2-Amino-5-nitrobenzophenone → (9H-fluoren-9-yl)methyl 1-(2-benzoyl-4-nitrophenylamino)-1-oxopropan-2-ylcarbamate

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Reaction Conditions

Reaction Steps

Commercially-available (S)-Fmoc-alanine (2.98 g, 0.96 mmol) was suspended in ethanol-free CHCl3 (30 mL) and SOCl2 (7 mL) was added under N2. The mixture was heated at 50° C. for 1 h, then the solvent was removed under vacuum, the residue was dissolved into CHCl3 (30 mL), commercially-available 2-amino-5-nitro-benzophenone (2.32 g, 0.96 mmol) was added, and the mixture was heated for 2 h at 60° C. After cooling, a saturated solution of NaHCO3 was added, the organic phase was collected and dried (Na2SO4), then the solvent was removed under vacuum obtaining (9H-fluoren-9-yl)methyl 1-(2-benzoyl-4-nitrophenylamino)-1-oxopropan-2-ylcarbamate (98% yield). This compound was dissolved in CH2Cl2 (40 mL), Et3N (10 mL) was added and the mixture was heated at 40° C. for 30 h under N2. The solvent was removed under vacuum and the residue was partitioned between 2N HCl and ethyl acetate; the aqueous layer was made alkaline with 10% NaOH and extracted with CH2Cl2. After drying (Na2SO4) and removal of solvent, the residue was purified by flash chromatography (cyclohexane/ethyl acetate 6:4 as eluent) yielding (S)-3-methyl-7-nitro-5-phenyl-1H-benzo[e][1,4]diazepin-2(3H)-one in 25% yield.

Provenance & Evidence