The synthesis and antistaphylococcal activity of dehydroabietic acid derivatives: modifications at C12 and C7

European Journal of Medicinal Chemistry 127 (2017) 917e927

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Research paper

The synthesis and antistaphylococcal activity of dehydroabietic acid derivatives: modifications at C12 and C7 Wen-Ming Zhang a, Teng Yang b, d, Xue-Ying Pan c, d, Xin-Lan Liu a, Hai-Xia Lin a, Zhao-Bing Gao d, Cai-Guang Yang d, **, Yong-Mei Cui a, d, * a

Department of Chemistry, Innovative Drug Research Center, College of Sciences, Shanghai University, Shanghai 200444, China Center for Research and Development of Fine Chemicals, Guizhou University, Guiyang, 550025 China Nano Science and Technology Institute, University of Science and Technology of China, Suzhou, 215123 China d State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai 201203, China b c

a r t i c l e i n f o

a b s t r a c t

Article history: Received 31 July 2016 Received in revised form 31 October 2016 Accepted 1 November 2016 Available online 3 November 2016

A series of 7-N-acylaminoethyl/propyloxime derivatives of dehydroabietic acid were synthesized and investigated for their antibacterial activity against Staphylococcus aureus Newman strain and multidrugresistant strains (NRS-1, NRS-70, NRS-100, NRS-108 and NRS-271). Most of the target compounds having trifluoromethyl phenyl/benzyl, halogen-substituted thiophenyl, benzothiophenyl or pyrrolyl moiety exhibited potent in vitro antibacterial activity. Among which, compounds 4m, 4x and 7j showed high antibacterial activity with minimum inhibitory concentration (MIC) values of 1.25e3.13 mg/mL against five multidrug-resistant S. aureus. © 2016 Elsevier Masson SAS. All rights reserved.

Keywords: Antistaphylococcal Multidrug-resistant Synthesis Oxime Dehydroabietic acid

1. Introduction The Gram-positive bacterium Staphylococcus aureus is a common cause of tissue carbuncles and food poisoning, implant-device and wound-related infections, bacteremia, etc [1]. It is a principal cause of hospital infections, and has become resistant to many different classes of antibiotics [2]. Of special concern are the strains designated as methicillin-resistant S. aureus (MRSA), which are broadly resistant to most b-lactam antibiotics, agents of historic choice for treatment of infections by S. aureus [3]. Thus search for novel classes of antibiotics effective against these organisms is necessarily urgent. Abietanes are a family of naturally occurring diterpenoids with interesting biological activities such as antiulcer, antitumor, antiviral, antimicrobial, and anti-inflammatory activities [4e9]. Interestingly, dehydroabietic acid (DHAA, Fig. 1) and its derivatives 1 inhibited the formation of bacterial biofilm during infections of

* Corresponding author. ** Corresponding author. E-mail addresses: [email protected] (Y.-M. Cui).

(C.-G.

Yang),

http://dx.doi.org/10.1016/j.ejmech.2016.11.002 0223-5234/© 2016 Elsevier Masson SAS. All rights reserved.

[email protected]

S. aureus, which demonstrated its ability not only to prevent bacterial colonization, but also to inhibit existing biofilms [10,11]. In addition to the several series of DHAA derivatives that displayed potent antimicrobial activities [12e14], there are still interesting modifications to be exploited, especially for antibiotic-resistant Gram-positive bacteria. Our previous study showed that DHAA structure provides a template for chemical modulators of largeconductance calcium-activated Kþ channels and have carried out various chemical modifications on it [15e20]. In an effort to identify new antibacterial agents, we have screened over our synthesized DHAA derivatives for their potential activity against S. aureus strain Newman and found that some of the 7-N-acylaminoethyloxime derivatives reported (4b-x, Table 1) could inhibit Newman with minimal inhibitory concentration (MIC) values of 1.25e2.5 mg/mL. In view of the above findings and as an extension of our study on the development of new antistaphylococcal agents [21,22], we designed and synthesized a new series of 7-N-acylaminopropyloxime derivatives with different terminal groups on the alkyl side chain (7a-s, 8a-d, Table 2). The in vitro antimicrobial activities against S. aureus strain Newman and five multidrug-resistant S. aureus were evaluated. We describe herein the structureactivity relationship (SAR) for antistaphylococcal activity for this

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W.-M. Zhang et al. / European Journal of Medicinal Chemistry 127 (2017) 917e927

Fig. 1. The structures of dehydroabietic acid (DHAA), 1 and 2.

set of molecules with modifications at C12 and C7 (general structure 2, Fig. 1). 2. Chemistry All the compounds are compiled in Tables 1 and 2. The known compounds 4a¡x were synthesized by the previously reported methods. Acylation of 4a with various carboxylic chlorides under basic conditions afforded 5a-d. Using similar procedures, acylation of 3 with various carboxylic chlorides under basic conditions, followed by hydrolysis of the methyl ester with KOBut and DMSO yielded corresponding compounds 7a-s. Treatment of 9a with NH2OCH2CH2CH2NHBoc in EtOH and pyridine under heating at reflux afforded the corresponding E-oxime 9b as the sole isolated product. Deprotection of the Boc group of 9b in the presence of trifluoroacetic acid, followed by reaction with appropriate acyl chloride, yielded corresponding compounds 8a-d (Scheme 1). 3. Antimicrobial studies All the newly synthesized DHAA derivatives were screened for the antibacterial activities. The strains used in this assay were Gram-positive bacteria, S. aureus Newman, five multidrug-resistant S. aureus, including NRS-1 (resistant to aminoglycosides and tetracycline), NRS-70 (resistant to erythromycin), NRS-100 (resistant to oxacillin and tetracycline), NRS-108 (resistant to gentamicin) and NRS-271 (linezolide resistant, containing phage type EMRSA 15), and the Gram-negative bacterium, E. coli AB1157. The antimicrobial activity was assessed in terms of MICs, defined as the lowest concentrations of compound at which microbial growth was inhibited. Vancomycin and tetracycline were assayed as positive controls. All strains were grown at 37  C overnight in TSB in the absence of antibiotic. Overnight cultures diluted 1000 fold were grown at 37  C for 2e3 h until A600 reaches 0.6. Bacteria were diluted 1:400 into fresh TSB medium, and then compounds were prepared in DMSO and diluted serially by two-fold to final concentrations in the range of 0.39e50 mg/mL. Equal volume of bacteria and compound were added to 96 well plates and mixed well by shaking. After 18 h incubation, the A600 of each well was visualized by Bioteksynergy2. The experiments were performed in triplicate for each condition. None of the compounds in this study was observed to be active against E. coli AB1157 at 50 mg/mL (data not shown). The antistaphylococcal activities of the newly synthesized DHAA derivatives MICs are summarized in Tables 1-3. 4. Results and discussion As shown in Table 1, the aminoethyloxime derivative 4a was inactive against the growth of S. aureus Newman at 50 mg/mL. Alkyl acylation (compounds 4b-e) showed no improvements on the activity, as compared with the N-unsbstituted amine 4a. That is, all the alkyl acylamino derivatives were inactive, except that compound 4d showed moderate antibacterial potential against

S. aureus with the MIC in the range of 7.5e10.0 mg/mL. The amide derivative with phenyl group 4f showed moderate antibacterial activity with MIC at 10e12.5 mg/mL. Among the aryl-group containing derivatives 4g-n, the activity is quite sensitive to the positions and properties of the aromatic substituents. In the series of compounds 4g-k, para-substitution of a methoxy group on the phenyl ring (compound 4h) decreased the activity, while orthosubstitution of a methoxy group (compound 4g) increased the activity, compared to 4f. The ethyl and fluoro derivatives (compounds 4h-j) also showed increased activity. Among the three regioisomers 4l-n of the trifluoromethyl substituent, the para isomer 4m with MIC at 2.5 mg/mL was more potent than the ortho and meta CF3substituted isomers (4l, 4n). In the series of compounds 5a-d, introduction of an electron-withdrawing CF3 group increased the activity, regardless of the positions (compounds 5b-d); compared to compound 5a that is lack of substitution. In the series of aromatic heterocycles such as furan, pyrrole, pyridine, and thiophene-containing derivatives (4o-s), antibacterial activity data showed that derivatives containing heteroaromatic rings having one nitrogen atom exhibited better activities compared to those with other five-membered rings (4o¡p vs 4q¡s). In particular, the pyrrole derivative 4o possessed the most potent antibacterial activities, with MICs ranging from 3.13 to 5 mg/ mL. The effects of the substitution on the thiophene ring were also explored. Both electron withdrawing and donating groups were introduced to explore the SAR. Interestingly, the introduction of any group to 2-thiophene ring improved the activity (4t-x). The 2substituted thiophene derivatives with 5-Me, 4-Br, 5-Br, and 5-Cl substituents displayed enhanced antibacterial activity (4t-w vs 4s), and compounds 4v and 4w were the most active compounds in this series. Fused with another phenyl ring in compound 4s dramatically improved the antibacterial activity (4x vs 4s). Similar trends were observed with the 7-N-acylaminopropyloxime derivatives (Table 2). In general, the amide derivatives bearing trifluoromethylphenyl, trifluoromethylbenzyl, pyrrolyl and substituted thiophenyl groups (7h-j, 8c-d and 7p-s) displayed good antibacterial activity. Compounds 7h and 7i, bearing an electronwithdrawing CF3 substituent in the 3- and 4-positions, respectively, showed higher activity compared to its 2-position regioisomer 7g, an observation similar to that found with the substituted benzyl derivatives 8b-d. The pyrrole derivative 7i displayed very potent antibacterial activity. Of note, compound 7k, fused with another phenyl ring, showed more than 10-fold decrease in activity. In the series of compounds 7n-s, introduction of a bromine or chlorine atom or fused with another phenyl ring (7p-s, MIC ¼ 1.25e2.5 mg/mL) enhanced the antibacterial activity greatly, compared to the unsubstituted compound 7n with MIC more than 50 mg/mL. The most active compounds against the growth of S. aureus Newman strain were further evaluated the inhibitory activities against five multidrug-resistant strains of S. aureus (Table 3). For the 7-N-acylaminoethyloxime derivatives, all compounds (4m and 4vx) displayed good in vitro antibacterial activity and had comparable MICs against all the five resistant strains, S. aureus NRS-1, NRS-70, NRS-100, NRS-108, and NRS-271. The m-CF3 phenyl derivative 4m and the 2-benzothiophene derivative 4x showed the most potent activity with MICs of 1.25e3.13 mg/mL. However, the elongation of an alkylenic spacer of 4x between the oximic group and the amide head resulted in loss of antistaphylococcal activity (7s vs 4x) and 7s failed to inhibit the growth of the five multidrug-resistant S. aureus stains at 25 mg/mL. For the other 7-N-acylaminopropyloxime derivatives, it's interesting to note that compound 7j with 2-pyrole displayed very potent antibacterial activity against all the tested strains. All the other compounds 7h-i, 7p-r and 8c-d showed potent antibacterial activity except for NRS-70 strain.

