Reaction Steps
To a stirred solution of 736 mg (2.83 mmol) of ethyl 2-bromo-3-nitrobenzoate and 579 mg (3.1 mmol, 1.1 eq) of 1-tert-butyloxycarbonylpiperazine in n-butanol (6 mL) was added 330 mg (3.1 mmol, 1.1 eq) of Na2CO3. The mixture was heated to reflux for 4 h. The solvent was removed under reduced pressure. The crude product was partitioned between EtOAc (100 mL) and 20 mL of H2O. The organic layer was washed with H2O (2×20 mL), dried over Na2SO4 and concentrated. Column chromatography (silica, 10-20% EtOAc/hexanes) provided 744 mg (72%) of 4-(2-methoxycarbonyl-6-nitro-phenyl)-piperazine-1-carboxylic acid tert-butyl ester. TLC (silica, 20% EtOAc/hexanes): Rf=0.5. 1H NMR (400 MHz, CDCl3): 7.67 (dd, J=8.2, 1.4 Hz, 1H), 7.62 (dd, J=8.2, 1.4 Hz, 1H), 7.16 (t, J=8.2 Hz, 1H), 3.86 (s, 3H), 3.44-3.36 (m, 4H), 3.03-2.95 (m, 4H), 1.48 (s, 9H). B. 2-(4-{2-Hydroxy-3-[5-methanesulfonyl-3-(4-trifluoromethyl-phenyl)-4,5,6,7-tetrahydro-pyrazolo[4,3-c]pyridin-1-yl]-propyl}-piperazin-1-yl)-3-methanesulfonylamino-benzoic acid methyl ester. A solution of 1.0 g (2.73 mmol) of 4-(2-methoxycarbonyl-6-nitro-phenyl)-piperazine-1-carboxylic acid tert-butyl ester in 18 mL of MeOH was treated with 893 mg (13.7 mmol, 5 eq) of zinc dust and glacial acetic acid (8 mL). The reaction mixture was stirred at 25° C. for 1 h. The reaction mixture was then filtered through a pad of celite and concentrated to obtain a thick oil. The residue was taken up in EtOAc (200 mL) and sat. NaHCO3 (100 mL). The organic layer was separated, washed with H2O (2×50 mL), dried over Na2SO4, and concentrated. Column chromatography (silica, 10-30% EtOAc/hexanes) provided the desired amine (844 mg, 92%). The amine (42 mg, 0.13 mmol) in CH2Cl2 (0.5 mL) was treated with 9.7 μL (0.13 mmol, 1.0 eq) of methanesulfonyl chloride and 34.9 μL (0.25 mmol, 2 eq) of triethylamine and the reaction mixture stirred at 25° C. for 1 h. EtOAc (20 mL) and sat. NaHCO3 (10 mL) were added. The organic layer was separated and washed with H2O (10 mL), brine (20 mL), dried over Na2SO4, and concentrated. The crude oil was dissolved in 2 mL of CH2Cl2 and treated with 0.5 mL of trifluoroacetic acid. The reaction mixture was stirred at 25° C. for 1 h before all volatiles were removed. The crude oil was dissolved in absolute EtOH (1.0 mL) and treated with 40 mg (0.1 mmol) of 5-methanesulfonyl-1-oxiranylmethyl-3-(4-trifluoromethyl-phenyl)-4,5,6,7-tetrahydro-1H-pyrazolo[4,3-c]pyridine and 200 μL of triethylamine. The reaction mixture was refluxed at 85° C. for 4 h and then the solvent was removed. Preparative TLC (silica, 7% MeOH/CH2Cl2) provided 35 mg (49% over 3 steps) of the title compound. TLC (silica, 5% MeOH/CH2Cl2): Rf=0.30. MS (electrospray): exact mass calculated for C30H37F3N6O7S2, 714.21; m/z found, 715.2 [M+H]+. 1H NMR (400 MHz, CDCl3): 8.11 (s, 1H), 7.74-7.59 (m, 5H), 7.30 (d, J=8.1 Hz, 1H), 7.21 (t, J=8.2 Hz, 1H), 4.62-4.49 (m, 2H), 4.25-3.99 (m, 3H), 3.90 (s, 3H), 3.80-3.57 (m, 3H), 3.53-3.27 (m, 2H), 3.14-2.78 (m, 4H), 3.05 (s, 3H), 2.86 (s, 3H), 2.76-2.65 (m, 2H), 2.61-2.20 (m, 4H).
