Catalytic Asymmetric Synthesis of Pyrroloindolines via a Rhodium(II)-Catalyzed Annulation of Indoles

Herein we report the synthesis of pyrrolo­indolines via a catalytic enantio­selective formal [3+2] cycloaddition of C(3)-substituted indoles. This methodology utilizes 4-aryl-1-sulfonyl-1,2,3-triazoles as carbenoid precursors and the rhodium­(II)-tetracarboxylate catalyst Rh₂(<i>S</i>-PTAD)₄. A variety of aryl-substituted pyrrolo­indolines were prepared in good yields and with high levels of enantio­induction