申请人:Hoechst Aktiengesellschaft
公开号:US05675034A1
公开(公告)日:1997-10-07
Process for preparing 3-(p-fluorophenyl)-2-methylpropionic acid and derivatives thereof of the formula (I), ##STR1## in which R is a hydroxy group, a linear or branched (C.sub.1 -C.sub.8)-alkoxy group, an aryloxygroup, an amino group or a (C.sub.1 -C.sub.8)-alkylamino group or a (C.sub.1 -C.sub.8)-dialkylamino group, by a) converting p-fluoroaniline into the p-fluorophenyldiazonium salt of the formula (II) ##STR2## in which X is the equivalent of an anion of an organic or inorganic acid having a pKa value of less than 7, b) reacting the diazonium salt of the formula (II) with a methacrylic acid derivative of the formula (III) ##STR3## in which R is as defined above in the presence of a palladium catalyst, if desired in the presence of a base and/or a solvent, to give the compounds of the formulae (IV) and (V) in which R is as defined above, ##STR4## and c) hydrogenating the resulting compounds of the formulae (IV) and (V) in the presence of a palladium catalyst with hydrogen.
制备3-(对氟苯基)-2-甲基丙酸及其衍生物的过程,其化学式为(I):
其中R是羟基、线性或支链(C1-C8)-烷氧基、芳氧基、氨基或(C1-C8)-烷基氨基或(C1-C8)-二烷基氨基,包括以下步骤:
a)将对氟苯胺转化为化学式(II)的对氟苯基重氮盐:
其中X是具有小于7的pKa值的有机或无机酸根离子的当量。
b)在钯催化剂的存在下,将式(II)的重氮盐与式(III)的甲基丙烯酸衍生物反应:
其中R如上定义,如有需要,在碱和/或溶剂的存在下进行反应,以得到式(IV)和(V)的化合物:
其中R如上定义;
c)在钯催化剂和氢气的存在下,对式(IV)和(V)的产物进行氢化。