The application relates to a preparation method of a compound F and a salt of the compound F, and a reaction as follows: comprising the following steps: (1)
condensation reaction of compound B and
compound C to prepare compound D; (2) reduction reaction of compound D to obtain
compound E; (3) nitro reaction of
compound E to prepare the compound F and the salt of the compound F. The application has the advantages of mild
process conditions, simple operation, high yield, simple post-treatment, product obtained through only a purification mode of
crystallization, reduction of "three wastes", and solution of the problems of the prior art, such as the need of ultralow temperature for reduction of methyl ester to
aldehyde, difficulty in controlling selectivity, and easy over-reduction, ingenious integration of hydrogenation and
salt formation reaction into a one-pot method, successful preparation of a
hydrochloride crystal form of the compound F with high yield and high purity, stable
crystal form, good reproducibility, and easy realization of industrialized production.