Rh(II)-Catalyzed Monocyclopropanation of Pyrroles and Its Application to the Synthesis Pharmaceutically Relevant Compounds.

Here we report Rh(II)-catalyzed monocyclopropanation reactions on pyrroles in the presence of aryldiazoacetates, providing the corresponding dearomatized products with high levels of enantioselectivity (up to >99% ee). Under the catalysis of Rh2(R-p-PhTPCP)4, a broad range of pyrrole substrates and aryldiazoacetates are shown to be compatible. Utilizing these valuable chiral building blocks, we further demonstrate the application of this transformation by synthesizing a homo-ß-proline analog and a ß-aminocarboxylic acid (ß-ACC) derivative from the monocyclopropanated product.

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

Rh(II)-catalyzed enantioselective cyclopropanations of furans, providing access to synthetically useful building blocks, are reported. After screening of 10 Rh(II) catalysts, Rh2(S-TCPTTL)4 was identified as a highly efficient and selective catalyst (up to 98% ee, TON 88000, and TOF 24/s) for the cyclopropanation of furans. These cyclopropanes were successfully applied to the enantioselective synthesis of novel paraconic acid derivatives.