title: [123]Tetramantane: parent of a new family of sigma-helicenes.
abstract: We present a new type of sigma-helical structure based on a diamondoid (nanodiamond) framework, C(2)-symmetric [123]tetramantane, whose (+) and (-) isomers could be enantioseparated by HPLC techniques. Bromination of the enantiopure hydrocarbon led to the isolation of (+)-7-bromo-[123]tetramantane, which could be crystallized and subjected to X-ray structure analysis. Using the anomalous dispersion, we have identified this compound as the P isomer for the hydrocarbon moiety. Experimental and computed optical rotatory dispersion (ORD) and vibrational circular dichroism (VCD) spectra independently and in agreement with the X-ray structure analysis gave M-(-) as the configuration of the second eluted parent hydrocarbon isomer.
authors.affiliation: Institut für Organische Chemie der Justus-Liebig-Universität, Heinrich-Buff-Ring 58, D-35392 Giessen, Germany. prs@org.chemie.uni-giesssen.de
authors.forename: Peter R
authors.initials: PR
authors.lastname: Schreiner
authors.forename: Andrey A
authors.initials: AA
authors.lastname: Fokin
authors.forename: Hans Peter
authors.initials: HP
authors.lastname: Reisenauer
authors.forename: Boryslav A
authors.initials: BA
authors.lastname: Tkachenko
authors.forename: Elemér
authors.initials: E
authors.lastname: Vass
authors.forename: Marilyn M
authors.initials: MM
authors.lastname: Olmstead
authors.forename: Dieter
authors.initials: D
authors.lastname: Bläser
authors.forename: Roland
authors.initials: R
authors.lastname: Boese
authors.forename: Jeremy E P
authors.initials: JE
authors.lastname: Dahl
authors.forename: Robert M K
authors.initials: RM
authors.lastname: Carlson