The present invention relates to a process for the preparation of compounds of formula wherein R
1
, R
2
and R
3
are each independently of the others hydrogen or C
1
-C
4
alkyl, by a) reacting compounds of formula (II) wherein R
1
, R
2
and R
3
are as defined for formula (I) and X is bromine or chlorine, with a compound of formula (III) wherein R
4
is hydrogen or C
1
-C
4
alkyl, in the presence of a base and catalytic amounts of at least one palladium complex compound, to form compounds of formula (IV) wherein R
1
, R
2
, R
3
and R
4
are as defined for formula (I), and b) converting those compounds, using a reducing agent, into compounds of formula (I).
本发明涉及一种制备式化合物的方法,其中R1、R2和R3各自独立地为氢或C1-C4烷基,通过a)在碱和至少一种
钯配合物催化剂存在下,将式(II)化合物与式(III)化合物反应,其中R1、R2和R3如式(I)所定义,X为
溴或
氯,形成式(IV)化合物,其中R1、R2、R3和R4如式(I)所定义;b)使用还原剂将这些化合物转化为式(I)化合物。