SYNTHESIS OF THE FIRST 1-AZAANALOGUES OF L-SUGARS

Two 1-azaanalogues of L-sugars were prepared. 2-C-methyl-1,2,5-trideox y-1,5-imino-L-ribitol (1) or 1-aza-2-deoxy-L-carbafucose was synthesiz ed from L-arabinose in 9 steps. L-Arabinose was converted to the benzy l glycoside, and then to the 3,4-acetonide. Oxidation of the 2-hydroxy group followed by Wittig methylenation gave benzyl ylidene-2-methylene -beta-L-erythro-pentopyranoside (6). Stereoselective hydrogenation fol lowed by reductive debenzylation and reduction led to 2-deoxy-3,4-O-is opropylidene-2-C-methyl-L-ribitol (9), which was ditosylated and treat ed with benzylamine to give a piperidine. Finally deprotection gave 1. oxy-2-C-hydroxymethyl-1,5-imino-D-erythro-pentitol (2) was prepared f rom lactose in 7 steps. ethylbenzenesulphonyl)-D-isosaccharino-1,4-lac tone (14) was reacted with ammonia to give the 1,5-lactam. Deprotectio n and reduction gave 2. Azasugar 1 was found to be a potent inhibitor of alpha-fucosidase. Copyright (C) 1996 Elsevier Science Ltd