Transition-Metal-Free Coupling of Alkynes with α-Bromo Carbonyl Compounds: An Efficient Approach towards β,γ-Alkynoates and Allenoates.

A direct transition-metal-free coupling between alkynes and α-bromo carbonyl compounds has been developed with ultraviolet (UV) light in aqueous media. This method represents a facile approach to synthetically useful β,γ-alkynyl esters and amides stereoselectively from two readily available starting materials. As an example of the synthetic application of the products, the alkynyl esters were readily converted into allenoates.