Rhodium Carbenoid Approach for Introduction of 4-Substituted (Z)-Pent-2-enoates into Sterically Encumbered Pyrroles and Indoles

An unusual rhodium carbenoid approach for introduction of 4-substituted (Z)-pent-2-enoates into sterically encumbered pyrroles and indoles is described. These studies show that (Z)-vinylcarbenoids have a greater tendency than (E)-vinylcarbenoids to react at the vinylogous position of the carbenoid rather than at the carbenoid center.