ON THE SYNTHESIS OF AMINOGLYCOSIDES OF CARDIOACTIVE STEROIDS - A STUDY DIRECTED TOWARDS BETA-SELECTIVE GLYCOSYLATIONS OF 3-AMINODIGITOXOSE WITH DIGITOXIGENIN ANALOGS

Carbamate derivatives of 3-aminodigitoxose (D-ristosamine) were prepar ed, with the purpose of synthesizing 3-amino-beta-digitoxosyl derivati ves of cardioactive steroids. A 1,3 participation procedure, used unde r acid or mercury salt catalysis, and the imidate procedure were inves tigated. A careful fine tuning of the glycosylation conditions was nec essary in order to obtain significant beta-D-stereoselectivity, which proved to be mainly dependent on the polarity of the solvent and the r elative reactivity of the sugar and the nucleophile.