T. Hirohashi, S. Inaba, Hisao. Yamamoto
Mar 1, 1975
Citations
0
Influential Citations
11
Citations
Journal
Bulletin of the Chemical Society of Japan
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.