W.-M. Zhang et al. / European Journal of Medicinal Chemistry 127 (2017) 917e927

5. Conclusions In summary, a study of antistaphylococcal activity of series of 7N-acylaminoethyl/propyloxime derivatives of dehydroabietic acid derivatives has been performed in vitro. Most of the target compounds having trifluoromethyl phenyl/benzyl, halogen-substituted thiophenyl, benzothiophenyl or pyrrolyl moiety exhibited potent in vitro antistaphylococcal activity. Among which, Compounds 4m, 4x and 7j showed high antibacterial activity with MIC values of 1.25e3.13 mg/mL against five multidrug-resistant S. aureus. This study highlights the value of dehydroabietic acid as starting point for the development of new antimicrobial agents to combat S. aureus infection. Further study in the antistaphylococcal mechanism of these DHAA derivatives is yet to be investigated. 6. Experimental 6.1. General Thin-layer chromatography (TLC) was conducted on silica gel GF254 plates. 1H NMR spectra and 13C NMR spectra were recorded on a Bruker Avance (500 MHz) spectrometer, using CDCl3 as solvent. Chemical shifts were reported in the scale relative to CHCl3 (7.26 ppm) for 1H NMR, and to CDCl3 (77.16 ppm) for 13C NMR, as internal references. Melting points were determined on an XD-4 digital micro melting point apparatus. High resolution mass spectrometer (HRMS) spectra were recorded on a Bruker Daltonics, Inc. APEXIII7.0 TESLA FTMS instrument. 6.2. General procedure for preparation of compounds 5a-5d A mixture of 4a [20] (0.11 mmol), Et3N (0.22 mol) and appropriate acyl chloride (0.13 mmol) in DMF (5 mL) was stirred at rt for 3 h under nitrogen atmosphere, then the solvent was evaporated in vacuum. The residue was diluted with water. The whole mixture was extracted with AcOEt for three times. The combined organic layer was washed with water, sat. brine, and dried over Na2SO4. The crude product was purified by column chromatography using petroleum ether/AcOEt (1/1e4/3, v/v) as eluent to afford 5a-d. 6.2.1. (1R,4aS,E)-6-Bromo-7-isopropyl-1,4a-dimethyl-9-((3-(2phenylacetamido)propoxy)imino)-1,2,3,4,4a,9,10,10aoctahydrophenanthrene-1-carboxylic acid (5a) Yellow oil, yield 33%. 1H NMR (500 MHz, CDCl3) d 7.75 (s, 1H), 7.44 (s, 1H), 7.27e7.19 (m, 5H), 5.97 (s, 1H), 4.23 (t, J ¼ 5.0 Hz, 2H), 3.65e3.52 (m, 4H), 3.31 (dq, J ¼ 13.9, 6.9 Hz, 1H), 2.67 (dd, J ¼ 18.7, 4.7 Hz, 1H), 2.48 (dt, J ¼ 18.7, 14.1 Hz, 1H), 2.35e2.21 (m, 2H), 1.82e1.72 (m, 4H), 1.66e1.57 (m, 1H), 1.37 (d, J ¼ 5.3 Hz, 3H), 1.25 (dd, J ¼ 12.6, 5.8 Hz, 6H), 1.10 (s, 3H); 13C NMR (125 MHz, CDCl3) d 182.57, 171.58, 154.25, 149.95, 146.53, 145.02, 134.72, 129.40, 128.91, 128.60, 128.32, 127.63, 127.27, 126.30, 122.48, 72.46, 46.13, 43.66, 41.31, 39.85, 37.06, 36.43, 33.73, 32.64, 23.78, 22.88, 22.86, þ 22.77, 18.03, 16.44. HR-MS: calcd for C30H79 37BrN2O4 ([MþH] ), 569.2016; found, 569.2009. 6.2.2. (1R,4aS,E)-6-Bromo-7-isopropyl-1,4a-dimethyl-9-((3-(2-(2(trifluoromethyl)phenyl)acetamido)propoxy)imino)1,2,3,4,4a,9,10,10a-octahydrophenanthrene-1-carboxylic acid (5b) Yellow oil, yield 29%. 1H NMR (500 MHz, CDCl3) d 7.72 (s, 1H), 7.43 (t, J ¼ 6.4 Hz, 2H), 7.42e7.36 (m, 2H), 7.26 (s, 1H), 5.90 (s, 1H), 4.23 (t, J ¼ 5.1 Hz, 2H), 3.86 (s, 2H), 3.60 (s, 2H), 3.29 (dt, J ¼ 13.5, 6.7 Hz, 1H), 2.64 (dd, J ¼ 18.8, 4.8 Hz, 1H), 2.52e2.47 (m, 1H), 2.32e2.18 (m, 2H), 1.80e1.69 (m, 4H), 1.66e1.52 (m, 1H), 1.35 (d, J ¼ 4.8 Hz, 3H), 1.24e1.19 (m, 6H), 1.09 (s, 3H); 19F NMR (470 MHz, CDCl3) d -59.72; 13C NMR (125 MHz, CDCl3) d 182.78, 175.43, 171.28,

919

170.07, 154.25, 149.91, 148.51, 146.63, 145.06, 132.64, 132.51, 132.18, 131.95, 128.35, 127.59, 127.46, 72.48, 46.08, 41.30, 40.27, 39.80, 37.10, 36.43, 32.63, 29.70, 27.81, 23.71, 22.80, 22.71, 17.94, 16.34. HRþ MS: calcd for C31H79 36BrF3N2O4 ([MþH] ), 637.1890; found, 637.1888. 6.2.3. (1R,4aS,E)-6-Bromo-7-isopropyl-1,4a-dimethyl-9-((3-(2-(3(trifluoromethyl)phenyl)acetamido)propoxy)imino)1,2,3,4,4a,9,10,10a-octahydrophenanthrene-1-carboxylic acid (5c) Yellow oil, yield 35%. 1H NMR (500 MHz, CDCl3) d 7.75 (s, 1H), 7.48 (dd, J ¼ 14.5, 6.7 Hz, 2H), 7.42 (d, J ¼ 9.6 Hz, 2H), 7.33 (dt, J ¼ 12.4, 7.7 Hz, 1H), 6.21 (s, 1H), 4.24 (t, J ¼ 5.1 Hz, 2H), 3.67e3.52 (m, 4H), 3.29 (dq, J ¼ 13.7, 6.9 Hz, 1H), 2.70 (dd, J ¼ 18.7, 4.6 Hz, 1H), 2.48 (dd, J ¼ 13.5, 5.1 Hz, 1H), 2.31e2.19 (m, 2H), 1.79e1.67 (m, 4H), 1.63e1.49 (m, 1H), 1.33 (d, J ¼ 5.5 Hz, 3H), 1.24e1.20 (m, 6H), 1.09 (s, 3H); 19F NMR (470 MHz, CDCl3) d -62.59; 13C NMR (125 MHz, CDCl3) d 182.81, 170.49, 154.52, 149.99, 145.08, 135.79, 132.67, 129.24, 129.20, 128.17, 127.73, 126.43, 126.07, 126.04, 124.04, 122.36, 72.32, 46.14, 43.14, 41.40, 40.01, 37.00, 36.45, 32.62, 32.41, 24.12, 23.78, 22.84, 22.77, 17.99, 16.34. HR-MS: calcd for C31H79 36BrF3N2O4 ([MþH]þ), 637.1890; found, 637.1888. 6.2.4. (1R,4aS,E)-6-Bromo-7-isopropyl-1,4a-dimethyl-9-((3-(2-(4(trifluoromethyl)phenyl)acetamido)propoxy)imino)1,2,3,4,4a,9,10,10a-octahydrophenanthrene-1-carboxylic acid (5d) Yellow oil, yield 28%. 1H NMR (500 MHz, CDCl3) d 7.75 (s, 1H), 7.49 (d, J ¼ 8.0 Hz, 1H), 7.42 (s, 1H), 7.39 (d, J ¼ 8.0 Hz, 1H), 7.33 (d, J ¼ 7.7 Hz, 2H), 6.20 (s, 1H), 4.25 (t, J ¼ 5.0 Hz, 2H), 3.66e3.48 (m, 4H), 3.30 (dt, J ¼ 13.6, 6.8 Hz, 1H), 2.69 (dd, J ¼ 18.7, 4.2 Hz, 1H), 2.49 (m, 1H), 2.26e2.18 (m, 2H), 1.79e1.68 (m, 4H), 1.65e1.50 (m, 1H), 1.33 (d, J ¼ 4.5 Hz, 3H), 134e1.19 (m, 6H), 1.07 (s, 3H); 19F NMR (470 MHz, CDCl3) d -60.48; 13C NMR (125 MHz, CDCl3) d 182.53, 170.48, 154.52, 150.01, 145.08, 138.85, 129.81, 129.64, 129.62, 128.17, 127.76, 126.46, 125.67, 125.51, 122.32, 122.06, 72.28, 46.14, 43.90, 41.45, 40.08, 36.96, 36.44, 33.74, 32.61, 23.79, 22.83, 22.78, 21.05, þ 17.99, 16.35. HR-MS: calcd for C31H79 36BrF3N2O4 ([MþH] ), 637.1890; found, 637.1879. 6.3. General procedure for preparation of compounds 3a-s A mixture of 3 (0.216 mmol), K2CO3 (0.324 mmol) in acetonitrile (25 mL), and the appropriate acyl chloride (0.26 mmol) was added under nitrogen atmosphere, stirred at rt for 3 h, the solvent was evaporated in vacuum. The residue was diluted with water. The whole mixture was extracted with AcOEt for three times. The combined organic layer was washed with water, sat. brine, and dried over Na2SO4. The crude product was purified by column chromatography using petroleum ether/AcOEt (2/1e5/1, v/v) as eluent to afford 3a-s. 6.3.1. (1R,4aS,E)-Methyl-6-bromo-7-isopropyl-1,4a-dimethyl-9((3-pivalamidopropoxy)imino)-1,2,3,4,4a,9,10,10aoctahydrophenanthrene-1-carboxylate (3a) White solid, yield 60%. 1H NMR (500 MHz, CDCl3) d 7.78 (s, 1H), 7.41 (s, 1H), 5.92 (s, 1H), 4.26 (t, J ¼ 5.9 Hz, 2H), 3.65 (s, 3H), 3.39 (dd, J ¼ 12.5, 6.4 Hz, 2H), 3.30 (m, 1H), 2.55 (d, J ¼ 8.6 Hz, 2H), 2.25 (dd, J ¼ 20.0, 10.9 Hz, 2H), 1.98e1.90 (m, 2H), 1.78e1.67 (m, 4H), 1.67e1.60 (m, 1H), 1.35 (s, 3H), 1.25 (d, J ¼ 4.9 Hz, 6H), 1.18 (s, 9H), 1.10 (s, 3H). 6.3.2. (1R,4aS,E)-Methyl-6-bromo-9-((3(cyclopropanecarboxamido)propoxy)imino)-7-isopropyl-1,4adimethyl-1,2,3,4,4a,9,10,10a-octahydrophenanthrene-1-carboxylate (3b) White solid, yield 53%. 1H NMR (500 MHz, CDCl3) d 7.78 (s, 1H), 7.41 (s, 1H), 5.99 (s, 1H), 4.29 (t, J ¼ 5.9 Hz, 2H), 3.64 (s, 3H),

920

W.-M. Zhang et al. / European Journal of Medicinal Chemistry 127 (2017) 917e927

Table 1 In vitro antibacterial activity of 7-N-acylaminoethyloxime derivatives against S. aureus Newman.

