Gold-catalyzed heterocyclic syntheses through α-imino gold carbene complexes as intermediates Dedicated to Professor Dr Julius Rebek, Jr. on the occasion of his 75th birthday.

Gold carbene complexes have been recognized as common intermediates in gold-catalyzed organic syntheses. In this field, alpha-imino gold carbene complexes, in the last few years, have emerged as valuable intermediates toward the synthesis of N-heterocycles. This review is dedicated toward formulating a comprehensive compilation of the different methodologies for heterocyclic synthesis, postulating the participation of alpha-imino gold carbene complexes as intermediates. In addition to the scarce examples involving the direct formation of alpha-imino diazo compounds from gold decomposition, the use of nitrogenated nucleophiles, through an initial attack on gold-activated alkynes followed by gold retrodonation and expulsion of a leaving group, constitutes the most commonly employed strategy for achieving this target. This review has been divided into different sections as follows according to the type of N-nucleophile used: azides, aza-ylides, 2H-azirines, isoxazoles and their derivatives, indazoles, and triazapentalenes. A large number of heterocycles, ranging from five-to seven-membered rings, have been efficiently synthesized following this methodology.