| 摘要 |
<p>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.</p> |
