Synthesis of regio- and stereospecifically C-deuterated derivatives of glycosidase inhibitors 1-deoxymannonojirimycin and 2,5-dideoxy-2,5-imino-d-mannitol by intramolecular reductive amination employing deuterium gas

6-Azido-1,3,4-tri-O-benzyl-6-deoxy-d-fructofuranose can be easily obtained in two steps from the known 6,6′-diazido-6,6′-dideoxysucrose, which is available in two steps from sucrose. Cyclisation of this material by controlled hydrogenation with 2H2 over Raney nickel and concomitant intramolecular reductive amination gave 3,4,6-tri-O-benzyl-1,5-dideoxy-1,5-imino-d-(5-2H)mannitol, a partially protected derivative of 1-deoxymannonojirimycin. Conventional deprotection furnished 1-deoxy-(5-2H)mannonojirimycin. Reduction and intramolecular reductive amination of free 5-azido-5-deoxy-d-fructopyranose gave 2,5-dideoxy-2,5-imino-d-(5-2H)mannitol in one step. Likewise, 2,5-dideoxy-2,5-imino-d-(5-2H)glucitol was obtained from 5-azido-5-deoxy-l-sorbopyranose.