A Novel Catalyst with a Cuboidal PdMo₃S₄ Core for the Cyclization of Alkynoic Acids to Enol Lactones

Abstract

Catalytic activity remarkably higher than that of mononuclear palladium catalysts is exhibited by the cuboidal sulfide cluster 1 (tacn = 1,4,7-triazacyclononane) in the lactonization of alkynoic acids (2 → 3). The reaction can even be conducted in water owing to the good solubility and stability of the cluster in this medium.