Ammonium Chloride → HCID 66599441, compound

Participants

Reaction Steps

KOtBu (2.81 g, 25.08 mmol) was dissolved into 20 ml DMSO in a round bottom flask. tert-butyl 4-(4-aminobenzoyl)piperazine-1-carboxylate (7 g, 22.92 mmol) in 30 ml DMSO was added and the resulting mixture was stirred for 15 minutes at room temperature, then cooled in an iced bath for 5 minutes. 5-bromo-2-fluorobenzonitrile (4.6 g, 23.00 mmol) in 20 ml DMSO was added. The ice bath was removed and the mixture stirred for 5 hours while warming to room temperature. LCMS showed product and unreacted starting materials. Additional KOtBu (2 g, 17.82 mmol) was added and the reaction stirred at room temperature overnight. The mixture was transferred into a separating funnel that was loaded with dichloromethane and dilute aq. NH4Cl solution. The layers were separated, the organic layer washed one more time with water, then brine, dried over Mg504, filtered and concentrated in vacuum. The crude was dissolved in dichloromethane, and refluxed while adding ethyl acetate until the solution becomes cloudy, then allowed to stand and cool to room temperature. The product precipitated and was collected by filtration. 6.40 g tert-butyl 4-(4-(4-bromo-2-cyanophenylamino)-benzoyl)piperazine-1-carboxylate were isolated as a white solid. The mother liquor was concentrated in vacuum and purified by column chromatography on silica, gradient from 100% dichloromethane to 50% ethyl acetate in dichloromethane. Product containing fractions were combined and evaporate to give additional 0.90 g product as a pale yellow solid. MS (ESI) m/z 485/487 (1 Br isotope pattern) (M+H), 429/431 (1 Br isotope pattern) (M+H—C4H8). 1H NMR (CDCl3) δ ppm 7.64 (s, 1H), 7.50 (d, 1H, J=9.2), 7.42 (d, 2H, J=8.3), 7.19-7.15 (m, 3H), 6.39 (s, 1H), 3.80-3.40 (b, 8H), 1.47 (s, 9H).

Provenance & Evidence