Functionalization of alkynes catalyzed by t-Bu-P4 base

The addition of O- and N-nucleophiles to alkynes catalyzed by a phosphazene base, t-Bu-P4 base, was investigated. Alkynes were easily transformed to enol ethers and enamines in DMSO by the addition of nucleophiles. When phenylacetylene was reacted with diisopropylamine, a unique head-to-head dimerization of phenylacetylene was observed to give the enyne derivative. Terminal proton of phenylacetylene was also catalytically activated by t-Bu-P4 base to generate the acetylide anion which was reacted with carbonyl compounds to give phenylpropargylic alcohol derivatives.