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Flexible molecules with defined shape, II. Control of n ‐heptane conformer populations by methyl substitution or ring annulation
Author(s) -
Hoffmann Reinhard W.,
Sander Thomas,
Brumm Martin
Publication year - 1992
Publication title -
chemische berichte
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 0009-2940
DOI - 10.1002/cber.19921251020
Subject(s) - conformational isomerism , chemistry , heptane , annulation , molecule , ring (chemistry) , chain (unit) , crystallography , stereochemistry , computational chemistry , organic chemistry , physics , astronomy , catalysis
The conformations of a flexible n ‐heptane chain are considered. Six‐membered ring annulation at the inner bonds leads to 1,3‐disubstituted cyclohexanes, at the outer bonds to dicyclohexylmethane derivatives. Force‐field calculations show that these molecules maintain the conformational mobility of the heptane chain to a large degree, yet some populate one particular conformer to more than 80% (up to 99% in the case of 17 ). The predominant conformers of the molecules described here allow to represent each of the regular (diamond lattice type) conformations of a heptane chain. Moreover, for the open‐chain heptane derivatives the effect of methyl substitution on the conformational preferences has been examined. Finally, the adamantane derivative 32 has been identified in giving the heptane chain a 93% preference for the tg + g + t ‐conformation.