A molecular orbital and crystallographic study of the structure and π-facial regioselectivity of 9-chloro-1,4,5,8-tetrahydro-4a,8a-methanonaphthalene

Abstract

The title compound 1 undergoes reaction with electrophilic reagents such as dichlorocarbene regioselectively on the π-face endo to the chlorine. The crystal structure of 1 indicates significant geometrical distortions of the two rings, which we attribute to a stabilising interaction between the C–Cl σ* orbital and the exoπ-orbital. PM3 calculations of these orbitals, the electrostatic potential and transition state models for dichlorocarbene addition all agree with the observed regioselectivity.