Patent ID: 8859769

Claim:
A process for preparing 4,6-dichloro-5-nitro-2-(propylthio)pyrimidine of formula II: comprising: a) reacting 2-thiobarbituric acid of formula V: with an alkylating agent of formula VI: wherein LG is a leaving group and is Br; in the presence of a phase transfer catalyst and a base in a first solvent to produce 2-propylthio-pyrimidine-4,6-diol of formula IV: or reacting an alkali metal salt of 2-thiobarbituric acid of formula V as a starting material with the alkylating agent of formula VI in the presence of a base, optionally in the presence of a phase transfer catalyst, in the first solvent to produce the 2-propylthio-pyrimidine-4,6-diol of formula IV; b) nitrating the compound of formula IV with a nitrating agent in a second solvent to produce 5-nitro-2-propylthiopyrimidine-4,6-diol of formula III: c) chlorinating the compound of formula III with a chlorinating agent in the presence of an aliphatic organic base, optionally in the presence of a third solvent, to produce substantially pure 4,6-dichloro-5-nitro-2-(propylthio)pyrimidine of formula II.