxy-4-(4-trifluoromethylphenoxy)-1-nitro-benzene (2d). Compound 2d was synthesized with 4-(trifluoromethyl)phenol by following the Section 4.1.1. Yield 55%; 1H NMR (300 MHz, CDCl3) d 7.97 (d, 1H, J = 9.0 Hz), 7.64 (d, 2H, J = 8.7 Hz), 7.39–7.33 (m, 5H), 6.68 (d, 1H, J = 2.4 Hz), 6.59 (dd, 1H, J = 9.0, 2.4 Hz), 5.18 (s, 2H). 4.1.1.5. 2-Benzyloxy-4-(3-trifluoromethylphenoxy)-1-nitrobenzene (2e). Compound 2e was synthesized with 3-(trifluoromethyl)phenol by following the Section 4.1.1. Yield 81%; 1H NMR (300 MHz, CDCl3) d 7.97 (d, 1H, J = 9.0 Hz), 7.55–7.51 (m, 2H), 7.42–7.31 (m, 6H), 7.21–7.18 (m, 1H), 6.68 (d, 1H, J = 2.4 Hz), 6.54 (dd, 1H, J = 9.0, 2.4 Hz), 5.18 (s, 2H). 4.1.2. General procedure for preparation of compounds 3a–3e To a solution of compound 2 (1.0 equiv) in DCM was added trifluoroacetic acid (excess), and then the mixture was stirred for 5 h at room temperature. The reaction mixture was evaporated under reduced pressure. The residue dissolved in EtOAc was washed with water and brine. The organic layer was dried over MgSO4, filtered and concentrated in vacuo. The resulting crude residue was purified by recrystallization with DCM/isopropyl alcohol system. 4.1.2.1. 5-(4-Chlorophenoxy)-2-nitro-phenol (3a). Yield 78%; H NMR (300 MHz, CDCl3) d 10.88 (s, 1H), 8.09 (d, 2H, J = 9.6 Hz), 7.41 (d, 2H, J = 8.7 Hz), 7.05 (d, 1H, J = 9.0 Hz), 6.59 (dd, 1H, J = 9.3, 2.4 Hz), 6.51 (d, 1H, J = 2.4 Hz).

1

4.1.2.2. 5-(4-Fluorophenoxy)-2-nitro-phenol (3c). Yield 86%; 1H NMR (300 MHz, CDCl3) d 10.90 (s, 1H), 8.09 (d, 1H, J = 9.6 Hz), 7.16– 7.05 (m, 4H), 7.58 (dd, 1H, J = 9.6, 2.7 Hz), 6.48 (d, 1H, J = 2.7 Hz). 4.1.2.3. 5-(4-Trifluoromethyl-phenoxy)-2-nitro-phenol (3d). Yield 74%; 1H NMR (300 MHz, CDCl3) d 10.88 (s, 1H), 8.13 (d, 1H,

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J = 9.0 Hz), 7.71 (d, 2H, J = 8.7 Hz), 7.21 (d, 2H, J = 8.7 Hz), 6.65–6.58 (m, 2H).

7.27–7.19 (m, 3H), 7.09–7.06 (m, 1H), 7.99 (d, 2H, J = 8.6 Hz), 2.35 (s, 3H), 1.34 (s, 9H).

4.1.2.4. 5-(3-Trifluoromethyl-phenoxy)-2-nitro-phenol (3e). Yield 99%; 1H NMR (300 MHz, CDCl3) d 7.38–7.27 (m, 2H), 7.16 (s, 1H), 7.05 (d, 1H, J = 7.9 Hz), 6.73 (d, 1H, J = 8.1 Hz), 6.40–6.35 (m, 2H); MS (FAB) m/z 299 [M+H]+.

4.1.4.3. Acetic acid 4-[6-(4-fluorophenoxy)-benzoxazol-2-yl]phenyl ester (5c). Yield 71%; 1H NMR (300 MHz, CDCl3) d 8.23 (d, 2H, J = 9.0 Hz), 7.69 (d, 1H, J = 8.7 Hz), 7.26 (d, 2H, J = 8.7 Hz), 7.16 (d, 1H, J = 2.1 Hz), 7.07–7.03 (m, 5H), 2.34 (s, 3H).

4.1.3. General procedure for preparation of compounds 4a–4e To a stirred solution of compound 3 in 2-propanol (1.0 equiv) was added tin(II)chloride (3.0 equiv) and concd HCl (cat.) at room temperature. The mixture was refluxed for 2 h, and then concentrated under reduced pressure. The residue was diluted with EtOAc and washed with saturated aqueous sodium bicarbonate solution, and brine. The organic layer was dried over MgSO4, filtered and concentrated in vacuo. The residue was purified by silica gel chromatography (EtOAc/n-Hex) to afford the corresponding compounds.

4.1.4.4. Acetic acid 4-[6-(4-trifluoromethyl-phenoxy)-benzoxazol-2-yl]-phenyl ester (5d). Yield 75%; 1H NMR (300 MHz, CDCl3) d 8.25 (d, 2H, J = 9.0 Hz), 7.75 (d, 1H, J = 8.7 Hz), 7.61 (d, 2H, J = 8.4 Hz), 7.28 (m, 3H), 7.12–7.08 (m, 2H), 2.35 (s, 3H).

4.1.3.1. 2-Amino-5-(4-chlorophenoxy)-phenol (4a). Yield 53%; 1 H NMR (300 MHz, CDCl3) d 7.23 (d, 2H, J = 9.0 Hz), 6.87 (d, 2H, J = 9.0 Hz), 6.76 (m, 1H), 6.46 (m, 2H). 4.1.3.2. 2-Amino-5-(4-tert-butylphenoxy)phenol (4b). To a stirred solution of compound 2b (1.0 g, 2.6 mmol) in DCM/THF (3:1) was added palladium on carbon (55% in H2O) at room temperature. The reaction mixture was stirred under H2 gas for 15 h. The reaction mixture was filtered through a pad of celite. The filtrate was evaporated under reduced pressure, and the resulting crude residue was purified by silica gel chromatography to afford the product. Yield 75%; 1H NMR (300 MHz, CDCl3) d 7.28 (d, 2H, J = 8.7 Hz), 6.86 (d, 2H, J = 8.7 Hz), 6.74 (d, 2H, J = 8.1 Hz), 1.28 (s, 9H). 4.1.3.3. 2-Amino-5-(4-fluorophenoxy)-phenol (4c). Yield 59%; 1H NMR (300 MHz, CDCl3) d 7.02–6.88 (m, 4H), 6.74 (d, 1H, J = 8.4 Hz), 6.47–6.38 (m, 2H). 4.1.3.4. 2-Amino-5-(4-trifluoromethyl-phenoxy)-phenol (4d). Yield 44%; 1H NMR (300 MHz, CDCl3) d 7.53 (d, 2H, J = 8.4 Hz), 6.98 (d, 2H, J = 8.4 Hz), 6.78 (d, 1H, J = 9.0 Hz), 6.50 (m, 2H). 4.1.3.5. 2-Amino-5-(3-trifluoromethyl-phenoxy)-phenol (4e). Yield 99%; 1H NMR (300 MHz, CDCl3) d 7.36–7.24 (m, 2H), 7.14 (s, 1H), 7.04 (d, 1H, J = 7.9 Hz), 6.69 (d, 1H, J = 8.1 Hz), 6.42–6.39 (m, 2H), 4.97 (br s, NH2). 4.1.4. General procedure for preparation of compounds 5a–5e A mixture of compound 4 (1.0 equiv) and 4-formylphenyl acetate (1.0 equiv) in methanol was heated to 45 °C for 2 h. The mixture was evaporated under reduced pressure. The residue was dissolved in methylene chloride and then 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ, 1.1 equiv) was added at room temperature. After 30 min, the mixture was diluted with methylenechloride, washed with saturated NaHCO3 solution, and brine. The organic layer was dried over MgSO4, filtered and concentrated in vacuo. The residue was purified by silica gel chromatography (EtOAc/n-Hex) to afford the corresponding products. 4.1.4.1. Acetic acid 4-[6-(4-chlorophenoxy)-benzoxazol-2-yl]phenyl ester (5a). Yield 59%; 1H NMR (300 MHz, CDCl3) d 8.23 (d, 2H, J = 9.0 Hz), 7.71 (d, 1H, J = 8.7 Hz), 7.35–7.24 (m, 4H), 7.21 (d, 1H, J = 2.4 Hz), 7.08–6.96 (m, 3H), 2.35 (s, 3H). 4.1.4.2. 4-(6-(4-tert-Butylphenoxy)benzo[d]oxazol-2-yl)phenyl acetate (5b). Yield 78%; 1H NMR (300 MHz, CDCl3) d 8.28 (d, 2H, J = 8.6 Hz), 7.68 (d, 1H, J = 8.6 Hz), 7.38 (d, 2H, J = 8.8 Hz),

4.1.4.5. Acetic acid 4-[6-(3-trifluoromethyl-phenoxy)-benzoxazol-2-yl]-phenyl ester (5e). Yield 43%; 1H NMR (300 MHz, CDCl3) d 8.22 (d, 2H, J = 8.6 Hz), 7.72 (d, 1H, J = 8.6 Hz), 7.48–7.35 (m, 2H), 7.29–7.18 (m, 5H), 7.07 (dd, 1H, J = 8.6, 2.2 Hz), 2.33 (s, 3H). 4.1.5. General procedure for preparation of compounds 6a–6e To a stirred solution of compound 5 (1.0 equiv) in MeOH was added 2 N NaOH (excess) at room temperature. After the mixture was stirred for 6 h, MeOH was removed under reduced pressure. The mixture was acidified with 1 N HCl and extracted with EtOAc. The organic layer was washed with brine, and dried over MgSO4. The final filtrate was concentrated in vacuo. The resulting residue was purified by silica gel chromatography (EtOAc/n-Hex) to afford the corresponding products. 4.1.5.1. 4-[6-(4-Chlorophenoxy)-benzoxazol-2-yl]-phenol (6a). Yield 99%; 1H NMR (300 MHz, CDCl3) d 8.10 (d, 2H, J = 8.7 Hz), 7.67 (d, 1H, J = 8.7 Hz), 7.32 (m, 2H), 7.20 (d, 1H, J = 2.1 Hz), 7.06–6.96 (m, 3H), 6.20 (br s, 1H). 4.1.5.2. 4-(6-(4-tert-Butylphenoxy)benzo[d]oxazol-2-yl)phenol (6b). Yield 88%; 1H NMR (300 MHz, CDCl3) d 8.10 (d, 2H, J = 8.8 Hz), 7.65 (d, 1H, J = 8.4 Hz), 7.37 (d, 2H, J = 8.8 Hz), 7.20 (d, 1H, J = 2.2 Hz), 7.07–7.03 (m, 1H), 7.00–6.94 (m, 4H), 5.56 (s, 1H), 1.33 (s, 9H). 4.1.5.3. 4-[6-(4-Fluorophenoxy)-benzoxazol-2-yl]-phenol (6c). Yield 99%; 1H NMR (300 MHz, DMSO) d 10.35 (br s, 1H), 8.00 (d, 2H, J = 8.7 Hz), 7.42 (d, 1H, J = 2.1 Hz), 7.24 (d, 2H, J = 8.7 Hz), 7.13–7.03 (m, 3H), 7.97 (d, 2H, J = 8.7 Hz). 4.1.5.4. 4-[6-(4-Trifluoromethyl-phenoxy)-benzoxazol-2-yl]phenol (6d). Yield 95%; 1H NMR (300 MHz, DMSO) d 10.37 (s, 1H), 8.02 (d, 2H, J = 8.7 Hz), 7.76 (d, 2H, J = 8.7 Hz), 7.64 (d, 1H, J = 2.1 Hz), 7.17 (m, 3H), 6.98–6.91 (m, 3H). 4.1.5.5. 4-[6-(3-Trifluoromethyl-phenoxy)-benzoxazol-2-yl]phenol (6e). Yield 97%; 1H NMR (300 MHz, CD3OD) d 8.22–7.98 (m, 2H), 7.62 (d, 1H, J = 8.6 Hz), 7.55–7.49 (m, 1H), 7.39 (d, 1H, J = 7.7 Hz), 7.28–7.21 (m, 3H), 7.04 (dd, 1H, J = 8.6, 2.2 Hz), 6.95– 6.91 (m, 2H). 4.1.6. General procedure for preparation of compounds 7 and 8 To a stirred solution of compound 6a, Boc-4-hydroxypiperidine (or N-Boc-4-piperidine–methanol or other alcohol) (1.5 equiv) and triphenylphosphine (1.5 equiv) in THF was added DIAD (1.5 equiv) at 0 °C. After the mixture was stirred for 1 h at 0 °C and another 48 h at room temperature, the reaction mixture was diluted with water. The resulting mixture was extracted with EtOAc, and washed with water and brine. The organic layer was dried over sodium sulfate, filtered and concentrated in vacuo. The crude residue was purified by silica gel chromatography to afford the corresponding compounds.

