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 alpha-bromo carbonyl compounds has been developed with ultraviolet (UV) light in aqueous media. This method represents a facile approach to synthetically useful beta,gamma-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.