The theoretical study of a borane catalyzed azide anion addition to fluorinated acetonitriles

Abstract

The borane catalyzed 1,3-polar cycloaddition of the azide anion to the nitriles was studied using the ab initio methods. The potential energy surface was investigated with the 6-311 + G ∗∗ basis set at the Hartree-Fock and second order Møller-Plesset theoretical levels. All of the reactions are exothermic with an energy gain range of 27.5–52.7 kcal mol −1. A multi-step mechanism was assumed. Initially, the formation of a borane-nitrile complex is combined with the addition of the azide anion to this complex, followed by a ring closure. The formation of the borane complex proceeds with an energy release that is comparable for all nitriles. The ring closure reaction which is extremely sensitive to the introduction of the fluorine in the acetonitrile is discussed.