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Bulletin of the Korean Chemical Society (BKCS)

ISSN 0253-2964(Print)
ISSN 1229-5949(Online)
Volume 16, Number 7
BKCSDE 16(7)
July 20, 1995 

Preparation of α-Linked 6-Deoxy-D-altro-heptopyranosidic Residues
Youngsook Shin, Keun Ho Chun, Jeong E. Nam Shin*, Gerald O. Aspinall
α-Linked D-altropyranosidic derivatives were obtained by configurational change at C-3 of α -D-mannopyranosides as the key step in preparation of allyl and methyl α -D-glycopyranosides of 6-deoxy-D-altro-heptose. The manno-altro conversion was effected by sequential reactions of Swern oxidation and stereoselective borohydride reduction. Allyl 4,6-O-benzylidene-2-O-p-methoxybenzyl-α -D-mannopyranoside was transformed to the corresponding altropyranoside via 3-oxo-arabino-hexopyranoside. Allyl 7-O-benzyl-6-deoxy-3,4-O-isopropylidene-α -D-altro-heptopyranoside has been prepared as a glycosyl acceptor to be coupled with β -D-GlcpNAc-(1→3)-α-D-Galp glycosyl donor for the synthesis of an O-antigen repeating unit of Campylobacter jejuni serotypes O:23 and O:36. Stereoselective borohydride reduction also succeeded in yielding methyl 2,4,7-tri-O-benzyl-6-deoxy-α -D-altro-heptopyranoside from the corresponding 3-oxo-α-D-arabino-heptopyranoside. C-6 Homologation was achieved by sequential reactions of cyanide displacement of 6-sulphonates, reduction of the resulting heptopyranosidurononitrile with diisobutylaluminum hydride, hydrolysis of the imine, and further reduction with sodium borohydride.
625 - 630
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