Collect. Czech. Chem. Commun. 1980, 45, 1366-1378

Structure and the properties of 18α,19βH-ursane derivatives with a lactone bridge to ring E

Eva Klinotová, Hana Skorkovská, Jiří Protiva and Alois Vystrčil

Department of Organic Chemistry, Charles University, 128 40 Prague 2


Oxidation of ketolactone II in alkaline medium led predominantly to hydroxy acid VI with an oxabicycloheptane arrangement of the E ring. Further oxidation of hydroxy acid VI with lead tetraacetate or the pyrolysis of its diacetate, VII, gave ketone XV which on further oxidation gave either lactone XVIII or XXIV, depending on conditions. The structure of both lactones was confirmed by reduction to tetrol XIX or pentol XXV, from lactone XXIV diketone XXXI was also obtained.