合成路线1

The acetylation of 4-aminobenzophenone (I) with acetic anhydride in hot benzene gives 4-acetamidobenzophenone (II), which is nitrated with 90% HNO3 in acetic acid-acetic anhydride yielding 4-acetamido-3-nitrobenzophenone (III). The hydrolysis of (III) with H2SO4 affords 4-amino-3-nitrobenzophenone (IV), which is reduced with H2 over Raney-Ni in THF to give 3,4-diaminobenzophenone (V). The cyclization of (V) with cyanogen bromide in methanol-water gives rise to 2-amino-5-benzoylbenzimidazol (VI), which is treated with isopropylsulfonyl chloride (A) and NaH in dimethoxyethane affording 2-amino-1-isopropylsulfonyl-6-benzoylbenzimidazol (VII). Finally, this compound is treated with hydroxylamine hydrochloride in refluxing methanol.