(2E)-4-Bromobut-2-enoic acid (106 mg, 0.64 mmol) and piperazine-1-carboxylic acid dimethylamide (107 mg, 0.68 mmol) were dissolved in DCM (5.0 mL), and DIPEA (111 mg, 0.85 mmol) was added. The mixture was stirred at rt for 2 h. Subsequently, the compound from Example 15A (150 mg, 0.43 mmol), DIPEA (55 mg, 0.43 mmol) and EDCI (82 mg, 0.43 mmol) were added. The reaction mixture was stirred at rt overnight. Then, water was added, and the mixture was extracted three times with DCM. The combined organic layers were dried over sodium sulfate. The solvent was removed in vacuo, and the residue was purified by preparative HPLC to yield 59 mg (24%) of the title compound.
