A stereoselective transformation of (−)-shikimic acid into (3R,4S,5R,7R)-7-(hydroxymethyl)azepane-3,4,5-triol, a potential glycosidase inhibitor

(i) TBDMSCI, imidazole, DMF, rt, 15 h (71% yield); (ii) O3, Ph3P, Cl2CH2/MeOH, −78 °C, 15 min (75% yield); (iii) NH4HCO3, NaCNBH3, MeOH, rt, 2 h, (78% yield); (iv) 6 N aq HCl, MeOH, 24 h, quantitative.