The reaction of 2-nitrobenzoic acid with SOCl2 gives the acyl chloride (II), which is condensed with D-proline (III) by means of TEA in dichloromethane yielding the acyl proline (IV). The reductive cyclization of (IV) with H2 over Pd/C in methanol affords the pyrrolobenzodiazepinedione (V). The selective reduction of the C-11 lactam group of (V) with NaBH4 and TFA in glyme gave the pyrrolobenzodiazepinone (VI), which is finally coupled with 4-[(2-phenylbenzoyl)amino]benzoyl chloride (VII) furnishing the title compound.
Condensation of 1-fluoro-2-nitrobenzene (I) with cis-4-hydroxy-D-proline methyl ester (II) in hot acetonitrile provided the N-(2-nitrophenyl)proline derivative (III). The stereochemical inversion of the hydroxyl group of (III) was achieved by Mitsunobu coupling with acetic acid, followed by basic hydrolysis of the resulting acetate ester (IV) to acid (V). The nitro acid (V) obtained was then hydrogenated over Pd/C to form the tricyclic lactam (VI). Further reduction of the lactam carbonyl group by means of NaBH4 in refluxing THF gave pyrroloquinoxaline (VII). This was finally coupled with 4-(4'-methyl-2-biphenylcarboxamido)benzoyl chloride (VIII) to furnish the target amide.
The reaction of 2-nitrobenzoic acid with SOCl2 gives the acyl chloride (II), which is condensed with D-proline (III) by means of TEA in dichloromethane yielding the acyl proline (IV). The reductive cyclization of (IV) with H2 over Pd/C in methanol affords the pyrrolobenzodiazepinedione (V). The reduction of both lactam groups of (V) with LiAlH4 gave the pyrrolobenzodiazepine (VI), which is finally coupled with 4-[(2-phenylbenzoyl)amino]-benzoyl chloride (VII) furnishing the title compound.