Synthesis and epimerization of 10-N-(6-deoxy-1,2 : 3,4-di-O-isopropylidene-alpha-D-galactopyranos-6-yl)-(11aS)-pyrrolo[2,1-c] [1,4]benzodiazepin-5,11-dione

摘要

The reaction of the 1.,2:3,4-di-O-isopropylidene-6-O-tosyl-alpha -D-galactopyranose 2 with (11aS)-pyrrolo[2,1-c][1,4]benzodiazepin-5.11-dione 1. prepared front L-proline and isatoic anhydride, gave two products which were previously reported as conformational isomers. In this work. an X-ray crystallographic study showed these to be the diastereomeric pair (HaS)- and (11aR)-10-N-(6-deoxy-1.2:3.4-di-O-isopropylidene-alpha -D-galactropyranos-6-yl)-pyrrolo[2,1-c,][1,4]benzodiazepin-5.11-diones as a consequence of C(11a) epimerization in the benzodiazepine moiety during glycosylation under basic reaction conditions, The hydrosolubility of the deprotected products ere compared with those of the analogous benzodiazepine derivatives. (C) 2001 Elsevier Science Ltd. All rights reserved. [References: 15]