Patent ID: 8252925

Claim:
A process for preparing a 3-phenyl(thio)uracil or -dithiouracil of the formula I where the variables are each defined as follows: R 1 is hydrogen, C 1 -C 6 -alkyl, C 1 -C 4 -cyanoalkyl, C 1 -C 6 -haloalkyl, C 3 -C 8 -cycloalkyl, C 2 -C 6 -alkenyl, C 2 -C 6 -haloalkenyl, C 3 -C 6 -alkynyl, C 3 -C 6 -haloalkynyl, phenyl-C 1 -C 4 -alkyl or amino, R 2 and R 3 are each independently hydrogen, C 1 -C 6 -alkyl, C 1 -C 6 -haloalkyl, C 3 -C 8 -cycloalkyl, C 2 -C 6 -alkenyl, C 2 -C 6 -haloalkenyl, C 3 -C 6 -alkynyl or C 3 -C 6 -haloalkynyl; X 1 , X 2 and X 3 are each independently oxygen or sulfur; Ar is phenyl which may be partly or fully halogenated and/or may carry from one to three radicals selected from the group consisting of cyano, C 1 -C 4 -alkyl and C 1 -C 4 -haloalkyl, and A is NR 4 R 5 where R 4 and R 5 are each independently hydrogen or C 1 -C 6 -alkyl; which process comprises reacting a carbamate of the formula II where the variables X 1 , X 3 , Ar and A are each as defined above and L 1 is C 1 -C 6 -alkoxy or C 1 -C 6 -alkylthio with an enamine of the formula III where the variables X 2 , R 1 , R 2 and R 3 are each as defined above and L 2 is selected from the group consisting of C 1 -C 6 -alkoxy, C 1 -C 6 -haloalkoxy, C 1 -C 4 -alkoxy-C 2 -C 4 -alkoxy, C 1 -C 4 -alkylthio-C 2 C 4 -alkoxy, C 2 -C 6 -alkenyloxy, C 2 -C 6 -haloalkenyl-oxy, C 3 -C 6 -alkynyloxy, C 3 -C 6 -haloalkynyloxy, C 3 -C 8 -cycloalkyloxy, C 1 -C 6 -cyanoalkoxy and benzyloxy which in turn may be partially or fully halogenated on the phenyl ring and/or may be substituted by from one to three radicals selected from the group consisting of cyano, nitro, C 1 -C 4 -alkyl, C 1 -C 4 -alkoxy and C 1 -C 4 -alkylthio; in the presence of an excess of base, based on the amount of the carbamate of the formula II.