The role of the polarity on the mechanism and selectivity in the [3+2] cycloaddition reaction between CF3-ynone ylide and azide group: A quantum chemical investigation

Abstract

The goal of the present study is to make a comprehension of the connection between selectivity and polarity, in that fact this reaction process was studied in presence of toluene, THF and DMSO solvent through Molecular Electron Density Theory (MEDT) at the B3LYP/6-31+G(d,p) computational level. A remarkable predominance of 4-trifluoroacetyl-1,2,3-triazoles derivatives (P3) has been generated via [3 + 2] cycloaddition between CF3-ynone and azide ylide, rationalized by the electrophilic P+ and nucleophilic P− Parr functions at the reactive sites of reagents, affording the N3-C1 regioselectivity observed experimentally. Furthermore, an exploration of the relative energies of reaction, Gibbs free energy and barrier activation profile obviously evidences that experimentally isolated P3 is the most reachable product of this reaction, in good to excellent yield with respect to the increase of polarity. Moreover, ELF topology analysis of the most stable product demonstrates that the formation of new bonds appears to be directed through two dissimilar fashions, the first is formed by donation of some nitrogen non-bonding electron-density to the carbon pseudoradical center and, the second is formed by sharing nitrogen non-bonding electron-density and a carbon pseudoradical center via a non-concerted two-stage one-step molecular mechanism.