Arylazo-glycenosides. Part IV. Synthesis and reactions of some 2- and 3-arylazo-derivatives of methyl 2,3-dideoxy-D-pent-2-enofuranoside

Abstract

A method for the modification of some methyl D-pentofuranosidulose derivatives at the position α to the carbonyl group has been studied. Preparations are described of some new 2- and 3-phenylazo- and p-nitrophenylazoderivatives of methyl 2,3-dideoxy-D-pent 2-enofuranoside using D-xylose as the initial material. The procedures adopted for the syntheses are essentially those developed in our laboratories for the preparation of phenylazoderivatives of sugars and described in Part I.The new arylazo-derivatives have been shown to be useful synthetic intermediates: they undergo 1,4-addition reactions in a highly stereoselective way with a wide range of nucleophiles. For example, the following have been used in addition reactions, ammonia and dimethylamine, water, acetic acid, methoxide and azide ions, hydride and deuteride ions, and a range of sulphur nucleophiles. Structures of the products have been established by analysis of their n.m.r. spectra.A brief examination is reported of the formation of methyl D-pentofuranosiduloses carrying a substituent at position α to the carbonyl group from their arylhydrazones, which are the initial products of the addition reactions.