Rhodium(ii) catalysed highly diastereoselective synthesis of indolyl-pyrrolo[2,1-a]isoindoles from phthalimide-derived N-sulfonyl-1,2,3-triazoles and indoles

Abstract

A synthetic method has been developed for the diastereoselective domino synthesis of indolyl-pyrrolo[2,1-a]isoindoles from phthalimide-derived N-sulfonyl-1,2,3-triazoles and indoles. The reaction proceeds via ring chain isomerization of triazoles to give α-imino diazo compounds. Then, denitrogenative generation of α-imino Rh(II) carbenes followed by intramolecular oxygen insertion and nucleophilic addition of indoles delivers the indolyl-pyrrolo[2,1-a]isoindoles. The synthetic utility of the products was also demonstrated through selective Grignard reagent addition and NaBH₄ reduction reactions.