Patent ID: 6660865
Filing Date: 2003-12-09
Classification: C07D

Abstract:
A process for the preparation of a compound of formula I whereinR1 is hydrogen or chlorine and R2 is hydrogen, C1-C8alkyl, or C1-C8alkyl substituted by C1-C6alkoxy or by C3-C6alkenyloxy, which process comprises a) introducing the major portion of the amount to be reacted of a compound of formula II â€ƒinto a solvent mixture comprising at least one organic solvent capable of forming an azeotrope with water, and at least one aprotic-dipolar solvent; b) metering in an aqueous strong base in an amount equivalent to that major portion of the total amount of the compound of formula II; c) adding the remaining portion of the amount to be reacted of the compound of formula II; d) adding a weak base in an amount that is at least equivalent to that remaining portion; e) removing the water from the reaction mixture by azeotropic distillation; f) adding a compound of formula III wherein R2 is as defined for formula I; and g) isolating the resulting compound of formula I from the reaction mixture.