1-Amino-1-deoxy-D-glucitol (14) was converted to the N-Boc-2,3;5,6-di-O-isopropylidene derivative 16 which was transformed further into the selectively protected 2,3-O-isopropylidene 6-azido piperidine 3. The synthesis proceeded via a double inversion at C-5 involving internal attack of 4-OH to form the 4,5-epoxide 28, and ring opening of this epoxide by 1-NH2 to generate the piperidine 3. This served as a valuable precursor of various target compounds, i.e. 6-azido- and 6-amino-1,6-dideoxynojirimycin 4 and 5, and the mono- and bicyclic derivatives 6-12. (C) 2000 Elsevier Science Ltd. All rights reserved.