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The preferred conformation of erythro- and threo-1,2-difluorocyclododecanes.

ABSTRACT: Cyclododecane adopts a square-like structure with corner and edge CH(2) groups. In this study erythro- and threo-1,2-difluorocyclododecanes were prepared to explore whether the two vicinal C-F bonds, with different relative configurations, preferably locate at corner/edge or edge/edge locations. Conformational analysis comparing the diastereoisomers was explored by using a combination of (19)F{(1)H} NMR spectroscopy, computational studies and, in the case of the threo isomer, X-ray structural analysis. In the lowest energy conformers for both diastereoisomers the vicinal C-F bonds are located corner/edge, rather than edge/edge. These structures avoid placing a C-F bond endo into the ring, and appear to benefit from C-CHF-C angle widening, which relaxes 1,4-H,H transannular interactions.

SUBMITTER: Wang Y

PROVIDER: S-EPMC3458748 | biostudies-literature | 2012

REPOSITORIES: biostudies-literature

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The preferred conformation of erythro- and threo-1,2-difluorocyclododecanes.

Wang Yi Y Kirsch Peer P Lebl Tomas T Slawin Alexandra M Z AM O'Hagan David D

Beilstein journal of organic chemistry 20120810

Cyclododecane adopts a square-like structure with corner and edge CH(2) groups. In this study erythro- and threo-1,2-difluorocyclododecanes were prepared to explore whether the two vicinal C-F bonds, with different relative configurations, preferably locate at corner/edge or edge/edge locations. Conformational analysis comparing the diastereoisomers was explored by using a combination of (19)F{(1)H} NMR spectroscopy, computational studies and, in the case of the threo isomer, X-ray structural an ...[more]

PMID: 23019458

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