ISSN print edition: 0366-6352 ISSN electronic edition: 1336-9075 Registr. No.: MK SR 9/7 Published monthly

1,3-dipolar cycloaddition between substituted phenyl azide and 2,3-dihydrofuran

Ahmad Reza Bekhradnia, Sattar Arshadi, and Seyed Amir Siadati

Pharmaceutical Sciences Research Center, Department of Medicinal Chemistry, Mazandaran University of Medical Sciences, Sari, Iran

E-mail: reza_bnia@yahoo.com

Abstract: A theoretical study was performed on the 1,3-dipolar cycloaddition between 2,3-dihydrofuran and substituted phenyl azide using Density Functional Theory (DFT) in combination with a 6-311++G(d,p) basis set. The optimum geometries for reactant, transition state and product, as well as the kinetic data, rate constants and reaction constant (ρ) were investigated to rationalise the substitution effects and reaction rates of the 1,3-dipolar cycloaddition process in various solvents. The DFT calculation and Frontier Molecular Orbital (FMO) theory as well as the atomic Fukui indices show that the electron-withdrawing substituents enhance the reaction constant (ρ > 0), especially in polar aprotic solvents. Consequently, small changes in the rate constant of the reaction in various solvents and geometric similarity between reactants and transition state structures were suggested as the early transition state mechanism for electron-withdrawing substituents. In addition, the slope of the Hammett plot and susceptibility of the reaction to electron-withdrawing substituents in various solvents confirmed the mechanism.

Keywords: DFT method – substituted phenyl azide – 2,3-dihydrofuran – 1,3-dipolar cycloadditions – Hammett equation – atomic Fukui indices

Full paper is available at www.springerlink.com.

DOI: 10.2478/s11696-013-0440-7

Chemical Papers 68 (2) 283–290 (2014)