A suspension of 5-(4-benzoylpiperazin-1-yl)-N1-phenylbenzene-1,2-diamine (0.2 g, 0.54 mmol), paraformaldehyde (0.025 g, 1.01 mmol), and 6 drops of acetic acid in 10 ml 1,2-dichloroethane was stirred at room temperature for 5 hours. Sodium triacetoxyborohydride (0.45 g, 2.2 mmol) was added and stirred overnight before quenching with 10 ml water. The mixture was extracted with ethyl acetate (3×20 ml) and dried over anhydrous sodium sulfate. ((4-(4-(Methylamino)-3-(phenylamino)phenyl)piperazin-1-yl)(phenyl)methanone (0.021 g, 10%) was obtained by flash column chromatograph (50% ethyl acetate in hexanes). 1H NMR (500 MHz, CDCl3) 8 (ppm) 2.86 (s, 3H), 2.97 (s, br, 4H), 3.58 (s, br, 2H), 3.94 (s, br, 3H), 5.18 (s, 1H), 6.88 (m, 6H), 7.25 (m, 2H), 7.47 (m, 6H).
