It is disclosed a process for the preparation of a compound of formula (I) or a salt thereof, comprising:
nitrating a compound of formula (II) or a salt thereof,
to obtain a compound of formula (IV) or a salt thereof,
reducing it, to obtain a compound of formula (V) or a salt thereof, and
subsequently cyclizing it to obtain a compound of formula (I) or a salt thereof and, if desired, converting a compound of formula (I) to a salt thereof, or vice versa, characterized in that: the nitration of a compound of formula (II) or a salt thereof is carried out with concentrated nitric acid in the presence of a strong inorganic acid and that the amino group in the compound of formula (II) is not protected.
本发明揭示了一种制备公式(I)化合物或其盐的方法,包括:硝化公式(II)化合物或其盐,以获得公式(IV)化合物或其盐,还原它,以获得公式(V)化合物或其盐,然后环化它以获得公式(I)化合物或其盐,如果需要,将公式(I)化合物转化为其盐,或反之,其特征在于:使用浓
硝酸和强
无机酸存在的情况下进行公式(II)化合物或其盐的硝化,并且公式(II)化合物中的
氨基未得到保护。