C(Cl)(=O)C(Cl)=O.[CH3:7][O:8][C:9]([C:11]1[CH:19]=[CH:18][C:14]([C:15]([OH:17])=O)=[CH:13][CH:12]=1)=[O:10].[CH3:20][N:21]1[CH2:26][CH2:25][NH:24][CH2:23][CH2:22]1.N1C=CC=CC=1>C(Cl)Cl.CN(C=O)C>[CH3:20][N:21]1[CH2:26][CH2:25][N:24]([C:15]([C:14]2[CH:13]=[CH:12][C:11]([C:9]([O:8][CH3:7])=[O:10])=[CH:19][CH:18]=2)=[O:17])[CH2:23][CH2:22]1
Oxalyl chloride (0.533 mL, 6.11 mmol) was added dropwise to a stirred suspension of 4-(methoxycarbonyl)benzoic acid (1 g, 5.55 mmol) in DCM (20 mL) under nitrogen. The resulting suspension was stirred at room temperature for 30 mins. DMF (0.05 mL) was added dropwise under nitrogen. The resulting suspension was stirred for 90 mins. A solution of 1-methylpiperazine (0.554 mL, 5.00 mmol) and pyridine (1.211 mL, 14.99 mmol) in DCM (15 mL) was added dropwise at 0° C., over a period of 60 mins under nitrogen. The resulting solution was stirred at room temperature for 3 h. The reaction mixture was evaporated to dryness to afford the crude product (1.791 g) as a dark orange solid. The solid was redissolved in DCM and washed with NaHCO3. The organic layer was evaporated to dryness to afford methyl 4-(4-methylpiperazine-1-carbonyl)benzoate (0.890 g, 61.1%) as an orange gum, which solidified on standing. Used without further purification.
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