Imidazole → (+)-(6aR,9S,9aR)-2,2,4,4-Tetraisopropyl-6,6a,9,9a-tetrahydrocyclopenta[f][1,3,5,2,4]trioxad-isilocin-9-ol

関与物質

反応手順

To a stirred mixture of triol 10 (5.8 g, 44.6 mmol) and imidazole (21.2 g, 312.3 mmol) in DMF (300 mL), 1,3-dichloro-1,1,3,3-tetraisopropyldisiloxane (14.7 mL, 46.8 mmol) was added drop wise at 0° C. under nitrogen. The mixture was stirred at room temperature for 2.5 h, quenched with water (200 mL) and extracted with ethyl acetate (3×200 ml). The combined organic layer was washed with brine (2×100 ml), followed by with water and dried over Na2SO4. The solvent was removed under reduced pressure and the residue was purified by silica gel column chromatography (EtOAc: Hexane 1:30 to 1:5) to give 11 (13.7 g, 82%) as an oil. [α]24D +45.87° (c 1.0, CHCl3); 1H NMR (500 MHz, CDCl3) δ 0.93-1.04 (m, 28H), 2.90 (m, 1H), 3.16 (d, J=2.0 Hz, 1H), 3.51 (m, 1H), 4.01 (dd, J=3.0, 11.0 Hz, 1H), 4.21 (t, 5.6 Hz, 1H), 4.47-4.45 (m, 1H), 5.60 (dd, J=1.5, 6.0 Hz, 1H), 5.86 (dd, J=3.0, 6.5 Hz, 1H); 13C NMR (125 MHz, CDCl3) δ 12.6, 12.7, 12.9, 13.2, 13.3, 13.4, 17.0, 17.1, 17.2, 17.3, 17.4, 17.6, 54.6, 66.7, 74.7, 76.3, 132.5, 134.4; HR-MS Calcd. For (C18H36O4Si2+Na)+ 395.2152. found 395.2052.

情報源と証拠