DFT calculations of properties of CF3-carbocations of the thiophene series as key intermediates in the synthesis of novel CF3-thiophenes

Abstract

Trimethylsilyl ethers of thiophen-2-yl-(trifluoromethyl)methanols undergo multichannel electrophilic transformations under the action of Brønsted superacid acid CF₃SO₃H to form a wide range of CF₃-substituted thiophene structures. The key cationic intermediates of these transformations are CF₃-carbocations. Electronic and orbital characteristics, global electrophilicity indices, and thermodynamic characteristics of these key intermediates have been calculated with a use of the density functional theory (DFT). Experimental data on the reactivity of intermediate cationic species have been explained on the basis of the results of quantum chemical calculations. It has been shown that reactions of the cations with aromatic nucleophiles are mainly ruled by orbital control.