Table 1 (continued ) Compound

Compound

R

mM

<2.5 <3.13 12.5e20 >50 >50 40e50

<1.73 <2.16 41.61e66.57 >110.77 >101.33 76.70e95.88

4d

7.5e10.0

13.64e18.20

4e

30e40

57.75e77.00

4f

10e12.5

18.00e22.50

4g

5e6.25

8.54e10.67

4h

15e20

25.62e34.16

e e e CH3

MIC

mg/mL

mM

4r

>50

>89.04

4s

>50

>89.04

4t

7.5e10

13.03e17.37

4u

3.75e5

5.86e7.81

4v

2.5

3.90

4w

2.5

4.19

4x

1.25e2.5

2.04e4.09

5a

10.0

17.56

5b

5.0

7.84

5c

3.75e5.0

5.88e7.84

5d

3.75e5.0

5.88e7.84

MIC

mg/mL vancomycin tetracycline DHAA 4a 4b 4c

R

4i

2.5e3.75

4.28e6.42

4j

7.5e10

13.08e17.44

4k

3.75e5.0

5.81e7.75

4l

6.25e12.5

10.02e20.05

4m

2.5

4.01

4n

3.13e5

5.02e8.02

4o

3.13e5

5.75e9.18

4p

15e20

26.95e35.94

4q

20e25

36.67e45.83

3.46e3.38 (m, 2H), 3.30 (dt, J ¼ 13.8, 6.9 Hz, 1H), 2.56 (d, J ¼ 9.2 Hz, 2H), 2.25 (dd, J ¼ 20.3, 11.1 Hz, 1H), 1.98e1.91 (m, 2H), 1.74 (s, 4H), 1.66e1.57 (m, 1H), 1.34 (s, 3H), 1.32e1.29 (m, 1H), 1.26e1.23 (m, 6H), 1.11 (s, 3H), 0.98e0.93 (m, 2H), 0.71 (dd, J ¼ 7.9, 2.9 Hz, 2H). 6.3.3. (1R,4aS,E)-Methyl-9-((3-benzamidopropoxy)imino)-6bromo-7-isopropyl-1,4a-dimethyl-1,2,3,4,4a,9,10,10aoctahydrophenanthrene-1-carboxylate (3c) White solid, yield 69%. 1H NMR (500 MHz, CDCl3) d 7.77 (s, 1H), 7.74e7.70 (m, 2H), 7.46 (t, J ¼ 7.4 Hz, 1H), 7.41 (s, 1H), 7.36 (t, J ¼ 7.6 Hz, 2H), 6.54 (s, 1H), 4.34 (t, J ¼ 5.9 Hz, 2H), 3.72e3.54 (m, 5H), 3.27 (dt, J ¼ 13.7, 6.8 Hz, 1H), 2.62e2.49 (m, 2H), 2.29e2.20 (m, 2H), 2.11e2.05 (m, 2H), 1.73 (s, 4H), 1.66e1.61 (m, 1H), 1.32 (s, 3H), 1.23 (d, J ¼ 7.0 Hz, 3H),1.22 (d, J ¼ 6.7 Hz, 3H),1.08 (s, 3H). 6.3.4. (1R,4aS,E)-Methyl-6-bromo-7-isopropyl-9-((3-(4methoxybenzamido)propoxy)imino)-1,4a-dimethyl1,2,3,4,4a,9,10,10a-octahydrophenanthrene-1-carboxylate (3d) White solid, yield 63%. 1H NMR (500 MHz, CDCl3) d 7.78 (s, 1H), 7.68 (d, J ¼ 8.8 Hz, 2H), 7.41 (s, 1H), 6.84 (d, J ¼ 8.8 Hz, 2H), 6.44 (s, 1H), 4.33 (t, J ¼ 6.0 Hz, 2H), 3.82 (s, 3H), 3.68e3.53 (m, 5H), 3.28 (m, 1H), 2.60e2.51 (m, 2H), 2.28e2.18 (m, 2H), 2.08e1.98 (m, 2H), 1.71 (s, 4H), 1.67e1.60 (m, 1H), 1.33 (s, 3H), 1.24 (d, J ¼ 6.7 Hz, 3H),1.23 (d, J ¼ 6.8 Hz, 3H),1.08 (s, 3H). 6.3.5. (1R,4aS,E)-Methyl-6-bromo-9-((3-(2-fluorobenzamido) propoxy)imino)-7-isopropyl-1,4a-dimethyl-1,2,3,4,4a,9,10,10aoctahydrophenanthrene-1-carboxylate (3e) White solid, yield 45%. 1H NMR (500 MHz, CDCl3) d 8.09 (dd,

W.-M. Zhang et al. / European Journal of Medicinal Chemistry 127 (2017) 917e927

J ¼ 8.8, 7.0 Hz, 1H), 7.78 (s, 1H), 7.45 (dd, J ¼ 13.3, 5.7 Hz, 1H), 7.40 (s, 1H), 7.24 (d, J ¼ 7.6 Hz, 1H), 7.09 (dd, J ¼ 12.0, 8.5 Hz, 1H), 7.02 (s, 1H), 4.33 (t, J ¼ 5.9 Hz, 2H), 3.68e3.59 (m, 5H), 3.28 (dt, J ¼ 13.6, 6.7 Hz, 1H), 2.59e2.54 (m, 2H), 2.29e2.20 (m, 2H), 2.11e2.03 (m, 2H), 1.79e1.69 (m, 4H), 1.61 (s, 1H), 1.34 (s, 3H), 1.25 (d, J ¼ 6.8 Hz, 3H),1.24 (d, J ¼ 6.8 Hz, 3H),1.10 (s, 3H). 6.3.6. (1R,4aS,E)-Methyl-6-bromo-7-isopropyl-1,4a-dimethyl-9((3-(perfluorobenzamido)propoxy)imino)-1,2,3,4,4a,9,10,10aoctahydrophenanthrene-1-carboxylate (3f) White solid, yield 71%. 1H NMR (500 MHz, CDCl3) d 7.71 (s, 1H), 7.41 (s, 1H), 6.40 (brs, 1H), 4.33 (t, J ¼ 5.7 Hz, 2H), 3.64e3.52 (m, 5H), 3.28 (dq, J ¼ 13.6, 6.9 Hz, 1H), 2.57e2.50 (m, 2H), 2.25e2.18 (m, 2H), 2.10e2.03 (m, 2H), 1.78e1.69 (m, 4H), 1.66e1.58 (m, 1H), 1.31 (s, 3H), 1.19 (dd, J ¼ 6.8, 4.5 Hz, 6H), 1.09 (s, 3H). 6.3.7. (1R,4aS,E)-Methyl-6-bromo-7-isopropyl-1,4a-dimethyl-9((3-(2-(trifluoromethyl)benzamido)propoxy)imino)1,2,3,4,4a,9,10,10a-octahydrophenanthrene-1-carboxylate (3g) White solid, yield 33%. 1H NMR (500 MHz, CDCl3) d 7.73 (s, 1H), 7.67 (t, J ¼ 8.3 Hz, 1H), 7.57e7.48 (m, 3H), 7.39 (s, 1H), 6.11 (s, 1H), 4.33 (t, J ¼ 6.0 Hz, 2H), 3.66e3.55 (m, 5H), 3.26 (dt, J ¼ 13.4, 6.7 Hz, 1H), 2.58e2.42 (m, 2H), 2.22 (dd, J ¼ 12.8, 5.5 Hz, 2H), 2.10e1.98 (m, 2H), 1.77e1.67 (m, 4H), 1.64e1.59 (m, 1H), 1.28 (s, 3H), 1.24 (d, J ¼ 6.7 Hz, 3H),1.23 (d, J ¼ 6.9 Hz, 3H),1.06 (s, 3H). 6.3.8. (1R,4aS,E)-Methyl-6-bromo-7-isopropyl-1,4a-dimethyl-9((3-(3-(trifluoromethyl)benzamido)propoxy)imino)1,2,3,4,4a,9,10,10a-octahydrophenanthrene-1-carboxylate (3h) White solid, yield 46%. 1H NMR (500 MHz, CDCl3) d 8.05 (s, 1H), 7.86 (d, J ¼ 7.7 Hz, 1H), 7.76 (s, 1H), 7.72 (d, J ¼ 7.6 Hz, 1H), 7.47 (t, J ¼ 7.8 Hz, 1H), 7.41 (s, 1H), 6.58 (brs, 1H), 4.33 (t, J ¼ 5.9 Hz, 2H), 3.72e3.56 (m, 5H), 3.27 (dt, 1H), 2.56 (dd, J ¼ 16.3, 9.1 Hz, 2H), 2.28e2.20 (m, 2H), 2.13e2.05 (m, 2H), 1.79e1.68 (m, 4H), 1.66e1.59 (m, 1H), 1.32 (s, 3H), 1.19 (t, J ¼ 6.7 Hz, 6H), 1.08 (s, 3H). 6.3.9. (1R,4aS,E)-Methyl-6-bromo-7-isopropyl-1,4a-dimethyl-9((3-(4-(trifluoromethyl)benzamido)propoxy)imino)1,2,3,4,4a,9,10,10a-octahydrophenanthrene-1-carboxylate (3i) White solid, yield 78%. 1H NMR (500 MHz, CDCl3) d 7.81 (d, J ¼ 8.0 Hz, 2H), 7.75 (s, 1H), 7.58 (d, J ¼ 8.2 Hz, 2H), 7.41 (s, 1H), 6.71 (s, 1H), 4.34 (t, J ¼ 5.7 Hz, 2H), 3.73e3.55 (m, 5H), 3.27 (dt, J ¼ 13.7, 6.9 Hz, 1H), 2.63e2.48 (m, 2H), 2.23 (dd, J ¼ 13.1, 5.4 Hz, 2H), 2.12e2.05 (m, 2H), 1.73 (s, 4H), 1.64e1.55 (m, 1H), 1.30 (s, 3H), 1.21e1.16 (m, 6H), 1.04 (s, 3H). 6.3.10. (1R,4aS,E)-Methyl-9-((3-(1H-pyrrole-2-carboxamido) propoxy)imino)-6-bromo-7-isopropyl-1,4a-dimethyl1,2,3,4,4a,9,10,10a-octahydrophenanthrene-1-carboxylate (3j) White solid, yield 31%. 1H NMR (500 MHz, CDCl3) d 9.68 (s, 1H), 7.78 (s, 1H), 7.42 (s, 1H), 6.82 (d, J ¼ 1.4 Hz, 1H), 6.32 (s, 1H), 6.27 (brs, 1H), 4.30 (t, J ¼ 5.8 Hz, 2H), 3.68e3.48 (m, 5H), 3.29 (dt, J ¼ 13.5, 6.8 Hz, 1H), 2.63e2.48 (m, 2H), 2.30e2.21 (m, 2H), 2.04e1.97 (m, 2H), 1.79e1.71 (m, 4H), 1.65e1.57 (m, 1H), 1.34 (s, 3H), 1.25 (d, J ¼ 7.0 Hz, 3H),1.25 (d, J ¼ 6.9 Hz, 3H),1.10 (s, 3H). 6.3.11. (1R,4aS,E)-Methyl-9-((3-(1H-indole-2-carboxamido) propoxy)imino)-6-bromo-7-isopropyl-1,4a-dimethyl1,2,3,4,4a,9,10,10a-octahydrophenanthrene-1-carboxylate (3k) White solid, yield 52%. 1H NMR (500 MHz, CDCl3) d 9.41 (s, 1H), 7.79 (s, 1H), 7.64 (d, J ¼ 8.1 Hz, 1H), 7.44e7.39 (m, 2H), 7.34 (t, J ¼ 7.6 Hz, 1H), 7.30 (brs, 1H), 7.21 (t, J ¼ 7.5 Hz, 1H), 4.36 (t, J ¼ 6.0 Hz, 2H), 3.75e3.66 (m, 2H), 3.64 (s, 3H), 3.27 (dt, J ¼ 13.7, 6.8 Hz, 1H), 2.60e2.54 (m, 2H), 2.26 (dd, J ¼ 11.3, 7.3 Hz, 1H), 2.22 (d, J ¼ 14.8 Hz, 1H), 2.14e2.08 (m, 2H), 1.78e1.67 (m, 4H), 1.65e1.61 (m,

