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 Rh-2(S-PTAD)(4). A variety of aryl-substituted pyrroloindolines were prepared in good yields and with high levels of enantioinduction.