Nucleophilic displacement reactions in carbohydrates. Part XXII. Formation of 1,4-anhydropyranoses from 1-O-acetyl-6-deoxy-2,3-O-isopropylidene-4-O-methylsulphonyl-α-L-manno- and -talo-pyranose with sodium azide

Abstract

1-O-Acetyl-6-deoxy-2,3-O-isopropylidene-4-O-methylsulphonyl-α-L-mannopyranose (10; R = Ac) and the epimeric L-talopyranose sulphonate (12; R = Ac) yielded 1,4-anhydro-6-deoxy-2,3-O-isopropylidene-β-L-talopyranose (11) and 1,4-anhydro-6-deoxy-2,3-O-isopropylidene-α-L-mannopyranose (13), respectively, on treatment with sodium azide in NN-dimethylformamide at 140°. A mechanism involving initial deacetylation is proposed for these and related reactions.