| 摘要 |
A process is provided for the preparation of compounds of Formula (1):wherein X1 and X2 are each independently H, Cl or F, provided that at least one of X1 and X2 is Cl or F; one of R1 and R2 is H and the other is OH; and R5 is an unsubstituted alkyl, preferably a C1-6 alkyl, group. The process comprises condensing a 2-chloroalkanoic acid with an optionally substituted benzyl alcohol to form a 2-(optionally substituted benzyloxy) alkanoic acid, converting the condensation product to the corresponding acid chloride and then either reacting the acid chloride with a compound of the Formula (2) in the presence of a source of copper (I) to give a compound of Formula (3) wherein one of R3 and R4 is H and the other is optionally substituted benzyloxy;or reacting the acid chloride with a compound of Formula (4):wherein A and B independently represent substituted alkyl, alkoxy, aryl or oxyaryl groups, or are linked to form a heterocyclic ring to form an amide, and then reacting the amide with a compound of Formula (2) to give a compound of Formula (3). The optionally substituted benzyl group from the compound of Formula (3) can removed by hydrogenation.
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