Gold-catalyzed [4+1]-annulation reactions between anthranils and 4-methoxy-1,2-dienyl-5-ynes involving a 1,2-allene shift.

Gold-catalyzed [4+1]-annulations of 4-methoxy-1,2-dienyl-5-ynes with anthranils are described. The mechanism of these annulations involves nitrene formation of α-imino gold carbenes that undergo a 1,2-allene shift to form (pyrrol-2-yl) methylgold intermediates. With allenyl ester substrates, these gold intermediates become enolate species to enable intramolecular aldol reactions to form useful pyrrolo[1,2-a]quinoline derivatives.