Cardenolide acid hydrolysis

Substituted cardenolides or cardenolides with epimeric configurations at several positions of the steroid nucleus have been made by appropriate modifications of known syntheses. In one of these, the steroid (510) was hydroxylated at C(14) by a microbiological method, acetylated, and reduced catalytically to the A/B-c/s-steroid (511). Sodium borohydride reduction gave the 3a-alcohol, which after acetylation and acid hydrolysis was transformed into the 3,14-di-... 

A doubly linked 4,6-dideoxy-D-j/ rgo-hexos-2-ulose residue was identified in the cardenolide glycoside (1) isolated from Asclepias curassavica stems, and a branched hexos-4-ulose derivative isolated from Pittosporum tobira flowers is covered in Chapter 14. Oxidation (MCPBAAleOH) of unsaturated derivative (2) (obtained by base treatment of methyl 3,4-0-isopropylidene-2,6-di-0-methyl-P-D-galactopyranoside) afforded L-arabino-hexos-S-ulose derivative (3) and then (4) after acid hydrolysis. The hexopyranosid-3-uloses (5) have been prepared by oxidation (Cr03/Ac20/pyridine) of the corresponding 3-alcohols. ... 

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