An in situ generated catalytic system comprised of a Pd-PEPPSI [Pyridine enhanced pre-catalystpreparation, initiation, and stabilization] complex, (NHC)PdBr₂(Pyridine), and PPh₃ co-ligand demonstratedexcellent activity for the Sonogashira cross-coupling reactions between phenylacetylene with aryl halides inneat water under the aerobic condition in presence of CuI as co-catalyst. The catalytic system was not onlycompatible with electronically diverse aryl bromides/ iodides but also effective for relatively difficult substrateslike heteroaryl bromides. Notably, under similar experimental conditions, the mixed PEPPSI/PPh₃system displayed superior activity over the free Pd-PEPPSI or Pd-phosphine system.

This article presents an in situ Pd-PEPPSI/PPh₃ catalytic system for aqueous Sonogashira reaction in presence of CuI under aerobic condition which was found to be highly efficient for coupling of anyl/heteroaryl halides with phenylacetylene to form substituted alkynes. Interestingly, it displayed superior activity over simple Pd-PEPPSI or Pd-PPh₃ catalysts