Nucleophilic displacement reactions in carbohydrates. Part XI. Reaction of methyl 6-deoxy-2,3-O-isopropylidene-4-O-methylsulphonyl-α-L-talopyranoside with sodium azide: a synthesis of L-perosamine (4-amino-4,6-dideoxy-L-mannose) derivatives

Abstract

The reaction of methyl 6-deoxy-2,3-O-isopropylidene-4-O-methylsulphonyl-α-L-talopyranoside (9) with sodium azide in boiling NN-dimethylformamide gave two products, in a ratio of 3 : 1, identified as methyl 4,6-dideoxy-2,3-O-isopropylidene-β-D-erythro-hex-4-enopyranoside (16) and methyl 4-azido-4,6-dideoxy-2,3-O-isopropylidene-α-L-mannopyranoside (10), respectively. Graded hydrolysis of the latter compound converted it into methyl 4-azido-4,6-dideoxy-α-L-mannopyranoside (12), which was hydrogenated to yield methyl 4-amino-4,6-dideoxy-α-L-mannopyranoside (13). The amino-sugar glycoside is enantiomeric with methyl perosaminide obtained by methanolysis of the antibiotic perimycin.