921

1H), 1.32 (s, 3H), 1.22 (d, J ¼ 6.7 Hz, 3H), 1.21 (d, J ¼ 7.0 Hz, 3H), 1.09 (s, 3H). 6.3.12. (1R,4aS,E)-Methyl-6-bromo-7-isopropyl-1,4a-dimethyl-9((3-(picolinamido)propoxy)imino)-1,2,3,4,4a,9,10,10aoctahydrophenanthrene-1-carboxylate (3l) White solid, yield 16%. 1H NMR (500 MHz, CDCl3) d 8.50 (d, J ¼ 4.6 Hz, 1H), 8.25 (brs, 1H), 8.20 (d, J ¼ 7.8 Hz, 1H), 7.84 (dd, J ¼ 7.7, 6.0 Hz, 1H), 7.80 (s, 1H), 7.43e7.38 (m, 2H), 4.32 (t, J ¼ 6.1 Hz, 2H), 3.68e3.55 (m, 5H), 3.28 (m, 1H), 2.57 (d, J ¼ 9.8 Hz, 1H), 2.22 (dd, J ¼ 7.6 Hz, 1H), 2.12e2.05 (m, 2H), 1.79e1.69 (m, 4H), 1.67e1.59 (m, 1H), 1.34 (s, 3H), 1.26 (d, J ¼ 10.7 Hz, 3H),1.25 (d, J ¼ 10.6 Hz, 3H),1.11 (s, 3H). 6.3.13. (1R,4aS,E)-Methyl-6-bromo-7-isopropyl-1,4a-dimethyl-9((3-(thiophene-3-carboxamido)propoxy)imino)-1,2,3,4,4a,9,10,10aoctahydrophenanthrene-1-carboxylate (3m) White solid, yield 65%. 1H NMR (500 MHz, CDCl3) d 7.79 (dd, J ¼ 3.0, 1.3 Hz, 1H), 7.77 (s, 1H), 7.42 (s, 1H), 7.32 (dd, J ¼ 5.1, 1.3 Hz, 1H), 7.29e7.27 (m, 1H), 6.38 (s, 1H), 4.33 (t, J ¼ 5.8 Hz, 2H), 3.68e3.49 (m, 5H), 3.28 (dt, J ¼ 13.7, 6.8 Hz, 1H), 2.63e2.50 (m, 2H), 2.29e2.21 (m, 2H), 2.08e1.99 (m, 2H), 1.78e1.68 (m, 4H), 1.67e1.61 (m, 1H), 1.34 (s, 3H), 1.22 (d, J ¼ 6.8 Hz, 6H), 1.09 (s, 3H). 6.3.14. (1R,4aS,E)-Methyl-6-bromo-7-isopropyl-1,4a-dimethyl-9((3-(thiophene-2-carboxamido)propoxy)imino)-1,2,3,4,4a,9,10,10aoctahydrophenanthrene-1-carboxylate (3n) White solid, yield 71%. 1H NMR (500 MHz, CDCl3) d 7.78 (s, 1H), 7.45e7.38 (m, 3H), 7.01 (dd, J ¼ 4.9, 3.8 Hz, 1H), 6.39 (s, 1H), 4.33 (t, J ¼ 5.8 Hz, 2H), 3.69e3.51 (m, 5H), 3.28 (dt, J ¼ 13.8, 6.8 Hz, 1H), 2.58 (dd, J ¼ 9.2, 6.0 Hz, 2H), 2.29e2.20 (m, 2H), 2.09e2.01 (m, 2H), 1.78e1.69 (m, 4H), 1.65e1.61 (m, 1H), 1.34 (s, 3H), 1.22 (d, J ¼ 6.8 Hz, 6H), 1.09 (s, 3H). 6.3.15. (1R,4aS,E)-Methyl-6-bromo-7-isopropyl-1,4a-dimethyl-9((3-(5-methylthiophene-2-carboxamido)propoxy)imino)1,2,3,4,4a,9,10,10a-octahydrophenanthrene-1-carboxylate (3o) White solid, yield 57%. 1H NMR (500 MHz, CDCl3) d 7.78 (s, 1H), 7.41 (s, 1H), 7.24 (d, J ¼ 3.7 Hz, 1H), 6.66 (d, J ¼ 2.7 Hz, 1H), 6.27 (s, 1H), 4.31 (t, J ¼ 5.8 Hz, 2H), 3.64 (s, 3H), 3.57 (ddd, J ¼ 17.8, 13.0, 6.6 Hz, 2H), 3.28 (dt, J ¼ 14.0, 7.1 Hz, 1H), 2.57 (dd, J ¼ 9.1, 5.2 Hz, 2H), 2.29e2.20 (m, 2H), 2.07e1.99 (m, 2H) 1.78e1.69 (m, 4H), 1.67e1.54 (m, 1H), 1.34 (s, 3H), 1.25 (d, J ¼ 6.9 Hz, 3H),1.25 (d, J ¼ 7.0 Hz, 3H),1.10 (s, 3H). 6.3.16. (1R,4aS,E)-Methyl-6-bromo-9-((3-(4-bromothiophene-2carboxamido)propoxy)imino)-7-isopropyl-1,4a-dimethyl1,2,3,4,4a,9,10,10a-octahydrophenanthrene-1-carboxylate (3p) White solid, yield 67%. 1H NMR (500 MHz, CDCl3) d 7.77 (s, 1H), 7.40 (s, 1H), 7.34 (d, J ¼ 0.9 Hz, 1H), 7.30 (d, J ¼ 0.8 Hz, 1H), 6.86 (s, 1H), 4.36e4.25 (m, 2H), 3.64e3.47 (m, 5H), 3.33e3.23 (m, 1H), 2.74 (dd, J ¼ 18.5, 4.4 Hz, 1H), 2.56e2.46 (m, 1H), 2.27e2.20 (m, 2H), 2.03e1.97 (m, 2H), 1.73 (s, 4H), 1.63e1.54 (m, 1H), 1.31 (s, 3H), 1.26 (d, J ¼ 8.3 Hz, 3H),1.25 (d, J ¼ 9.4 Hz, 3H),1.09 (s, 3H). 6.3.17. (1R,4aS,E)-Methyl-6-bromo-9-((3-(5-bromothiophene-2carboxamido)propoxy)imino)-7-isopropyl-1,4a-dimethyl1,2,3,4,4a,9,10,10a-octahydrophenanthrene-1-carboxylate (3q) White solid, yield 70%. 1H NMR (500 MHz, CDCl3) d 7.78 (s, 1H), 7.41 (s, 1H), 7.17 (d, J ¼ 3.9 Hz, 1H), 6.93 (d, J ¼ 3.9 Hz, 1H), 6.60 (s, 1H), 4.30 (t, J ¼ 11.9, 5.2 Hz, 2H), 3.63e3.44 (m, 5H), 3.28 (dt, J ¼ 13.6, 6.8 Hz, 1H), 2.76 (dd, J ¼ 18.3, 4.2 Hz, 1H), 2.51 (dd, J ¼ 18.3, 13.8 Hz, 1H), 2.28e2.21 (m, 2H), 2.03e1.95 (m, 2H), 1.75 (s, 4H), 1.63e1.53 (m, 1H), 1.31 (s, 3H), 1.22 (d, J ¼ 6.7 Hz, 3H),1.21 (d, J ¼ 6.8 Hz, 3H),1.10 (s, 3H).

922

W.-M. Zhang et al. / European Journal of Medicinal Chemistry 127 (2017) 917e927

Table 2 In vitro antibacterial activity of 7-N-acylaminopropyloxime derivatives against S. aureus Newman.

Table 2 (continued ) Compound

Compound

vancomycin tetracycline DHAA 6a 7a

R

e e e

R

MIC

mg/mL

mM

7o

3.75e5

6.36e8.48

7p

1.25e2.5

1.91e3.82

7q

1.25e2.5

1.91e3.82

7r

1.25e2.5

2.05e4.10

MIC

mg/mL

mM

7s

2.5

4.00

<2.5 <3.13 12.5e20 >50 40e50

<1.73 <2.16 41.61e66.57 >107.43 72.79e90.99

8a

10.0

17.14

8b

5.0

7.67

8c

1.25e2.5

1.92e3.84

8d

2.5

3.84

7b

30e40

56.23e74.98

7c

5

8.78

7d

7.5e10

12.51e16.68

7e

5e6.25

8.51e10.64

7f

3.75e5.0

5.69e7.58

7g

5e6.25

7.84e9.80

7h

1.25e2.5

1.96e3.92

7i

1.25e2.5

1.96e3.92

7j

2.5

4.48

7k

>25

>41.08

7l

12.5

21.91

7m

10

17.37

7n

>50

>86.87

6.3.18. (1R,4aS,E)-Methyl-6-bromo-9-((3-(5-chlorothiophene-2carboxamido)propoxy)imino)-7-isopropyl-1,4a-dimethyl1,2,3,4,4a,9,10,10a-octahydrophenanthrene-1-carboxylate (3r) White solid, yield 45%. 1H NMR (500 MHz, CDCl3) d 7.76 (s, 1H), 7.42 (s, 1H), 7.15 (d, J ¼ 4.0 Hz, 1H), 6.81 (d, J ¼ 4.0 Hz, 1H), 6.37 (s, 1H), 4.32 (t, J ¼ 5.7 Hz, 2H), 3.64 (s, 3H), 3.63e3.48 (m, 2H), 3.29 (dt, J ¼ 13.7, 6.9 Hz, 1H), 2.60e2.51 (m, 2H), 2.29e2.20 (m, 2H), 2.07e1.97 (m, 2H), 1.78e1.68 (m, 4H), 1.66e1.53 (m, 1H), 1.34 (s, 3H), 1.22 (d, J ¼ 6.9 Hz, 6H), 1.09 (s, 3H).

6.3.19. (1R,4aS,E)-Methyl-9-((3-(benzo[b]thiophene-2carboxamido)propoxy)imino)-6-bromo-7-isopropyl-1,4a-dimethyl1,2,3,4,4a,9,10,10a-octahydrophenanthrene-1-carboxylate (3s) White solid, yield 30%. 1H NMR (500 MHz, CDCl3) d 8.14 (s, 1H), 7.90 (t, J ¼ 8.8 Hz, 2H), 7.81 (d, J ¼ 6.3 Hz, 2H), 7.71 (d, J ¼ 6.9 Hz, 1H), 7.67 (s, 1H), 6.56 (s, 1H), 4.36 (t, J ¼ 5.8 Hz, 2H), 3.72e3.60 (m, 5H), 3.27 (m, 1H), 2.59 (dd, J ¼ 12.4, 9.3 Hz, 2H), 2.24 (dd, J ¼ 13.8, 10.9 Hz, 2H), 2.11e2.07 (m, 2H), 1.71 (s, 4H), 1.63e1.59 (m, 1H), 1.32 (s, 3H), 1.20 (t, J ¼ 6.5 Hz, 6H), 1.05 (s, 3H).

6.4. General procedure for preparation of compounds 7a-s Compounds 3a-s (0.1 mmol) was treated with KOBut (0.30 mmol) in DMSO (2 mL) at rt for about 1 h. Then the reaction mixture was poured on ice water, acidified with 1 N HCl, and then extracted with AcOEt. The combined organic layer was washed with H2O and brine, dried over anhydrous Na2SO4, filtered, and then the solvent was evaporated in vacuum. The crude residue was purified by column chromatography using petroleum ether/AcOEt (2/1, v/v) as eluent to afford compounds 7a-s.

W.-M. Zhang et al. / European Journal of Medicinal Chemistry 127 (2017) 917e927

923

Scheme 1. Regents and conditions: (a) RCOCl, Et3N, DMF, N2, rt, 20e43%; (b) RCOCl, K2CO3, CH3CN, N2, rt, 16e78%; (c) KOBut, DMSO, 36e79%; (d) NH2OCH2CH2CH2NHBoc, Py, EtOH, 90  C, 97%; (e) TFA, CH2Cl2, rt.

