Trifluoroacetic acid → N-(2,4-Dioxo-2,3,4,5-tetrahydro-1H-benzo[b][1,4]diazepin-3-yl)-2,2,2-trifluoro-acetamide

Participants

Reaction Steps

Add 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride (7.67 g, 40.0 mmol), and 4-(dimethylamino)pyridine (0.244 g, 2.00 mmol) to a solution of 3-amino-1,5-dihydro-benzo[b][1,4]diazepine-2,4-dione (7.65 g, 40.0 mmol) in anhydrous N,N-dimethylformamide (50 mL). Rinse solids into reaction with anhydrous N,N-dimethylformamide (50 mL), and cool reaction to 0° C. in an ice/water bath. Add via syringe trifluoroacetic acid (3.08 mL, 40.0 mmol). After 10 minutes, remove cooling, and after 5.5 hours at ambient temperature, add an additional 0.2 equivalents of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride (1.53 g) and trifluoroacetic acid (0.62 mL) and stir at ambient temperature. After an overnight period, concentrate under reduced pressure to give a residue. Reconstitute the residue in isopropanol: chloroform (1:3, 20 mL) and set 5 minutes. Collect solid formed by suction filtration, wash with isopropanol: chloroform (3:1), and dry at ambient temperature under vacuum to give the title compound. Filter the filtrate, which contained precipitated solid and dry this solid at ambient temperature under vacuum to give a second crop of the title compound: mass spectrum (ES neg., m/e): 286.0 (M−1); NMR (1H, 300 MHz, DMSO-d6): δ 10.93 (s, 2H), 9.42 (d, 1H, J=6.9 Hz), 7.29-7.15 (m, 4H), 4.91 (d, 1H, J=7.2 Hz).

Provenance & Evidence