Bicyclic thiophene derivatives, 1,5-dimethyl-(1) and 3,5-dimethyl-4-(o-fluorophenyl)-l,2-dihydrothieno[2,3-d]-pyrimidin-2-ones (3), 2-acetylamino-3-(o-fluorobenzoyl)-4-methylthiophene (5), and some derivatives (2, 4, 6, 7), have been prepared. 1H, 19F Spin couplings over seven bonds, 7JHF, attributable to a through-space mechanism have been observed in the 1H NMR spectra of these compounds.