To obtain a 3-rayl-uracil in a high yield by reacting phenyl isocyanate with an N-alkyl-enamine in a specific solvent in the presence of a specific amount of a base at a specific temperature.

The objective compound of formula V is obtained by reacting one equivalent of a compound of the formula O=C=N-Q [Q is expressed by formula I (R3 is H, F or Cl; R4 is R3, cyano, etc.; R5 is H, a halogen, OH, etc.), formula II (R6 is OH, a 1-6C alkoxy, etc.), formula III (R9 is H, OH, a 2-8C alkoxyalkyl, etc.), etc.] with two equivalents of an enamine of formula IV (R1 is methyl or ethyl; R2 is CF3, CClF2, CCl2F or C2F5 R19 is a 1-6C alkyl) in the presence of a base (e.g. potassium tert-butyrate) in an amount of 0.25-0.35 eq. Based on the enamine in a solvent (e.g. Pure dimethylformamide) at a temp. from -5°C to +40°C, preferably from 0°C to +5°C.