A computational study on the mechanism and the transition states of the cyclization of 1-trifluoromethyl-1,3-dicarbonyl compounds with azides to form 1,2,3-triazoles

Concerted and stepwise, electrocyclization/H-shift, pathways of the reaction between azide and trifluoromethyl-dicarbonyl compounds have been investigated computationally using M06-2X/6-311 + g(d,p) level of theory in the gas phase. Transition state structures and related intermediates have been optimized. The energy requirement for transition states for both of the concerted and stepwise routes are roughly at the same level. The concerted pathway is showing high amount of asynchronicity. Based on these findings, the stepwise approach is suggested as the prefer pathway. In some cases there is good relationship between the ESP charges and activation energies. In some other cases HOMO–LUMO interactions are good to explain the energy necessities.