Au(I)/Ag(I) co-operative catalysis: interception of Ag-bound carbocations with α-gold(I) enals in the imino-alkyne cyclizations with N-allenamides

A co-operative Au(I)/Ag(I) catalyst system has been developed to utilize N-allenamides as nucleophilic enal equivalents for the interceptive capturing of incipient carbocations generated through π-acid-triggered imino-alkyne cyclization. The salient features include the in situ generation of silver-bound carbocations (from iminoalkynes), α-gold(I) enals (from N-allenamides) and union of these two species to form indolizines with the regeneration of Au and Ag catalysts.