Synthesis of 2-acyl-1-naphthols by gold-catalyzed oxidative cyclization of 2-alkenylphenyl alkynyl ketones

Tetrahedron 71 (2015) 869e874

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Synthesis of 2-acyl-1-naphthols by gold-catalyzed oxidative cyclization of 2-alkenylphenyl alkynyl ketones Takanori Matsuda *, Yahiro Nishida, Kentaro Yamanaka, Yusuke Sakurai Department of Applied Chemistry, Tokyo University of Science, 1-3 Kagurazaka, Shinjuku-ku, Tokyo 162-8601, Japan

a r t i c l e i n f o

a b s t r a c t

Article history: Received 7 October 2014 Received in revised form 11 December 2014 Accepted 12 December 2014 Available online 18 December 2014

The gold(I)-catalyzed oxidative cyclization of 2-alkenylphenyl alkynyl ketones employing organic oxides as oxidants has been developed. This reaction involves aromatization to furnish 2-acyl-1-naphthols. Also, 10-acyl-9-phenanthrenols are analogously produced from the reaction of alkynyl 2-biphenyl ketones. Ó 2014 Elsevier Ltd. All rights reserved.

Keywords: Enynes Gold Cyclization Aromatization Naphthols

1. Introduction Being a valuable method for the synthesis of variously substituted aromatic compounds, gold-catalyzed benzannulation reactions have been extensively studied.1,2 Liu et al. reported oxidative cyclization of 2-alkenylphenyl alkynyl carbinols with H2O2 under the catalysis of Pt(II) or Au(I) complexes to afford 2-naphthyl aldehydes and ketones (Scheme 1a).1g However, the reaction of the corresponding ketones, i.e., 2-alkenylphenyl alkynyl ketones, is yet to be studied. In this paper, we report oxidative cyclization of ketoenynes with N-oxides or a sulfoxide in the presence of gold(I) catalysts (Scheme 1b).3,4 The reaction proceeded efficiently at rt, resulting in benzannulation to afford a variety of 2-acyl-1-naphthol derivatives. This was subsequently applied for the synthesis of 10-acyl-9-phenanthrenols by reacting alkynyl 2-biphenyl ketones at 120
C under gold catalysis. 2. Results and discussion When 2-(1-phenylvinyl)phenyl prop-1-yn-1-yl ketone (1a) was reacted at 0
C for 30 min, and then at rt in 1,2-dichloroethane (DCE) in the presence of 2 mol % gold(I) catalyst, (JohnPhos)AuNTf2, a complex mixture of products was obtained. On the other hand, when the reaction was performed in the presence of 2.5 equiv of

* Corresponding author. Tel.: þ81 3 5228 8258; fax: þ81 3 5261 4631; e-mail address: [email protected] (T. Matsuda). http://dx.doi.org/10.1016/j.tet.2014.12.041 0040-4020/Ó 2014 Elsevier Ltd. All rights reserved.

Scheme 1. Catalyzed oxidative cyclization of 2-alkenylphenyl alkynyl carbinols and ketones.

quinoline N-oxide (QO) and 1.5 equiv of camphorsulfonic acid (CSA), oxidative cyclization of 1 with QO occurred, resulting in the isolation of 2-acetyl-4-phenyl-1-naphthol (2a) in 35% yield (Table 1, entry 1). The use of pyridine N-oxide (PO) as the oxidant improved the yield of 2a to 75% (entry 2).5 The efficiency of the reaction deteriorated significantly in the absence of CSA (entry 3).6 We found that diphenyl sulfoxide (Ph2SO) could also be employed as an alternative oxidant for the oxidative cyclization and is preferable for operation because the acid additive is not required (entry 4). After screening the phosphine ligands of the gold(I) complexes, (tBuXPhos)AuNTf2 was determined to be the optimal catalyst for this reaction (entries 5 and 6).

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T. Matsuda et al. / Tetrahedron 71 (2015) 869e874

Table 1 Selected optimization experiments for gold(I)-catalyzed oxidative cyclization of 1a with oxidesa

Entry

Au catalyst

ZþeO

Additive

Yieldb (%)

1 2 3 4 5 6

(JohnPhos)AuNTf2 (JohnPhos)AuNTf2 (JohnPhos)AuNTf2 (JohnPhos)AuNTf2 (XPhos)AuNTf2 (t-BuXPhos)AuNTf2

QO PO PO Ph2SO Ph2SO Ph2SO

CSA CSA None None None None

35 75 19 75 79 84

a

Enyne 1a (0.100 mmol) was reacted in the presence of oxide (0.250 mmol), additive (0.150 mmol), Au catalyst (2.0 mmol) in 1,2-dichloroethane (1.0 mL) at 0
C for 30 min, and then at rt for 12 h. b Isolated yield.

