Prediction of Thermal Isomerization Temperatures of Substituted Benzocyclobutenes to o-Quinodimethanes by Semi-Empirical Molecular Orbital Calculation

Bezocyclobutenes are useful compounds as precursors to o-quinodimethanes, which are highly reactive dienes. However, the thermal isomerization temperatures(IT) of substituted benzocyclobutenes to o-quinodimethanes have not been predictable based on the simple substituent effect. In this paper, we provide a simple method to predict the IT of benzocyclobutenes by calculation of the activation energies using a semi-empirical molecular orbital calculation. ITs of the various substituted benzocyclobutenes were estimated by this method.