Rh(III)-Catalyzed Annulation of (Het)aryl Amides with α-Allenyl-Containing α-Amino Acid Derivatives

An efficient pathway to a new series of CF₃-substituted α-amino acid derivatives decorated with pharmacophore isoquinolone and pyrimido[1,6-a]indolone cores has been developed. The method includes Rh(III)-catalyzed C−H activation/[4+2]-annulation of N-(pivaloyloxy)-substituted aryl hydroxamates and indole-1-carboxamides with readily available allenyl-containing α-amino carboxylates and their phosphorus analogues. It was established that the reactions occur via Rh-σ-alkenyl intermediates to provide new C−C bond forming process with the participation of terminal carbon atom of allene moiety.