Two mechanistic scenarios explain the gold-catalyzed oxidative cyclization reaction of enyne 1a to produce naphthol 2a (Scheme 2). The first scenario (path a) involves initial cyclization of 1a by Au(I) in a 6-exo-dig fashion. The resulting six-membered intermediate A aromatizes to generate carbene gold B, which is subsequently intercepted by the oxide (ZþeO) to furnish 2a via C. Alternatively, the alkyne moiety of 1a initially reacts with Au(I) and N-oxide to give a,a0 -dioxo carbene gold E, which subsequently reacts with the pendant alkene moiety to give F (path b). Finally, protodemetalation, followed by aromatization, leads to 2a.

Scheme 2. Two possible reaction pathways.

Various keto-enynes 1 were then subjected to a reaction with Ph2SO in the presence of (t-BuXPhos)AuNTf2 (Table 2). Enynes 1b and 1c, possessing 4-methoxyphenyl and 4-chlorophenyl groups at

Table 2 Synthesis of 2-acyl-1-naphthols 2 by gold(I)-catalyzed oxidative cyclization of 1 with Ph2SOa

Entry

Enyne 1 (R, R0 )

Product 2

Yieldb (%)

1 2 3 4 5 6 7

1b (4-MeOC6H4, Me) 1c (4-ClC6H4, Me) 1d (Ph, Pr) 1e (Me, Me) 1f (Me, H) 1g (Ph, H) 1h (Ph, Ph)

2b 2c 2d 2e 2f 2g 2h

75 79 63 74 72 78 21

a Enyne 1 (0.100 mmol) and Ph2SO (0.250 mmol) were reacted in 1,2dichloroethane (1.0 mL) at rt in the presence of (t-BuXPhos)AuNTf2 (2.0 mmol). b Isolated yield.

the internal olefinic carbons, afforded 4-aryl 2-acetyl-1-naphthols 2b and 2c, respectively, in good yields (entries 1 and 2). Pent-1yn-1-yl ketone 1d and 2-isopropenylphenyl ketone 1e also gave the corresponding products 2d and 2e (entries 3 and 4). Furthermore, ethynyl ketones (1f and 1g) were converted into 2-formyl-1naphthols (2f and 2g) (entries 5 and 6). However, as evident by the low yield, 1h (R¼R0 ¼Ph) was largely averse to oxidative cyclization (entry 7).7 Substrates possessing substituents on the o-phenylene tether and heteroarene-tethered enynes were also examined (Table 3). Fluoro- and methylenedioxy-substituted naphthols 2i and 2j were synthesized in 52% and 61% yields, respectively, and phenanthrenol 2k was also obtained analogously from the 1,2naphthylene derivative 1k (entries 1e3). The gold-catalyzed cyclization was applicable to thienylene-tethered enyne 1l, which provided access to trisubstituted benzo[b]thiophene 2l, albeit with diminished yields (entry 4).8 The reaction of the pyridylene derivative 1m produced trisubstituted quinoline 2m in only 18% yield, even when the reaction was performed at 120
C (entry 5).8 In cases where an enyne lacked the substituent at the internal olefinic carbon, aromatization producing naphthalene was not observed. Instead, cyclopropanation occurred generating diketone 3 in a 46% yield (Scheme 3).9 The results may suggest that the cyclization likely proceeds via path b rather than path a. Our attention was subsequently drawn to the reaction of alkynyl 2-biphenyl ketones 1oeq with an expectation that the aryl group can participate in the benzannulation reaction as an alkene surrogate. The reaction failed to proceed at rt; however, it occurred at 120
C in p-xylene, giving rise to the formation of 10-acyl-9phenanthrenols 2oeq (Scheme 4).10 Yields of the reaction were in the range of 16e57%; the highest yield was achieved when the phenylethynyl derivative 1q reacted with PO. Interestingly, naphthol 2a was also prepared by gold(I)catalyzed reaction of the isomeric alkynyl ketone 4 (Scheme 5). This reaction employing PO as the oxidant gave 2a in a 57% yield. In sharp contrast, the use of Ph2SO did not result in oxidation, instead leading to the exclusive formation of alkylideneindene 5 through intramolecular hydroalkenylation.1x The reaction of substrates possessing alcohol oxidation levels under our conditions was also investigated (Scheme 6). Both 6a (R¼H) and 6b (R¼Me) underwent the gold(I)-catalyzed oxidative cyclization with Ph2SO at 40
C to afford 2-acetylnaphthalenes 7a and 7b in 42% and 37% yields, respectively, by way of dehydration.

T. Matsuda et al. / Tetrahedron 71 (2015) 869e874

871

Table 3 Gold(I)-catalyzed reaction of enynes 1iem with Ph2SOa

Entry

Enyne 1

Product 2

Yieldb (%)

Scheme 4. Reaction of alkynyl 2-biphenyl ketones 1oeq.

