Studies on Digitalis Glycosides. XXVI. Gitoxin Acetates. (1). Deacetylation of Pentaacetylgitoxin

Abstract

Hydrolysis of pentaacetylgitoxin (I) with diastase gave selectively 3', 3'', 3''', 16-tetraacetylgitoxin (IIa) as a main product. When IIa was treated with potassium hydrogen carbonate, acetyl groups were successively eliminated in the order of those at C-3''', -16, -3'' or -3' positions to afford 3', 3'', 16-triacetylgitoxin (IIc), 3', 3''-diacetylgitoxin (IId), 3'-monoacetylgitoxin (acetylgitoxin-γ, IIe) and gitoxin (IIf). These partial acetates did not agree with those obtained in acetylation of gitoxin (IIf), in which acetyl groups were introduced in the order at C-4''', -16, -3''' or -3' positions. The partial acetates obtained by the former method (deacetylation) were thought to be more essential for the study of metabolism of I than those prepared by the latter method (acetylation).