A solution of tert-butyl 4-(3-chloro-5-formylphenyl)piperazine-1-carboxylate (3, 0.300 g, 0.918 mmol) and 2-amino-4,6-dimethoxybenzamide (4, 0.120 g, 0.612 mmol) in DMA (4 mL) was treated with p-TsOH (0.424 g, 1.46 mmol) and NaHSO3 (0.290 g, 1.84 mmol) and then heated at 110° C. for 16 h. The reaction mixture was cooled to room temperature, trifluoroacetic acid (5 mL) was added and the mixture was heated at 70° C. for 1 h. The reaction mixture was cooled to room temperature and concentrated. The residue was purified by silica gel chromatography eluting with 0-100% 92:7:1 CHCl3/MeOH/concentrated NH4OH in CH2Cl2. This material was further purified by reverse phase HPLC eluting with 10% to 90% CH3CN in H2O with 0.1% TFA. The product fractions were concentrated and the residue was dissolved in acetonitrile and water. The mixture was basified with concentrated NH4OH and the precipitate filtered, washed with water, and dried under vacuum to afford the title compound (0.072 g, 29%) as an off-white solid: 1H NMR (500 MHz, DMSO-d6) δ 7.60-7.70 (m, 2H), 7.08-7.12 (m, 1H), 6.78 (d, J=2.3 Hz, 1H), 6.55 (d, J=2.3 Hz, 1H), 3.89 (s, 3H), 3.85 (s, 3H), 3.24 (t, J=5.2 Hz, 4H), 3.28 (t, J=5.2 Hz, 4H); ESI MS m/z 401 [M+H]+.
