Bismuth(III) triflate catalyzed condensation of isatin with indoles and pyrroles: A facile synthesis of 3,3-diindolyl- and 3,3-dipyrrolyl oxindoles

Indoles and pyrroles undergo a rapid condensation with isatin in the presence of 2 mol% of Bi(OTf)(3), under mild reaction conditions, to afford the corresponding 3,3-di(3-indolyl)- and 3,3di(2-pyrroryl)oxindoles in excellent yields and high regioselectivity. This method is ideal for the direct introduction of indoles and pyrroles onto an isatin moiety at the 3-position.