jihuenirue - production manner null of Telecom

摘要

A process for preparing a compound of formula (II): CHEM or a tautomer or salt thereof in substantially pure form wherein R1 is C1-6 alkyl optionally substituted by one or more halogen atoms; R3 is hydrogen, fluorine, chlorine, bromine or iodine, C1-6 alkyl, trifluoromethyl or a cyano group; R4 is hydrogen, fluorine, chlorine, bromine, iodine or trifluoromethyl; R5 is fluorine, chlorine, bromine, iodine or trifluoromethyl; and R6 is hydrogen or C1-4 alkyl; which process comprises nitrating a compound of formula (III): CHEM or a salt thereof wherein R1, R3, R4, R5 and R6 are as defined above, in a solvent which is resistant to nitration under the desired reaction conditions and suitable for purification of the product of formula (II), heating the resultant solution to a temperature sufficient to at least partially dissolve the desired product and impurities and cooling the solution to precipitate the compound of formula (II) in substantially pure form.