Synthesis of 1-deoxy-l-gulonojirimycin and 1-deoxy-l-talonojirimycin

De novo synthesis of noncompetitive glycosidase inhibitors l-gulo-DNJ and l-talo-DNJ has been achieved in 9–10 steps starting from Garner’s aldehyde. Key to the success of this procedure was the construction of the 2,3-unsaturated piperidine 14, which syn dihydroxylation under Kishi’s and Donohoe’s conditions led to the desired iminosugars.