52

1

1i

2i

61

2

1j

2j Scheme 5. Gold(I)-catalyzed reaction of methyl [2-(1-phenylvinyl)phenyl]ethynyl ketone (4).

3

89

4

33 Scheme 6. Reaction of (1-phenylvinyl)phenyl prop-1-yn-1-yl carbinols 6a and 6b.

1l

2l 4. Experimental section 4.1. General

5c

18

1m a

Enyne 1 (0.100 mmol) and Ph2SO (0.250 mmol) were reacted in 1,2dichloroethane (1.0 mL) at rt in the presence of (t-BuXPhos)AuNTf2 (2.0 mmol). b Isolated yield. c The reaction was performed at 120
C in p-xylene.

All reactions were carried out with standard Schlenk techniques under a nitrogen atmosphere. Column chromatography was performed on WakogelÒ C-200 (75e150 mm). Preparative thin-layer chromatography was performed on WakogelÒ B-5F. Proton chemical shifts were referenced to residual CHCl3 signal at 7.26 ppm. Carbon chemical shifts were referenced to CDCl3 at 77.0 ppm. Melting points were not corrected.

4.2. General procedure for gold(I)-catalyzed cyclization

Scheme 3. Reaction of prop-1-yn-1-yl 2-vinylphenyl ketone (1n).

3. Conclusion In summary, we developed a gold-catalyzed cyclization of 2alkenylphenyl alkynyl ketones using N-oxides or Ph2SO as oxidants. The reaction resulted in aromatization to afford 2-acyl-1naphthols. The oxidative cyclization can be applied to alkynyl 2biphenyl ketones, thereby enabling the synthesis of 10-acyl-9phenanthrenols.

A Schlenk tube was charged with substrate (0.100 mmol), (tBuXPhos)AuNTf2 (2.0 mmol, 2 mol %), organic oxidant (0.250 mmol), and camphorsulfonic acid (0.150 mmol) (liquid substrates were added via syringe after 1,2-dichloroethane). The tube was evacuated and backfilled with argon. 1,2-Dichloroethane (or p-xylene, 1.0 mL) was added via a syringe through the septum. The mixture was stirred at 0
C for 30 min, and then at the indicated temperature for the indicated time. The reaction mixture was filtered through a plug of FlorisilÒ washing with hexane/AcOEt (1:1), and the filtrate was concentrated. The residue was purified by preparative TLC on silica gel to afford the following compounds. 4.2.1. 2-Acetyl-4-phenyl-1-naphthol (2a). According to the general procedure, 1a (24.6 mg, 0.100 mmol), (t-BuXPhos)AuNTf2 (1.8 mg,

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T. Matsuda et al. / Tetrahedron 71 (2015) 869e874

2.0 mmol), and Ph2SO (50.6 mg, 0.250 mmol) were reacted in 1,2dichloroethane (1.0 mL): rt for 12 h. Purification by preparative TLC on silica gel (hexane/AcOEt¼10:1) afforded 2a (21.9 mg, 0.083 mmol, 84%) as a yellow solid. Compound 2a was obtained in 57% yield (14.5 mg, 0.055 mmol) from 4 (23.7 mg, 0.096 mmol), pyridine Noxide (24.5 mg, 0.258 mmol), and camphorsulfonic acid (35.2 mg, 0.152 mmol). Mp 178e181
C (lit. 182e183
C;11a 178e180
C11b); 1H NMR (CDCl3, 500 MHz) d 2.71 (s, 3H), 7.42e7.62 (m, 8H), 7.80 (d, J¼8.0 Hz, 1H), 8.56 (d, J¼7.5 Hz, 1H), 14.01 (s, 1H). The spectral data matched those reported in the literature.11

2.2 mmol), and Ph2SO (51.4 mg, 0.254 mmol) were reacted in 1,2dichloroethane (1.0 mL): rt for 25 h. Purification by preparative TLC on silica gel (hexane/AcOEt¼10:1) afforded 2f (13.8 mg, 0.074 mmol, 72%) as a pale yellow solid. Mp 68e69
C; 1H NMR (CDCl3, 500 MHz) d 2.60 (s, 3H), 7.29 (s, 1H), 7.57 (t, J¼7.5 Hz, 1H), 7.72 (t, J¼7.8 Hz, 1H), 7.92 (d, J¼8.0 Hz, 1H), 8.48 (d, J¼8.5 Hz, 1H), 9.93 (s, 1H), 12.5 (s, 1H); 13C NMR (CDCl3, 126 MHz) d 18.7, 113.8, 124.2, 124.6, 124.8, 125.4, 125.8, 125.9, 130.5, 136.8, 160.6, 196.3; HRMS (ESI) calcd for C12H10NaO2 [MþNa]þ 209.0573, found 209.0571; IR (n/cm1): 3420, 1597, 1448, 755.

