AM1 study of the two ways of retro-ene reaction for the cyanomethildiallylamine

• Leonardo Rodríguez Universidad del Zulia-Venezuela
• Rafael Añez Universidad del Zulia-Venezuela
• Jorge Angel Universidad del Zulia-Venezuela
• Alfonso Chirinos Universidad del Zulia-Venezuela
• Edgar Ocando Mavarez Instituto Venezolano de Investigaciones Científicas (I.V.I.C)

Palabras clave: AM1, transition state, retro-ene, allylamines

Resumen

The transition state (TS) geometries of propene elimination from cyanomethildiallylamine (1) to obtain N-cyanomethilvinylimine (2) and N-propenilcyanoimine (3) were calculated with the semiempirical AM1 method. For the two cases, our calculations led to TS's that consist of non planar six center cyclic structures with distorted chair-like geometries. These results show that the TS geometries have a marked “reactant-like” character and the TS geometries for the two reactions are remarkably similar. It is also found that the TS are of polar character and that a negative charge is developed on the carbon atom from which the hydrogen atom is transfered, thus, the activaction energy increases when strong electron-attractor substituents are coordinated to this carbon atom. The calculated activation energies indicate that the reaction with formation of 2 is favored over the reaction with formation of 3, in agreement with experimental evidence.