Reaction Steps
A solution of ammonium chloride (220 mg, 4.3 mmol) in water (2.5 mL) was added to a solution of 5-[3-(4-chlorophenyl)-4-[1-(4-chloro-2-nitrophenyl)ethyl]-7-iodo-2,5-dioxo-1,4-benzodiazepin-1-yl]valeric acid tert-butyl ester (230 mg, 0.306 mmol) in ethanol (5 mL). The resulting solution was heated to 80° C. and iron (200 mg, 3.58 mmol) was added. After 2 h at 80° C., the reaction mixture was cooled at room temperature, filtered through celite and evaporated. The residue was partitioned between ethyl acetat and water, dried (Na2SO4), and evaporated. Chromatography on silica (EtOAc/hexanes, 1:1) afforded the title compound (210 mg, 95%) as a colorless solid: 1H NMR (400 MHz, CDCl3) δ 1.44 (s, 9H, 3 CH2)), 1.57–1.63 (m, 4H, 2 CH2), 1.74 (d, J=7.2 Hz, 3H, CH3), 2.24 (t, J=7.2 Hz, 2H, CH2), 3.63–3.70 (m, 1H, CH), 4.28–4.35 (m, 1H, CH), 4.75 (br s, 2H, NH2), 5.28 (s, 1H, CH), 6.27 (q, J=7.2 Hz, 1H, CH), 6.60–6.69 (m, 5H, ArH), 6.90 (d, J=9.2 Hz, 2H, ArH), 7.20 (d, J=8.4 Hz, 1H, ArH), 7.49 (dd, J=8.8 Hz, J=2.4 Hz, 1H, ArH), 7.93 (d, J=2.0 Hz, 1H, ArH). Mass spectrum (LCMS, ESI pos.): Calcd for C32H34Cl2IN3O4: 721.0; found: 722.0 (M+H)+.
