Au-allenylidene promoted decarboxylative annulation to access unsaturated γ-lactams/lactones.

A novel Au-allenylidene promoted decarboxylative annulation by intramolecular α-nucleophilic addition has been disclosed. The unsaturated cyclic ethynylethylene carbamates/carbonates can be converted to unique nucleophiles attached with alkylidene ketenes by sequential decarboxylation and oxidation processes. Such alkylidene ketenes can be rapidly trapped by intramolecular α-attacking annulation to generate potential biological active unsaturated γ-lactams/lactones with broad scope, facile post-modification, high regioselectivity and efficiency.

Gold-Catalyzed Anti-Markovnikov Oxidation of Au-Allenylidene to Generate Alkylidene Ketene.

It remains a long-standing challenge to directly convert alkynes to carboxylic derivatives. Herein, a unexpectedly anti-Markovnikov oxidation of a unique Au-allenylidene pathway instead of a traditional α-oxo gold carbene routine is disclosed for in situ formation and transformation of highly unsaturated alkylidene ketenes, which are subsequently trapped by broad nucleophiles such as alcohols, phenols, water, amines, and sulfoximines to easily access α,ß-unsaturated drugs and natural product derivatives by a multicomponent reaction. Based on this scenario, polyacrylate and polyacrylamide are efficiently afforded by corresponding multicomponent polymerization.

Copper-Catalyzed One-Step Formation of Four C-N Bonds toward Polyfunctionalized Triazoles via Multicomponent Reaction.

A novel four-component reaction of alkynes, amines, azides, and 2H-azirines has been developed for the first time by the efficient formation of four C-N bonds in one step under mild conditions, rapidly preparing polyfunctionalized triazoles with molecular diversity involving three different intermediates of copper-acetylide, copper-allenylidene, and copper-vinyl nitrene. Propargylic ester is disclosed as a "three-in-one" building block possessing triplicate cycloaddition and nucleophilic and electrophilic properties, which could enable such a four-component transformation by high yields, broad substrate scope, and functionalization.

Copper-catalyzed Z-selective synthesis of acrylamides and polyacrylamides via alkylidene ketenimines.

It remains very important to discover and study new fundamental intermediates consisting of carbon and nitrogen as the abundant elements of organic molecules. The unique alkylidene ketenimine could be formed in situ under mild conditions by an unexpected copper-catalyzed three-component reaction of alkyne, azide and water involving a successive cycloaddition, N2 extrusion and carbene-assisted rearrangement. Only Z-α,ß-unsaturated amides instead of E-α,ß-unsaturated amides or triazoles were acquired from alkylidene ketenimines with excellent selectivities and stereospecificities. In addition, a series of "approximate" alternating copolymers (poly (triazole-alt-Z-acrylamides)) with high Mns and yields were efficiently afforded by multicomponent polymerization through a very simple operation basing on this multicomponent reaction.

Visible-Light-Induced N-Acylation of Sulfoximines.

A metal-, base-, and additive-free N-acylation of sulfoximines was developed under mild conditions using organic photoredox catalyst. This green strategy featured broad substrate scope, good compatibility with air, and high yields (up to 96%). It could be further applied to amino acid modifications and α-keto N-acyl sulfoximine synthesis without any complicated transformations or operations.