Chemistry of cage-shaped hydrocarbons. Ring transformations on a tricyclo[5.2.1.0(4,10)]decane system

A series of triquinane (tricyclo[5.2.1.0(4,10)]decane) derivatives were pre pared from oxidation of pentaquinandiene 1. Ozonolysis of 1, followed by re duction, yielded three products 4, 5, and 6 with poly-hydroxy groups. The h ydroxy group of 5 was transformed to an iodo group in 8 with triphenylphosp hine and iodine. An attempted dehydro-iodination of 8 with base upon heatin g produced 10 with an unexpected geometry. The structure of an isomer 11 ha s 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.