Table 3 MICs of selected derivatives against S. aureus NRS-1, NRS-70, NRS-100, NRS-108 and NRS-271. Compound

MIC NRS-1

vancomycin tetracycline 4m 4v 4w 4x 7h 7i 7j 7p 7q 7r 7s 8c 8d

NRS-70

NRS-100

NRS-108

NRS-271

mg/mL

mM

mg/mL

mM

mg/mL

mM

mg/mL

mM

mg/mL

mM

2.5e5 >25 3.13 3.13e6.25 3.13e6.25 2.5e3.13 >12.5 6.25e12.5 3.13 3.13e6.25 >12.5 6.25e12.5 >25 >12.5 >12.5

1.72e3.45 >56.25 5.02 4.89e9.76 5.25e10.49 4.09e5.12 >19.61 9.80e19.61 5.60 4.78e9.55 >19.10 10.25e20.49 >39.96 >19.19 >19.19

<2.5 <3.13 1.56e2.5 1.56e2.5 1.56e2.5 1.25e2.5 3.13 1.25e1.56 1.56e2.5 1.25e1.56 1.56e2.5 1.56e2.5 >25 1.25e1.56 1.56e2.5

<1.72 <7.04 2.50e4.01 2.44e3.90 2.62e4.19 2.04e4.09 4.91 1.96e2.45 2.79e4.48 1.91e2.38 2.38e3.82 2.56e4.10 >39.96 1.92e2.39 2.39e3.84

1.25e2.5 <3.13 3.13 3.13 2.5 1.56e2.5 3.13 3.13 1.56e2.5 3.13 3.13 3.13 >25 2.5e3.13 3.13e6.25

0.86e1.72 <7.04 5.02 4.89 4.19 2.55e4.09 4.91 4.91 2.79e4.48 4.78 4.78 5.13 >39.96 3.84e4.80 4.80e9.59

<2.5 <3.13 1.56e2.5 1.56e2.5 1.56e2.5 1.56e2.5 2.5e3.13 1.56e2.5 1.56e2.5 1.56e2.5 1.56e2.5 1.56e2.5 >25 1.56e2.5 1.56e2.5

<1.72 <7.04 2.50e4.01 2.44e3.90 2.62e4.19 2.55e4.09 3.92e4.91 2.45e3.92 2.79e4.48 2.38e3.82 2.38e3.82 2.56e4.10 >39.96 2.39e3.84 2.39e3.84

<2.5 <3.13 1.56e2.5 1.56e2.5 1.56e2.5 1.25e1.56 2.5e3.13 1.56e2.5 1.56e2.5 1.56e2.5 1.56e2.5 1.56e2.5 >25 1.56e2.5 3.13e6.25

<1.72 <7.04 2.50e4.01 2.44e3.90 1.56e2.5 2.05e2.55 3.92e4.91 2.45e3.92 2.79e4.48 2.38e3.82 2.38e3.82 2.56e4.10 >39.96 2.39e3.84 4.80e9.59

6.4.1. (1R,4aS,E)-6-Bromo-7-isopropyl-1,4a-dimethyl-9-((3pivalamidopropoxy)imino)-1,2,3,4,4a,9,10,10aoctahydrophenanthrene-1-carboxylic acid (7a) White solid, yield 38%. Mp 105e107  C. 1H NMR (500 MHz, CDCl3) d 7.78 (s, 1H), 7.40 (s, 1H), 6.01 (brs, 1H), 4.30e4.22 (m, 2H), 3.41e3.26 (m, 2H), 3.28 (dt, J ¼ 13.7, 6.8 Hz, 1H), 2.78 (dd, J ¼ 18.3, 4.2 Hz, 1H), 2.50 (dd, J ¼ 18.3, 13.7 Hz,1H), 2.29e2.21 (m, 2H), 1.96e1.86 (m, 2H), 1.75 (s, 4H), 1.61e1.56 (m, 1H), 1.33 (s, 3H), 1.23 (dd, J ¼ 6.1, 2.4 Hz, 6H), 1.17 (s, 9H), 1.12 (s, 3H). 13C NMR (126 MHz, CDCl3) d 182.01, 179.12, 154.38, 150.08. 145.04, 128.57, 127.93, 126.32, 122.50, 72.15, 64.51, 46.37, 42.06, 38.76, 37.40, 37.27, 36.89,

36.71, 32.75, 29.19, 27.68, 24.14, 23.04, 22.93, 22.86, 21.17, 18.16, þ 16.43. HR-MS: calcd for C28H79 41BrN2O4 ([MþH] ), 549.2329; found, 549.2322. 6.4.2. (1R,4aS,E)-6-Bromo-9-((3-(cyclopropanecarboxamido) propoxy)imino)-7-isopropyl-1,4a-dimethyl-1,2,3,4,4a,9,10,10aoctahydrophenanthrene-1-carboxylic acid (7b) White solid, yield 79%. Mp 87e88  C. 1H NMR (500 MHz, CDCl3) d 7.79 (s, 1H), 7.41 (s, 1H), 6.27 (s, 1H), 4.33e4.24 (m, 2H), 3.40 (dd, J ¼ 12.5, 6.7 Hz, 2H), 3.29 (dq, J ¼ 13.6, 6.8 Hz, 1H), 2.79 (dd, J ¼ 18.2, 4.2 Hz, 1H), 2.50 (dd, J ¼ 18.2, 13.8 Hz, 1H), 2.29e2.21 (m, 2H),

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1.98e1.86 (m, 2H), 1.74 (s, 4H), 1.60e1.56 (m, 1H), 1.38e1.34 (m, 1H), 1.32 (s, 3H), 1.26e1.23 (m, 6H), 1.12 (s, 3H), 0.96e0.95 (m, 2H), 0.71e0.69 (m, 2H). 13C NMR (126 MHz, CDCl3) d 181.92, 174.36, 154.30, 150.07, 145.06, 128.53, 127.95, 126.33, 122.48, 72.15, 46.39, 42.09, 37.56, 37.28, 36.84, 36.73, 32.75, 29.24, 24.11, 23.07, 22.96, 22.85, 21.18, 18.18, 16.41, 14.98, 7.33. HR-MS: calcd for C27H79 37BrN2O4 ([MþH]þ), 533.2016; found, 533.2008. 6.4.3. (1R,4aS,E)-9-((3-Benzamidopropoxy)imino)-6-bromo-7isopropyl-1,4a-dimethyl-1,2,3,4,4a,9,10,10aoctahydrophenanthrene-1-carboxylic acid (7c) White solid, yield 67%. Mp 105e107  C. 1H NMR (500 MHz, CDCl3) d 7.77 (s, 1H), 7.73 (d, J ¼ 7.5 Hz, 2H), 7.46 (t, J ¼ 7.4 Hz, 1H), 7.41 (s, 1H), 7.36 (t, J ¼ 7.7 Hz, 2H), 6.54 (brs, 1H), 4.34 (t, J ¼ 5.9 Hz, 2H), 3.67e3.57 (m, 2H), 3.27 (dq, J ¼ 13.8, 6.9 Hz, 1H), 2.61e2.50 (m, 2H), 2.27e2.22 (m, 2H), 2.09e2.05 (m, 2H), 1.75e1.71 (m, 4H), 1.63e1.49 (m, 1H), 1.32 (s, 3H), 1.20 (dd, J ¼ 6.9, 4.0 Hz, 6H), 1.08 (s, 3H). 13C NMR (126 MHz, CDCl3) d 182.45, 168.06, 154.38, 150.06, 145.08, 134.53, 131.52, 128.61, 128.59, 128.52, 127.87, 127.08, 127.03, 126.33, 122.49, 71.99, 46.32, 41.87, 37.70, 36.92, 36.66, 32.72, 29.36, 24.17, 23.01, 22.91, 22.80, 21.16, 18.11, 16.43. HR-MS: calcd for þ C30H79 37BrN2O4 ([MþH] ), 569.2016; found, 569.2004. 6.4.4. (1R,4aS,E)-6-Bromo-7-isopropyl-9-((3-(4methoxybenzamido)propoxy)imino)-1,4a-dimethyl1,2,3,4,4a,9,10,10a-octahydrophenanthrene-1-carboxylic acid (7d) White solid, yield 49%. Mp 206e207  C. 1H NMR (500 MHz, CDCl3) d 7.78 (s, 1H), 7.68 (d, J ¼ 8.8 Hz, 2H), 7.40 (s, 1H), 6.80 (d, J ¼ 8.8 Hz, 2H), 6.68 (brs, 1H), 4.35e4.27 (m, 2H), 3.79 (s, 3H), 3.62e3.50 (m, 2H), 3.27 (dq, J ¼ 13.8, 6.9 Hz, 1H), 2.79 (dd, J ¼ 18.3, 4.2 Hz, 1H), 2.49 (dd, J ¼ 18.3, 13.8 Hz, 1H), 2.27e2.20 (m, 2H), 2.07e1.97 (m, 2H), 1.74 (s, 4H), 1.60e1.50 (m, 1H), 1.30 (s, 3H), 1.21 (dd, J ¼ 6.1, 1.6 Hz, 6H), 1.08 (s, 3H). 13C NMR (126 MHz, CDCl3) d 182.24, 167.64, 162.20, 154.41, 150.09, 145.07, 128.88, 128.85, 128.54, 127.89, 126.81, 126.75, 126.32, 122.49, 113.78, 72.06, 55.46, 46.31, 41.94, 37.68, 37.22, 36.88, 36.68, 32.73, 29.39, 24.15, 23.03, þ 22.91, 22.82, 18.13, 16.43. HR-MS: calcd for C31H79 39BrN2O5([MþH] ), 599.2121; found, 599.2119. 6.4.5. (1R,4aS,E)-6-Bromo-9-((3-(2-fluorobenzamido)propoxy) imino)-7-isopropyl-1,4a-dimethyl-1,2,3,4,4a,9,10,10aoctahydrophenanthrene-1-carboxylic acid (7e) White solid, yield 79%. Mp 78e79  C. 1H NMR (500 MHz, CDCl3) d 8.09 (td, J ¼ 7.9, 1.8 Hz, 1H), 7.82 (s, 1H), 7.47e7.42 (m, 1H), 7.41 (s, 1H), 7.21 (dd, J ¼ 14.1, 6.7 Hz, 1H), 7.06 (dd, J ¼ 12.1, 8.3 Hz, 1H), 6.98 (s, 1H), 4.38e4.29 (m, 2H), 3.66e3.57 (m, 2H), 3.28 (hept, J ¼ 6.8 Hz, 1H), 2.89 (dd, J ¼ 18.4, 4.3 Hz, 1H), 2.48 (dd, J ¼ 20.9, 10.4 Hz, 1H), 2.30e2.22 (m, 2H), 2.11e2.00 (m, 2H), 1.81e1.71 (m, 4H), 1.62e1.56 (m, 1H), 1.33 (s, 3H), 1.23 (dd, J ¼ 6.8, 5.3 Hz, 6H), 1.14 (s, 3H). 19F NMR (471 MHz, CDCl3) d -113.48.13C NMR (126 MHz, CDCl3) d 182.40, 161.68, 154.22, 150.02, 145.03, 133.32, 132.16, 128.62, 127.73, 126.25, 124.92, 122.57, 121.09, 116.17, 115.97, 71.78,46.36, 41.95, 37.62, 37.23, 36.93, 36.69, 32.74, 29.29, 24.09, 23.04, 22.80, þ 21.17, 18.14, 16.42. HR-MS: calcd for C30H79 36BrFN2O4 ([MþH] ), 587.1921; found, 587.1919. 6.4.6. (1R,4aS,E)-6-Bromo-7-isopropyl-1,4a-dimethyl-9-((3(perfluorobenzamido)propoxy)imino)-1,2,3,4,4a,9,10,10aoctahydrophenanthrene-1-carboxylic acid (7f) White solid, yield 64%. Mp 99e100  C. 1H NMR (500 MHz, CDCl3) d 7.73 (d, J ¼ 2.9 Hz, 1H), 7.40 (d, J ¼ 7.4 Hz, 1H), 6.67 (d, J ¼ 27.6 Hz, 1H), 4.32 (t, J ¼ 7.3, 4.3 Hz, 2H), 3.64e3.43 (m, 2H), 3.27 (td, J ¼ 13.4, 6.7 Hz, 1H), 2.75e2.61 (m, 1H), 2.60e2.44 (m, 1H), 2.27e2.17 (m, 2H), 2.05e1.99 (m, 2H), 1.74 (brs, 4H), 1.61e1.54 (m, 1H), 1.30 (s, 3H), 1.21 (dd, J ¼ 15.2, 7.7 Hz, 6H), 1.09 (s, 3H). 19F NMR (471 MHz, CDCl3)

