STUDIES ON REACTIONS OF 2-BROMO-3-KETOTRITERPENOIDS .3. REDUCTION OF 2-ALPHA-BROMO AND 2,2-DIBROMO DERIVATIVES OF LUPANONE AND METHYL DIHYDROBETULONATE WITH LITHIUM ALUMINUM-HYDRIDE AND SODIUM-BOROHYDRIDE

Reduction of methyl 2 alpha-bromodihydrobetulonate/2 alpha-bromolupanone (1/2) and methyl 2, 2-dibromodihydrobetulonate/2, 2-dibromolupanone (1a/2a) with LAH at room temperature results in the formation of methyl 2 alpha-bromo-3 beta-hydroxydihydrobetulonate/2 alpha-bromo-3 beta-hydroxylupane (3/4), methyl dihydrobetulinate/lupanol (3b/4b) and methyl 2 alpha-bromo dihydrobetulonate/2 alpha-bromolupanone (1/2), methyl dihydrobetulinate/lupanol (3b/4b),lupan-2 beta-3 beta-diol (5) (from 2a) respectively, while the reduction of 1/2 and 1a/2a with NaBH4 affords 3/4, 3b/4b and methyl dihydrobetulonate/lupanone (1b/2b), 3b/4b respectively.