Catalytic transformations involving metal carbenes are considered one of the most important aspects of homogeneous transition metal catalysis. Recently, gold-catalyzed generation of gold carbenes from readily available alkynes represents a significant advance in metal carbene chemistry. This Review summarizes the advances in the gold-catalyzed nitrene-transfer reactions of alkynes with nitrogen-transfer reagents, such as azides, nitrogen ylides, isoxazoles, and anthranils, and gold-catalyzed carbene-transfer reactions, involving oxygen atom-transfer reactions of alkynes with nitro compounds, nitrones, sulfoxides, and pyridine N-oxides, through the presumable α-imino gold carbene and α-oxo gold carbene intermediates, respectively. Gold-catalyzed processes are reviewed by highlighting their product diversity, selectivity, and applicability, and the mechanistic rationale is presented where possible.

Two new gold-catalyzed annulations of isoxazoles with propiolates have been developed. Most isoxazoles follow an initial O attack on the alkyne to afford a [4+1] annulation product. This process results in a remarkable alkyne cleavage of initial propiolates. Unsubstituted isoxazoles proceed through an N attack step to yield formal [2+2+1]/[4+2] annulation products. These two annulation products arise initially from two seven-membered heterocyclic intermediates, which then lead to products.

This work describes gold-catalyzed annulations of electron-deficient alkynes with benzisoxazoles to yield quinoline oxides chemoselectively. Chemical functionalizations of these resulting azacyclic compounds afforded various oxygenated tetrahydroquinolines which are present as the cores of many bioactive molecules. With the same reactants, a new relay catalysis using gold and zinc(II) catalysts affords highly oxygenated tetrahydroquinoline derivatives stereoselectively.

Gold-catalyzed cycloadditions of ynamides with azidoalkenes or 2H-azirines give [3+2] or [4+3] formal cycloadducts of three classes. Cycloadditions of ynamides with 2H-azirine species afford pyrrole products with two regioselectivities when the Cβ -substituted 2H-azirine is replaced from an alkyl (or hydrogen) with an ester group. For ynamides substituted with an electron-rich phenyl group, their reactions with azidoalkenes proceed through novel [4+3] cycloadditions to deliver 1H-benzo[d]azepine products instead.

The catalytic formation of gold enolates from alkynes, nitrones, and nucleophiles is described, and their Mannich reactions result in nucleophile-directed chemoselectivity through cooperative catalysis. For 1-alkyn-4-ols and 2-ethynylphenols, their gold-catalyzed nitrone oxidations afforded N-containing dihydrofuran-3(2H)-ones with syn selectivity. The mechanism involves the Mannich reactions of gold enolates with imines through an O-H-N hydrogen-bonding motif. For aryloxyethynes, their gold enolates react selectively with nitrones to deliver 3-alkylidenebenzofuran-2-ones, as controlled by a C-H-O hydrogen-bonding motif.