Branched-chain sugars. Part VIII. A contribution to the chemistry of 2-C-methyl-L-arabinose and -ribose

Abstract

Treatment of methyl 3,4-O-isopropylidene-β-L-erythro-pentosulopyranoside with diazomethane followed by lithium aluminium hydride yields two isomeric 2-C-methylpentoside derivatives: the preponderant product has the ribo-configuration. Evidence to support the configurations assigned to the products is provided. The stabilities of 2-C-methyl-L-ribose and -arabinose in acidic and basic media have been compared qualitatively with those of L-arabinose and D-ribose. Preliminary results on the treatment of methyl 2,2′-anhydro-2-C-hydroxymethyl-3,4-O-isopropylidene-β-L-pentoside (a mixture of the arabino- and ribo-isomers) with methanolic ammonia are noted.