Chemistry of cage-shaped hydrocarbons. Ring transformations on a tricyclo[5.2.1.04,10]decane system

Abstract

A series of triquinane (tricyclo[5.2.1.0^4,10]decane) derivatives were prepared from oxidation of pentaquinandiene 1. Ozonolysis of 1, followed by reduction, yielded three products 4, 5, and 6 with poly-hydroxy groups. The hydroxy group of 5 was transformed to an iodo group in 8 with triphenylphosphine and iodine. An attempted dehydroiodination of 8 with base upon heating produced 10 with an unexpected geometry. The structure of an isomer 11 has been solved by single-crystal X-ray diffraction analysis, in which an exo-oriented cyclopropyl group indicated that an inversion has happened at C(3). The mechanism of the reaction from 8 to 10 was depicted as going through a multi-step sequence as outlined in Scheme 3.