Copper(I)-Catalyzed Enyne Oxidation/Cyclopropanation: Divergent and Enantioselective Synthesis of Cyclopropanes.

An efficient copper(I)-catalyzed enyne oxidation/cyclopropanation for the modular synthesis of cyclopropane derivatives is described, which represents the first non-noble metal-catalyzed enynes oxidation/cyclopropanation by the in situ generated α-oxo copper carbenes. This protocol allows the assembly of valuable cyclopropane-γ-lactams in generally good to excellent yields with excellent diastereoselectivity. More significantly, the enantioselective version of enyne oxidation/cyclopropanation has been disclosed with chiral copper catalysts.

Cu(I)-Catalyzed Oxidative Cyclization of Enynamides: Regioselective Access to Cyclopentadiene Frameworks and 2-Aminofurans.

An efficient Cu(I)-catalyzed oxidative cyclization of alkynyl-tethered enynamides for the construction of fused bicyclic cyclopentadiene derivatives is disclosed. The cascade proceeds through alkyne oxidation, carbene/alkyne metathesis, and formal (3 + 2) cycloaddition. Employing aryl-tethered enynamides as starting materials, substituted 2-aminofurans can be exclusively formed.

Recent advances in catalytic asymmetric intermolecular oxidation of alkynes.

In recent years, gold-catalyzed intermolecular alkyne oxidation by an N-oxide oxidant, which presumably involves a gold carbenoid intermediate, has attracted increasing attention because it circumvents the employment of hazardous and potentially explosive diazocarbonyl compounds as starting materials for carbene generation. More importantly, the development of a catalytic enantioselective version of the reaction can help achieve an array of asymmetric synthesis processes modified from various racemic transformations of the gold carbenoid intermediate. In this review, we will present an overview of these recent advances in the asymmetric transformations by utilizing chiral ligands, chiral N,N'-dioxides and chiral substrates, aiming to facilitate progress in this fascinating field of research.