H.-C. Lin et al. / Tetrahedron 72 (2016) 184e191
189
4.4.1. 3-Phenylbut-3-en-2-one (25). 1H NMR (300 MHz, CDCl3):
while stirring for a total of 2 h. The residue was purified by column
chromatography (1% EA/hexanes) to give yellow liquid 25 (0.57 g,
70%), white solid 27 and 28 (0.23 g, 27: 28¼1: 13, 25%).
d
¼7.30e7.42 (m, 5H), 6.18 (s, 1H), 5.98 (s, 1H), 2.45 ppm (s, 3H). 13
C
NMR (75 MHz, CDCl3):
(CH), 128.09 (CH), 128.04 (CH), 125.86 (CH2), 27.32 (CH3).
d
¼199.28 (C), 149.36 (C), 136.96 (C), 128.40
4.4.2. 1a-Methyl-7b-phenyl-1a,2-dihydro-1H-cyclopropa[a]-naph-
thalen-3(7bH)-one (26). Mp 100e101 ꢁC. IR (neat): ṽ¼3061, 2972,
2870, 1678, 1595, 1494, 1476, 1452, 1410, 1380, 1351, 1287, 1252,
4.7. The oxidation of the ene dimers 40 and 41
Methyllithium (1.5 M in ether, 10 mL, 15 mmol) was added
dropwise from a syringe to stirred solution of 1,1,2-tribromo-2-
phenylcyclopropane (19) (2 g, 5.6 mmol) in 8 mL of dry ether at
ꢀ78 ꢁC. The mixture was allowed to warm to rt and stirred for 0.5 h.
Methyl iodide (1.8 mL, 29 mmol) was added and stirred for 12 h.
The mixture was poured into a 250-mL beaker with 50 g of crushed
ice. The organic layer was separated and washed with water and
brine, and then dried over anhydrous magnesium sulfate. Ether was
removed under reduced pressure and the residue was stirred at
room temperature for 6 h. About 10 mL of CH2Cl2 was added, and
stirred with oxygen for 12 h, and the mixture was concentrated,
and chromatographed (3% EA/hexanes) to give white solid 39
(0.54 g, 70%).
1194, 1159, 1113, 1079, 1080, 1016, 964, 951, 923, 887, 860, 840 cmꢀ1
.
1H NMR (300 MHz, CDCl3):
d
¼7.93 (dd, J¼7.7, 1.4 Hz, 1H), 7.32e7.50
(m, 4H), 7.16e7.31 (m, 3H), 6.79 (dd, J¼7.7, 0.7 Hz, 1H), 3.11 (d,
J¼17.8 Hz, 1H), 2.88 (d, J¼17.8 Hz, 1H), 1.70 (d, J¼4.9 Hz, 1H), 1.02 (s,
3H), 0.76 (d, J¼4.9 Hz, 1H). 13C NMR (75 MHz, CDCl3):
¼197.03 (C),
d
150.09 (C), 140.07 (C), 133.18 (CH), 131.97 (CH), 130.75 (CH), 130.14
(C), 128.97 (CH), 128.70 (CH), 127.15 (CH), 126.99 (CH), 125.45 (CH),
43.88 (CH2), 35.11 (C), 32.28 (CH2), 23.10 (CH3), 22.01 (C). MS: m/z
(%)¼248 (100) [M]þ, 233 (40), 215 (38), 207 (37), 193 (29), 178 (33),
165 (26), 128(8), 115(8), 91 (9), 77 (7). HRMS: calcd for C18H16
O
248.1201; found 248.1210. C18H16O (248.32): calcd. C 87.06, H 6.49,
found C 86.99, H 6.79.
4.4.3. (Z)-4-Hydroxy-4-phenylbut-3-en-2-one (27) and tautomer
4.7.1. (Z)-3-(trans-1-Methyl-2-phenylcyclopropyl)-2-phenylbut-2-
enal (39). Mp 95e96 ꢁC. IR (neat): ṽ¼3029, 2932, 2922, 1671, 1601,
1494, 1450, 1372, 1214, 1144, 1085, 1056, 1024, 1101, 970, 934,
28. 1H NMR (300 MHz, CDCl3):
d
¼7.84e7.92 (m, 2H), 7.41e7.54 (m,
3H), 6.19 (s, 1H), 2.21 (s, 3H). 13C NMR (75 MHz, CDCl3):
d
¼193.82
(C), 183.45 (C), 135.02 (C), 132.35 (CH), 128.69 (CH), 127.09 (CH),
96.78 (CH), 25.91 (CH3).
846 cmꢀ1. 1H NMR (300 MHz, CDCl3):
d
¼10.65 (s, 1H), 7.31e7.44 (m,
5H), 7.22e7.31 (m, 3H), 7.03e7.10 (m, 2H), 2.38 (t, J¼7.8 Hz, 1H),
2.02 (s, 3H), 1.38e1.50 (m, 2H), 1.17 (s, 3H). 13C NMR (75 MHz,
4.5. The [4D2] cyclization of enone 25
CDCl3):
d
¼191.90 (CH), 164.41 (C), 140.28 (C), 137.45 (C), 135.48 (C),
129.82 (CH), 128.80 (CH), 128.40 (CH), 128.27 (CH), 127.50 (CH),
126.53 (CH), 28.94 (CH), 27.56 (C), 21.22 (CH3), 20.39 (CH3), 20.23
(CH2). MS: m/z (%)¼276 (3) [M]þ, 247 (29), 172 (100), 122 (22), 105
(15), 70 (31), 61 (58). HRMS: calcd for C20H20O 276.1514; found
276.1513.
