反应详情

Prepared according to WO 2010/031816. A 250 mL RBF containing 1-(4-bromo-1H-pyrrol-2-yl)-2,2,2-trichloroethanone (Combi-Blocks Inc. San Diego, Calif., 2.40 g, 8.24 mmol) was treated with DCM (80 mL) followed by DIPEA (10 mL, 57.7 mmol). To this stirring solution at RT was slowly added (E)-ethyl 4-aminobut-2-enoate 2,2,2-trifluoroacetate (4.01 g, 16.47 mmol) in DCM (20 mL), and the resulting solution was stirred at RT for 6 h. The reaction mixture was then concentrated in vacuo, and the residue was purified by silica gel chromatography (40-70% EtOAc in hexanes) to provide (E)-ethyl 4-(4-bromo-1H-pyrrole-2-carboxamido)but-2-enoate (2.35 g, 7.80 mmol, 95% yield) as a light yellow crystalline solid: 1H NMR (400 MHz, CDCl3) δ ppm 9.48 (1H, br. s.), 6.89-7.01 (2H, m), 6.58 (1H, dd, J=2.7, 1.4 Hz), 5.89-6.02 (2H, m), 4.16-4.24 (4H, m), 1.23-1.32 (3H, m). m/z (ESI, +ve ion) 301.0/302.9 (M+H)+.

1. customPrepared
2. customat RT
3. concentrationThe reaction mixture was then concentrated in vacuo
4. customthe residue was purified by silica gel chromatography (40-70% EtOAc in hexanes)