The catalytic activities of triphenylphosphine and N-heterocyclic carbene, namely 3-benzyl-4,5-dimethylthiazolylidene, have been compared by carrying out oxa–Michael additions of some phenols with dimethyl acetylenedicarboxylate in the presence of one of these catalysts. The experimental results have been rationalised on the basis of theoretical calculations. (Image credit: Priyanka Suthar.)

In the CPC micellar environment, the more hydrophobic reactant component (L-Tyrosine) and the extended aliphatic chain of CPC reside in the micelle’s core. The micelle Stern layer preserves the polar components of the surfactant (Me₃N⁺), substrate (–NH₂, and –COOH) and reactive species of NBS and Ru^III in proximity, hence promoting the oxidation of L-Tyr. The elevated concentration of reactant molecules at the micellar interface enhances the effective collision frequency among the reacting molecules, significantly promoting the oxidation process. (Image credit: Abhishek Srivastava.)