Cycloaddition Reaction of Azides with Di-Alkynes: a Quantum Chemistry Study

In the present research, we have focused on the cycloaddition reaction of dialkynes withazides that leads to a statistical mixture of monotriazoles and ditriazoles [1]. It should be noticedthat copper catalysis dramatically improves regioselectivity to afford 1,4-regioisomer. Theorigins of regioselective behavior of azide-dialkyne cycloaddition reaction were investigatedfrom the structural, electronic and thermodynamical viewpoints via Density Functional Theory(DFT) methods [2] in combination with Quantum Theory of Atoms in Molecules (QTAIM)analysis [3]. We have determined the ground state structures of all reagents, products andtransition states without any symmetry restrictions using GAMESS suite of programs [4] based onM08-HX functional in connection with 6-311G** orbital basis sets. Then, we calculatedthermochemical data, including reaction energies (with and without zero-point energycorrections), enthalpies and Gibbs free energies in the gas and two solution phases via polarizedcontinuum model (PCM) [5]. The obtained results confirmed the experimentally observed in thepresence of mixture of monotriazoles and ditriazoles. Finally, electronic aspect ofaforementioned reaction was investigated via topological QTAIM analysis of electron densityand electronic energy density indicators at selected critical points that mainly participate incycloaddition reaction.

Keywords:

Density Function Theory , Polarized Continuum Model , Quantum Theory of Atoms in Molecules , Dialkynes