CENTROHEXACYCLIC OR K-5 MOLECULES - DEVELOPMENT OF A GROWING FAMILY OF TOPOLOGICALLY NONPLANAR ORGANIC-COMPOUNDS

This article gives a comprehensive review of the synthetic development of centrohexacyclic organic compounds (''centrohexacyclanes'') during the past decade. With their unique feature of having molecular consti tution that corresponds to the complete graph K-5, centrohexacyclanes represent the majority of the rare class of topologically nonplanar co mpounds. Starting from the few previously known organic, element-organ ic and inorganic K-5 compounds, the syntheses of various organic centr ohexacyclanes are discussed, based mainly on three different strategie s that have emanated from the chemistry of centropolyindanes: the prop ellane, fenestrate, and ''broken fenestrane'' routes. In addition, the first results of some targeted transformations of centrohexaindane, t he T-d-symmetrical hexabenzoannelated centrohexaquinane, are presented .