| 摘要 |
Compounds of formula (I), wherein R1 is hydrogen or chlorine and R2 is hydrogen, C1-C8alkyl, or C1-C8 alkyl substituted by C1-C6alkoxy or by C3-C6alkenyloxy, can be prepared by: a) introducing the major portion of the amount to be reacted of a compound of formula (II) into 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. |
