Reactions of electron-deficient alkynes and allenes under phosphine catalysis

The development of some new synthetic reactions derived from nucleophilic a ddition of phosphines to electron-deficient carbon-carbon triple bonds is d escribed. These reactions show that the phosphine plays the role of a nucle ophile as well as an excellent leaving group. The central problem is to gen erate a 1,3-dipole from atkynoates or allenoates; (2,3-butadienoates) by in teraction with various phosphines. This study illuminates the unusual pheno mena and shows how this understanding allows control of the reaction.