Methyllithium (1.5 M in ether, 23.5 mL, 35 mmol) was added
dropwise from a syringe to stirred solution of 1,1,2-tribromo-2-
phenylcyclopropane (19) (5.0 g, 14 mmol) in 30 mL of dry ether at
ꢀ78 ꢁC. The mixture was allowed to warm to rt and stirred for 0.5 h.
Methyl iodide (4.4 mL, 71 mmol) was added and stirred for 12 h.
The mixture was poured into a 250-mL beaker with 100 g of
crushed ice. The organic layer was separated and washed with
water and brine, and then dried over anhydrous magnesium sul-
fate. After filtration, the solvent changed from ether to CH2Cl2
(30 mL) and stirred with oxygen for 19 h. The residue was purified
by column chromatography (3% EA/hexanes) to give yellow liquid
25. And a solution of 25 in CH2Cl2 (30 mL) at room temperature was
stirred for 56 h. The mixture was purified by readily by flash column
chromatography to give white solid 35 (1.76 g, 86%).
4.8. Ene reactions trapped with thiophenol
Methyllithium (1.5 M in ether, 23.5 mL, 35 mmol) was added
dropwise from a syringe to stirred solution of 1,1,2-tribromo-2-
phenylcyclopropane (19) (5.0 g, 14 mmol) in 30 mL of dry ether
at ꢀ78 ꢁC. The mixture was allowed to warm to rt and stirred for
0.5 h. Methyl iodide (4.4 mL, 71 mmol) was added and stirred for
12 h. The mixture was poured into a 250-mL beaker with 100 g of
crushed ice. The organic layer was separated and washed with
water and brine, and then dried over anhydrous magnesium
sulfate. Ether was removed under reduced pressure and the
residue was stirred at room temperature for 1d. A solution of
thiophenol (7 mL, 68 mmol) and CH2Cl2 was added and stirred
for 2 days, and the mixture was concentrated, and chromato-
graphed (hexanes) to give white solid 42 (0.96 g, 42%), white
solid 43 (0.33 g, 14%), white solid 44 (0.16 g, 7%), white solid 45
(0.12 g, 5%).
4.5.1. 1-(6-Methyl-2,5-diphenyl-3,4-dihydro-2H-pyran-2-yl)-etha-
none (35). 1H NMR (300 MHz, CDCl3):
d
¼7.53 (d, J¼7.4 Hz, 2H), 7.39
(t, J¼7.3 Hz, 2H), 7.26e7.35 (m, 3H), 7.20 (t, J¼7.3 Hz, 1H), 7.12 (d,
J¼7 Hz, 2H), 2.55e2.70 (m, 1H), 2.25e2.40 (m, 1H), 2.18 (s, 3H),
2.06e2.16 (m, 2H), 1.98 (s, 3H). 13C NMR (75 MHz, CDCl3):
d
¼209.16
(C), 145.94 (C), 141.46 (C), 139.35 (C), 128.83 (CH), 128.63 (CH),
128.17 (CH), 127.93 (CH), 126.27 (CH), 125.16 (CH), 111.51 (C), 85.88
(C), 30.08 (CH2), 24.89 (CH2), 24.53 (CH3), 18.21 (CH3).
4.6. The photosensitized oxidation of 18
4.8.1. (1R*,10R*,2S*,20S*,3S*)-1,10-Dimethyl-20,3-diphenyl-2-
phenylsulfenyl bicyclopropane (42). Mp 98e99 ꢁC. IR (neat):
ṽ¼3080, 3067, 3023, 2988, 2976, 2952, 2927, 1600, 1579, 1495, 1476,
1449,1438, 1376,1150, 1084,1069, 1025, 776, 759, 739, 688 cmꢀ1. 1H
Methyllithium (1.5 M in ether, 10 mL, 15 mmol) was added
dropwise from a syringe to stirred solution of 1,1,2-tribromo-2-
phenylcyclopropane (19) (2.0 g, 5.6 mmol) in 8 mL of dry ether at
ꢀ78 ꢁC. The mixture was allowed to warm to rt and stirred for 0.5 h.
Methyl iodide (1.8 mL, 29 mmol) was added and stirred for 12 h. The
mixture was poured into a 250-mL beaker with 50 g of crushed ice.
The organic layer was separated and washed with water and brine,
and then dried over anhydrous magnesium sulfate. After filtration,
a solution of 18 in 12 mL of CH2Cl2 was purged with oxygen and ir-
radiated with UVevis light, equipped with a water-cooled 450W 5
inch arc IMMER UVevis lamp (Mode #7825-34, Ace Glass, Inc.),
NMR (300 MHz, CDCl3):
d
¼7.36e7.45 (m, 2H), 7.25e7.35 (m, 9H),
7.12e7.25 (m, 4H), 2.63 (d, J¼8.8 Hz, 1H), 2.48 (d, J¼8.8 Hz, 1H), 2.06
(dd, J¼8.8, 6.6 Hz, 1H), 1.26 (s, 3H), 0.93e1.06 (m, 4H), 0.83 (t,
J¼6 Hz, 1H). 13C NMR (75 MHz, CDCl3):
¼139.28 (C), 138.14 (C),
d
136.21 (C), 130.47 (CH), 129.05 (CH), 128.94 (CH), 128.24 (CH),
128.13 (CH), 128.08 (CH), 126.56 (CH), 125.95 (CH), 125.65 (CH),
32.30 (C), 30.90 (CH), 30.55 (CH), 29.20 (C), 27.64 (CH), 18.36 (CH3),
15.81 (CH2), 15.10 (CH3). MS: m/z (%)¼370 (4) [M]þ, 261 (21), 212
(16), 170 (87),169 (49),167 (29),149 (26),105 (21), 91 (100), 70 (34),