Nuclear Magnetic Resonance Studies of Bicyclic Thiophene Derivatives. II. Through Space H–F Coupling in o-Fluorophenyl Derivatives of Benzoylthiophene, Thienopyrimidine and Thienodiazepine Derivatives
- 1 March 1975
- journal article
- Published by Oxford University Press (OUP) in Bulletin of the Chemical Society of Japan
- Vol. 48 (3) , 974-979
- https://doi.org/10.1246/bcsj.48.974
Abstract
Proton–fluorine coupling over six bonds has been observed between fluorine and Hβ of the thiophene ring in ortho fluorophenyl derivatives of 4-phenylthienopyrimidines (1), 2-acetylamino-3-benzoylthiophenes (2), 5-phenyl-1,4-thienodiazepines (3) and 5-phenyl-1,4-thienodiazepine-4-oxides (4). The solvent effect and the N-methylation effect on the coupling constant can be explained by considering that the H–F coupling is a through space coupling. The value of coupling constant (JHF: 0.5 Hz to 4.1 Hz) depends upon the geometry of the ring system condensed at 2-C and 3-C of thiophene ring, decreasing in the order of 1>2>3>4. A discussion is given on the manner of steric repulsion between the benzene ring and some atoms on the other moiety of these compounds.Keywords
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