Pd(II)-catalyzed intramolecular aminopalladation/direct C-H arylation under aerobic conditions: synthesis of pyrrolo[1,2-a]indoles

Heating a DMA/pivalic acid (v/v=4/1) solution of diversely substituted 6-(phenylamino)hex-2-ynoates in the presence of a catalytic amount of Pd(OAc)2 under oxygen atmosphere afforded pyrrolo[1,2-a]indoles in moderate to good yields. A domino sequence involving intramolecular aminopalladation followed by C-H activation and reductive elimination was proposed to account for the observed bis-cyclization.