4.2.2. 2-Acetyl-4-(4-methoxyphenyl)-1-naphthol (2b). According to the general procedure, 1b (27.9 mg, 0.101 mmol), (t-BuXPhos) AuNTf2 (1.7 mg, 1.9 mmol), and Ph2SO (50.2 mg, 0.248 mmol) were reacted in 1,2-dichloroethane (1.0 mL): rt for 12 h. Purification by preparative TLC on silica gel (hexane/AcOEt¼8:1, two times) afforded 2b (22.1 mg, 0.076 mmol, 75%) as a pale yellow solid. Mp 140e141
C; 1H NMR (CDCl3, 500 MHz) d 2.70 (s, 3H), 3.91 (s, 3H), 7.02e7.07 (m, 2H), 7.37e7.41 (m, 2H), 7.62e7.71 (m, 3H), 7.80 (d, J¼7.5 Hz, 1H), 8.55 (d, J¼8.0, 1.5 Hz, 1H), 13.99 (s, 1H); 13C NMR (CDCl3, 126 MHz) d 27.0, 55.4, 112.8, 113.8, 124.6, 125.3, 125.4, 125.8, 125.9, 130.0, 130.6, 131.1, 132.3, 136.0, 158.9, 161.6, 204.5; HRMS (ESI) calcd for C19H16NaO3 [MþNa]þ 315.0992, found 315.0993; IR (n/cm1): 3433, 1628, 1512, 1389, 1234.

4.2.7. 2-Formyl-4-phenyl-1-naphthol (2g). According to the general procedure, 1g (24.1 mg, 0.104 mmol), (t-BuXPhos)AuNTf2 (1.9 mg, 2.1 mmol), and Ph2SO (51.0 mg, 0.252 mmol) were reacted in 1,2dichloroethane (1.0 mL): rt for 12 h. Purification by preparative TLC on silica gel (hexane/AcOEt¼10:1) afforded 2g (20.2 mg, 0.081 mmol, 78%) as a yellow solid. Mp 121e123
C; 1H NMR (CDCl3, 500 MHz) d 7.40e7.52 (m, 6H), 7.52e7.58 (m, 2H), 7.85 (d, J¼8.0 Hz, 1H), 8.54 (d, J¼9.0 Hz, 1H), 9.99 (s, 1H), 12.64 (s, 1H); 13C NMR (CDCl3, 126 MHz) d 113.8, 124.5, 124.7, 126.0, 126.9, 127.4, 128.5, 129.3, 130.0, 130.7, 132.1, 135.9, 139.5, 161.1, 196.4; HRMS (ESI) calcd for C17H12NaO2 [MþNa]þ 271.0730, found 271.0730; IR (n/ cm1): 3433, 1635, 764.

