[123]Tetramantane: parent of a new family of sigma-helicenes.
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.
Schreiner
Peter R
PR
Institut für Organische Chemie der Justus-Liebig-Universität, Heinrich-Buff-Ring 58, D-35392 Giessen, Germany. prs@org.chemie.uni-giesssen.de
Fokin
Andrey A
AA
Reisenauer
Hans Peter
HP
Tkachenko
Boryslav A
BA
Vass
Elemér
E
Olmstead
Marilyn M
MM
Bläser
Dieter
D
Boese
Roland
R
Dahl
Jeremy E P
JE
Carlson
Robert M K
RM