Rh(II)-Catalyzed Cyclopropanation of Furans and Its Application to the Total Synthesis of Natural Product Derivatives

Abstract

Rh(II)-catalyzed enantioselective cyclopropanations of furans, providing access to synthetically useful building blocks, are reported. After screening of 10 Rh(II) catalysts, Rh-2(S-TCPTTL)(4) was identified as a highly efficient and selective catalyst (up to 98% ee, TON 88000, and TOF 24/s) for the cydopropanation of furans. These cyclopropanes were successfully applied to the enantioselective synthesis of novel paraconic acid derivatives.