Synthesis and Reactions of 3-C-Branched-Chain Analogues of 3,6-Anhydrodeoxynojirimycin

The syntheses of 3,6-anhydro-1-deoxy-3-C-ethoxycarbonylmethyl- (4) and 3-C-(2-hydroxyethyl)nojirimycin (5) from 5-azido-6-O-tert-butyldiphenylsilyl-5-deoxy-1,2-O-isopropylidene-α-D-glucofuranose (8) are described. The key intermediate is 5-azido-6-O-tert-butyldiphenylsilyl-3,5-dideoxy-3-C-ethoxycarbonylmethylene-1,2-O-isopropylidene-α-D-ribo-hex-3-enofuranose (11) which was obtained by condensation of 5-azido-6-O-tert-butyldiphenylsilyl-5-deoxy-1,2-O-isopropylidene-α-D-ribo-hexos-3-ulofuranose (10) with (ethoxycarbonylmethylene)triphenylphosphorane. Conventional benzoylation of 4 resulted in the formation of the lactones 13a and 13b. The 3-C-(2-hydroxyethyl) analogue (5) was synthesized by lithium aluminum hydride reduction of 3,6-anhydro-5-azido-5-deoxy-3-C-ethoxycarbonylmethyl-1,2-O-isopropylidene-α-D-glucofuranose (12), followed by deacetalation, and hydrogenation.