4.2.3. 2-Acetyl-4-(4-chlorophenyl)-1-naphthol (2c). According to the general procedure, 1c (29.1 mg, 0.104 mmol), (t-BuXPhos) AuNTf2 (1.8 mg, 2.0 mmol), and Ph2SO (50.9 mg, 0.252 mmol) were reacted in 1,2-dichloroethane (1.0 mL): rt for 12 h. Purification by preparative TLC on silica gel (hexane/AcOEt¼10:1) afforded 2c (24.4 mg, 0.082 mmol, 79%) as a yellow solid. Mp 145e147
C; 1H NMR (CDCl3, 500 MHz) d 2.70 (s, 3H), 7.35e7.43 (m, 2H), 7.43e7.51 (m, 2H), 7.52e7.64 (m, 3H), 7.70e7.76 (m, 1H), 8.52e8.59 (m, 1H), 14.03 (s, 1H); 13C NMR (CDCl3, 75.6 MHz) d 26.9, 112.7, 124.8, 125.4, 125.6, 126.0, 128.4, 128.6, 130.1, 130.3, 131.4, 133.4, 135.6, 138.4, 162.1, 204.3; HRMS (ESI) calcd for C18H13ClNaO2 [MþNa]þ 319.0496, found 319.0496; IR (n/cm1): 3442, 1619, 1398, 767. 4.2.4. 2-Butyryl-4-phenyl-1-naphthol (2d). According to the general procedure, 1d (30.9 mg, 0.113 mmol), (t-BuXPhos)AuNTf2 (1.8 mg, 2.0 mmol), and Ph2SO (50.6 mg, 0.250 mmol) were reacted in 1,2dichloroethane (1.0 mL): rt for 12 h. Purification by preparative TLC on silica gel (hexane/AcOEt¼10:1 then 15:1) afforded 2d (20.6 mg, 0.071 mmol, 63%) as a pale yellow solid. Mp 142e144
C; 1H NMR (CDCl3, 500 MHz) d 1.04 (t, J¼7.3 Hz, 3H), 1.84 (sext, J¼7.4 Hz, 2H), 3.05 (t, J¼7.2 Hz, 2H), 7.42e7.63 (m, 8H), 7.79 (d, J¼8.0 Hz, 1H), 8.53e8.58 (m, 1H), 14.16 (s, 1H); 13C NMR (CDCl3, 126 MHz) d 13.9, 18.0, 40.5, 112.4, 124.7, 125.0, 125.5, 125.82, 125.84, 127.3, 128.4, 130.0, 130.1, 130.8, 135.6, 140.1, 161.9, 206.7; HRMS (ESI) calcd for C20H18NaO2 [MþNa]þ 313.1199, found 313.1198; IR (n/cm1): 3433, 1620, 1389. 4.2.5. 2-Acetyl-4-methyl-1-naphthol (2e). According to the general procedure, 1e (17.9 mg, 0.097 mmol), (t-BuXPhos)AuNTf2 (1.8 mg, 2.0 mmol), and Ph2SO (51.5 mg, 0.255 mmol) were reacted in 1,2dichloroethane (1.0 mL): rt for 12 h. Purification by preparative TLC on silica gel (hexane/AcOEt¼10:1) afforded 2e (14.3 mg, 0.071 mmol, 74%) as a yellow solid. Mp 121e122
C; 1H NMR (CDCl3, 500 MHz) d 2.60 (s, 3H), 2.70 (s, 3H), 7.46 (s, 1H), 7.56 (t, J¼7.5 Hz, 1H), 7.69 (t, J¼7.7 Hz, 1H), 7.90 (d, J¼8.5 Hz, 1H), 8.50 (d, J¼8.0 Hz, 1H), 13.88 (s, 1H); 13C NMR (CDCl3, 126 MHz) d 30.6, 36.9, 105.6, 114.6, 114.7, 115.0, 115.3, 115.6, 115.9, 119.3, 124.7, 144.3, 178.7; HRMS (ESI) calcd for C13H12NaO2 [MþNa]þ 223.0730, found 223.0735; IR (n/cm1): 3433, 1620, 1234, 848, 764. 4.2.6. 2-Formyl-4-methyl-1-naphthol (2f). According to the general procedure, 1f (17.4 mg, 0.102 mmol), (t-BuXPhos)AuNTf2 (2.0 mg,

