The condensation of 2,5-difluoronitrobenzene (I) with ethyl 2-amino-5-methylthiophene-3-carboxylate (II) by means of triethylamine in hot DMSO or 2-methoxyethanol giving ethyl 2-(4-fluoro-2-nitroanilino)-5-methylthiophene-3-carboxylate (III), which is reduced with H2 over Pd/C in ethanol to ethyl 2-(4-fluoro-2-aminoanilino)-5-methylthiophene-3-carboxylate (IV). The cyclization of (IV) by means of NaH in DMSO affords 9,10-dihydro-7-fluoro-2-methyl-4H-thieno[2,3b][1,5]benzodiazepin-2-one (V), which is finally condensed with N-methylpiperazine by means of TiCl4 in anisole at 120 C.