d -75.85.13C NMR (126 MHz, CDCl3) d 183.72, 183.44, 154.41, 154.05, 150.06, 149.97, 145.21, 145.09, 128.47, 128.38, 127.71, 126.49, 126.31, 122.62, 122.47, 72.55, 46.25, 41.53, 38.16, 37.73, 37.10, 36.57, 36.55, 32.66, 29.18, 28.42, 22.83, 22.69, 21.12, 16.30. HR-MS: calcd for þ C30H79 32BrF5N2O4 ([MþH] ), 659.1545; found, 659.1542. 6.4.7. (1R,4aS,E)-6-Bromo-7-isopropyl-1,4a-dimethyl-9-((3-(2(trifluoromethyl)benzamido)propoxy)imino)-1,2,3,4,4a,9,10,10aoctahydrophenanthrene-1-carboxylic acid (7g) White solid, yield 50%. Mp 95e96  C. 1H NMR (500 MHz, CDCl3) d 7.74 (s, 1H), 7.66 (d, J ¼ 6.1 Hz, 1H), 7.50 (s, 3H), 7.39 (s, 1H), 6.22 (s, 1H), 4.32 (brs, 2H), 3.58 (dd, J ¼ 12.6, 6.4 Hz, 2H), 3.26 (hept, J ¼ 6.8 Hz, 1H), 2.73 (dd, J ¼ 18.2, 4.1 Hz, 1H), 2.47 (dd, J ¼ 18.3, 13.7 Hz, 1H), 2.22 (dd, J ¼ 13.7, 4.6 Hz, 2H), 2.04e2.01 (m, 2H), 1.74 (s, 4H), 1.59e1.55 (m, 1H), 1.27 (s, 3H), 1.19 (d, J ¼ 6.8 Hz, 6H), 1.07 (s, 3H). 19F NMR (471 MHz, CDCl3) d -58.76.13C NMR (126 MHz, CDCl3) d 182.46, 168.18, 154.11, 149.99, 145.10, 136.01, 132.15, 129.87, 128.75, 128.56, 127.83, 127.37, 126.44, 126.30, 124.85, 122.50, 71.80, 46.29, 41.83, 37.75, 37.19, 36.98, 36.66, 32.72, 29.18, 24.10, 23.01, 22.91, þ 22.79, 18.10, 16.41. HR-MS: calcd for C31H79 36BrF3N2O4 ([MþH] ), 637.1890; found, 637.1880. 6.4.8. (1R,4aS,E)-6-Bromo-7-isopropyl-1,4a-dimethyl-9-((3-(3(trifluoromethyl)benzamido)propoxy)imino)-1,2,3,4,4a,9,10,10aoctahydrophenanthrene-1-carboxylic acid (7h) White solid, yield 55%. Mp 104e106  C. 1H NMR (500 MHz, CDCl3) d 8.03 (s, 1H), 7.87 (d, J ¼ 7.7 Hz, 1H), 7.77 (s, 1H), 7.68 (d, J ¼ 7.8 Hz, 1H), 7.43 (t, J ¼ 7.8 Hz, 1H), 7.40 (s, 1H), 6.95 (t, J ¼ 5.4 Hz, 1H), 4.35e4.27 (m, 2H), 3.67e3.53 (m, 2H), 3.27 (hept, J ¼ 6.8 Hz, 1H), 2.76 (dd, J ¼ 18.4, 4.4 Hz, 1H), 2.50 (dd, J ¼ 18.5, 13.8 Hz, 1H), 2.25e2.20 (m, 2H), 2.10e2.04 (m, 2H), 1.74 (s, 4H), 1.58e1.53 (m, 1H), 1.28 (s, 3H), 1.19 (d, J ¼ 6.9 Hz, 6H), 1.08 (s, 3H). 19F NMR (471 MHz, CDCl3) d -62.72.13C NMR (126 MHz, CDCl3) d 182.79, 166.61, 154.46, 150.03, 145.14, 135.40, 131.30, 131.04, 130.23, 129.22, 128.46, 127.90, 126.41, 124.28, 122.70, 122.47, 71.83, 46.35, 41.85, 37.85, 37.17, 36.95, 36.66, 32.71, 29.29, 24.17, 22.99, 22.89, 22.78, þ 18.09, 16.37. HR-MS: calcd for C31H79 36BrF3N2O4 ([MþH] ), 637.1890; found, 637.1886. 6.4.9. (1R,4aS,E)-6-Bromo-7-isopropyl-1,4a-dimethyl-9-((3-(4(trifluoromethyl)benzamido)propoxy)imino)-1,2,3,4,4a,9,10,10aoctahydrophenanthrene-1-carboxylic acid (7i) White solid, yield 59%. Mp 108e109  C. 1H NMR (500 MHz, CDCl3) d 7.80 (d, J ¼ 8.1 Hz, 2H), 7.76 (s, 1H), 7.54 (d, J ¼ 8.2 Hz, 2H), 7.40 (s, 1H), 6.97 (s, 1H), 4.36e4.29 (m, 2H), 3.67e3.52 (m, 2H), 3.27 (hept, J ¼ 6.9 Hz, 1H), 2.73 (dd, J ¼ 18.5, 4.4 Hz, 1H), 2.49 (dd, J ¼ 18.5, 13.7 Hz, 1H), 2.20 (dd, J ¼ 13.6, 4.3 Hz, 2H), 2.09e2.03 (m, 2H), 1.72 (s, 4H), 1.57e1.53 (m, 1H), 1.27 (s, 3H), 1.18 (dd, J ¼ 6.7, 4.7 Hz, 6H), 1.17 (s, 3H). 19F NMR (471 MHz, CDCl3) d -62.95.13C NMR (126 MHz, CDCl3) d 182.81, 166.76, 154.47, 150.05, 145.17, 137.90, 133.27, 133.01, 128.37, 127.90, 127.52, 126.48, 125.62, 125.59, 124.81, 122.43, 72.17, 46.28, 41.71, 38.01, 37.11, 36.97, 36.59, 32.69, 29.26, 24.22, 22.93, 22.86, 22.78, 18.05, 16.37. HR-MS: calcd for þ C31H79 36BrF3N2O4 ([MþH] ), 637.1890; found, 637.1877. 6.4.10. (1R,4aS,E)-9-((3-(1H-Pyrrole-2-carboxamido)propoxy) imino)-6-bromo-7-isopropyl-1,4a-dimethyl-1,2,3,4,4a,9,10,10aoctahydrophenanthrene-1-carboxylic acid (7j) White solid, yield 55%. Mp 126e128  C. 1H NMR (500 MHz, CDCl3) d 11.13 (s, 1H), 7.83 (s, 1H), 7.43 (s, 1H), 6.83 (s, 1H), 6.27 (s, 1H), 6.07 (brs, 1H), 4.22 (t, J ¼ 5.5 Hz, 2H), 3.64e3.53 (m, 1H), 3.33e3.18 (m, 2H), 2.86 (dd, J ¼ 18.7, 4.4 Hz, 1H), 2.50 (dd, J ¼ 18.4, 13.9 Hz, 1H), 2.29e2.18 (m, 2H), 1.94e1.84 (m, 2H), 1.70e1.48 (m, 4H), 1.44e1.33 (m, 1H), 1.29 (s, 3H), 1.23 (dd, J ¼ 9.6, 6.9 Hz, 6H), 1.10 (s, 3H). 13C NMR (126 MHz, CDCl3) d 182.21, 161.11, 154.89, 150.18,

