In this study, the kinetics and mechanism of the reaction between 6,2-dimethylphenyl isocyanide and dimethyl acetylene dicarboxylate (DMAD) in the presence of 2-isocyanato-1,3-dimethylbenzene were investigated through quantum calculations. Theoretical calculations were performed using density functional theory at the B3LYP-6-311++g(d,p) level, and the geometric structures of the reactant species, intermediates, transition states, and possible products were optimized. In order to identify the optimal reaction pathway, relative energies, activation energies, and thermodynamic parameters were calculated. The results showed that the reaction starts with the formation of an initial zwitterionic intermediate and then proceeds to the final product by nucleophilic attack and sequential rearrangements. The energy profile of the reaction showed that the initial intermediate formation step determines the reaction rate and has the highest energy barrier. Also, the effect of methyl and solvent ether groups on the potential energy levels of the structures was evaluated. The findings of this study provide a comprehensive view of the mechanistic details and factors affecting the kinetics of this reaction and can be used in the targeted design and synthesis of new heterocyclic compounds and organic derivatives. Finally, in order to better understand the molecular interactions, the natural bond orbital (NBO) method was used.