5-cyano-3,4-dihydroxypyrrolidin-2-ones has been achieved by the use of the commerciallyavailable and inexpensive reagent, molecular iodine, in the presence oftert-butyldimethyl cyanide. Interestingly, the catalyst directs the reaction toward the selective rearrangement reaction of the β-lactam nucleus rather than cyanohydrin formation.
I2-Catalyzed enantioselective ring expansion of β-lactams to γ-lactams through a novel C3–C4 bond cleavage. Direct entry to protected 3,4-dihydroxypyrrolidin-2-one derivatives
Molecular iodine (10 mol%) efficiently catalyzes the ring expansion of 4-oxoazetidine-2-carbaldehydes 1 in the presence of tert-butyldimethyl cyanide to afford protected 5-cyano-3,4-dihydroxypyrrolidin-2-ones 2 with good yield and high diastereoselectivity, through a novel C3âC4 bond cleavage of the β-lactam nucleus.