STUDIES ON OXIDATI0N OF TRITERPENOIDS: PART VII. TRANSFORMATION OF OLEANANE AND URSANE SKELETONS TO 11α,12α-OXIDOTRITERPENOIDS WITH HYDROGEN PEROXIDE AND SELENIUM DIOXIDE AND THEIR CARBON-13 NMR DATA.

Article abstract of DOI:10.1016/S0040-4020(01)90326-6

Hydrogen peroxide-selenium dioxide in t-butanol has been found to be a good reagent for the preparation of 11α,12α-oxidotriterpenoids of oleanane and ursane skeletons; whereas α-amyrin and β-amyrin acetates furnished 11α,12α-epoxyurs-14-en-3β-yl acetate (4c) and 11α,12α-epoxytaraxer-14-en-3β-yl acetate (4a) respectively, uvaol and ursolic acid/methyl ester gave 11α,12α-epoxyurs-28->13-olide-3β-ol (5d); erythrodiol (3c) and oleanolic acid (3b)/methyl ester (3d) afforded 11α,12α-epoxy-oleanan-28->13-olide-3β-ol (5); olean-12-en-2α,3β,28-yl triacetate (3j) on similar reaction furnished 11α,12α-epoxytaraxer-14-en-3β-ol-2α,28-yl diacetate (4d) and 11α,12α-epoxytaraxer-14-en-2α,3β-diol-28-ylacetate (4e).