1H NMR spectra of the 2-trifluoroacetyl derivatives of benzo[b]furan and benzo[b]thiophene

✍ Scribed by Rois Benassi; Ugo Folli; Dario Iarossi; Luisa Schenetti; Ferdinando Taddei

• Publisher: John Wiley and Sons
• Year: 1984
• Tongue: English
• Weight: 257 KB
• Volume: 22
• Category: Article
• ISSN: 0749-1581
• DOI: 10.1002/mrc.1270220315

✦ Synopsis

H NMR Spectra of the 2-'Iki!luoroacetyl Derivatives of Benzo[b]fuwn and Benzo[b]thiopltene

The 'H NMR spectra of the 2-trifluoroacetyl derivatives of benzo[blfuran and benzo[blthiophene were recorded at 200MHz in two solvents, chloroform and acetone. A long-range coupling constant, 5J(HF), between the fluorine nuclei of the trifluoroacetyl group and H-3, of a value higher than 1 Hz, was measured. From the comparison of the 'H chemical shifts of, and the solvent effects on, the trifluoroacetyl compounds and those of the corresponding 2-acetyl derivatives, and on the basis of an empirical interpretation of the 5J(HF) coupling constant, a predominant Z conformation was tentatively assigned to these derivatives.