The Synthesis of Aldos-4-ulose Derivatives and Branched Chain Sugars.

Abstract : Crystalline L-threo-pentopyranos-4-ulose diethyl dithiacetal has been prepared and converted to L-threo-pentos-4-ulose and L-threo-pentulose. This represents a new synthesis of the latter compound in six steps from L-arabinose. The dithioacetal triacetate, reacted with piperidine to give several products, one of which was 2,3,-di-O-acetyl-a -L-threo-pentopyranos-4-ulose diethyl dithioacetal. Reduction of 1.2,3,6-tetra-O-benzoyl-a-D-xylo-hexopyranos-4-ulose with sodium borodeuteride followed by debenzoylation gave 4-deuterio-D- glucose. 4-Deuterio-D-talose and 4-deuterio-D-xylose were similarly prepared. Methyl 5-O-benzyl-3-deoxy-3-dithianyl-a-D-arabinofuranoside, a branched-chain sugar derivative, was obtained in low yield by reaction of methyl 5-O-benzyl-2,3-anhydro-a-D-lyxofuranoside with -lithio-1,3-dithiane. Reactions of 2,3-anhydrolyxosides with potassium cyanide were complicated by epimerisations and intramolecular reactions.