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4.1.6.1. 2-(4-(1-Methylpiperidin-4-yloxy)phenyl)-6-(4-chlorophenoxy)-benzo[d]oxazole (7). Compound 7 was synthesized with Boc-4-hydroxypiperidine by following the Section 4.1.6. Yield 78%; 1H NMR (300 MHz, CDCl3) d 8.13 (d, 2H, J = 8.7 Hz), 7.67 (d, 1H, J = 8.7 Hz), 7.31 (d, 2H, J = 8.7 Hz), 7.19 (d, 1H, J = 2.4 Hz), 7.05–6.96 (m, 5H), 4.59 (m, 1H), 3.70 (m, 2H), 3.38 (m, 5H), 1.95 (m, 2H), 1.82 (m, 2H), 1.47 (s, 9H); MS (FAB) m/z 521 [M+H]+; mp 140 °C. 4.1.6.2. 4-{4-[6-(4-Chlorophenoxy)-benzoxazol-2-yl]-phenoxymethyl}-piperidine-1-carboxylic acid tert-butyl ester (8). Compound 8 was synthesized with N-Boc-4-piperidine methanol by following the Section 4.1.6. Yield 40%; 1H NMR (300 MHz, CDCl3) d 8.19 (d, 2H, J = 9.0 Hz), 7.66 (d, 1H, J = 8.6 Hz), 7.64 (d, 2H, J = 9.0 Hz), 7.19 (d, 1H, J = 2.2 Hz), 7.05–6.95 (m, 5H), 4.16 (br, 2H), 3.88 (d, 2H, J = 6.4 Hz), 2.76 (t, 2H, J = 13.1 Hz), 2.00 (br, 1H), 1.84 (d, 2H, J = 13.1 Hz), 1.47 (s, 9H), 1.35–1.27 (m, 2H); MS (FAB) m/z 535 [M+H]+; mp 210 °C. 4.1.7. General procedure for preparation of compounds 9 and 10 To a stirred solution of compounds 7 or 8 in DCM was added trifluoroacetic acid (20 equiv) at room temperature. After the mixture was stirred for 5 h, the reaction mixture was evaporated under reduced pressure. The residue dissolved in DCM was washed with NaHCO3 and brine. The organic layer was dried over MgSO4 and concentrated in vacuo. The resulting crude residue was purified by recrystallization in DCM/hexane system. 4.1.7.1. 6-(4-Chlorophenoxy)-2-(4-(piperidin-4-yloxy)phenyl)benzo[d]oxazole (9). Yield 79%; 1H NMR (400 MHz, CDCl3) d 8.11 (d, 2H, J = 8.8 Hz), 7.64 (d, 1H, J = 8.4 Hz), 7.29 (d, 2H, J = 8.4 Hz), 7.17 (d, 1H, J = 2.0 Hz), 7.02–6.94 (m, 5H), 4.48 (m, 1H), 3.15 (m, 2H), 2.77 (m, 5H), 2.04 (m, 2H), 1.72 (m, 2H); MS (FAB) m/z 421 [M+H]+; mp 117 °C. 4.1.7.2. 6-(4-Chlorophenoxy)-2-[4-(piperidin-4-ylmethoxy)phenyl]-benzoxazole (10). Yield 91%; 1H NMR (300 MHz, CDCl3) d 8.13 (d, 2H, J = 9.1 Hz), 7.66 (d, 1H, J = 8.6 Hz), 7.30 (d, 2H, J = 9.0 Hz), 7.19 (d, 1H, J = 2.4 Hz), 7.05–6.94 (m, 5H), 3.88 (d, 2H, J = 6.2 Hz), 3.49 (s, 1H), 3.21–3.17 (br, 2H), 2.73–2.65 (m, 2H), 1.98–1.76 (m, 3H), 1.43–1.34 (m, 2H); MS (FAB) m/z 435 [M+H]+; mp 198 °C. 4.1.8. 2-(4-(1-Methylpiperidin-4-yloxy)phenyl)-6-(4-chlorophenoxy)-benzo[d]oxazole (11) This compound was prepared with 4-hydroxy-1-methylpiperidine by following the general procedure described for compounds 7 and 8. Yield 25%; 1H NMR (300 MHz, CDCl3) d 8.13 (d, 2H, J = 9.0 Hz), 7.67 (d, 1H, J = 8.7 Hz), 7.31 (d, 2H, J = 9.0 Hz), 7.19 (d, 1H, J = 2.1 Hz), 7.05–6.94 (m, 5H), 4.45 (m, 1H), 2.73 (m, 2H), 2.34 (m, 5H), 2.07 (m, 2H), 1.91 (m, 2H); MS (FAB) m/z 435 [M+H]+; mp 115 °C. 4.1.9. 2-(4-(1-Ethylpiperidin-4-yloxy)phenyl)-6-(4-chlorophenoxy)-benzo[d]oxazole (12) To a stirred solution of compound 17 (0.037 g, 0.080 mmol) in THF (20 mL) was added LAH (1 M sol. in THF) (0.16 mL, 0.16 mmol) at 0 °C. The reaction mixture was stirred for 2 h at room temperature, and then quenched with water and saturated NaHCO3 solution. The resulting mixture was dried over sodium sulfate, filtered and concentrated in vacuo. The residue was purified by silica gel chromatography to afford the product. Yield 14%; 1H NMR (300 MHz, CDCl3) d 8.13 (d, 2H, J = 9.0 Hz), 7.67 (d, 1H, J = 8.7 Hz), 7.31 (d, 2H, J = 9.0 Hz), 7.19 (d, 1H, J = 2.4 Hz), 7.05–6.95 (m, 5H), 4.48 (m, 1H), 2.80 (m, 2H), 2.50 (m, 4H), 2.11 (m, 2H), 1.94 (m, 2H), 1.15 (d, 3H, J = 7.2 Hz); MS (FAB) m/z 449 [M+H]+; mp 100 °C.

4.1.10. 2-(4-(1-Isopropylpiperidin-4-yloxy)phenyl)-6-(4-chlorophenoxy)benzo[d]oxazole (13) A mixture of compound 9 (0.040 g, 0.095 mmol), 2-iodo-propane (0.010 mL, 0.095 mmol) and potassium carbonate (0.026 g, 0.190 mmol) in DMF was stirred overnight at room temperature. The reaction mixture was evaporated under reduced pressure. The residue dissolved in DCM was washed with water, and brine. The organic layer was dried over MgSO4 sulfate and concentrated in vacuo. The resulting crude residue was chromatographed on a silica gel to give the product. Yield 34%; 1H NMR (300 MHz, CDCl3) d 8.13 (d, 2H, J = 8.7 Hz), 7.67 (d, 1H, J = 8.7 Hz), 7.31 (d, 2H, J = 9.0 Hz), 7.19 (d, 1H, J = 2.4 Hz), 7.05–6.94 (m, 5H), 4.47 (m, 1H), 2.84 (m, 3H), 2.53 (m, 2H), 2.14 (m, 2H), 1.92 (m, 2H), 1.12 (d, 6H, J = 6.6 Hz); MS (FAB) m/z 463 [M+H]+; mp 104 °C. 4.1.11. 2-(4-(1-Phenylpiperidin-4-yloxy)phenyl)-6-(4-chlorophenoxy)benzo[d]oxazole (14) To a solution of compound 9 (0.050 g, 0.12 mmol), bromobenzene (0.015 mL, 0.14 mmol), 2-(di-t-butylphosphino)biphenyl (0.007 g, 0.024 mmol) and Pd2(dba)3 (0.003 g, 0.012 mmol) in toluene was added sodium tert-butoxide (0.014 g, 0.14 mmol). After the mixture was stirred at 80 °C for 8 h, the mixture was filtered and concentrated. The resulting residue was diluted in EtOAc and washed with NaHCO3 solution and brine. The organic layer was dried and concentrated. The crude residue was chromatographed on a silica gel to give the product. Yield 47%; 1H NMR (300 MHz, CDCl3) d 8.15 (d, 2H, J = 8.7 Hz), 7.67 (d, 1H, J = 8.7 Hz), 7.33–7.25 (m, 4H), 7.19 (d, 1H, J = 2.1 Hz), 7.06–6.96 (m, 5H), 6.87 (t, 1H, J = 7.2 Hz), 4.59 (m, 1H), 3.53 (m, 2H), 3.15 (m, 2H), 2.15 (m, 2H), 2.00 (m, 2H); MS (FAB) m/z 497 [M+H]+; mp 147 °C. 4.1.12. 2-(4-(1-(Pyrimidin-2-yl)piperidin-4-yloxy)phenyl)-6-(4chlorophenoxy)benzo[d]oxazole (15) To a suspension of compound 9 (0.050 g, 0.12 mmol) and potassium carbonate (0.033 g, 0.24 mmol) in DMF was added 2chloropyrimidine (0.016 g, 0.14 mmol). The mixture was refluxed overnight. The reaction mixture was evaporated under reduced pressure. The residue was dissolved in EtOAc, and then washed with water, and brine. The organic layer was dried over MgSO4 and concentrated in vacuo. The residue was purified by silica gel chromatography to afford the product. Yield 45%; 1H NMR (300 MHz, CDCl3) d 8.32 (d, 2H, J = 4.8 Hz), 8.15 (d, 2H, J = 9.0 Hz), 7.67 (d, 1H, J = 9.4 Hz), 7.31 (d, 2H, J = 3.0 Hz), 7.20 (d, 1H, J = 2.1 Hz), 7.07–6.96 (m, 5H), 6.49 (t, 1H, J = 4.8 Hz), 4.69 (m, 1H), 3.18 (m, 2H), 3.75 (m, 2H), 2.05 (m, 2H), 1.90 (m, 2H); MS (FAB) m/z 499 [M+H]+; mp 175 °C. 4.1.13. 2-(4-(1-Benzylpiperidin-4-yloxy)phenyl)-6-(4-chlorophenoxy)benzo[d]oxazole (16) To a suspension of compound 9 (0.035 g, 0.083 mmol), potassium carbonate (0.023 g, 0.17 mmol) in acetonitrile was added benzylbromide (0.011 mL, 0.091 mmol). The mixture was refluxed overnight. The reaction mixture was evaporated under reduced pressure. The residue was dissolved in EtOAc and then washed with water, and brine. The organic layer was dried over MgSO4 and concentrated in vacuo. The residue was purified by silica gel chromatography to afford the product. Yield 59%; 1H NMR (300 MHz, CDCl3) d 8.12 (d, 2H, J = 9.0 Hz), 7.66 (d, 1H, J = 8.7 Hz), 7.34–7.27 (m, 6H), 7.19 (d, 1H, J = 2.1 Hz), 7.05–6.95 (m, 6H), 4.43 (m, 1H), 3.55 (s, 2H), 2.76 (m, 2H), 2.35 (m, 2H), 2.02 (m, 2H), 1.87 (m, 2H); MS (FAB) m/z 511 [M+H]+; mp 140 °C. 4.1.14. 1-(4-(4-(6-(4-Chlorophenoxy)benzo[d]oxazol-2-yl)phenoxy)piperidin-1-yl)ethanone (17) To a stirred mixture of compound 9 (0.050 g, 0.12 mmol) and acetyl chloride (0.010 mL, 0.14 mmol) in DCM was added TEA

