8a,9a-Epoxy Nor-31-lanosten-3-one

To the epoxide 1 (1 g, 2.32 mmol) in acetone (50 ml) [1] was added dropwise at 0°C a solution of CrO3 (0.7 g, 7 mmol) in acetone (20 ml). After stirring for 2 hours, the solvent was removed in vacum. Water was added and the product was extracted by 3 times CH2Cl2. The organic layer was dried (Na2SO4), concentrated and purified by chromatography on silica gel column using hexane/EtOAc 93/7 as solvent to give 2 (0.73 g, 72 %).

Mp : 153-154 °C. IR : 1740 cm-1.

MS (EI, 70eV) : 428.7 (M+.).

¹H NMR (200 MHz, CDCl3) : 0.74 (s, C18-H3); 0.82 (s, C19-H3); 0.79 (d, J=6 Hz, C21-H3); 0.77 (d, J=6 Hz, C26 and C27-H6); 1.22 (s, C28-H3); 0.80 (d, J=6 Hz, C29-H3).

¹³C NMR (50 MHz, CDCl3) : 33.13 (C1); 38.44 (C2); 211.10 (C3); 47.31 (C4); 44.06 (C5); 21.50 (C6);

27.44 (C7); 68.27 (C8); 66.93 (C9); 47.73 (C10); 22.04 (C11); 30.90 (C12); 42.61 (C13); 36.38 (C14);

35.3 (C15); 35.13 (C16); 41.95 (C17); 10.55 (C18); 18.89 (C19); 25.85 (C20); 19.81 (C21); 36.59 (C22);

23.03 (C23); 26.95 (C24); 36.22 (C25); 15.16 (C26); 14.51 (C27); 21.51 (C28); 21.80 (C29).

The structure of the compound 2 were established by X-ray crystal structure determination.