The experimental procedure follows a novel protocol developed recently by us [
1]. All reactions were carried out under an atmosphere of dry argon by using standard Schlenk tube techniques. A solution of diisopropylamine (1.26 mL, 9.0 mmol) in THF (30 mL) was treated at 0 °C with a solution of
n-butyllithium (3.0 mL, 2.5M in hexane, 7.5 mmol) and stirred for 15 min. At 40 °C butyrophenone (1.11mL, 7.50 mmol) was added and the mixture was stirred at 40 °C for 1 h. Then InCl
3 (2.5 mmol) was added and the mixture was stirred for 30 min at 40 °C and 1 h at room temperature. After addition of benzaldehyde (0.25 mL, 2.5 mmol) in THF (30 mL), the reaction mixture was stirred for 2 h at 25°C. The reaction was quenched with saturated aqueous NaHCO
3 (50 mL). The layers were separated and the aqueous layer was extracted three times with diethylether. The combined organic layers were washed with saturated aqueous NaCl and dried with Na
2SO
4. Crystallisation from hexane afforded 70% of the title compound in a diastereomerically pure form as white crystals.
M.p. 160 °C.
IR (KBr): 3412, 3089, 3062, 3031, 2963, 2930, 2906, 2872, 1654, 1602, 1497, 1448, 1388, 1312, 1273, 1238, 1225, 1190, 1146, 1130, 1077, 1046, 1029, 755, 738, 700, 553 cm-1.
1H-NMR (600MHz; CDCl3): -0.15 (t, 3J=7.6Hz, 3H, CH3), -0.02 (t, 3J=7.5Hz, 3H, CH3), 0.96-1.19 (m, 2H, CH2), 1.28-1.33 (m, 2H, CH2), 2.12 (td, 3J=3.9Hz, 4J=1.4Hz, 1H, 3-H), 2.16 (ddd, 3J=10.6Hz, 3J=5.4Hz, 3J=2.5Hz, 1H, 5-H), 3.96 (d, 4J=1.4Hz, OH), 4.03 (s, 1H, OH), 5.08 (d, 3J=10.6Hz, 1H, 6-H), 7.21-7.24 (m, 1H, Ph-H), 7.27-7.40 (br m, 9H, Ph-H), 7.52-7.55 (m, 2H, Ph-H), 7.66-7.69 (m, 2H, Ph-H), 7.75-7.79 (br m, 1H, Ph-H).
13C-NMR (151MHz, CDCl3): 13.6 (CH3), 14.5 (CH3), 17.9 (CH2), 19.4 (CH2), 53.5 (C5), 55.2 (C3), 75.3 (C6), 79.4 (C4), 101.5 (C2), 124.9 (br s, Ph), 126.0 (Ph), 126.5 (Ph), 126.6 (br s, Ph), 127.8 (br s, Ph), 128.0 (Ph), 128.1 (Ph), 128.2 (Ph), 128.3 (Ph), 140.6 (quart.-Ph), 143.4 (quart.-Ph), 144.0 (quart.-Ph).
MS-EI (70 eV): 403 [M+], 385 [M+ - H2O].
Anal. Calcd. for C27H30O3, C: 80.56, H: 7.51; Found C: 80.64, H: 7.84.