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(0.020 mL, 0.14 mmol) at room temperature for 2 h. The reaction mixture was evaporated under reduced pressure. The residue dissolved in EtOAc was washed with water, and brine. The organic layer was dried over MgSO4 and concentrated in vacuo. The resulting residue was chromatographed on a silica gel to give the product. Yield 81%; 1H NMR (300 MHz, CDCl3) d 8.15 (d, 2H, J = 9.0 Hz), 7.67 (d, 1H, J = 8.4 Hz), 7.31 (d, 2H, J = 9.0 Hz), 7.19 (d, 1H, J = 2.4 Hz), 7.06–6.96 (m, 5H), 4.67 (m, 1H), 3.78–3.67 (m, 3H), 3.46 (m, 1H), 2.14 (s, 3H), 1.99–1.86 (m, 4H); MS (FAB) m/z 463 [M+H]+; mp 156 °C. 4.1.15. 6-(4-Chlorophenoxy)-2-[4-(1-ethyl-piperidin-4-ylmethoxy)phenyl]-benzoxazole (18) To a stirred solution of LAH (0.004 g, 0.092 mmol) in THF was added compound 23 (0.020 g, 0.046 mmol) at 0 °C. The reaction mixture was stirred for 2 h at room temperature, and then quenched with water and saturated NaHCO3 solution. The resulting mixture was dried over sodium sulfate, filtered and concentrated in vacuo. The residue was purified by silica gel chromatography to afford the product. Yield 37%; 1H NMR (300 MHz, CDCl3) d 8.12 (d, 2H, J = 9.0 Hz), 7.64 (d, 1H, J = 8.4 Hz), 7.28 (d, 2H, J = 9.0 Hz), 7.17 (d, 1H, J = 1.8 Hz), 7.03–6.93 (m, 5H), 4.68 (m, 1H), 3.93–3.85 (m, 2H), 3.13–3.04 (m, 1H), 2.63–2.55 (m, 1H), 2.09 (s, 3H), 2.02–1.83 (m, 2H), 1.35–1.23 (m, 6H); MS (FAB) m/z 463 [M+H]+; mp 142 °C. 4.1.16. 6-(4-Chlorophenoxy)-2-[4-(1-isopropyl-piperidin-4-ylmethoxy)-phenyl]-benzoxazole (19) A mixture of compound 10 (0.025 g, 0.057 mmol), 2-iodo-propane (0.010 mL, 0.097 mmol) and potassium carbonate (0.0080 g, 0.057 mmol) in DMF was stirred for 14 h at room temperature. The reaction mixture was evaporated under reduced pressure. The residue dissolved in DCM was washed with water, and brine. The organic layer was dried over MgSO4 and concentrated in vacuo. The resulting residue was chromatographed on a silica gel to give the product. Yield 40%; 1H NMR (300 MHz, CDCl3) d 8.13 (d, 2H, J = 9.0 Hz), 7.66 (d, 1H, J = 8.6 Hz), 7.30 (d, 2H, J = 8.7 Hz), 7.19 (d, 1H, J = 2.4 Hz), 7.05–6.95 (m, 5H), 3.92 (br, 3H), 3.21 (br, 3H), 2.50 (br, 2H), d 2.02–1.25 (m, 9H), 0.88–0.85 (m, 1H); MS (FAB) m/z 477 [M+H]+; mp 179 °C. 4.1.17. 6-(4-Chlorophenoxy)-2-[4-(1-phenyl-piperidin-4-ylmethoxy)-phenyl]-benzoxazole (20) To a solution of compound 10 (0.025 g, 0.057 mmol), bromobenzene (0.010 mL, 0.068 mmol), 2-(di-t-butylphosphino)biphenyl (0.0030 g, 0.011 mmol) and Pd2(dba)3 (0.0060 g, 0.0057 mmol), in toluene was added sodium tert-butoxide (0.0060 g, 0.069 mmol) and the mixture was stirred at 80 °C for 2 h. The reaction mixture was filtered and concentrated. The resulting residue was diluted in EtOAc and washed with NaHCO3 solution and brine. The organic layer was dried and concentrated. The resulting crude residue was chromatographed on a silica gel to give the product. Yield 34%; 1H NMR (300 MHz, CDCl3) d 8.14 (d, 2H, J = 8.8 Hz), 7.66 (d, 1H, J = 8.6 Hz), 7.32–7.24 (m, 3H), 7.19 (d, 1H, J = 2.2 Hz), 7.05–6.95 (m, 5H), 6.85 (t, 1H, J = 7.3 Hz), 3.94 (d, 2H, J = 6.1 Hz), 3.75 (d, 2H, J = 12.4 Hz), 2.81–2.74 (m, 2H), 2.00–1.97 (m, 3H), 1.58–1.54 (m, 2H); MS (FAB) m/z 511 [M+H]+; mp 165 °C. 4.1.18. 6-(4-Chlorophenoxy)-2-[4-(1-pyrimidin-2-yl-piperidin4-ylmethoxy)-phenyl]benzoxazole (21) To a suspension of compound 10 (0.025 g, 0.057 mmol) and potassium carbonate (0.016 g, 0.11 mmol) in DMF was added 2chloropyrimidine (0.008 g, 0.069 mmol). The mixture was refluxed overnight. The reaction mixture was evaporated under reduced pressure. The residue was dissolved in EtOAc, and then washed

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with water and brine. The organic layer was dried over MgSO4 and concentrated in vacuo. The crude residue was purified by silica gel chromatography to afford the product. Yield 48%; 1H NMR (300 MHz, CDCl3) d 8.31 (d, 2H, J = 4.7 Hz), 8.14 (d, 2H, J = 8.8 Hz), 7.66 (d, 1H, J = 8.6 Hz), 7.30 (d, 2H, J = 9.0 Hz), 7.19 (d, 1H, J = 2.2 Hz), 7.05–6.95 (m, 5H), 6.46 (t, 1H, J = 4.8 Hz), 4.84 (d, 2H, J = 13.2 Hz), 3.91 (d, 2H, J = 6.4 Hz), 2.98–2.89 (m, 2H), 2.17–1.94 (m, 3H), 1.43–1.35 (m, 2H); MS (FAB) m/z 513 [M+H]+; mp 176 °C. 4.1.19. 2-[4-(1-Benzyl-piperidin-4-ylmethoxy)-phenyl]-6-(4chlorophenoxy)-benzoxazole (22) To suspension of compound 10 (0.025 g, 0.057 mmol), potassium carbonate (0.016 g, 0.11 mmol) in acetonitrile was added benzylbromide (0.010 mL, 0.063 mmol). The mixture was refluxed overnight. The reaction mixture was evaporated under reduced pressure. The residue was dissolved in EtOAc and then washed with water and brine. The organic layer was dried over MgSO4 and concentrated in vacuo. The crude residue was purified by silica gel chromatography to afford the product. Yield 76%; 1H NMR (300 MHz, CDCl3) d 8.13 (d, 2H, J = 8.8 Hz), 7.66 (d, 1H, J = 8.6 Hz), 7.51–7.40 (m, 5H), 7.31 (d, 2H, J = 9.0 Hz), 7.19 (d, 1H, J = 2.6 Hz), 7.05–6.94 (m, 5H), 5.43 (s, 2H), 4.95 (s, 2H), 4.09–4.03 (m, 4H), 3.25–3.17 (m, 2H), 2.37–2.04 (m, 3H MS (FAB) m/z 525 [M+H]+; mp 103 °C. 4.1.20. 1-(4-{4-[6-(4-Chlorophenoxy)-benzoxazol-2-yl]-phenoxymethyl}-piperidin-1-yl)-ethanone (23) To a stirred mixture of compound 10 (0.050 g, 0.11 mmol) and acetyl chloride (0.010 mL, 0.14 mmol) in DCM was added TEA (0.02 mL, 0.14 mmol) at room temperature for 1 h. The reaction mixture was evaporated under reduced pressure. The residue dissolved in EtOAc was washed with water, and brine. The organic layer was dried over MgSO4 and concentrated in vacuo. The resulting crude residue was chromatographed on a silica gel to give the product. Yield 72%; 1H NMR (300 MHz, CDCl3) d 8.12 (d, 2H, J = 9.0 Hz), 7.64 (d, 1H, J = 8.4 Hz), 7.28 (d, 2H, J = 9.0 Hz), 7.17 (d, 1H, J = 1.8 Hz), 7.03–6.93 (m, 5H), 4.68 (d, 1H, J = 13.2 Hz), 3.93–3.85 (m, 2H), 3.13–3.04 (m, 1H), 2.63–2.55 (m, 1H), 2.09 (s, 3H), 2.02–1.83 (m, 2H), 1.35–1.23 (m, 4H); MS (FAB) m/z 477 [M+H]+; mp 160 °C. 4.1.21. General procedure for preparation of compounds 24 and 25 To a stirred solution of compound 6 (1.0 equiv) in acetonitrile was added 1-bromo-2-chloroethane (or 1-bromo-3-chloro-propane) (2.0 equiv) and potassium carbonate (2.0 equiv) at room temperature. After the mixture was stirred overnight at 60 °C, the reaction mixture was evaporated under reduced pressure. The residue was dissolved in EtOAc, and then washed with water, and brine. The organic layer was dried over sodium sulfate and concentrated in vacuo. The crude residue was purified by silica gel chromatography to afford the corresponding products. 4.1.21.1. 2-[4-(2-Chloroethoxy)-phenyl]-6-(4-chloro-phenoxy)benzoxazole (24a). Yield 85%; 1H NMR (300 MHz, CDCl3) d 8.14 (d, 2H, J = 9.0 Hz), 7.68 (d, 1H, J = 8.7 Hz), 7.31 (d, 2H, J = 9.0), 7.20 (d, 1H, J = 2.1), 7.06–6.96 (m, 5H), 4.32 (t, 2H, J = 5.7 Hz), 3.86 (t, 2H, J = 5.7 Hz). 4.1.21.2. 6-(4-Chlorophenoxy)-2-[4-(3-chloro-propoxy)-phenyl]benzoxazole (25a). Yield 81%; 1H NMR (300 MHz, CDCl3) d 8.10–8.17 (m, 2H), 7.66 (d, 1H, J = 8.6 Hz), 7.28–7.33 (m, 2H), 7.20 (d, 1H, J = 2.2 Hz), 6.95–7.05 (m, 5H), 4.21 (t, 2H, J = 5.8 Hz), 3.77 (t, 2H, J = 6.2 Hz), 2.24–2.32 (m, 2H). 4.1.21.3. 6-(4-tert-Butylphenoxy)-2-(4-(3-chloropropoxy)phenyl)benzo[d]oxazole (25b). Yield 69%; 1H NMR (300 MHz, CDCl3) d

