THIONYL CHLORIDE—A GOOD LIGAND COUPLING REAGENT

Abstract

Abstract Thionyl chloride was found to react with phenylethynyllithium and heteroaryllithium affording 1,4-diphenylbutadiyne and biheteroaryl, and the corresponding sulfoxides and sulfides, respectively. Apparently, ligand coupling proceeded within the intermediary sulfurane. The occurrence of ligand coupling was estimated from the pKa value of the carbon acid as a nucleophile. Furthermore, it was found that the presence of p-orbital, i.e., π-bond, is preferable at the ipso carbon atom of the nucleophile for a good ligand coupling reaction, while for alkyllithiums and alkylmagnesium chloride do not give bialkyl as the main coupling product, but others, which are different from the organic lithium or magnesium chloride used.