Reaction Steps
Ynone 32 (5.28 g, 5.71 mmol) was taken up in i-PrOH (58 mL). The (S,S)-Noyori catalyst (0.77 g, 1.15 mmol, 20 mol %) was added in one portion and the solution was stirred overnight. The solvent was removed under vacuum, and the crude residue was purified by flash chromatography on silica gel (hexane/EtOAc 97:3), affording propargylic alcohol 33 (4.18 g, 79%) as a pale yellow oil: IR (CHCl3) 3469, 2955, 2856, 1471, 1448, 1252, 1084, 836, 774 cm−1; 1H NMR (300 MHz, CDCl3) δ 7.55 (m, 6H), 7.36 (m, 9H), 5.71 (m, 2H), 4.59 (m, 1H), 4.03 (quint, J=3.9 Hz, 1H), 3.65 (d, J=3.9 Hz, 2H), 3.58 (dd, J=4.6, 3.2 Hz, 1H), 3.55 (dd, J=10.1, 5.1 Hz, 1H), 3.38 (dd, J=9.7, 6.8 Hz, 1H), 2.71 (m, 1H), 2.50 (m, 1H), 2.32 (d, J=5.4 Hz, 1H), 1.88 (m, 1H), 1.80 (m, 2H), 1.55 (m, 1H), 1.23 (d, J=7.1 Hz, 3H), 1.11 (d, J=6.8 Hz, 3H), 0.98 (m, 34H), 0.20 (s, 3H), 0.17 (s, 3H), 0.16 (s, 3H), 0.14 (s, 3H), 0.12 (s, 6H); 13C NMR (75 MHz, CDCl3) δ 144.3, 134.0, 128.6, 127.8, 127.1, 126.9, 88.1, 86.8, 83.0, 72.6, 68.3, 65.8, 65.1, 59.5, 41.9, 40.3, 38.7, 33.5, 33.2, 32.1, 26.0, 25.9, 18.4, 18.1, 17.7, 17.4, 15.7, 15.3, 14.2, −3.9, −4.0, −4.4, −4.5, −5.3; LRMS (ESI) 949.7 [M+Na]+, 413.3, 243.1; HRMS (ESI) calcd for C56H90O5Si3Na 949.5994 [M+Na]+, found 949.6018; [α]20D−10.0 (c 1.2, CHCl3).