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8.14 (d, 2H, J = 9.0 Hz), 7.65 (d, 1H, J = 8.6 Hz), 7.37 (d, 1H, J = 8.8 Hz), 7.18 (d, 1H, J = 2.0 Hz), 7.04–6.96 (m, 5H), 4.21 (t, 2H, J = 5.9 Hz), 3.78 (t, 2H, J = 6.2 Hz), 2.35–2.22 (m, 2H), 1.33 (s, 9H). 4.1.21.4. 6-(4-Fluorophenoxy)-2-[4-(3-chloropropoxy)-phenyl]benzoxazole (25c). Yield 73%; 1H NMR (300 MHz, CDCl3) d 8.14 (d, 2H, J = 8.7 Hz), 7.66 (d, 1H, J = 8.7 Hz), 7.15 (d, 2H, J = 2.4 Hz), 7.06–7.00 (m, 7H), 4.21 (t, 2H, J = 6.3 Hz), 3.78 (t, 2H, J = 6.0 Hz), 2.28 (m, 2H). 4.1.21.5. 6-(4-Trifluoromethyl-phenoxy)-2-[4-(3-chloropropoxy)phenyl]-benzoxazole (25d). Yield 75%; 1H NMR (300 MHz, CDCl3) d 8.17 (d, 2H, J = 9.0 Hz), 7.72 (d, 1H, J = 8.7 Hz), 7.60 (d, 2H, J = 8.7 Hz), 7.26 (m, 1H), 7.09–7.00 (m, 2H). 4.1.21.6. 6-(3-Trifluoromethyl-phenoxy)-2-[4-(3-chloropropoxy)phenyl]-benzoxazole (25e). Yield 80%; 1H NMR (300 MHz, CDCl3) d 8.16 (d, 2H, J = 9.0 Hz), 7.71 (d, 1H, J = 8.6 Hz), 7.48–7.43 (m, 1H), 7.36 (d, 1H, J = 7.9 Hz), 7.27–7.18 (m, 3H), 7.08–7.02 (m, 3H), 4.21 (t, 2H, J = 5.9 Hz), 3.78 (t, 2H, J = 6.2 Hz), 2.32–2.24 (m, 2H). 4.1.22. General procedure for preparation of compounds 26–75 A mixture of compounds 24a (for compounds 26–30; 1.0 equiv) or 25a–25e (for compounds 31–75; 1.0 equiv), secondary amine (1.5 equiv), KI (2.0 equiv), and Na2CO3 (6.0 equiv) in n-BuOH was heated to 105 °C for 24 h. The mixtures was cooled to room temperature and evaporated under reduced pressure. The residue was dissolved in EtOAc and then washed with water, and brine. The organic layer was dried over sodium sulfate and concentrated in vacuum. The resulting residue was purified by silica gel chromatography to afford the corresponding products (18–99%). 4.1.22.1. (3-{4-[6-(4-Chlorophenoxy)-benzoxazol-2-yl]-phenoxy}ethyl)-diethylamine (26). Compound 26 was prepared with diethylamine by following the Section 4.1.22. Yield 49%; 1H NMR (300 MHz, CDCl3) d 8.14 (d, 2H, J = 9.0 Hz), 7.67 (d, 1H, J = 8.7 Hz), 7.31 (m, 2H), 7.19 (d, 1H, J = 2.4 Hz), 7.05–6.96 (m, 5H), 4.15 (t, 2H, J = 6.0 Hz), 2.94 (t, 2H, J = 6.2 Hz), 2.68 (d, 4H, J = 7.2 Hz), 1.10 (t, 3H, J = 7.2 Hz). MS (FAB) m/z 437 [M+H]+; mp 98 °C. 4.1.22.2. 6-(4-Chlorophenoxy)-2-[4-(2-piperidin-1-yl-ethoxy)phenyl]-benzoxazole (27). Compound 27 was prepared with piperidine by following the Section 4.1.22. Yield 58%; 1H NMR (300 MHz, CDCl3) d 8.14 (m, 2H), 7.67 (d, 1H, J = 8.7 Hz), 7.31 (m, 2H), 7.19 (d, 1H, J = 2.1 Hz), 7.05–6.96 (m, 5H), 4.24 (t, 2H, J = 5.9 Hz), 2.87 (t, 2H, J = 5.9 Hz), 2.60 (br s, 4H), 1.66 (m, 4H), 1.49 (m, 2H). MS (FAB) m/z 449 [M+H]+; mp 130 °C. 4.1.22.3. 6-(4-Chlorophenoxy)-2-[4-(3-morpholin-4-yl-ethoxy)phenyl]-benzoxazole (28). Compound 28 was prepared with morpholine by following the Section 4.1.22. Yield 47%; 1H NMR (300 MHz, CDCl3) d 8.14 (m, 2H), 7.67 (d, 1H, J = 8.7 Hz), 7.31 (m, 2H), 7.19 (d, 1H, J = 2.1 Hz), 7.05–6.96 (m, 5H), 4.20 (t, 2H, J = 5.7 Hz), 3.75 (t, 4H, J = 4.7 Hz), 2.84 (m, 2H), 2.60 (t, 4H, J = 4.7 Hz). MS (FAB) m/z 451 [M+H]+; mp 139 °C. 4.1.22.4. 4-(3-{4-[6-(4-Chlorophenoxy)-benzoxazol-2-yl]-phenoxy}ethyl)-piperazine-1-carboxylic acid tert-butyl ester (29). Compound 29 was prepared with N-Boc piperidine by following the Section 4.1.22. Yield 42%; 1H NMR (300 MHz, CDCl3) d 8.14 (m, 2H), 7.67 (d, 1H, J = 8.7 Hz), 7.31 (m, 2H), 7.19 (d, 1H, J = 2.4 Hz), 7.05–6.95 (m, 5H), 4.19 (t, 2H, J = 5.6 Hz), 3.47 (m, 4H), 2.86 (m, 4H), 2.54 (m, 4H), 1.48 (s, 9H). MS (FAB) m/z 550 [M+H]+; mp 100 °C. 4.1.22.5. 6-(4-Chlorophenoxy)-2-{4-[2-(4-pyrimidin-2-yl-piperazin-1-yl)-ethoxy]-phenyl}-benzoxazole (30). Compound 30

was prepared with 1-(2-pyrimidyl)-piperazine by following the Section 4.1.22. Yield 83%; 1H NMR (300 MHz, CDCl3) d 8.31 (d, 2H, J = 4.77 Hz), 8.14 (d, 2H, J = 8.61 Hz), 7.67 (d, 1H, J = 8.58 Hz), 7.31 (d, 2H, J = 8.25 Hz), 7.2 (d, 1H, J = 2.19 Hz), 7.05 (d, 2H, J = 8.79 Hz), 6.97 (d, 2H, J = 8.4 Hz), 6.51 (t, 1H, J = 4.77 Hz), 4.24 (t, 2H, J = 5.31 Hz), 3.87 (t, 2H, J = 4.77 Hz), 2.91 (s, 2H), 2.68 (s, 4H); MS (FAB) m/z 528 [M+H]+; mp 164 °C. 4.1.22.6. (3-{4-[6-(4-Chlorophenoxy)-benzoxazol-2-yl]-phenoxy}propyl)-diethyl-amine (31). Compound 31 was prepared with diethylamine by following the Section 4.1.22. Yield 32%; 1H NMR (300 MHz, CDCl3) d 8.13–8.17 (m, 2H), 7.66 (d, 1H, J = 8.6 Hz), 7.29–7.32 (m, 3H), 7.19 (d, 1H, J = 2.4 Hz), 6.96–7.05 (m, 4H), 4.14 (t, 2H, J = 5.8 Hz), 2.86 (m, 6H), 2.20 (m, 2H), 1.27 (m, 6H). MS (FAB) m/z 450 [M+H]+; mp 155 °C. 4.1.22.7. 6-(4-Chlorophenoxy)-2-[4-(3-pyrrolidin-1-yl-propoxy)phenyl]-benzoxazole (32). Compound 32 was prepared with 1-(2-pyrimidyl)-piperazine by following the Section 4.1.22. Yield 59%; 1H NMR (300 MHz, CDCl3) d 8.13 (m, 2H), 7.67 (d, 1H, J = 8.7 Hz), 7.31 (m, 2H), 7.19 (d, 1H, J = 2.1 Hz), 7.05–6.95 (m, 5H), 4.13 (t, 2H, J = 6.3 Hz), 2.71 (m, 6H), 2.11 (m, 2H), 1.85 (m, 4H). MS (FAB) m/z 448 [M+H]+; mp 98 °C. 4.1.22.8. (R)-[1-(3-{4-[6-(4-Chlorophenoxy)-benzoxazol-2-yl]phenoxy}-propyl)-pyrrolidin-3-yl]-carbamic acid tert-butyl ester (33). Compound 33 was prepared with (R)-3-(Boc-amino)pyrrolidine by following the Section 4.1.22. Yield 66%; 1H NMR (300 MHz, CDCl3) d 8.14 (d, 2H, J = 8.7 Hz), 7.67 (d, 1H, J = 8.7 Hz), 7.31 (d, 2H, J = 8.7 Hz), 7.19 (d, 1H, J = 2.4 Hz), 7.05–6.96 (m, 5H), 4.86 (br s, 1H), 4.13 (m, 3H), 2.87 (br s, 1H), 2.65 (m, 4H), 2.32 (m, 2H), 2.03 (m, 2H), 1.63 (br s, 1H), 1.46 (s, 9H). MS (FAB) m/z 564 [M+H]+; mp 124 °C. 4.1.22.9. (S)-[1-(3-{4-[6-(4-Chlorophenoxy)-benzoxazol-2-yl]phenoxy}-propyl)-pyrrolidin-3-yl]-carbamic acid tert-butyl ester (34). Compound 34 was prepared with (S)-3-(Bocamino)pyrrolidine by following the Section 4.1.22. Yield 63%; 1H NMR (300 MHz, CDCl3) d 8.14 (d, 2H, J = 9.0 Hz), 7.67 (d, 1H, J = 8.7 Hz), 7.32 (d, 2H, J = 9.9 Hz), 7.19 (d, 1H, J = 2.1 Hz), 7.05– 6.95 (m, 5H), 4.85 (br s, 1H), 4.13 (m, 3H), 2.88 (br s, 1H), 2.65 (m, 4H), 2.29 (m, 2H), 2.03 (m, 2H), 1.65 (br s, 1H), 1.45 (s, 9H). MS (FAB) m/z 564 [M+H]+; mp 125 °C. 4.1.22.10. (R)-1-(3-{4-[6-(4-Chloro-phenoxy)-benzooxazol-2yl]-phenoxy}-propyl)-pyrrolidin-3-ylamine (35). To a stirred solution of compound 33 (0.060 g, 0.13 mmol) in DCM (1.0 mL) was added trifluoroacetic acid (0.16 mL, 2.1 mmol) at room temperature. After stirred for 5 h, the reaction mixture was evaporated under reduced pressure. The residue dissolved in DCM was washed with 2 N NaOH and brine. The organic layer was dried over MgSO4 and concentrated in vacuo. The resulting crude was purified recrystallization with DCM/hexane system. Yield 51%; 1H NMR (300 MHz, CDCl3) d 8.13 (d, 2H, J = 9.7 Hz), 7.67 (d, 1H, J = 8.7 Hz), 7.31 (d, 2H, J = 9.0 Hz), 7.19 (d, 1H, J = 2.4 Hz), 7.05–6.96 (m, 5H), 4.12 (t, 2H, J = 6.0 Hz), 3.66 (m, 1H), 3.01–2.61 (m, 6H), 2.26–2.08 (m, 3H), 1.67 (m, 1H). MS (FAB) m/z 464(M+H); mp 110 °C. 4.1.22.11. (S)-1-(3-{4-[6-(4-Chlorophenoxy)-benzoxazol-2-yl]phenoxy}-propyl)-pyrrolidin-3-ylamine (36). This compound was prepared from compound 34 by following the procedure described for compound 35. Yield 43%; 1H NMR (300 MHz, CDCl3) d 8.13 (d, 2H, J = 8.7 Hz), 7.67 (d, 1H, J = 8.4 Hz), 7.31 (d, 2H, J = 8.7 Hz), 7.19 (d, 1H, J = 2.4 Hz), 7.05–6.96 (m, 5H), 4.12 (t, 2H, J = 6.0 Hz), 3.52 (m, 1H), 2.78–2.56 (m, 4H), 2.49 (m, 1H), 2.35 (m, 1H), 2.22 (m, 1H), 2.02 (m, 2H), 1.49 (m, 1H). MS (FAB) m/z 464 [M+H]+; mp 106 °C.

