NEW MATERIAL:Trifluorovitamin Ks expressed by the formula (R is allyl, prenyl, geranyl or phytyl).

EXAMPLE: 2-Trifluoromethyl-3-allyl-1,4-naphthoquinone.

USE: Useful for preventing and treating vitamin K deficiency, hemorrhage in surgical operation, related to biosynthesis of various factors required for blood coagulation, such as various hemorrhages, edema (cirrhosis, valvular disease of heart, etc.), neonatal hemorrhagic diathesis and hemophilia, etc., and further related to electron transport systems together with coenzyme Q in vivo and for maintaining constancy of living bodies.

PREPARATION: A compound expressed by formula II is reacted with chloromethyl methyl ether to provide a compound expressed by formula III, which is then reacted with a bromide expressed by formula IV to afford a compound expressed by formula V. The resultant compound expressed by formula V is subsequently oxidized to provide the aimed compounds expressed by formula I. The above-mentioned compound expressed by formula V is obtained by carrying out reaction at -78°CWambient temperature in the presence of a catalyst in a solvent and the subsequent oxidative reaction is carried out in a solvent at -78°CWambient temperature.