Synthesis and kinetic analysis of the N-acetylhexosaminidase inhibitor XylNAc-isofagomine

An efficient 10-step preparation from 4-methoxypyridine of (2R,3R,4R)-2-acetamido-3,4-dihydroxy-piperidine ('XylNAc-isofagomine') in optically active form is described. Key steps include an enantioselective reduction with cateholborane/(S)-2-methyl-CBS-oxazaborolidine, and a stereoselective pseudo-glycosylation of lithium azide by a cyclic sulfite ester.