LAUSR

The π-accepting property of alkene-like phosphaethenes (-P=C<) has been attractive to develop Lewis-acidic transition-metal catalysts. Stereoselective monoalkynylation of a sterically encumbered gem-dibromophosphaethene via the Sonogashira process was accomplished, and the corresponding 2-alkynyl-2-bromophosphaethenes were obtained. Subsequent arylation of the 2-bromo-2-alkynyl-1-phosphaethenes by the palladium version of Kumada-Tamao-Corriu (KTC) reaction gave the corresponding 2-aryl-1-phosphaethen-3-ynes through the inversion of configuration. The 2-alkynyl-2-aryl-1-phosphaethenes were converted into the corresponding chlorogold(I) complexes, and screening of their catalytic activity revealed that both employing appropriate π-conjugative substituents and the stereochemistry were decisive for efficiency of the gold-catalyzed reactions under the activation-free conditions.