title: Towards perfunctionalized dodecahedranes--en route to C20 fullerene.
abstract: "One-pot" substitution of the twenty hydrogen atoms in pentagonal dodecahedrane (C(20)H(20)) by OH, F, Cl, and Br atoms is explored. Electrophilic insertion of oxygen atoms with DMDO and TFMDO as oxidizing reagents ended, far off the desired C(20)(OH)(20), in complex polyol mixtures (up to C(20)H(10)(OH)(10) decols, a trace of C(20)H(OH)(19)?). Perfluorination was successful in a NaF matrix but (nearly pure) C(20)F(20) could be secured only in very low yield. "Brute-force" photochlorination (heat, light, pressure, time) provided a mixture of hydrogen-free, barely soluble C(20)Cl(16) dienes in high yield and C(20)Cl(20) as a trace component. Upon electron-impact ionization of the C(20)Cl(16) material sequential loss of the chlorine atoms was the major fragmentation pathway furnishing, however, only minor amounts of chlorine-free C(20) (+) ions. "Brute-force" photobrominations delivered an extremely complex mixture of polybromides with C(20)HBr(13) trienes as the highest masses. The MS spectra exhibited exclusive loss of the Br substituents ending in rather intense singly, doubly, and triply charged C(20)H(4-0) (+(2+)(3+)) ions. The insoluble approximately C(20)HBr(13) fraction (C(20)Br(14) trienes as highest masses) obtained along a modified bromination protocol, ultimately allowed the neat mass selection of C(20) (-) ions. The C(20)Cl(16) dienes and C(20)H(0-3)Br(14-12) tri-/tetraenes, in spite of their very high olefinic pyramidalization, proved resistant to oxygen and dimerization (polymerization) but added CH(2)N(2) smoothly. Dehalogenation of the respective cycloaddition products through electron-impact ionization resulted in C(22-24)H(4-8) (+(2+)) ions possibly constituting bis-/tris-/tetrakis-methano-C(20) fullerenes or partly hydrogenated C(22), C(23), and C(24) cages.
authors.affiliation: Institut für Organische Chemie und Biochemie, Albert-Ludwigs-Universität, 79104 Freiburg, Germany.
authors.forename: Fabian
authors.initials: F
authors.lastname: Wahl
authors.forename: Andreas
authors.initials: A
authors.lastname: Weiler
authors.forename: Peter
authors.initials: P
authors.lastname: Landenberger
authors.forename: Emmerich
authors.initials: E
authors.lastname: Sackers
authors.forename: Torsten
authors.initials: T
authors.lastname: Voss
authors.forename: Alois
authors.initials: A
authors.lastname: Haas
authors.forename: Max
authors.initials: M
authors.lastname: Lieb
authors.forename: Dieter
authors.initials: D
authors.lastname: Hunkler
authors.forename: Jürgen
authors.initials: J
authors.lastname: Wörth
authors.forename: Lothar
authors.initials: L
authors.lastname: Knothe
authors.forename: Horst
authors.initials: H
authors.lastname: Prinzbach