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4.1.22.12. 6-(4-Chlorophenoxy)-2-[4-(3-piperidin-1-yl-propoxy)phenyl]-benzoxazole (37). This compound was prepared with piperidine by following the Section 4.1.22. Yield 69%; 1H NMR (300 MHz, CDCl3) d 8.13 (d, 2H, J = 9.0 Hz), 7.66 (d, 1H, J = 8.6 Hz), 7.30 (d, 2H, J = 9.0 Hz), 7.19 (d, 1H, J = 2.2 Hz), 6.94–7.05 (m, 5H), 4.14 (t, 2H, J = 5.9 Hz), 2.85–2.90 (m, 6H), 2.29 (m, 2H), 1.89 (m, 2H), 1.61 (m, 2H), 0.82–0.94 (m, 2H). MS (FAB) m/z 462 [M+H]+; mp 200 °C. 4.1.22.13. 2-{4-[3-(4-tert-Butyl-piperidin-1-yl)-propoxy]-phenyl}6-(4-chlorophenoxy)-benzoxazole (38). This compound was prepared with 4-tert-butyl-piperidin HCl salt by following the Section 4.1.22. Yield 62%; 1H NMR (300 MHz, CDCl3) d 8.14 (m, 2H), 7.67 (d, 1H, J = 8.7 Hz), 7.31 (m, 2H), 7.19 (d, 1H, J = 2.1 Hz), 7.05–6.95 (m, 5H), 4.10 (t, 2H, J = 6.6 Hz), 3.06 (d, 1H, J = 1.1 Hz), 2.54 (t, 2H, J = 7.5 Hz), 2.10–1.89 (m, 4H), 1.68 (d, 2H, J = 13.2 Hz), 1.39 (m, 2H), 1.01 (m, 1H), 0.86 (s, 9H). MS (FAB) m/z 519 [M+H]+; mp 128 °C. 4.1.22.14. 6-(4-Chlorophenoxy)-2-{4-[3-(4-phenyl-piperidin-1yl)-propoxy]-phenyl}-benzoxazole (39). This compound was prepared with 4-phenyl-piperidin by following the Section 4.1.22. Yield 26%; 1H NMR (300 MHz, CDCl3) d 8.14 (d, 2H, J = 8.7 Hz), 7.67 (d, 1H, J = 8.7 Hz), 7.34–7.19 (m, 8H), 7.05– 6.96 (m, 5H), 4.14 (t, 2H, J = 6.3 Hz), 3.13 (d, 2H, J = 11.4 Hz), 2.64–2.50 (m, 3H), 2.10 (m, 4H), 1.87 (m, 4H). MS (FAB) m/z 539 [M+H]+; mp 120 °C. 4.1.22.15. 6-(4-Chlorophenoxy)-2-[4-(3-morpholin-4-yl-propoxy)phenyl]-benzoxazole (40). This compound was prepared with morpholine by following the Section 4.1.22. Yield 45%; 1H NMR (300 MHz, CDCl3) d 8.14 (d, 2H, J = 9.0 Hz), 7.67 (d, 1H, J = 8.6 Hz), 7.30 (d, 2H, J = 9.0 Hz), 7.19 (d, 1H, J = 2.2 Hz), 6.94–7.05 (m, 5H), 4.11 (t, 2H, J = 6.2 Hz), 3.71–3.74 (m, 4H), 2.46–2.57 (m, 6H), 1.96–2.05 (m, 2H). MS (FAB) m/z 464 [M+H]+; mp 130 °C. 4.1.22.16. 6-(4-Chlorophenoxy)-2-[4-(3-piperazin-1-yl-propoxy)phenyl]-benzoxazole (41). This compound was prepared from compound 48 by following the Section 4.1.7. Yield 54%; 1H NMR (300 MHz, CDCl3) d 7.77 (d, 2H, J = 8.7 Hz), 7.45 (d, 1H, J = 8.7 Hz), 7.34–7.25 (m, 2H), 7.18 (m, 1H), 7.01–6.90 (m, 5H), 6.83 (s, 1H), 4.08 (t, 2H, J = 6.3 Hz), 2.92 (t, 4H, J = 4.9 Hz), 2.50 (m, 6H), 2.00 (m, 2H). MS (FAB) m/z 463 [M+H]+; mp 120 °C. 4.1.22.17. 6-(4-Chlorophenoxy)-2-{4-[3-(4-methyl-piperazin-1yl)-propoxy]-phenyl}-benzoxazole (42). This compound was prepared with 4-methyl-piperazine by following the Section 4.1.22. Yield 86%; 1H NMR (300 MHz, CDCl3) d 8.14 (d, 2H, J = 8.7 Hz), 7.67 (d, 1H, J = 8.7 Hz), 7.31 (d, 2H, J = 9.0 Hz), 7.19 (d, 1H, J = 2.1 Hz), 7.05–6.96 (m, 5H), 4.11 (t, 2H, J = 6.3 Hz), 2.57 (m, 10H), 2.33 (s, 3H), 2.02 (m, 2H). MS (FAB) m/z 478 [M+H]+; mp 110 °C. 4.1.22.18. 2-(4-(3-(4-(6-(4-chlorophenoxy)benzo[d]oxazol-2-yl)phenoxy)-propyl)-piperazin-1-yl)ethanol (43). A mixture of compound 24 (0.040 g, 0.086 mmol), 2-bromoethanol and K2CO3 (0.024 g, 0.17 mmol) in DMF was heated to 100 °C for 18 h. The mixtures was cooled to room temperature and evaporated under reduced pressure. The residue was dissolved in EtOAc and then washed with water, and brine. The organic layer was dried over sodium sulfate, filtered and concentrated in vacuum. The resulting residue was purified by silica gel chromatography to afford the product. Yield 34%; 1H NMR (300 MHz, CDCl3) d 8.13 (d, 2H, J = 9.0 Hz), 7.67 (d, 1H, J = 8.7 Hz), 7.30 (d, 2H, J = 8.4 Hz), 7.19 (d, 1H, J = 2.1 Hz), 7.05–6.96 (m, 5H), 4.10 (t, 2H, J = 6.3 Hz), 3.62 (t,

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2H, J = 5.4 Hz), 2.56 (m, 12), 2.01 (m, 2H); MS (FAB) m/z 508 [M+H]+; mp 112 °C. 4.1.22.19. 4-(3-{4-[6-(4-Chlorophenoxy)-benzoxazol-2-yl]-phenoxy}-propyl)-piperazine-1-carboxylic acid methyl ester (44). This compound was prepared with piperazine-1-carboxylic acid methyl ester by following the Section 4.1.22. Yield 63%; 1H NMR (300 MHz, CDCl3) d 8.14 (d, 2H, J = 8.7 Hz), 7.67 (d, 1H, J = 8.7 Hz), 7.31 (m, 2H), 7.20 (d, 1H, J = 2.1 Hz), 7.05–6.96 (m, 5H), 4.11 (t, 2H, J = 6.3 Hz), 3.70 (s, 3H), 3.50 (br s, 4H), 2.56 (t, 2H, J = 7.1 Hz), 2.43 (br s, 4H), 2.01 (m, 2H). MS (FAB) m/z 522 [M+H]+; mp 144 °C. 4.1.22.20. 4-(3-{4-[6-(4-Chlorophenoxy)-benzoxazol-2-yl]-phenoxy}-propyl)-piperazine-1-carboxylic acid ethyl ester (45). This compound was prepared with piperazine-1-carboxylic acid ethyl ester by following the Section 4.1.22. Yield 62%; 1H NMR (300 MHz, CDCl3) d 8.14 (d, 2H, J = 8.7 Hz), 7.67 (d, 1H, J = 8.7 Hz), 7.31 (m, 2H), 7.19 (d, 1H, J = 2.4 Hz), 7.05–6.96 (m, 5H), 4.18–4.09 (m, 4H), 3.50 (t, 4H, J = 5.0 Hz), 2.56 (t, 2H, J = 7.2 Hz), 2.44 (t, 4H, J = 5.0 Hz), 2.01 (m, 2H), 1.27 (t, 3H, J = 7.1 Hz). MS (FAB) m/z 536 [M+H]+; mp 123 °C. 4.1.22.21. 4-(3-{4-[6-(4-Chlorophenoxy)-benzoxazol-2-yl]-phenoxy}-propyl)-piperazine-1-carboxylic acid isobutyl ester (46). This compound was prepared with piperazine-1-carboxylic acid isobutyl ester by following the Section 4.1.22. Yield 60%; 1H NMR (300 MHz, CDCl3) d 8.14 (d, 2H, J = 9.0 Hz), 7.67 (d, 2H, J = 8.7 Hz), 7.31 (m, 2H), 7.19 (d, 1H, J = 2.4 Hz), 7.05–6.96 (m, 5H), 4.11 (t, 2H, J = 6.3 Hz), 3.87 (d, 2H, J = 6.6 Hz), 3.51 (t, 4H, J = 5.1 Hz), 2.56 (t, 2H, J = 7.2 Hz), 2.44 (t, 4H, J = 4.8 Hz), 2.04– 1.89 (d, 3H), 0.94 (d, 6H, J = 6.6 Hz). MS (FAB) m/z 564 [M+H]+; mp 107 °C. 4.1.22.22. 4-(3-{4-[6-(4-Chlorophenoxy)-benzoxazol-2-yl]-phenoxy}-propyl)-piperazine-1-carboxylic acid isopropyl ester (47). This compound was prepared with piperazine-1-carboxylic acid isopropyl ester by following the Section 4.1.22. Yield 58%; 1 H NMR (300 MHz, CDCl3) d 8.14 (d, 2H, J = 8.7 Hz), 7.67 (d, 1H, J = 8.7 Hz), 7.31 (m, 2H), 7.19 (d, 1H, J = 2.1 Hz), 7.05–6.96 (m, 5H), 4.92 (m, 1H), 4.11 (t, 2H, J = 6.3 Hz), 3.49 (t, 4H, J = 5.0 Hz), 2.55 (t, 2H, J = 7.2 Hz), 2.43 (t, 4H, J = 4.8 Hz), 2.01 (m, 2H), 1.24 (d, 6H, J = 6.3 Hz). MS (FAB) m/z 550 [M+H]+; mp 108 °C. 4.1.22.23. 4-(3-{4-[6-(4-Chlorophenoxy)-benzoxazol-2-yl]-phenoxy}-propyl)-piperazine-1-carboxylic acid tert-butyl ester (48). This compound was prepared with N-Boc-piperzaine by following the Section 4.1.22. Yield 36%; 1H NMR (300 MHz, CDCl3) d 8.13 (d, 2H, J = 9.0 Hz), 7.66 (d, 1H, J = 8.6 Hz), 7.30 (d, 2H, J = 9.0 Hz), 7.18 (d, 1H, J = 2.2 Hz), 6.95–7.05 (m, 5H), 4.11 (t, 2H, J = 6.2 Hz), 3.42–3.46 (m, 4H), 2.55 (t, 2H, J = 7.0 Hz), 2.40–2.43 (m, 4H), 1.98–2.03 (m, 2H), 1.46 (s, 9H). MS (FAB) m/z 564 [M+H]+; mp 147 °C. 4.1.22.24. 6-(4-Chlorophenoxy)-2-{4-[3-(4-phenyl-piperazin-1yl)-propoxy]-phenyl}-benzoxazole (49). This compound was prepared with N-phenyl piperazine by following the Section 4.1.22. Yield 61%; 1H NMR (300 MHz, CDCl3) d 8.14 (d, 2H, J = 8.7 Hz), 7.67 (d, 1H, J = 8.7 Hz), 7.33–7.25 (m, 4H), 7.20 (d, 1H, J = 2.4 Hz), 7.05–6.84 (m, 8H), 4.14 (t, 2H, J = 6.3 Hz), 3.23 (t, 4H, J = 4.8 Hz), 2.64 (m, 6H), 2.06 (m, 2H). MS (FAB) m/z 540 [M+H]+; mp 162 °C. 4.1.22.25. 2-(4-(3-(4-(Pyrimidin-2-yl)piperazin-1-yl)propoxy)phenyl)-6-(4-chlorophenoxy)-benzo[d]oxazole (50). This

