Synthesis of phenyl 3,4-di-O-benzyl-2,4-dideoxy-3-C-methyl-1-thio-alpha,beta-L-xylo-hexopyranoside. A glycosyl donor for axenose

A new synthesis of the methyl-branched sugar axenose is described. Axenose is found in the antibiotics axenomycin, dutomycin, and polyketomycin. The s ynthesis is based on additions of organometallic reagents to pentodialdo-1, 4-furanosides and allows the preparation of derivatives of methyl alpha-L-a xenoside which are protected at the tertiary C-3 hydroxyl group. Conversion to thioglycoside derivatives for use in oligosaccharide synthesis was carr ied out directly from the methyl glycoside by treatment with phenylthiotrim ethylsilane and trimethylsilyl trifluoromethanesulfonate. (C) 2000 Elsevier Science Ltd. All rights reserved.