Stabilizing a different cyclooctatetraene stereoisomer.

ABSTRACT: An unconventional cis-cis-cis-trans or (Z,Z,Z,E) structure B of cyclooctatetraene (COT) is calculated to lie only 23 kcal/mol above the well-known tub-shaped (Z,Z,Z,Z) isomer A; one example of this type of structure is known. The barrier for B returning to A is small, 3 kcal/mol. However, by suitable choice of substituents, the (Z,Z,Z,E) isomer can be made to lie in energy below the tub-shaped structure. Steric, clamping, and electronic strategies are proposed for achieving this. In the steric strategy, the C₈H₄(CH₃)₂(C( ^t Bu)₃)₂ structure B is predicted to lie 21 kcal/mol below structure A, which is separated from form B only by a small barrier. A simple clamping strategy, effective for COT planariz

SUBMITTER: Li L 

PROVIDER: S-EPMC5604035 | biostudies-literature | 2017 Sep

REPOSITORIES: biostudies-literature