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compound was prepared with 2-(piperazin-1-yl)pyrimidine by following the Section 4.1.22. Yield 34%; 1H NMR (300 MHz, CDCl3) d 8.31 (d, 2H, J = 4.8 Hz), 8.14 (d, 2H, J = 8.7 Hz), 7.67 (d, 1H, J = 8.7 Hz), 7.30 (d, 2H, J = 8.4 Hz), 7.19 (d, 1H, J = 2.1 Hz), 7.04– 6.96 (m, 5H), 6.49 (t, 1H, J = 4.8 Hz), 4.16 (t, 2H, J = 6.3 Hz), 3.85 (t, 2H, J = 5.1 Hz), 2.61–2.53 (m, 6), 2.01 (m, 2H); MS (FAB) m/z 542 [M+H]+; mp 114 °C.

compound was prepared with tert-butyl piperazine-1-carboxylate by following the Section 4.1.22. Yield 68%; 1H NMR (300 MHz, CDCl3) d 8.13 (d, 2H, J = 9.0 Hz), 7.64 (d, 1H, J = 8.8 Hz), 7.37 (d, 2H, J = 8.8 Hz), 7.18 (d, 1H, J = 2.2 Hz), 6.95–7.06 (m, 5H), 4.11 (t, 2H, J = 6.4 Hz),3.44 (t, 4H, J = 4.9 Hz), 2.54 (t, 2H, J = 7.0 Hz), 2.42 (t, 4H, J = 5.0 Hz), 1.96–2.05 (m, 2H), 1.46 (s, 9H), 1.33 (s, 9H); MS(FAB) m/z 586 [M+H]+; mp 146 °C.

4.1.22.26. 6-(4-Chlorophenoxy)-2-(4-{3-[4-(5-fluoro-pyrimidin2-yl)-piperazin-1-yl]-propoxy}-phenyl)-benzoxazole (51). This compound was prepared with 5-fluoro-2-piperazin-1-yl-pyrimidine by following the Section 4.1.22. Yield 35%; 1H NMR (300 MHz, CDCl3) d 8.19 (s, 2H), 8.14 (d, 2H, J = 8.6 Hz), 7.66 (d, 1H, J = 8.6 Hz), 7.31 (d, 2H, J = 8.6 Hz), 7.19 (d, 1H, J = 2.2 Hz), 7.05–6.95 (m, 5H), 4.14 (t, 2H, J = 6.2 Hz), 3.79 (t, 4H, J = 4.7 Hz), 2.61–2.52 (m, 6H), 2.05 (t, 2H, J = 7.5 Hz); MS (FAB) m/z 542 [M+H]+; mp 114 °C.

4.1.22.33. 6-(4-tert-Butylphenoxy)-2-(4-(3-(4-(pyrimidin-2-yl)piperazin-1-yl)propoxy)phenyl)benzo[d]oxazole (58). This compound was prepared with 2-(piperazin-1-yl)pyrimidine by following the Section 4.1.22. Yield 53%; 1H NMR (300 MHz, CDCl3)d 8.31 (d, 2H, J = 4.8 Hz), 8.13 (d, 2H, J = 9.0 Hz), 7.64 (d, 1H, J = 8.6 Hz), 7.36 (d, 2H, J = 8.8 Hz), 7.18 (d, 1H, J = 2.2 Hz), 6.95–7.06 (m, 5H), 6.48 (t, 1H, J = 4.8 Hz), 4.13 (t, 2H, J = 6.2 Hz), 3.85 (t, 4H, J = 5.0 Hz), 2.52–2.61 (m, 6H), 2.00–2.10 (m, 2H), 1.33 (s, 9H); MS(FAB) m/z 564 [M+H]+; mp 129 °C.

4.1.22.27. 6-(4-Chlorophenoxy)-2-(4-{3-[4-(5-chloro-pyrimidin2-yl)-piperazin-1-yl]-propoxy}-phenyl)-benzoxazole (52). This compound was prepared 5-chloro-2-piperazin-1-yl-pyrimidine by following the Section 4.1.22. Yield 19%; 1H NMR (300 MHz, CDCl3) d 8.22 (s, 2H), 8.14 (d, 2H, J = 8.8 Hz), 7.66 (d, 1H, J = 8.6 Hz), 7.31 (d, 2H, J = 9.0 Hz), 7.19 (d, 1H, J = 2.2 Hz), 7.05– 6.96 (m, 5H), 4.14 (t, 2H, J = 6.2 Hz), 3.82 (t, 4H, J = 4.9 Hz), 2.62– 2.52 (m, 6H), 2.08–2.03 (m, 2H); MS (FAB) m/z 576 [M+H]+; mp 160 °C.

4.1.22.34. 6-(4-tert-Butylphenoxy)-2-(4-(3-(pyrrolidin-1-yl)propoxy)phenyl)benzo[d]oxazole (59). This compound was prepared with pyrrolidine by following the Section 4.1.22. Yield 94%; 1H NMR (300 MHz, CDCl3) d 8.13 (d, 2H, J = 8.8 Hz), 7.64 (d, 1H, J = 8.6 Hz), 7.37 (d, 2H, J = 9.0 Hz), 7.18 (d, 1H, J = 2.0 Hz), 6.94–7.06 (m, 5H), 4.13 (t, 2H, J = 6.2 Hz), 2.73–2.89 (m, 6H), 2.13–2.23 (m, 2H), 1.90–1.95 (m, 4H), 1.33 (s, 9H); MS(FAB) m/z 471 [M+H]+; mp 155 °C.

4.1.22.28. 3-(4-(6-(4-tert-Butylphenoxy)benzo[d]oxazol-2-yl)phenoxy)-N,N-diethylpropan-1-amine (53). This compound was prepared with diethylamine by following the Section 4.1.22. Yield 79%; 1H NMR (300 MHz, CDCl3) d 8.13 (d, 2H, J = 9.0 Hz), 7.64 (d, 1H, J = 8.6 Hz), 7.36 (d, 2H, J = 8.8 Hz), 7.18 (d, 1H, J = 2.2 Hz), 6.95–7.06 (m, 5H), 4.12 (t, 2H, J = 6.2 Hz), 2.70–2.83 (m, 6H), 2.02–2.14(m, 2H), 1.33 (s, 9H), 1.16 (t, 6H, J = 7.1 Hz); MS (FAB) m/z 473 [M+H]+; mp 84 °C. 4.1.22.29. 6-(4-tert-Butylphenoxy)-2-(4-(3-(piperidin-1-yl)propoxy)phenyl)benzo[d]oxazole (54). This compound was prepared with piperidine by following the Section 4.1.22. Yield 99%; 1 H NMR (300 MHz, CDCl3) d 8.12 (d, 2H, J = 8.6 Hz), 7.64 (d, 1H, J = 8.6 Hz), 7.36 (d, 2H, J = 7.0 Hz), 7.18 (d, 1H, J = 2.2 Hz), 6.95– 7.06 (m, 5H), 4.09 (t, 2H, J = 6.2 Hz), 2.49–2.61 (m, 6H), 2.03–2.13 (m, 2H), 1.63–1.70 (m, 4H), 1.43–1.54 (m, 2H), 1.33 (s, 9H); MS(FAB) m/z 485 [M+H]+; mp 122 °C. 4.1.22.30. 6-(4-tert-Butylphenoxy)-2-(4-(3-morpholinopropoxy)phenyl)benzo[d]oxazole (55). This compound was prepared with morpholine by following the Section 4.1.22. Yield 89%; 1H NMR(300 MHz, CDCl3) d 8.13 (d, 2H, J = 8.8 Hz), 7.64 (d, 1H, J = 8.6 Hz), 7.37 (d, 2H, J = 8.8 Hz), 7.18 (d, 1H, J = 2.4 Hz), 6.95–7.06 (m, 5H), 4.11 (t, 2H, J = 6.2 Hz), 3.73 (t, 4H, J = 4.6 Hz), 2.46–2.56 (m, 6H), 1.95–2.05 (m, 2H), 1.33 (s, 9H); MS(FAB) m/z 487 [M+H]+; mp 127 °C. 4.1.22.31. 6-(4-tert-Butylphenoxy)-2-(4-(3-(4-tert-butylpiperazin-1-yl)propoxy)phenyl)benzo[d]-oxazole (56). This compound was prepared with tert-butyl piperazine by following the Section 4.1.22. Yield 96%; 1H NMR (300 MHz, CDCl3) d 8.12 (d, 2H, J = 9.0 Hz), 7.64 (d, 1H, J = 8.6 Hz), 7.37 (d, 2H, J = 8.8 Hz), 7.18 (d, 1H, J = 2.2 Hz), 6.95–7.06 (m, 5H), 4.09 (t, 2H, J = 6.4 Hz), 2.55–2.75 (m, 10H), 1.96–2.06 (m, 2H), 1.33 (s, 9H), 1.17 (s, 9H); MS(FAB) m/z 542 [M+H]+; mp 158 °C. 4.1.22.32. tert-Butyl 4-(3-(4-(6-(4-tert-butylphenoxy)benzo[d]oxazol-2-yl)phenoxy)propyl)piperazine-1-carboxylate (57). This

