Diisopropylethylamine → (E)-ethyl 4-(4-bromo-1H-pyrrole-2-carboxamido)but-2-enoate

Participants

Reaction Steps

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)+.

Provenance & Evidence