Centropentaindan, a fenestrane bearing five mutually fused indan units: Syntheses, molecular structure, and bridgehead substitution

• Published in: Chemistry : a European journal Vol. 2; no. 1; pp. 58 - 67
• Main Authors: Kuck, D, Schuster, A, Gestmann, D, Posteher, F, Pritzkow, H
• Format: Journal Article
• Language: English
• Published: DEERFIELD BEACH Wiley 01.01.1996
• Subjects: Chemistry; Chemistry, Multidisciplinary; Physical Sciences; Science & Technology; BENZOANNELATED CENTROPOLYQUINANES; WEISS REACTION; BENZOANELLATED CENTROPOLYQUINANES; cyclodehydrogenation; triquinacenes; TRICARBONYLCHROMIUM MONOCOMPLEXES; centropolyindans; BIS-COMPLEXES; POLYQUINENES; TRIS-COMPLEXES; GENERAL-APPROACH; FORCE-FIELD; fenestranes; DERIVATIVES; polycycles
• ISSN: 0947-6539
• DOI: 10.1002/chem.19960020112

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.