Reaction Steps
Potassium tert-butoxide (1.0 M in THF, 0.86 ml, 0.86 mmol, 4.0 equiv) was added at room temperature under an atmosphere of argon to a solution of (1H-indol-3-yl)-oxo-acetic acid methyl ester (66 mg, 0.32 mmol, 1.5 equiv) and of 2-(6-chloro-3-dimethylaminomethyl-quinoxalin-5-yl)-acetamide (60 mg, 0.22 mmol) in anhydrous tetrahydrofuran (3.0 ml, dried over molecular sieves). The reaction mixture was stirred for 15 minutes at room temperature. It was then diluted with EtOAc and poured into a saturated aqueous NH4Cl solution. After three extractions with EtOAc, the combined organic layers were dried over Na2SO4, filtered and concentrated in vacuo. Purification of the residue via preparative HPLC afforded the title compound (32 mg, 27%) and 3-(3-dimethylaminomethyl-6-hydroxy-quinoxalin-5-yl)-4-(1H-indol-3-yl)-pyrrole-2,5-dione (14 mg, 12%) as their trifluoroacetate salts. Data for 3-(6-chloro-3-dimethylaminomethyl-quinoxalin-5-yl)-4-(1H-indol-3-yl)-pyrrole-2,5-dione: 1H NMR (400 MHz, d6-DMSO): δ=11.97 (s, 1H), 11.26 (s, 1H), 9.86 (s, 1H), 9.01 (s, 1H) 8.29 (d, J=9.0 Hz, 1H), 8.06-8.04 (m, 2H), 7.35 (d, J=8.0 Hz, 1H), 6.96 (dt, J=7.6/1.0 Hz, 1H), 6.49 (dt, J=8.1/1.0 Hz, 1H), 6.09 (d, J=8.3 Hz, 1H), 4.68 (s, 2H), 2.66 (s, 6H). MS (ES+): 432.2 (M+H)+. Data for 3-(3-dimethylaminomethyl-6-hydroxy-quinoxalin-5-yl)-4-(1H-indol-3-yl)-pyrrole-2,5-dione: 1H NMR (400 MHz, d6-DMSO): δ=11.80 (s, 1H), 11.01 (s, 1H), 10.64 (s, 1H), 9.79 (s, 1H), 8.75 (s, 1H), 8.08 (d, J=9.3 Hz, 1H), 7.95 (d, J=2.9 Hz, 1H), 7.51 (d, J=9.0 Hz, 1H), 7.32 (d, J=8.1 Hz, 1H), 6.93 (dt, J=7.6/0.9 Hz, 1H), 6.48 (dt, J=8.1/1.0 Hz, 1H), 6.34 (d, J=8.3 Hz), 4.58 (s, 2H), 2.67 (s, 6H). MS (ES+): 414.3 (M+H)+.
