Catalytic Asymmetric Synthesis of Cyclopentyl beta-Amino Esters by [3+2] Cycloaddition of Enecarbamates with Electrophilic Metalloenolcarbene Intermediates

摘要

Chiral cyclopentyl beta-amino esters are formed catalytically by [3+2] cycloaddition reactions of enecarbamates with electrophilic metalloenolcarbenes in high yield with up to 98% ee and excellent diastereocontrol. Use of beta-silyl-substituted enoldiazoacetates with a chiral dirhodium catalyst and trans-beta-arylvinylcarbamates are optimal for this transformation, which occurs with hydrogen-bond association between the vinylcarbamate and the intermediate metalloenol-carbene. Reductive conversion of the protected amino esters forms highly functionalized cyclopentyl beta-amino acids and 3-aminocyclopentanones.