The assignment of the correct structures and conformational analysis of the isomeric t-5- and t-4-phenyl-t(c)-2-benzoyl-r-1-cyclohexanecarboxylic acids by NMR and FT-IR spectroscopy

Karel D. Klika, Petri Tähtinen, Martti Dahlqvist, József A. Szabó, G. Stájer, Jari Sinkkonen, Kalevi Pihlaja

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Abstract

The AlCl3 catalysed addition of benzene to cis-2-benzoylcyclohex-4-enecarboxylic acid results in the product, t-5-phenyl-c-2-benzoyl-r-1-cyclohexanecarboxylic acid (2), but not in its 2-trans epimer (5) as has been reported previously in the literature. The latter was obtained instead by treating 2 with NaOH in EtOH-H2O. The structures and conformational assignment of 2, its 4-trans phenyl positional isomer (4), and both their 2-trans benzoyl epimers (5 and 6, respectively, prepared by base-induced epimerisation) were elucidated by means of NMR spectroscopy. The postulated trans→cis transformation of the 2-trans isomer 5 to the product 2 does not in fact occur; indeed it is the reverse transformation that is viable. All of the compounds showed substantial intramolecular hydrogen-bonding in solution (e.g. in CDCl3) by FT-IR measurements and, furthermore, a dynamic equilibrium between hydrogen-bonded and non hydrogen-bonded forms was observed by NMR for compound 2.

Original languageEnglish
Pages (from-to)687-692
Number of pages6
JournalJournal of the Chemical Society, Perkin Transactions 2
Issue number4
Publication statusPublished - Apr 2000

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Cyclohexanecarboxylic Acids
Isomers
Hydrogen
Infrared spectroscopy
Nuclear magnetic resonance
Benzene
Nuclear magnetic resonance spectroscopy
Hydrogen bonds
Acids

ASJC Scopus subject areas

  • Chemistry(all)

Cite this

The assignment of the correct structures and conformational analysis of the isomeric t-5- and t-4-phenyl-t(c)-2-benzoyl-r-1-cyclohexanecarboxylic acids by NMR and FT-IR spectroscopy. / Klika, Karel D.; Tähtinen, Petri; Dahlqvist, Martti; Szabó, József A.; Stájer, G.; Sinkkonen, Jari; Pihlaja, Kalevi.

In: Journal of the Chemical Society, Perkin Transactions 2, No. 4, 04.2000, p. 687-692.

Research output: Contribution to journalArticle

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