Over the past decade,nucleophilic phosphine catalyzed reactions have attracted much research efforts.As a result,a number of highly efficient synthetic reactions including new annulations to form carbocycles and heterocycles have been developed.Recently,Chuang and coworkers found that dialkyl hex-2-en-4-ynedioate,which can be easily prepared in quantitative yield by base-catalyzed dimerization of alkyl propiolate under mild reaction conditions,is also a very useful enyne in phosphine catalyzed nucleophilic addition reactions.