摘要:
The disaccharide portion of the anthracycline antibiotic polyketomycin consists of the trideoxy sugar D-amicetose attached to the methyl-branched sugar L-axenose. The polyketomycin disaccharide was synthesized from methyl 2,3,6-trideoxy-alpha-D-erythro-hexopyranoside (methyl alpha-D-amicetoside) and phenyl 3,4-di-O-benzyl-2,6-dideoxy-3-C-methyl-l-thio-alpha,beta-L-xylo-hexopyranoside. The key coupling step was carried out by N-bromosuccinimide activation of the thioglycoside and gave the desired alpha (1-->4) linked disaccharide exclusively in 71% yield, which was debenzylated by sodium and liquid ammonia. (C) 2003 Elsevier Ltd. All rights reserved.