Abstract
Odoroside H (la) was converted into 14,15[beta] -epoxy-5[beta] -card-20(22)-enolide-3[beta] -ol-[beta] -D-monodigitaloside (IIIa) in the following reaction sequence: Dehydration of odoroside H diacetate (Ib) withthionyl chloride in pyridine to give 14-anhydrodigitoxigenin monodigitaloside diacetate (IIc). Mild hydrolysis of IIc with acid afforded the corresponding acetyl-free glycoside (IIa) together with monoacetate (IIb) These 14-anhydro compounds (IIa, IIb and IIc) were treated with N-bromoacetamide followed by alumina chromatography to yield 14[beta] ,15[beta] -epoxy-5[beta] -card-20(22)-enolide-3[beta] -ol-[beta] -D-monodigitaloside (IIIa), and its mono-and diacetate (IIIb and IIIc) respectively. Microbiological deacetylation of IIIc furnished IIIa. In the same manner, digitoxin tetraacetate (VI) was changed into 14[beta],15[beta] -epoxy-5[beta] -card-20(22)-enolide-3[beta] -ol-[beta] -D-tri-digitoxoside (Villa).