Rhodium-Catalyzed [3+2] Annulation of Indoles

An effective Rh-2(S-DOSP)(4)-catalyzed asymmetric cyclopentannulation of indolyl rings has been developed. Depending on the Substitution pattern of the indole. two distinct regioisomeric products can be generated. These studies demonstrate that rhodium-catalyzed reactions of donor/acceptor carbenoids proceeding by means of zwitterionic intermediates can be carried out with very high asymmetric induction.