ORBITAL DISTORTION IN DIBENZOBICYCLO[2.2.2]OCTATRIENES. BIASED EPOXIDATION AND DIHYDROXYLATION OF THE OLEFIN MOIETY

Abstract

Epoxidation and dihydroxylation of the olefin moiety of 2-substituted dibenzobicyclo[2.2.2] octatrienes were investigated. These reactions exhibited substituent effect : 2-nitodibenzo bicyclo[2.2.2]octatriene gave predominantly the syn-epoxide and the syn-diol, with a diastereomeric excess of 54% to 76%. respectively. On the other hand, the 2-methoxy substrate showed only a small preference in the reactions, giving a slight excess of the antiproducts. This effect can be interpreted in terms of the perturbation of the occupied π orbital of the ethylene moiety arising from the mixing of the π orbitals (in particular, the HOMO) of convex-substituted dihydroxyanthracene, wherein the σ type overlaps are involved in a manner similar to the longicyclic conjugation.