A Au(I)-catalyzed N-acyl iminium ion cyclization cascade

A one-pot Au(I)-catalyzed reaction cascade to multi-ring heterocyclic products from alkynoic acids and primary amines is reported. The gold catalyst initially primes the alkynoic acid, via cyclization to an enol lactone, to react with a primary amine tethered to an electron rich heteroaromatic system. Then, via postulated Lewis acid assisted acidity, the Au(I) catalyst activates the amido ketone intermediate to undergo an N-acyl iminium ion cyclization. The reaction sequence is simple to perform, efficient, and broad in its scope to a diverse range of complex heterocyclic products.