4.2.8. 2-Benzoyl-4-phenyl-1-naphthol (2h). According to the general procedure, 1h (31.4 mg, 0.102 mmol), (t-BuXPhos)AuNTf2 (1.8 mg, 2.0 mmol), and Ph2SO (52.7 mg, 0.261 mmol) were reacted in 1,2-dichloroethane (1.0 mL): rt for 12 h. Purification by preparative TLC on silica gel (hexane/AcOEt¼8:1) afforded 2h (7.1 mg, 0.022 mmol, 21%) as a yellow solid. Mp 161e164
C (lit. 160e161
C;11a 156e157
C11b); 1H NMR (CDCl3, 500 MHz) d 7.37e7.64 (m, 11H), 7.72e7.77 (m, 2H), 7.79e7.84 (m, 1H), 8.60e8.65 (m, 1H), 13.97 (s, 1H). The spectral data matched those reported in the literature.11 4.2.9. 2-Acetyl-6-fluoro-4-phenyl-1-naphthol (2i). According to the general procedure, 1i (26.8 mg, 0.101 mmol), (t-BuXPhos)AuNTf2 (1.8 mg, 2.0 mmol), and Ph2SO (50.8 mg, 0.251 mmol) were reacted in 1,2-dichloroethane (1.0 mL): rt for 12 h. Purification by preparative TLC on silica gel (hexane/AcOEt¼8:1) afforded 2i (14.7 mg, 0.052 mmol, 52%) as a white solid. Mp 140e141
C; 1H NMR (CDCl3, 301 MHz) d 2.70 (s, 3H), 7.24e7.56 (m, 7H), 7.61 (s, 1H), 8.56 (dd, J¼9.0, 6.3 Hz, 1H), 14.06 (s, 1H); 13C NMR (CDCl3, 126 MHz) d 26.9, 110.1 (2JCeF¼22.4 Hz), 112.5, 115.8 (d, 2JCeF¼25.3 Hz), 122.2, 126.8, 127.6, 127.8 (d, 3JCeF¼9.4 Hz), 128.6, 129.9, 130.3 (d, 4JCeF¼5.1 Hz), 137.7 (d, 3JCeF¼9.4 Hz), 139.5, 161.7, 163.7 (d, 1JCeF¼250.7 Hz), 204.3; HRMS (ESI) calcd for C18H13FNaO2 [MþNa]þ 303.0792, found 303.0791; IR (n/cm1): 3433, 1620, 1265. 4 . 2 .10 . 2-Acetyl-6,7-methylenedioxy-4-phenyl-1-naphthol (2j). According to the general procedure, 1j (28.7 mg, 0.099 mmol), (t-BuXPhos)AuNTf2 (1.9 mg, 2.1 mmol), and Ph2SO (51.0 mg, 0.252 mmol) were reacted in 1,2-dichloroethane (1.0 mL): rt for 12 h. Purification by preparative TLC on silica gel (hexane/AcOEt¼8:1, two times) afforded 2j (18.5 mg, 0.060 mmol, 61%) as a pale yellow solid. Mp 171e174
C; 1H NMR (CDCl3, 500 MHz) d 2.66 (s, 3H), 6.06 (s, 2H), 7.07 (s, 1H), 7.40e7.52 (m, 6H), 7.80 (s, 1H), 13.80 (s, 1H); 13C NMR (CDCl3, 126 MHz) d 26.8, 101.2, 101.6, 103.0, 112.4, 121.4, 124.7, 127.3, 128.5, 130.0, 130.3, 134.0, 140.3, 147.4, 151.0, 160.5, 204.2; HRMS (ESI) calcd for C19H14NaO4 [MþNa]þ 329.0784, found 329.0785; IR (n/ cm1): 3440, 1620, 1466, 1250. 4.2.11. 2-Acetyl-4-phenylphenanthren-1-ol (2k). According to the general procedure, 1k (29.2 mg, 0.099 mmol), (t-BuXPhos)AuNTf2 (1.7 mg, 1.9 mmol), and Ph2SO (50.2 mg, 0.248 mmol) were reacted in 1,2-dichloroethane (1.0 mL): rt for 12 h. Purification by preparative