4.1.22.35. (R)-tert-Butyl 1-(3-(4-(6-(4-tert-butylphenoxy)benzo-[d]oxazol-2-yl)phenoxy)propyl)pyrrolidin-3-ylcarbamate (60). This compound was prepared with (R)-(+)-3-tert-butyl pyrrolidin-3-ylcarbamate by following the Section 4.1.22. Yield 91%; 1H NMR (300 MHz, CDCl3) d 8.13 (d, 2H, J = 9.0 Hz), 7.65 (d, 1H, J = 8.6 Hz), 7.37 (d, 2H, J = 8.8 Hz), 7.18 (d, 1H, J = 2.2 Hz), 6.95–7.07 (m, 5H), 4.97 (br s, 1H), 4.21 (br s, 1H), 4.11(t, 2H, J = 6.2 Hz), 2.93 (m, 1H), 2.65–2.70 (m, 4H), 2.27–2.38 (m, 2H), 2.02–2.06 (m, 3H), 1.48–1.65 (m, 1H), 1.44 (s, 9H), 1.33 (s, 9H);MS(FAB) m/z 586 [M+H]+; mp 126 °C. 4.1.22.36. (S)-tert-Butyl 1-(3-(4-(6-(4-tert-butylphenoxy)benzo[d]oxazol-2-yl)phenoxy)propyl)pyrrolidin-3-ylcarbamate (61). This compound was prepared with (S)-(+)-3-tert-butyl pyrrolidin-3-ylcarbamate by following the Section 4.1.22. Yield 90%; 1H NMR (300 MHz, CDCl3) d 8.12 (d, 2H, J = 8.6 Hz), 7.65 (d, 1H, J = 8.4 Hz), 7.37 (d, 2H, J = 8.6 Hz), 7.18 (d, 1H, J = 2.4 Hz), 6.96–7.07 (m, 5H), 4.11 (t, 2H, J = 6.2 Hz), 2.80–2.91 (m, 1H), 2.60–2.63 (m, 3H), 2.20– 2.35 (m, 1H), 1.96–2.07 (m, 2H), 1.58 (br s, 5H), 1.44 (s, 9H), 1.33 (s, 9H); MS(FAB) m/z 586 [M+H]+; mp 106 °C. 4.1.22.37. (R)-1-(3-(4-(6-(4-tert-Butylphenoxy)benzo[d]oxazol2-yl)phenoxy)propyl)pyrrolidin-3-amine (62). This compound was prepared from compound 60 by following the procedure described for compound 35. Yield 25%; 1H NMR (300 MHz, CDCl3) d 8.12 (d, 2H, J = 8.8 Hz), 7.64 (d, 1H, J = 8.6 Hz), 7.37 (d, 2H, J = 8.6 Hz), 7.18 (d, 1H, J = 2.2 Hz), 6.96–7.06 (m, 5H), 4.11 (t, 2H, J = 6.4 Hz), 3.70–3.76 (m, 1H), 2.89–3.13 (m, 6H), 2.75–2.79 (m, 2H), 2.23–2.30 (m, 1H), 2.09–2.14 (m, 2H), 1.70–1.80 (m, 1H), 1.33 (s, 9H); MS(FAB) m/z 486 [M+H]+; mp 142 °C. 4.1.22.38. (S)-1-(3-(4-(6-(4-tert-Butylphenoxy)benzo[d]oxazol2-yl)phenoxy)propyl)pyrrolidin-3-amine (63). This compound was prepared from compound 61 by following the procedure described for compound 35. Yield 42%; 1H NMR (300 MHz, CDCl3) d 8.12 (d, 2H, J = 8.8 Hz), 7.64 (d, 1H, J = 8.6 Hz), 7.37 (d, 2H, J = 8.8 Hz), 7.18 (d, 1H, J = 2.2 Hz), 6.96–7.06 (m, 5H), 4.11 (t, 2H, J = 6.4 Hz), 3.63–3.72 (m, 1H), 2.91–3.07 (m, 4H), 2.87 (t, 2H, J = 7.5 Hz),2.66–2.80 (m, 2H), 2.22–2.29 (m, 1H), 2.09–2.14 (m,

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K. Choi et al. / Bioorg. Med. Chem. xxx (2015) xxx–xxx

2H), 1.64–1.72 (m, 1H), 1.33 (s, 9H); MS(FAB) m/z 486 [M+H]+; mp 119 °C. 4.1.22.39. (3-{4-[6-(4-Fluorophenoxy)-benzoxazol-2-yl]-phenoxy}-propyl)-diethylamine (64). This compound was prepared with diethylamine by following the Section 4.1.22. Yield 20%; 1H NMR (300 MHz, CDCl3) d 8.13 (d, 2H, J = 9.0 Hz), 7.65 (d, 1H, J = 8.4 Hz),), 7.15 (d, 1H, J = 2.1 Hz),), 7.06–6.99 (m, 7H),), 4.12 (t, 2H, J = 6.0 Hz),), 2.72 (m, 6H)), 2.07 (m, 2H),), 1.13 (t, 6H, J = 7.1 Hz). MS (FAB) m/z 435 [M+H]+; mp 99 °C. 4.1.22.40. 6-(4-Fluorophenoxy)-2-[4-(3-piperidin-1-yl-propoxy)phenyl]-benzoxazole (65). This compound was prepared with piperidine by following the Section 4.1.22. Yield 67%; 1H NMR (300 MHz, CDCl3) d 8.13 (m, 2H), 7.65 (d, 1H, J = 8.4 Hz), 7.15 (d, 1H, J = 2.4 Hz), 7.06–7.00 (m, 7H), 4.11 (t, 2H, J = 6.3 Hz), 2.58– 2.51 (m, 6H), 2.09 (m, 2H), 1.67 (m, 4H), 1.48 (br s, 2H). MS (FAB) m/z 446 [M+H]+; mp 123 °C. 4.1.22.41. 6-(4-Fluorophenoxy)-2-[4-(3-morpholin-4-yl-propoxy)phenyl]-benzoxazole (66). This compound was prepared with morpholine by following the Section 4.1.22. Yield 79%; 1H NMR (300 MHz, CDCl3) d 8.13 (m, 2H), 7.65 (d, 1H, J = 8.4 Hz), 7.15 (d, 1H, J = 2.4 Hz), 7.06–7.00 (m, 7H), 4.12 (t, 2H, J = 6.3 Hz), 3.74 (t, 4H, J = 4.7 Hz), 2.60–2.48 (m, 6H), 2.02 (m, 2H). MS (FAB) m/z 448 [M+H]+; mp 130 °C. 4.1.22.42. 4-(3-{4-[6-(4-Fluorophenoxy)-benzoxazol-2-yl]-phenoxy}-propyl)-piperazine-1-carboxylic acid tert-butyl ester (67). This compound was prepared with N-Boc-piperazine by following the Section 4.1.22. Yield 65%; 1H NMR (300 MHz, CDCl3) d 8.13 (m, 2H), 7.65 (d, 1H, J = 8.7 Hz), 7.15 (d, 1H, J = 2.1 Hz), 7.06–7.00 (d, 7H), 4.11 (t, 2H, J = 6.3 Hz), 3.45 (t, 4H, J = 5.0 Hz), 2.55 (t, 2H, J = 7.2 Hz), 2.42 (m, 4H), 2.01 (m, 2H), 1.48 (s, 9H). MS (FAB) m/z 548 [M+H]+; mp 155 °C. 4.1.22.43. (3-{4-[6-(4-Trifluoromethyl-phenoxy)-benzoxazol-2yl]-phenoxy}-propyl)-diethyl-amine (68). This compound was prepared with diethylamine by following the Section 4.1.22. Yield 58%; 1H NMR (300 MHz, CDCl3) d 8.15 (m, 2H), 7.71 (d, 1H, J = 8.7 Hz), 7.60 (d, 2H, J = 9.0 Hz), 7.27 (d, 1H, J = 2.4 Hz), 7.09– 7.01 (m, 5H), 4.12 (t, 2H, J = 6.2 Hz), 2.73–2.65 (m, 6H), 2.05 (m, 2H), 1.11 (t, 6H, J = 7.2 Hz). MS (FAB) m/z 485 [M+H]+; mp 93 °C. 4.1.22.44. 6-(4-Trifluoromethyl-phenoxy)-2-[4-(3-piperidin-1yl-propoxy)-phenyl]-benzoxazole (69). This compound was prepared with diethylamine by following the Section 4.1.22. Yield 62%; 1H NMR (300 MHz, CDCl3) d 8.15 (d, 2H, J = 8.4 Hz), 7.71 (d, 1H, J = 8.4 Hz), 7.60 (d, 2H, J = 9.0 Hz), 7.27 (d, 1H, J = 2.4 Hz), 7.09–7.01 (m, 5H), 4.11 (t, 2H, J = 6.3 Hz), 2.58–2.51 (m, 6H), 2.09 (m, 2H), 1.67 (m, 4H), 1.48 (br s, 2H). MS (FAB) m/z 497 [M+H]+; mp 121 °C. 4.1.22.45. 6-(4-Trifluoromethyl-phenoxy)-2-[4-(3-morpholin-4yl-propoxy)-phenyl]-benzoxazole (70). This compound was prepared with morpholine by following the Section 4.1.22. Yield 78%; 1H NMR (300 MHz, CDCl3) d 8.15 (d, 2H, J = 9.0 Hz), 7.71 (d, 1H, J = 8.4 Hz), 7.60 (d, 2H, J = 8.7 Hz), 7.27 (d, 1H, J = 3.0 Hz), 7.09–7.02 (m, 5H), 4.12 (d, 2H, J = 6.3 Hz), 3.74 (d, 4H, J = 4.7 Hz), 2.58–2.50 (m, 6H), 2.03 (m, 2H). MS (FAB) m/z 499 [M+H]+; mp 110 °C. 4.1.22.46. 4-(3-{4-[6-(4-Trifluoromethyl-phenoxy)-benzoxazol2-yl]-phenoxy}-propyl)-piperazine-1-carboxylic acid tert-butyl ester (71). This compound was prepared with N-Boc-piperazine by following the Section 4.1.22. Yield 57%; 1H NMR

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(300 MHz, CDCl3) d 8.15 (d, 2H, J = 8.7 Hz), 7.71 (d, 1H, J = 8.7 Hz), 7.60 (d, 2H, J = 8.4 Hz), 7.27 (d, 1H, J = 3.0 Hz), 7.09–7.01 (m, 5H), 4.12 (d, 2H, J = 6.3 Hz), 3.46 (br s, 4H), 2.56 (m, 2H), 2.43 (m, 4H), 2.02 (m, 2H), 1.47 (s, 9H). MS (FAB) m/z 598 [M+H]+; mp 149 °C. 4.1.22.47. (3-{4-[6-(3-Trifluoromethyl-phenoxy)-benzooxazol2-yl]-phenoxy}-propyl)-diethylamine (72). This compound was prepared with diethylamine by following the Section 4.1.22. Yield 19%; 1H NMR (300 MHz, CDCl3) d 8.19–8.16 (m, 2H), 7.71 (d, 1H, J = 8.6 Hz), 7.49–7.36 (m, 2H), 7.25–7.18 (m, 3H), 7.09– 6.99 (m, 3H), 4.21 (t, 2H, J = 5.5 Hz), 3.34–3.22 (m, 6H), 2.49 (m, 2H), 1.51 (t, 6H, J = 7.1 Hz). MS (FAB) m/z 485 [M+H]+; mp 95 °C. 4.1.22.48. 6-(4-Trifluoromethyl-phenoxy)-2-[4-(3-piperidin-1yl-propoxy)-phenyl]-benzoxazole (73). This compound was prepared with piperidine by following the Section 4.1.22. Yield 18%; 1H NMR (300 MHz, CDCl3) d 8.18–8.15 (m, 2H), 7.71 (d, 1H, J = 8.6 Hz), 7.49–7.36 (m, 2H), 7.25–7.19 (m, 3H), 7.09–6.98 (m, 3H), 4.17 (t, 2H, J = 5.7 Hz), 3.19–3.14 (m, 6H), 2.54–2.51 (m, 2H), 2.17–2.04 (m, 4H), 1.73 (m, 2H). MS (FAB) m/z 497 [M+H]+; mp 76 °C. 4.1.22.49. 6-(3-Trifluoromethyl-phenoxy)-2-[4-(3-morpholin-4yl-propoxy)-phenyl]-benzoxazole (74). This compound was prepared with morpholine by following the Section 4.1.22. Yield 73%; 1H NMR (300 MHz, CDCl3) d 8.15 (d, 2H, J = 8.8 Hz), 7.70 (d, 1H, J = 8.6 Hz), 7.48–7.43 (m, 1H), 7.36 (d, 1H, J = 7.7 Hz), 7.27– 7.18 (m, 3H), 7.08–7.00 (m, 3H), 4.12 (t, 2H, J = 6.2 Hz), 3.73 (t, 4H, J = 4.6 Hz), 2.57–2.48 (m, 6H), 2.06–1.97 (m, 2H). MS (FAB) m/z 499 [M+H]+; mp 108 °C. 4.1.22.50. 4-(3-{4-[6-(3-Trifluoromethyl-phenoxy)-benzoxazol2-yl]-phenoxy}-propyl)-piperazine-1-carboxylic acid tert-butyl ester (75). This compound was prepared with N-Boc-piperazine by following the Section 4.1.22. Yield 91%; 1H NMR (300 MHz, CDCl3) d 8.15 (d, 2H, J = 8.8 Hz), 7.70 (d, 1H, J = 8.6 Hz), 7.48–7.43 (m, 1H), 7.36 (d, 1H, J = 7.7 Hz), 7.27–7.18 (m, 3H), 7.08–7.01 (m, 3H), 4.12 (t, 2H, J = 6.2 Hz), 3.45 (t, 4H, J = 4.8 Hz), 2.55 (t, 2H, J = 7.1 Hz), 2.42 (t, 4H, J = 4.8 Hz), 2.06–1.97 (m, 2H), 1.47 (s, 9H). MS (FAB) m/z 598 [M+H]+; mp 110 °C. 4.2. Biological study 4.2.1. Preparation of biotinylated-human-RAGE and human Ab1–42 Biotinylated-human-RAGE proteins and Ab peptides were prepared as previously described.35 Briefly, the bacterially expressed RAGE proteins were purified by immobilized metal affinity chromatography. Dried Ab42-FITC (M2585, BACHEM) and Ab peptides (American peptide Inc. USA) were completely dissolved in hexafluoroisopropanol at rt for 1–3 days and lyophilized. The resulting Ab film was stored at 80 °C Before each use, the Ab film was dissolved in dimethylsulfoxide (DMSO). For Ab induced cytotoxicity test, 200 lM of Ab peptides solution in PBS was incubated for 24 h at 4 °C to generate toxic aggregates. 4.2.2. FRET assay FRET assays were performed using a F200 reader (TECAN). In this format, 2.5 lg of biotinylated-human-RAGE and 200 ng of Cy3-streptavidin (016-160-084, Jackson ImmunoResearch) were mixed in 100 lL of PBS and incubated at rt for 30 min. And, then 50 lL of 40 nM Ab42-FITC (M2585, BACHEM) and 50 lL of 4 lM of each compound were added to the mixture. Assays were performed at a final volume of 200 lL and a final DMSO concentration of 0.1% v/v in untreated 96 well clear bottom black plate (Corning). All measurements were carried out in triplicate. Plates were read at

