A ROUTE TO (2-ALPHA,3-BETA,4-ALPHA)-(+ -)-2-(HYDROXYMETHYL)-3,4-PYRROLIDINEDIOL BASED ON THE ALPHA-SILYLOXYALLYLATION OF A GLYCOLALDEHYDE-DERIVED NITRONE/

A protected form of title compound 6a, whose two enantiomers are known to be potent alpha-glycosidase inhibitors, was obtained through a fiv e-step synthesis based on two thoroughly diastereo-controlled steps. A n anti-selective alpha-silyloxyallylation of nitrone 9 afforded hydrox ylamine 8a which, after O-silylation, was subjected to iodocyclisation to give 5-iodomethylisoxazolidine 7a as a single diastereo-isomer. Di splacement of iodide by mesylate and hydrogenolysis of mesylate 7b fur nished 6b in 20 % overall yield starting from tert-butyldimethylsilylo xyacetaldehyde.