The Me ester of 2-fluoro-3-methoxyacrylic acid and the corresponding acyl chloride were used for the efficacious synthesis of fluorine-bearing pyrazolones, pyrimidines, coumarines and benzothiopyranones. Depending on the C3F component and the conditions employed, the same cyclization partner (e.g., 2-aminothiophenol) may lead to two or even three different products. The condensation of phenylhydrazine with (Z)-2-fluoro-3-methoxy-2-propenoyl chloride gave (Z)-2-fluoro-3-methoxy-2-propenoic acid 2-phenylhydrazide. The cyclocondensation of the latter gave 4-fluoro-1,2-dihydro-1-phenyl-3H-pyrazol-3-one. [on SciFinder (R)]