W.-M. Zhang et al. / European Journal of Medicinal Chemistry 127 (2017) 917e927

145.00, 128.50, 127.99, 126.42, 124.68, 122.39, 119.85, 113.01, 109.17, 71.09, 46.41, 41.96, 37.18, 36.86, 36.68, 36.26, 32.81, 29.61, 24.14, 23.18, 22.90, 22.86, 18.20, 16.45. HR-MS: calcd for C28H79 36BrN3O4 ([MþH]þ), 558.1969; found, 558.1971. 6.4.11. (1R,4aS,E)-9-((3-(1H-Indole-2-carboxamido)propoxy) imino)-6-bromo-7-isopropyl-1,4a-dimethyl-1,2,3,4,4a,9,10,10aoctahydrophenanthrene-1-carboxylic acid (7k) White solid, yield 36%. Mp 106e107  C. 1H NMR (500 MHz, CDCl3) d 11.13 (s, 1H), 7.87 (s, 1H), 7.53 (d, J ¼ 8.0 Hz, 1H), 7.44 (t, J ¼ 4.0 Hz, 2H), 7.30 (t, J ¼ 7.6 Hz, 1H), 7.15 (t, J ¼ 7.5 Hz, 1H), 6.92 (t, J ¼ 5.4 Hz, 1H), 4.21 (t, J ¼ 5.7 Hz, 2H), 3.74 (dd, J ¼ 13.5, 6.8 Hz, 1H), 3.29 (hept, J ¼ 6.8 Hz, 1H), 3.02 (dd, J ¼ 18.4, 4.0 Hz, 2H), 2.56 (dd, J ¼ 18.4, 13.8 Hz, 1H), 2.30 (dd, J ¼ 13.8, 4.1 Hz, 1H), 2.21 (d, J ¼ 9.0 Hz, 1H), 1.91e1.82 (m, 2H), 1.66e1.43 (m, 5H), 1.30 (s, 3H), 1.25 (dd, J ¼ 6.4, 2.2 Hz, 6H), 1.12 (s, 3H). 13C NMR (126 MHz, CDCl3) d 182.99, 160.91, 155.15, 150.04, 144.77, 134.49, 128.55, 127.83, 126.18, 125.49, 125.32, 124.63, 122.36, 120.92, 119.22, 112.67, 105.52, 70.33, 46.30, 41.99, 37.06, 36.64, 36.55, 35.60, 32.71, 29.71, 29.61, 29.33, 24.00, 22.73, 18.10, 16.31. HR-MS: calcd for C32H79 38BrN3O4 ([MþH]þ), 608.2126; found, 608.2124. 6.4.12. (1R,4aS,E)-6-Bromo-7-isopropyl-1,4a-dimethyl-9-((3(picolinamido)propoxy)imino)-1,2,3,4,4a,9,10,10aoctahydrophenanthrene-1-carboxylic acid (7l) White solid, yield 77%. Mp 102e103  C. 1H NMR (500 MHz, CDCl3) d 8.50 (d, J ¼ 4.0 Hz, 1H), 8.24e8.17 (m, 2H), 7.87e7.79 (m, 2H), 7.43e7.40 (m, 2H), 4.38e4.26 (m, 2H), 3.66e3.57 (m, 2H), 3.28 (hept, J ¼ 6.9 Hz, 1H), 2.97 (dd, J ¼ 17.0, 2.8 Hz, 1H), 2.45 (dd, J ¼ 17.6, 13.9 Hz, 1H), 2.31 (dd, J ¼ 13.9, 3.5 Hz, 1H), 2.24 (d, J ¼ 12.3 Hz, 1H), 2.13e1.98 (m, 2H), 1.83e1.69 (m, 4H), 1.62e1.55 (m, 1H), 1.33 (s, 3H), 1.25e1.21 (m, 6H), 1.16 (s, 3H). 13C NMR (126 MHz, CDCl3) d 180.95, 164.79, 154.88, 150.08, 149.79, 148.17, 144.99, 137.63, 128.54, 128.17, 126.40, 126.31, 122.60, 122.48, 71.33, 46.57, 42.79, 37.45, 36.96, 36.48, 32.78, 29.84, 29.31, 23.91, 23.23, 22.97, 22.85, 18.29, 16.40. þ HR-MS: calcd for C29H79 36BrN3O4 ([MþH] ), 570.1968; found, 570.1962. 6.4.13. (1R,4aS,E)-6-Bromo-7-isopropyl-1,4a-dimethyl-9-((3(thiophene-3-carboxamido)propoxy)imino)-1,2,3,4,4a,9,10,10aoctahydrophenanthrene-1-carboxylic acid (7m) White solid, yield 64%. Mp 89e91  C. 1H NMR (500 MHz, CDCl3) d 7.85 (s, 1H), 7.77 (s, 1H), 7.40 (s, 1H), 7.34 (s, 1H), 7.24 (s, 1H), 6.69 (s, 1H), 4.35e4.25 (m, 2H), 3.63e3.50 (m, 2H), 3.27 (hept, J ¼ 6.8 Hz, 1H), 2.76 (dd, J ¼ 18.3, 3.6 Hz, 1H), 2.52 (dd, J ¼ 17.9, 13.8 Hz, 1H), 2.29e2.18 (m, 2H), 2.04 (s, 2H), 1.75 (s, 4H), 1.61e1.56 (m, 1H), 1.32 (s, 3H), 1.21 (dd, J ¼ 6.7, 1.6 Hz, 6H), 1.09 (s, 3H). 13C NMR (126 MHz, CDCl3) d 182.84, 176.84, 154.20, 149.95, 145.01, 128.85, 128.54, 128.41, 127.74, 126.46, 126.26, 126.02, 122.43, 71.97, 46.23, 41.66, 37.36, 37.06, 36.52, 32.63, 24.11, 22.89, 22.81, 22.71, 20.83, 19.16, þ 18.00, 16.34. HR-MS: calcd for C28H79 35BrN2O4S ([MþH] ), 575.1580; found, 575.1586. 6.4.14. (1R,4aS,E)-6-Bromo-7-isopropyl-1,4a-dimethyl-9-((3(thiophene-2-carboxamido)propoxy)imino)-1,2,3,4,4a,9,10,10aoctahydrophenanthrene-1-carboxylic acid (7n) White solid, yield 44%. Mp 200e202  C. 1H NMR (500 MHz, CDCl3) d 7.80 (s, 1H), 7.45 (dd, J ¼ 3.7, 1.0 Hz, 1H), 7.43 (dd, J ¼ 5.0, 1.0 Hz, 1H), 7.41 (s, 1H), 7.01 (dd, J ¼ 5.0, 3.8 Hz, 1H), 6.38 (brs, 1H), 4.40e4.26 (m, 2H), 3.63e3.53 (m, 2H), 3.28 (hept, J ¼ 6.9 Hz, 1H), 2.85 (dd, J ¼ 18.1, 4.1 Hz, 1H), 2.50 (dd, J ¼ 18.2, 13.8 Hz, 1H), 2.32e2.20 (m, 2H), 2.09e1.96 (m, 2H), 1.76 (d, J ¼ 5.1 Hz, 4H), 1.64e1.52 (m, 1H), 1.33 (s, 3H), 1.23 (dd, J ¼ 6.8, 5.1 Hz, 6H), 1.13 (s, 3H). 13C NMR (126 MHz, CDCl3) d 182.59, 162.23, 154.23, 149.93, 145.02, 138.85, 129.86, 128.44, 128.15, 127.76, 127.60, 126.25, 122.45,

925

71.99, 46.25, 41.78, 37.62, 36.56, 32.65, 30.33, 29.71, 29.24, 24.08, 22.91, 22.81, 22.72, 18.01, 16.32. HR-MS: calcd for C28H79 35BrN2O4S ([MþH]þ), 575.1580; found, 575.1568. 6.4.15. (1R,4aS,E)-6-Bromo-7-isopropyl-1,4a-dimethyl-9-((3-(5methylthiophene-2-carboxamido)propoxy)imino)1,2,3,4,4a,9,10,10a-octahydrophenanthrene-1-carboxylic acid (7o) White solid, yield 76%. Mp 110e112  C. 1H NMR (500 MHz, CDCl3) d 7.78 (s, 1H), 7.40 (s, 1H), 7.28 (d, J ¼ 3.5 Hz, 1H), 6.63 (d, J ¼ 3.0 Hz, 1H), 6.52 (brs, 1H), 4.36e3.25 (m, 2H), 3.60e3.46 (m, 2H), 3.27 (hept, J ¼ 6.8 Hz, 1H), 2.78 (dd, J ¼ 18.4, 4.1 Hz, 1H), 2.52 (dd, J ¼ 18.3, 13.7 Hz, 1H), 2.44 (s, 3H), 2.32e2.18 (m, 2H), 2.03e1.95 (m, 2H), 1.74 (s, 4H), 1.64e1.52 (m, 1H), 1.31 (s, 3H), 1.22 (dd, J ¼ 12.3, 6.7 Hz, 6H), 1.10 (s, 3H). 13C NMR (126 MHz, CDCl3) d 182.53, 162.49, 154.30, 150.05, 145.21, 145.07, 136.16, 128.73, 128.57, 127.83, 126.31, 126.16, 122.55, 72.06, 46.33, 41.87, 37.59, 37.20, 36.66, 32.74, 29.38, 24.18, 23.02, 22.90, 22.82, 21.16, 18.12, 16.43, 15.70. HR-MS: calcd for þ C29H79 37BrN2O4S ([MþH] ), 589.1736; found, 589.1726. 6.4.16. (1R,4aS,E)-6-Bromo-9-((3-(4-bromothiophene-2carboxamido)propoxy)imino)-7-isopropyl-1,4a-dimethyl1,2,3,4,4a,9,10,10a-octahydrophenanthrene-1-carboxylic acid (7p) White solid, yield 62%. Mp 110e112  C. 1H NMR (500 MHz, CDCl3) d 7.77 (s, 1H), 7.40 (s, 1H), 7.34 (d, J ¼ 0.9 Hz, 1H), 7.30 (d, J ¼ 0.8 Hz, 1H), 6.85 (t, 5.6 Hz, 1H), 4.34e4.26 (m, 2H), 3.63e3.48 (m, 2H), 3.27 (hept, J ¼ 6.9 Hz, 1H), 2.74 (dd, J ¼ 18.5, 4.4 Hz, 1H), 2.56e2.46 (m, 1H), 2.27e2.20 (m, 2H), 2.03e2.01 (m, 2H), 1.74 (s, 4H), 1.61e1.56 (m, 1H), 1.31 (s, 3H), 1.21 (dd, J ¼ 6.8, 4.4 Hz, 6H), 1.09 (s, 3H). 13C NMR (126 MHz, CDCl3) d 182.94, 161.08, 154.40, 150.03, 145.14, 140.09, 130.12, 128.43, 127.89, 127.52, 126.44, 122.50, 110.04, 72.03, 46.31, 41.72, 37.85, 37.14, 37.03, 36.62, 32.73, 29.27, 24.22, 23.00, 22.92, 22.83, 18.09, 16.43. HR-MS: calcd for C28H79 34Br2N2O4S ([MþH]þ), 653.0685; found, 653.0678. 6.4.17. (1R,4aS,E)-6-Bromo-9-((3-(5-bromothiophene-2carboxamido)propoxy)imino)-7-isopropyl-1,4a-dimethyl1,2,3,4,4a,9,10,10a-octahydrophenanthrene-1-carboxylic acid (7q) White solid, yield 64%. Mp 114e115  C. 1H NMR (500 MHz, CDCl3) d 7.78 (s, 1H), 7.41 (s, 1H), 7.17 (d, J ¼ 3.9 Hz, 1H), 6.93 (d, J ¼ 3.9 Hz, 1H), 6.60 (brs, 1H), 4.34e4.26 (m, 2H), 3.61e3.54 (m, 1H), 3.53e3.48 (m, 1H), 3.28 (hept, J ¼ 6.4 Hz, 1H), 2.76 (dd, J ¼ 18.3, 4.2 Hz, 1H), 2.51 (dd, J ¼ 18.3, 13.8 Hz, 1H), 2.29e2.20 (m, 2H), 2.03e1.97 (m, 2H), 1.75 (s, 4H), 1.62e1.53 (m, 1H), 1.31 (s, 3H), 1.22 (dd, J ¼ 6.7, 3.2 Hz, 6H), 1.10 (s, 3H). 13C NMR (126 MHz, CDCl3) d 183.02, 160.92, 154.87, 150.00, 145.13, 139.87, 130.09, 128.19, 127.64, 127.40, 126.57, 122.53, 109.98, 72.16, 46.10, 41.31, 40.79, 37.07, 36.93, 36.44, 32.65, 24.35, 24.19, 22.86, 22.82, 22.71, 17.94, þ 16.38. HR-MS: calcd for C28H79 34Br2N2O4S ([MþH] ), 653.0685; found, 653.0676. 6.4.18. (1R,4aS,E)-6-Bromo-9-((3-(5-chlorothiophene-2carboxamido)propoxy)imino)-7-isopropyl-1,4a-dimethyl1,2,3,4,4a,9,10,10a-octahydrophenanthrene-1-carboxylic acid (7r) White solid, yield 36%. Mp 110e112  C. 1H NMR (500 MHz, CDCl3) d 7.76 (s, 1H), 7.40 (s, 1H), 7.21 (dd, J ¼ 3.9, 1.4 Hz, 1H), 6.77 (d, J ¼ 3.8 Hz, 1H), 6.75 (s, 1H), 4.28 (t, J ¼ 5.6 Hz, 2H), 3.60e3.47 (m, 2H), 3.27 (hept, J ¼ 6.8 Hz, 1H), 2.74 (dd, J ¼ 18.3, 3.4 Hz, 1H), 2.51 (dd, J ¼ 18.3, 13.7 Hz, 1H), 2.30e2.18 (m, 2H), 2.02e1.94 (m, 2H), 1.74 (s, 4H), 1.62e1.51 (m, 1H), 1.31 (s, 3H), 1.21 (dd, J ¼ 6.6, 3.6 Hz, 6H), 1.09 (s, 3H). 13C NMR (126 MHz, CDCl3) d 182.65, 161.38, 154.36, 150.03, 145.12, 137.57, 135.16, 128.46, 127.84, 127.38, 127.02, 126.40, 122.51, 72.09, 46.30, 41.77, 37.75, 37.15, 36.98, 36.62, 32.72, 29.26, 24.20, 22.98, 22.88, 21.13, 18.08, 16.41. HR-MS: calcd for 35 þ C28H79 34Br ClN2O4S ([MþH] ), 609.1190; found, 609.1168.

