Reaction Steps
Oxidation of hippuristanol (1) to yield hippuristanol 11-one (4) and hippuristanol 3, 11-dione (5). To an ice-cooled solution of hippuristanol (1, 31.7 mg) in pyridine (0.5 mL), Cornforth reagent (0.7 mL) was added dropwise. The mixture was kept stirring for 30 min. in an ice bath, then 3 hr at RT. The mixture was taken up in ether and the suspension was filtered. The filtrate was washed with dilute hydrochloric acid, dried over Na2SO4, and concentrated. The resulting product was separated on silica TLC (CHCl3/EtOAc, 3:1, v/v) to give 8.8 mg of hippuristanol 11-one (4, 28%) and 17.7 mg of hippuristanol 3,11-dione (5, 56%). Hippuristanol 3,11-dione (5). white crystals. mp 181-183.5° C.; 1H NMR (CDCl3) δ 4.42 (m, 2H), 3.02 (s, 1H), 2.82 (ddd, J=13.0, 6.5, 2.0 Hz, 1H), 2.63 (d, J=12.0 Hz, 1H), 2.45 (dt, J=6.5, 14.5 Hz, 1H), 2.37 (dd, J=13.0, 8.0 Hz, 1H), 1.31 (s, 3H), 1.22 (s, 6H), 1.20 (s, 3H), 1.11 (s, 3H), 0.99 (d, J=7.0 Hz, 3H); 13C NMR (CDCl3) δ 211.6, 210.0, 115.0, 84.9, 80.4, 79.1, 63.9, 63.4, 58.8, 54.5, 46.9, 46.3, 44.3, 41.8, 40.5, 38.0, 37.0, 35.5, 35.2, 33.7, 32.4, 28.7, 28.5, 28.2, 23.0, 17.3, 14.8, 11.0; IR (KBr) 3510, 1695 cm−1; EIMS m/z 458 (M+, 5), 316 (92), 84 (100%).
