Theoretical study of the electronic effects in the intramolecular ketene-styrene [2+2] cycloaddition

Abstract

DFT (B3LYP/6-31+G*) and post-Hartree-Fock (MP2/6- 31+G*//B3LYP/6-31G*) calculations were carried out in order to explain the effect of a remote substituent in the intramolecular ketene-styrene [2+2] cycloaddition of p-substituted 2-methyl-7-arylhepta- 1,6-dien-1-one which produces the bicycle[3.1.1] or the bicycle[3.2.0] heptanones according to Bèlanger experimental results. The transition state geometries were found as an asynchronous process with a three-member ring structure and an incipient positive charge development. Kinetic and thermodynamic controls were proposed at B3LYP/6-31+G* to determine which product is most likely to form in a competence reaction. In addition, the value of the ρ experimental reaction constant was reproduced, ρ ~ -1.34. © 2010, Sociedad Química de México.