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6.4.19. (1R,4aS,E)-9-((3-(Benzo[b]thiophene-2-carboxamido) propoxy)imino)-6-bromo-7-isopropyl-1,4a-dimethyl1,2,3,4,4a,9,10,10a-octahydrophenanthrene-1-carboxylic acid (7s) White solid, yield 55%. Mp 126e128  C. 1H NMR (500 MHz, CDCl3) d 7.81 (s, 1H), 7.79 (d, J ¼ 8.1 Hz, 1H), 7.70 (d, J ¼ 5.2 Hz, 2H), 7.40 (s, 1H), 7.39e7.31 (m, 2H), 6.64 (t, J ¼ 5.6 Hz, 1H), 4.38e4.31 (m, 2H), 3.67e3.57 (m, 2H), 3.27 (hept, J ¼ 6.9 Hz, 1H), 2.82 (dd, J ¼ 18.3, 4.2 Hz, 1H), 2.51 (dd, J ¼ 18.5, 13.8 Hz, 1H), 2.27e2.18 (m, 2H), 2.10e2.05 (m, 2H), 1.74 (s, 4H), 1.61e1.50 (m, 1H), 1.30 (s, 3H), 1.21 (d, J ¼ 6.9 Hz, 6H), 1.08 (s, 3H). 13C NMR (126 MHz, CDCl3) d 181.88, 162.58, 154.43, 149.95, 145.03, 140.75, 139.05, 138.23, 128.36, 127.85, 126.31, 126.26, 125.43, 125.03, 124.84, 122.66, 122.41, 71.99, 46.23, 41.88, 37.91, 37.09, 36.58, 32.64, 29.22, 24.06, 22.91, 22.80, 22.71, þ 21.06, 18.01, 16.28. HR-MS: calcd for C32H79 37BrN2O4S ([MþH] ), 627.1736; found, 627.1731. 6.5. (1R,4aS,E)-6-Bromo-9-((3-((tert-butoxycarbonyl)amino) propoxy)imino)-7-isopropyl-1,4a-dimethyl-1,2,3,4,4a,9,10,10aoctahydrophenanthrene-1-carboxylic acid (9b) A mixture of compound 9a (4.5 g, 11 mmol), pyridine (2.8 mL), and NH2OCH2CH2CH2NHBoc (5.57 g, 34 mmol) in EtOH (40 mL) was stirred at 90  C for 3 h. After cooling down, the solvent was evaporated in vacuum. The mixture was extracted with ethyl acetate, and the organic layer was washed with water, brine and then dried over Na2SO4. Evaporation of the solvent followed by column chromatography on silica gel (petroleum ether/AcOEt, 16/1, v/v) yielded compound 9b as yellow oil (6.2 g, 97%). 1H NMR (500 MHz, CDCl3) d 7.85 (s, 1H), 7.42 (s, 1H), 6.56 (s, 1H), 4.40e4.30 (m, 2H), 3.66e3.59 (m, 2H), 3.32e3.22 (m, 1H), 2.94 (dd, J ¼ 17.9, 3.8 Hz, 1H), 2.45 (dd, J ¼ 17.7, 13.9 Hz, 1H), 2.28e2.24 (m, 2H), 2.24e2.21 (m, 2H), 1.78 (s, 4H), 1.59e1.53 (m, 1H), 1.34 (s, 3H), 1.25e1.22 (m, 15H), 1.16 (s, 3H). 6.6. (1R,4aS,E)-9-((3-Aminopropoxy)imino)-6-bromo-7-isopropyl1,4a-dimethyl-1,2,3,4,4a,9,10,10a-octahydrophenanthrene-1carboxylic acid (6a) To a solution of 9b (0.01 mol) in CH2Cl2 (26 mL) was dropwise added a solution of TFA (0.13 mol) in CH2Cl2 (54 mL) and the reaction was run at rt over 5 h. The solvent was evaporated in vacuum, and the residue was diluted with water. The whole mixture was extracted with AcOEt for three times. The combined organic layer was washed with water, sat. NaHCO3, and brine, then dried over Na2SO4. The crude mixture was purified by flash chromatography (CH2Cl2/MeOH ¼ 10:1) to afford 6a as white solid. 1H NMR (500 MHz, CDCl3) d 7.76 (s, 1H), 7.48 (s, 1H), 4.25e4.14 (m, 2H), 3.21 (hept, J ¼ 6.9 Hz, 1H), 2.84 (dd, J ¼ 14.9, 6.4 Hz, 2H), 2.69 (dd, J ¼ 17.7, 3.5 Hz, 1H), 2.36 (dd, J ¼ 14.1, 3.6 Hz, 1H), 2.26 (d, J ¼ 13.1 Hz,1H), 2.15 (dd, J ¼ 13.8, 3.7 Hz, 1H), 1.89e1.80 (m, 2H), 1.64e1.61 (m, 3H), 1.53e1.51 (m, 1H), 1.42e1.37 (m, 1H), 1.20e1.17 (m, 9H),1.06 (s, 3H). 6.7. General procedure for preparation of compounds 8a-d Starting from compound 6a, 8a-d was obtained using similar procedures for preparation of 5a-d. 6.7.1. (1R,4aS,E)-6-Bromo-7-isopropyl-1,4a-dimethyl-9-((3-(2phenylacetamido)propoxy)imino)-1,2,3,4,4a,9,10,10aoctahydrophenanthrene-1-carboxylic acid (8a) Yellow oil, yield 21%. 1H NMR (500 MHz, CDCl3) d 7.78 (s, 1H), 7.41 (s, 1H), 7.32e7.28 (m, 3H), 7.23 (d, J ¼ 7.4 Hz, 2H), 5.73 (brs, 1H), 4.20e4.10 (m, 2H), 3.57 (s, 2H), 3.35e3.26 (m, 3H), 2.80 (dd, J ¼ 18.1, 4.1 Hz, 1H), 2.45 (dd, J ¼ 18.0, 13.8 Hz, 1H), 2.28e2.22 (m, 2H),

1.79e1.70 (m, 6H), 1.60e1.54 (m, 1H), 1.32 (s, 3H), 1.24 (dd, J ¼ 9.2, 5.5 Hz, 6H), 1.12 (s, 3H). 13C NMR (126 MHz, CDCl3) d 181.39, 171.76, 154.31, 149.95, 144.89, 134.69, 129.45, 129.38, 129.03, 128.63, 128.38, 127.89, 127.39, 126.21, 122.34, 71.38, 46.29, 43.71, 42.14, 41.00, 37.20, 36.67, 36.59, 32.64, 28.94, 23.87, 22.99, 22.86, 22.74, þ 18.08, 16.30. HR-MS: calcd for C31H79 39BrN2O4 ([MþH] ), 583.2172; found, 583.2169. 6.7.2. (1R,4aS,E)-6-Bromo-7-isopropyl-1,4a-dimethyl-9-((3-(2-(2(trifluoromethyl)phenyl)acetamido)propoxy)imino)1,2,3,4,4a,9,10,10a-octahydrophenanthrene-1-carboxylic acid (8b) Yellow oil, yield 20%. 1H NMR (500 MHz, CDCl3) d 7.76 (s, 1H), 7.65 (t, J ¼ 6.3 Hz, 2H), 7.39 (t, J ¼ 7.6 Hz, 3H), 5.79 (brs, 1H), 4.20e4.12 (m, 2H), 3.85 (s, 2H), 3.36 (dd, J ¼ 12.9, 6.7 Hz, 2H), 3.29 (hept, J ¼ 6.9 Hz, 1H), 2.71 (dd, J ¼ 18.6, 3.0 Hz, 1H), 2.50e2.48 (m, 1H), 2.27e2.23 (m, 2H), 1.90e1.85 (m, 2H), 1.74 (s, 4H), 1.59e1.53 (m, 1H), 1.33e1.31 (m, 3H), 1.24 (dd, J ¼ 11.7, 6.7 Hz, 6H), 1.10 (s, 3H). 19 F NMR (471 MHz, CDCl3) d -59.94. 13C NMR (126 MHz, CDCl3) d 182.75, 170.56, 154.05, 150.00, 145.05, 132.76, 132.68, 132.05, 129.01, 127.79, 127.66, 127.62, 126.26, 126.20, 126.16, 122.54, 71.54, 46.32, 41.80, 40.34, 38.08, 37.29, 36.62, 32.73, 29.06, 27.92, 22.97, 22.90, 22.80, 22.25, 18.09, 16.37. HR-MS: calcd for C32H79 38BrF3N2O4 ([MþH]þ), 651.2046; found, 651.2030. 6.7.3. (1R,4aS,E)-6-Bromo-7-isopropyl-1,4a-dimethyl-9-((3-(2-(3(trifluoromethyl)phenyl)acetamido)propoxy)imino)1,2,3,4,4a,9,10,10a-octahydrophenanthrene-1-carboxylic acid (8c) Yellow oil, yield 43%. 1H NMR (500 MHz, CDCl3) d 7.77 (s, 1H), 7.54e7.46 (m, 3H), 7.41 (t, J ¼ 9.1 Hz, 2H), 6.09 (brs, 1H), 4.25e4.17 (m, 2H), 3.57 (s, 2H), 3.37 (dd, J ¼ 12.7, 6.7 Hz, 2H), 3.29 (hept, J ¼ 6.9 Hz, 1H), 2.74 (dd, J ¼ 18.4, 4.4 Hz, 1H), 2.53e2.47 (m, 1H), 2.27e2.21 (m, 2H), 1.94e1.84 (m, 2H), 1.73 (s, 4H), 1.63e1.52 (m, 1H), 1.31 (s, 3H), 1.25e1.21 (m, 6H), 1.10 (s, 3H). 19F NMR (471 MHz, CDCl3) d -62.56. 13C NMR (126 MHz, CDCl3) d 182.46, 170.86, 154.18, 150.03, 145.11, 135.94, 132.80, 129.35, 129.13, 128.47, 127.87, 126.38, 126.13, 126.10, 124.15, 122.50, 71.78, 46.33, 43.24, 41.85, 37.47, 37.18, 36.65, 32.74, 29.02, 24.13, 22.99, 22.92, 22.83, 22.26, 18.10, 16.40. þ HR-MS: calcd for C32H79 38BrF3N2O4 ([MþH] ), 651.2046; found, 651.2037. 6.7.4. (1R,4aS,E)-6-Bromo-7-isopropyl-1,4a-dimethyl-9-((3-(2-(4(trifluoromethyl)phenyl)acetamido)propoxy)imino)1,2,3,4,4a,9,10,10a-octahydrophenanthrene-1-carboxylic acid (8d) Yellow oil, yield 39%. 1H NMR (500 MHz, CDCl3) d 7.78 (s, 1H), 7.59e7.54 (m, 3H), 7.42 (s, 1H), 7.35 (d, J ¼ 7.9 Hz, 1H), 5.94 (s, 1H), 4.25e4.19 (m, 2H), 3.57 (s, 2H), 3.37 (dd, J ¼ 12.7, 6.6 Hz, 2H), 3.32e3.23 (m, 1H), 2.75 (dd, J ¼ 18.2, 2.5 Hz, 1H), 2.53e2.46 (m, 1H), 2.28e2.21 (m, 2H), 1.93e1.83 (m, 2H), 1.74 (s, 4H), 1.62e1.55 (m, 1H), 1.31 (s, 3H), 1.23 (dd, J ¼ 13.3, 7.0 Hz, 6H), 1.11 (s, 3H). 19F NMR (471 MHz, CDCl3) d -62.53. 13C NMR (126 MHz, CDCl3) d 182.20, 170.61, 154.17, 149.91, 146.55, 145.03, 138.82, 129.82, 129.65, 129.44, 128.30, 127.85, 126.33, 125.76, 125.52, 122.33, 71.70, 46.26, 43.29, 41.87, 37.45, 37.09, 36.74, 36.58, 32.63, 28.93, 24.00, 22.92, 22.81, þ 22.73, 18.00, 16.29. HR-MS: calcd for C32H79 38BrF3N2O4 ([MþH] ), 651.2046; found, 651.2038. Acknowledgements We thank Dr H. Deng at the Instrumental Analysis &Research Center of Shanghai University for structural analysis. This work was in part supported by the National Natural Science Foundation of China (81202402, 21272154, and 8161101140) and the State Key Laboratory of Drug Research (SIMM1601KF-11).

W.-M. Zhang et al. / European Journal of Medicinal Chemistry 127 (2017) 917e927

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