NEW MATERIAL:A compound shown by the formula 3 (R1 is H, nonfluoro or fluoro aliphatic, or aromatic hydrocarbon; R2 and R3 are H, or substituent groups in nonfluoro or fluoro aliphatic hydrocarbon group, hydroxyl group, etc.)

USE: Useful as a physiologically active substance such as an insecticide, a fungicide, etc., or an intermediate for their building block.

PREPARATION: Phenol or a phenol derivative is condensed with α-fluoroacetoacetate shown by the formula 2 in the presence of H2SO4 or POCl3, to give a 3-fluorocoumarin such as a compound shown by the formula 8. The compound shown by the formula 2 is obtained by reacing trifluoroethene with acetyl chloride in the presence of AlCl3 according to the reaction formula to give an adduct shown by the formula 1, followed by decomposing it with an alcohol.