THE CONVERSION OF D(-)GALACTOPYRANOSIDES INTO 2-AMINO-2-DEOXY-D-TALOPYRANOSYL DERIVATIVES - SOME NEW DATA

The known oxidation-oximation-reduction sequence leading from D-galact opyranosides to 2-amino-2-deoxy-D-talopyranosides through replacement of the 2-hydroxy by a 2-amino group with inversion has been reinvestig ated. The easily obtainable methyl (1-methoxy-1-methylethyl)-beta-D-ga lactopyranoside (1) was chosen as the suitably protected starting mate rial. The single steps in the synthetic sequence were analyzed in some detail from the point of view of different reagents, stereoselectivit ies, side products, NMR spectra and conformations of intermediates. Ow ing to side reactions in the oxidative and reductive steps and to the incomplete diastereoselectivity in the latter, the overall yields in t he conversion of 1 into methyl 2-deoxy-3,4-O-isopropylidene-beta-D-tal opyranoside did not exceed 50%. (C) 1996 Elsevier Science Ltd.