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
Ring Expansion versus Cyclization in 4-Oxoazetidine-2- carbaldehydes Catalyzed by Molecular Iodine: Experimental and Theoretical Study in Concert
作者:Benito Alcaide、Pedro Almendros、Gema Cabrero、Ricardo Callejo、M. Pilar Ruiz、Manuel Arnó、Luis R. Domingo
DOI:10.1002/adsc.201000171
日期:——
yield and high diastereoselectivity, through a C3C4 bondcleavage of the β‐lactamnucleus. Interestingly, in contrast to the iodine‐catalyzed reactions of 3‐alkoxy‐β‐lactam aldehydes which lead to the corresponding γ‐lactam derivatives (rearrangement adducts), the reactions of 3‐aryloxy‐β‐lactam aldehydes under similar conditions gave β‐lactam‐fused chromanes (cyclization adducts) as the sole products
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.