New method of preparation of cardioglycoside hemisuccinates

Abstract

An indirect method for preparation of hemisuccinates (hydrogen butanedioates) is described, consisting in reaction of hydroxy derivatives with 2-(trimethylsilyl)ethyl hemisuccinate (I) followed by removal of the 2-(trimethylsilyl)ethyl group from the mixed succinate with tetrabutylammonium fluoride. It has been applied to the synthesis of hemisuccinates derived from cholesterol (II), (20E)-21-methoxycarbonylpregna-5,20-dien-3β-ol (V), digitoxigenin (XII), digitoxin (XV) and digoxin (XVIII). The method, however, is not suitable for the preparation of estrone hemisuccinate X which is cleaved with tetrabutylammonium fluoride to give estrone(VIII).