Reactions of ionized methyl benzoate with methyl isocyanide in the gas phase: nucleophilic aromatic substitutions vs hydrogen migrations.
The chemistry leading to the competitive eliminations of H, CH(3), and OCOCH(3) from adducts of ionized methyl benzoate and neutral methyl isocyanide has been explored using density functional theory molecular orbital calculations. The energies of the various reactants and transition structures were estimated at the B3LYP/6-31+G(d,p) level of theory. Nucleophilic aromatic substitution is proposed to account for the H and OCOCH(3) eliminations. The corresponding sigma-complex intermediates, B(1ipso) and B(1ortho), are stable species lying in deep energy wells situated 70 and 120 kJ/mol, respectively, below the reactants, ionized methyl benzoate and methyl isocyanide. The latter complex, B(1ortho), may be also at the origin of a multistep rearrangement involving hydrogen migrations and methyl elimination from the original methoxy group of the benzoate moiety.
Bouchoux
Guy
G
Laboratoire des Mécanismes Réactionnels, UMR CNRS 7651, Département de Chimie, Ecole Polytechnique, Palaiseau Cedex, France.
Flammang
Robert
R
De Winter
Julien
J
Gerbaux
Pascal
P