PUB - Publikationen an der Universität Bielefeld

Syntheses, properties, and some reactions of a novel centropolycyclic hydrocarbon, centropentaindan (1), are described. The molecular structure of 1 consists of a tetrabenzo[5.5.5.5]fenestrane bearing a fifth centrically fused indan unit. Independent syntheses have been developed employing i) twofold cyclodehydrogenation of tribenzotriquinacene (7) with Pd/C at 500 degrees C, which gives 1 in 50 % yield, and ii) a two-step procedure by te-trabromination of di-fuso-centrotriindan (8) followed by condensation with two molecules of benzene, which provides 1 in 88% yield. Some bridgehead-substituted centropentaindans are described, including the highly labile dibromo derivative 19, and the centrohexacyclic, topologically nonplanar endo-peroxide 26 and endo-disulfide 28. The notably rigid ring fusion in the molecular framework of 1 is shown both by X-ray structural analysis and by particular steric interactions of the two mutually compressed bridgehead substituents.