NEW MATERIAL:Pyrimidine derivatives shown by the formula I (R1 and R2 are H, alkyl aliphatic acyl, alkoxycarbonyl, halogenated carbonyl, aryl, etc.; with the proviso that a combination wherein R1 and R2 are H and/or CH3; R3 and R4 are H, halogen, nitro, etc. except that both R3 and R4 are not H simultaneously) and shown by the formula II [R5 is H, halogen, or (substituted) OH; R6 is halogen, (substituted) OH, or amino; with the proviso that and R5 both R6 are not nonsubstituted groups simultaneously].

EXAMPLE: N1-Ethoxymethyl-5-cyanouracil.

USE: A drug to be used with an antitumor agent, and an intermediate for synthesizing 5-fluorouracils.

PROCESS: A compound shown by the formula Y-R1' (R1' is R1 except H; Y is halogen) is condensed with a compound shown by the formula III (R7 is H, OH, or halogen; R8 is halogen, OH, or amino) in a nonproton organic solvent in the presence of a base, to give a compound shown by the formula I wherein R1 is R2 or a compound shown by the formula II.