title: Pentagonal dodecahedranes: polyfunctionalization and MS fragmentation.
abstract: With the use of four- to eight-fold functionalized dodecahedranes (1-3), opportunities to arrive at highly strained dodecahedranes with two to four pairs of vicinal, eclipsed bromine substituents through front-side substitution and addition reactions have been explored. In standard processes, the interception of beta-OCH(3) radical/cationic intermediates was not problematic (9-12, 37, 50). The interception of beta-CO(2)R radicals was possible for Cl(*) (18) but not for Br(*) (17). The interception of beta-chloro radicals was possible for Cl(*) (27) but not for Br(*) (26), and the interception of beta-Br cations ("bromonium ions") with Br(-) was modest (45) to highly inefficient (24, 26). Two X-ray structural analyses (dimethoxy dibromide 9 and tetramethoxy tetrabromide 53) indicated the structural consequences of the molecular strain introduced by the two (four) vicinal CH(3)O/Br pairs. A systematic analysis of the MS spectra confirms that, in virtually all cases studied, the elimination of the substituents occurs without significant carbon-cage disruption, leading ultimately to multiply unsaturated dodecahedral ions for dodecahedrahexa(C(20)H(8))enes, -hepta(C(20)H(6))enes, and -octa(C(20)H(4))enes.
authors.affiliation: Chemisches Laboratorium der Universität Freiburg i. Br., Institut für Organische Chemie und Biochemie, Albertstrasse 21, D-79104 Freiburg i.Br., Germany.
authors.forename: P
authors.initials: P
authors.lastname: Landenberger
authors.forename: K
authors.initials: K
authors.lastname: Scheumann
authors.forename: M
authors.initials: M
authors.lastname: Keller
authors.forename: D
authors.initials: D
authors.lastname: Hunkler
authors.forename: H
authors.initials: H
authors.lastname: Fritz
authors.forename: J
authors.initials: J
authors.lastname: Wörth
authors.forename: L
authors.initials: L
authors.lastname: Knothe
authors.forename: H
authors.initials: H
authors.lastname: Prinzbach