Direct Synthesis of Protected Enantiopure 5-Cyano-3,4-dihydroxypyrrolidin-2-ones from β-Lactam Aldehydes Catalyzed by Iodine

Abstract

A single-step catalytic ring-expansion approach from 4-oxoazetidine-2-carbaldehydes to protected enantiopure 5-cyano-3,4-dihydroxypyrrolidin-2-ones has been achieved by the use of the commercially available and inexpensive reagent, molecular iodine, in the presence of tert-butyldimethyl cyanide. Interestingly, the catalyst directs the reaction toward the selective rearrangement reaction of the β-lactam nucleus rather than cyanohydrin formation.