T. Matsuda et al. / Tetrahedron 71 (2015) 869e874

TLC on silica gel (hexane/AcOEt¼10:1) afforded 2k (27.4 mg, 0.088 mmol, 89%) as a yellow solid. Mp 191e194
C; 1H NMR (CDCl3, 500 MHz) d 2.72 (s, 3H), 7.12 (t, J¼7.5 Hz, 1H), 7.38e7.43 (m, 2H), 7.45e7.53 (m, 4H), 7.66 (s, 1H), 7.72 (d, J¼9.0 Hz, 1H), 7.83 (d, J¼8.5 Hz, 1H), 7.87 (d, J¼8.0 Hz, 1H), 8.46 (d, J¼9.5 Hz, 1H), 13.61 (s, 1H); 13C NMR (CDCl3, 126 MHz) d 26.9, 114.0, 121.0, 124.3, 125.0, 127.2, 127.4, 127.6, 128.5, 128.7, 129.1, 129.2, 129.6, 129.9, 131.0, 134.1, 135.0, 144.7, 160.3, 204.4; HRMS (ESI) calcd for C22H16NaO2 [MþNa]þ 335.1043, found 335.1043; IR (n/cm1): 3433, 1635, 1234, 756. 4.2.12. 6-Acetyl-4-phenylbenzo[b]thiophen-7-ol (2l). According to the general procedure, 1l (25.5 mg, 0.101 mmol), (t-BuXPhos) AuNTf2 (1.8 mg, 2.0 mmol), and Ph2SO (50.5 mg, 0.250 mmol) were reacted in 1,2-dichloroethane (1.0 mL): rt for 12 h. Purification by preparative TLC on silica gel (hexane/AcOEt¼20:1, three times) afforded 2l (9.0 mg, 0.034 mmol, 33%) as a yellow solid. Mp 171e175
C; 1H NMR (CDCl3, 301 MHz) d 2.72 (s, 3H), 7.32e7.73 (m, 8H), 13.33 (s, 1H); 13C NMR (CDCl3, 126 MHz) d 27.0, 113.9, 124.1, 126.1, 127.4, 128.7, 128.9, 129.0, 129.1, 132.2, 140.0, 144.5, 158.1, 204.6; HRMS (ESI) calcd for C16H12NaO2S [MþNa]þ 291.0450, found 291.0449; IR (n/cm1): 3433, 1620, 1257. 4.2.13. 6-Acetyl-8-phenylquinolin-5-ol (2m). According to the general procedure, 1m (24.7 mg, 0.100 mmol), (t-BuXPhos)AuNTf2 (1.8 mg, 2.0 mmol), and Ph2SO (50.7 mg, 0.251 mmol) were reacted in p-xylene (1.0 mL): at 120
C for 12 h. Purification by preparative TLC on silica gel (hexane/AcOEt¼8:1) afforded 2m (4.8 mg, 0.018 mmol, 18%) as a pale yellow solid. Mp 202e205
C; 1H NMR (CDCl3, 301 MHz) d 2.75 (s, 3H), 7.38e7.56 (m, 4H), 7.65 (d, J¼6.9 Hz, 2H), 7.90 (s, 1H), 8.83 (dd, J¼8.3, 1.7 Hz, 1H), 9.03 (dd, J¼4.4, 1.7 Hz, 1H), 13.92 (s, 1H); 13C NMR (CDCl3, 75.6 MHz) d 27.1, 113.4, 120.82, 120.84, 127.4, 128.2, 129.1, 130.4, 131.9, 133.1, 138.9, 149.6, 153.4, 161.4, 204.5; HRMS (ESI) calcd for C17H14NO2 [MþNa]þ 264.1019, found 264.1019; IR (n/cm1): 3433, 1620, 1396. 4.2.14. 6a-Acetylbenzo[b]bicyclo[3.1.0]hexan-6-one (3). According to the general procedure, 1n (17.0 mg, 0.100 mmol), (t-BuXPhos)AuNTf2 (1.8 mg, 2.0 mmol), and Ph2SO (50.6 mg, 0.250 mmol) were reacted in 1,2-dichloroethane (1.0 mL): rt for 16 h. Purification by preparative TLC on silica gel (hexane/AcOEt¼10:1) afforded 3 (8.6 mg, 0.046 mmol, 46%) as a colorless oil. 1H NMR (CDCl3, 500 MHz) d 1.80 (dd, J¼4.5, 3.5 Hz, 1H), 2.42 (dd, J¼7.5, 3.5 Hz, 1H), 2.61 (s, 3H), 3.42 (dd, J¼7.5, 4.5 Hz, 1H), 7.35 (dt, J¼1.5, 7.5 Hz, 1H), 7.44 (d, J¼7.5 Hz, 1H), 7.52 (dt, J¼1.5, 7.5 Hz, 1H), 7.71 (d, J¼7.5 Hz, 1H); 13C NMR (CDCl3, 126 MHz) d 29.8, 34.6, 43.5, 46.2, 124.4, 125.2, 127.7, 134.2, 134.3, 151.6, 198.2, 202.1; HRMS (ESI) calcd for C12H10NaO2 [MþNa]þ 209.0573, found 209.0569; IR (n/cm1): 1726, 1344, 1168. 4.2.15. 10-Acetylphenanthren-9-ol (2o). According to the general procedure, 1o (21.1 mg, 0.096 mmol), (t-BuXPhos)AuNTf2 (1.9 mg, 2.1 mmol), and Ph2SO (50.8 mg, 0.251 mmol) were reacted in pxylene (1.0 mL): 120
C for 12 h. Purification by preparative TLC on silica gel (hexane/AcOEt¼10:1) afforded 2o (10.4 mg, 0.044 mmol, 46%) as a pale yellow solid. Mp 95e98
C; 1H NMR (CDCl3, 500 MHz) d 2.85 (s, 3H), 7.52 (t, J¼7.2 Hz, 1H), 7.58 (t, J¼7.2 Hz, 1H), 7.65 (t, J¼7.5 Hz, 1H), 7.76e7.83 (m, 1H), 8.01 (d, J¼8.5 Hz, 1H), 8.53e8.60 (m, 3H), 14.7 (s, 1H). The spectral data matched those reported in the literature.12 4.2.16. 10-Acetyl-2-methoxyphenanthren-9-ol (2p). According to the general procedure, 1p (25.2 mg, 0.101 mmol), (t-BuXPhos) AuNTf2 (1.9 mg, 2.1 mmol), and Ph2SO (50.6 mg, 0.250 mmol) were reacted in p-xylene (1.0 mL): 120
C for 12 h. Purification by preparative TLC on silica gel (toluene) afforded 2p (8.0 mg, 0.030 mmol, 30%) as yellow solid. Mp 109e110
C; 1H NMR (CDCl3, 500 MHz) d 2.85 (s, 3H), 3.95 (s, 3H), 7.12 (dd, J¼9.5,