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1 h after mixing the components. FEs were calculated using the following formula:

FE ¼ 1 

F da þ inhibitor F d þ vehicle

where da is the donor emission in the presence of the acceptor and d is the donor emission in the absence of the acceptor and vehicle is 0.1% DMSO. Percentage inhibition was determined using the calculated FEs. 4.2.3. Cytotoxicity test Mouse hippocampal HT22 cells were received from Dr. Inhee Mook-Jung at Seoul National University (Seoul, Korea). The cells were cultured in DMEM (Dulbecco’s Modified Eagle’s Medium, Gibco-BRL) supplemented with 10% fetal bovine serum, 100 U/mL penicillin, and 100 mg/mL streptomycin at 37 °C in a humidified atmosphere containing 5% CO2 and 95% air. The cells were plated into 96 well culture plates at a density of 5000 cells per well in 100 lL DMEM. The following day the cells were treated with 10 lM of each compound and incubated for 18 h. For determination of cell viability, 15 lL of 5 mg/mL of 3-[4,5-dimethylthiazol2-yl]-2,5-diphenyltetrazolium bromide (MTT) was added to each well and incubated for 3 h. The formazan formed was dissolved in acidic 2-propanol, and optical density was measured at 570 nm using a microplate reader (Sunrise, TECAN). MTT reduction measured at 570 nm was converted to percentage cell growth by using the following formula.

% Cell MTT metabolism ¼ ðSample Abs 570 nm  blank Abs 570 nmÞ=control Abs 570 nm:

4.2.4. Ab induced cytotoxicity For determination of blocking effect against Ab induced cytotoxicity, HT22 cells were plated into 96 well culture plates at a density of 5000 cells per well in 100 lL DMEM. On the following day, cells were treated with 2 lM of aggregated Ab and 10 lM of each compound, and incubated for 18 h. The cell viability was measured by following the same method described for cytotoxicity test. 4.2.5. Ab lowering effects in transgenic mice 4.2.5.1. Disease model study in transgenic mice. APPsw/PS1 mice were obtained from the Jackson Laboratory (Bar Harbor, ME). All mice were maintained on a 12-h dark and 12-h light cycle with free access to rodent chow and water. All procedures for animal tests were approved by the Medifron Animal Care and Use Committee. All surgical procedures were performed with care to minimize pain and discomfort. To evaluate the inhibitory effect of the test compounds on Ab deposition in this AD model, the test compounds were administrated by gavage of 50 mg/kg to 34 weeks old male APPsw/PS1 mice (n = 4–5) every 2 days for 4 weeks. 4.2.5.2. ELISA of brain Ab. Postmortem brains of the mice were immediately removed. The brain samples were homogenized in 3 mL of RIPA buffer (100 mM Tris, pH 8.0, 150 mM NaCl, 0.5% DOC, 1% NP-40, 0.2% SDS and proteinase inhibitor cocktail) and sonicated for 20 s on ice. The total Ab1–40 and Ab1–42 level from the brain homogenates were measured using ELISA kits (Cat# 27713 for 40, Cat# 27711 for 42, IBL), by following the manufacturer’s protocol. 4.2.5.3. Amyloid plaque staining. For histological analysis, animals were sacrificed and the brains were removed. The brains ware

stored at 4 °C overnight in neutral buffered 10% formalin solution then immersed in a solution of 30% sucrose in PBS. Serial 30-lmthick coronal tissue sections were cut on a cryostat (Leica) and stored in cryoprotectant (25% ethylene glycol and 25% glycerol in 0.05 M PB) at 20 °C. Areas of amyloid deposition in mice brain were determined by staining with 0.2% Congo-Red (Sigma) solution as described in the manufacturer’s protocol. For quantification, digital images were captured at 10 magnification on an Olympus IX81 Imaging System. Image J software (NIH Image, Bethesda, MD) was used to quantify positive pixels and total area. 4.2.6. Statistical analysis All data are shown as mean ± SEM. Statistical differences between groups were defined by t-test using GraphPad Prism 4 software (Version 4.03, GraphPad software, Inc.). A p-value <0.05 was considered statistically significant. Acknowledgments This work was supported by the Korea Science and Engineering Foundation (KOSEF) Grant (NRF-2009-0081669) funded by the Korea Government (MOST). References and notes 1. Kawas, C. H. N. Engl. J. Med. 2003, 349, 1056. 2. Tiraboschi, P.; Hansen, L. A.; Thal, L. J.; Corey-Bloom, J. Neurology 2004, 62, 1984. 3. Zlokovic, B. V.; Ghiso, J.; Mackic, J. B.; McComb, J. G.; Weiss, M. H.; Frangione, B. Biochem. Biophys. Res. Commun. 1993, 197, 1034. 4. Zlokovic, B. V.; Yamada, S.; Holtzman, D.; Ghiso, J.; Frangione, B. Nat. Med. 2000, 6, 718. 5. Zlokovic, B. V. Nat. Rev. Neurosci. 2011, 12, 723. 6. Karran, E.; Mercken, M.; De Strooper, B. Nat. Rev. Drug. Disc. 2011, 10, 698. 7. Deane, R.; Du Yan, S.; Submamaryan, R. K.; LaRue, B.; Jovanovic, S.; Hogg, E.; Welch, D.; Manness, L.; Lin, C.; Yu, J.; Zhu, H.; Ghiso, J.; Frangione, B.; Stern, A.; Schmidt, A. M.; Armstrong, D. L.; Arnold, B.; Liliensiek, B.; Nawroth, P.; Hofman, F.; Kindy, M.; Stern, D.; Zlokovic, B. Nat. Med. 2003, 9, 907. 8. Mackic, J. B.; Stins, M.; McComb, J. G.; Calero, M.; Ghiso, J.; Kim, K. S.; Yan, S. D.; Stern, D.; Schmidt, A. M.; Frangione, B.; Zlokovic, B. V. J. Clin. Invest. 1998, 102, 734. 9. Neeper, M.; Schmidt, A. M.; Brett, J.; Yan, S. D.; Wang, F.; Pan, Y. C.; Elliston, K.; Stern, D.; Shaw, A. J. Biol. Chem. 1992, 267, 14998. 10. Schmidt, A. M.; Vianna, M.; Gerlach, M.; Brett, J.; Ryan, J.; Kao, J.; Esposito, C.; Hegarty, H.; Hurley, W.; Clauss, M. J. Biol. Chem. 1992, 267, 14987. 11. Fritz, G. Trends Biochem. Sci. 2011, 36, 625. 12. Hofmann, M. A.; Drury, S.; Fu, C.; Qu, W.; Taguchi, A.; Lu, Y.; Avila, C.; Kambham, N.; Bierhaus, A.; Nawroth, P.; Neurath, M. F.; Slattery, T.; Beach, D.; McClary, J.; Nagashima, M.; Morser, J.; Stern, D.; Schmidt, A. M. Cell 1999, 97, 889. 13. Hori, O.; Brett, J.; Slattery, T.; Cao, R.; Zhang, J.; Chen, J. X.; Nagashima, M.; Lundh, E. R.; Vijay, S.; Nitecki, D. J. Biol. Chem. 1995, 270, 25752. 14. Logsdon, C. D.; Fuentes, M. K.; Huang, E. H.; Arumugam, T. Curr. Mol. Med. 2007, 7, 777. 15. Yamamoto, H.; Watanabe, T.; Yamamoto, Y.; Yonekura, H.; Munesue, S.; Harashima, A.; Ooe, K.; Hossain, S.; Saito, H.; Murakami, N. Curr. Mol. Med. 2007, 7, 752. 16. Bucciarelli, L. G.; Wendt, T.; Qu, W.; Lu, Y.; Lalla, E.; Rong, L. L.; Goova, M. T.; Moser, B.; Kislinger, T.; Lee, D. C.; Kashyap, Y.; Stern, D. M.; Schmidt, A. M. Circulation 2002, 106, 2827. 17. Yan, S. D.; Bierhaus, A.; Nawroth, P. P.; Stern, D. M. J. Alzheimers Dis. 2009, 16, 833. 18. Yan, S. D.; Zhu, H.; Fu, J.; Yan, S. F.; Roher, A.; Tourtellotte, W. W.; Rajavashisth, T.; Chen, X.; Godman, G. C.; Stern, D.; Schmidt, A. M. Proc. Natl. Acad. Sci. U.S.A. 1997, 94, 5296. 19. Clynes, R.; Moser, B.; Yan, S. F.; Ramasamy, R.; Herold, K.; Schmidt, A. M. Curr. Mol. Med. 2007, 7, 743. 20. Yan, S. D.; Chen, X.; Fu, J.; Chen, M.; Zhu, H.; Roher, A.; Slattery, T.; Zhao, L.; Nagashima, M.; Morser, J.; Migheli, A.; Nawroth, P.; Stern, D.; Schmidt, A. M. Nature 1996, 382, 685. 21. Yan, S. D.; Roher, A.; Chaney, M.; Zlokovic, B.; Schmidt, A. M.; Stern, D. Biophys. Acta 2000, 1502, 145. 22. Yan, S. D.; Zhu, H.; Zhu, A.; Golabek, A.; Du, H.; Roher, A.; Yu, J.; Soto, C.; Schmidt, A. M.; Stern, D.; Kindy, M. Nat. Med. 2000, 6, 643. 23. Hudson, B. I.; Bucciarelli, L. G.; Wendt, T.; Sakaguchi, T.; Lalla, E.; Qu, W.; Lu, Y.; Lee, L.; Stern, D. M.; Naka, Y.; Ramasamy, R.; Yan, S. D.; Yan, S. F.; D’Agati, V.; Schmidt, A. M. Arch. Biochem. Biophys. 2003, 419, 80.

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