Chemoenzymatic Synthesis of trans‐4,5‐Dihydroxycyclopent‐2‐enones: Conversion to D‐1‐Deoxynojirimycin.

(4R,5S)-trans-4,5-Bis(tert-butyldimethylsilyloxy)cyclopent-2-enone 8 and (4R,5S)-trans-4,5-di(benzyloxy)cyclopent-2-enone 20 are prepared by equilibration of the corresponding cis derivatives; enone 8 is transformed into the glucosidase inhibitor, D-1-deoxynojirimycin 14.