873

2.5 Hz, 1H), 7.41 (d, J¼2.5 Hz, 1H), 7.54e7.58 (m, 1H), 7.71e7.77 (m, 1H), 8.42 (d, J¼9.0 Hz, 1H), 8.46 (d, J¼8.5 Hz, 1H), 8.51 (dd, J¼8.0, 1.0 Hz, 1H), 14.80 (s, 1H); 13C NMR (CDCl3, 126 MHz) d 31.6, 55.4, 108.8, 111.9, 112.7, 120.3, 121.9, 124.4, 124.9, 125.4, 126.1, 131.1, 131.3, 134.3, 158.6, 163.8, 203.8; HRMS (ESI) calcd for C17H14NaO3 [MþNa]þ 289.0835, found 289.0837; IR (n/cm1): 3433, 1612, 1219, 764. 4.2.17. 10-Benzoylphenanthren-9-ol (2q). According to the general procedure, 1q (28.9 mg, 0.102 mmol), (t-BuXPhos)AuNTf2 (1.9 mg, 2.1 mmol), pyridine N-oxide (23.7 mg, 0.249 mmol), and camphorsulfonic acid (34.8 mg, 0.150 mmol) were reacted in p-xylene (1.0 mL): 120
C for 12 h. Purification by preparative TLC on silica gel (hexane/AcOEt/toluene¼95:5:1) afforded 2q (17.5 mg, 0.059 mmol, 57%) as a yellow solid. Mp 137e138
C; 1H NMR (CDCl3, MHz) d 7.15e7.20 (m, 1H), 7.33e7.43 (m, 4H), 7.51e7.56 (m, 1H), 7.61e7.65 (m, 2H), 7.66e7.72 (m, 1H), 7.80e7.85 (m, 1H), 8.54 (d, J¼8.0 Hz, 1H), 8.57e8.64 (m, 2H), 12.76 (s, 1H). The spectral data matched those reported in the literature.13 4.2.18. 1-(2-Oxopropylidene)-3-phenyl-1H-indene (5). According to the general procedure, 4 (23.9 mg, 0.097 mmol), (t-BuXPhos) AuNTf2 (1.8 mg, 2.0 mmol), and Ph2SO (50.7 mg, 0.251 mmol) were reacted in 1,2-dichloroethane (1.0 mL): rt for 12 h. Purification by preparative TLC on silica gel (hexane/AcOEt¼10:1) afforded 5 (15.9 mg, 0.065 mmol, 67%) as an amber oil. 1H NMR (CDCl3, 500 MHz) d 2.46 (s, 3H), 6.84 (s, 1H), 7.22e7.27 (m, 1H), 7.30e7.35 (m, 1H), 7.40e7.52 (m, 5H), 7.61 (d, J¼6.5 Hz, 1H), 7.68e7.72 (m, 2H); 13C NMR (CDCl3, 126 MHz) d 31.9, 119.7, 120.5, 121.3, 124.0, 126.5, 127.6, 128.7, 129.1, 129.7, 134.6, 138.4, 142.3, 149.0, 152.6, 198.7; HRMS (ESI) calcd for C18H14NaO [MþNa]þ 269.0937, found 269.0942; IR (n/cm1): 1682, 1604, 756. 4.2.19. 3-Acetyl-1-phenylnaphthalene (7a). According to the general procedure, 6a (24.9 mg, 0.100 mmol), (t-BuXPhos)AuNTf2 (1.8 mg, 2.0 mmol), and Ph2SO (51.1 mg, 0.253 mmol) were reacted in 1,2-dichloroethane (1.0 mL): rt for 12 h. Purification by preparative TLC on silica gel (hexane/AcOEt¼8:1) afforded 7a (10.3 mg, 0.042 mmol, 42%) as a colorless oil. 1H NMR (CDCl3, 500 MHz) d 2.76 (s, 3H), 7.43e7.60 (m, 7H), 7.90e7.95 (m, 1H), 7.98 (d, J¼2.5 Hz, 1H), 8.02e8.06 (m, 1H), 8.49 (s, 1H). The spectral data matched those reported in the literature.14 4.2.20. 2-Acetyl-1-methyl-4-phenylnaphthalene (7b). According to the general procedure, 6b (26.2 mg, 0.100 mmol), (t-BuXPhos) AuNTf2 (1.8 mg, 2.0 mmol), and Ph2SO (50.5 mg, 0.250 mmol) were reacted in 1,2-dichloroethane (1.0 mL): rt for 12 h. Purification by preparative TLC on silica gel (hexane/AcOEt¼8:1) afforded 7b (9.7 mg, 0.037 mmol, 37%) as a colorless oil. 1H NMR (CDCl3, 500 MHz) d 2.67 (s, 3H), 2.84 (s, 3H), 7.43e7.53 (m, 7H), 7.57e7.63 (m, 1H), 7.91 (d, J¼8.0 Hz, 1H), 8.24 (d, J¼8.5 Hz, 1H); 13C NMR (CDCl3, 126 MHz) d 15.8, 30.9, 124.8, 125.5, 126.5, 126.6, 127.1, 127.5, 128.3, 130.1, 132.4, 132.9, 133.2, 136.6, 138.6, 140.2, 204.3; HRMS (ESI) calcd for C19H16NaO [MþNa]þ 283.1093, found 283.1091; IR (n/ cm1): 1598, 1541, 1536, 755, 681. Acknowledgements This work was supported by Japan Society for the Promotion of Science, Japan (Grant-in-Aid for Scientific Research (C) No. 25410054) and the Sumitomo Foundation (No. 130325). Supplementary data Copies of 1H and 13C NMR spectra for all products. Supplementary data associated with this article can be found in the online

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version, at http://dx.doi.org/10.1016/j.tet.2014.12.041. These data include MOL files and InChiKeys of the most important compounds described in this article.

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