The invention relates to a process for the preparation of a compound of formula (I), wherein R
1
, R
2
and R
3
are as defined in claim
1,
which process comprises a) adding a compound of formula (II), in the presence of an inert organic solvent to a mixture comprising an organic nitrite of formula (III) (R
4
—O—N═O (III)), wherein R
4
is C
1
-C
8
alkyl, a compound of formula (IV), and an inert organic solvent; b) reacting the resulting compound of formula (V), with H
2
N—O—CH
3
to the compound of formula (VII), c) reducing the compound of formula (VII) to the compound of formula (VIII), d) and reacting the compound of formula VIII with a compound of formula (IX), in which R* is halogen, hydroxy or C
1-6
alkoxy, to the compound of formula (I).
本发明涉及一种制备式(I)化合物的方法,其中R1、R2和R3如权利要求1所定义,该方法包括:a)在惰性有机溶剂的存在下将式(II)化合物加入到混合物中,所述混合物包括式(III)有机
亚硝酸酯(R4-O-N═O(III)),其中R4是C1-C8烷基,式(IV)化合物和惰性有机溶剂;b)将所得的式(V)化合物与
H2N-O-
CH3反应得到式(VII)化合物;c)还原式(VII)化合物得到式(VIII)化合物;d)将式(VIII)化合物与式(IX)化合物反应,其中R*是卤素、羟基或C1-6烷氧基,以制备式(I)化合物。