4-Aminobenzoic Acid → Ameltolide

Beteiligte Stoffe

Reaktionsschritte

Oxalyl chloride (1.9 mL, 22 mmol) was added dropwise to a solution of DMF (1.7 mL, 22 mmol) and DCM (22 mL) that was kept at 0° C. The resulting foamy white suspension was stirred for 30 min and allowed to warm to room temperature, then cooled again to 0° C. 4-Aminobenzoic acid (1.50 g, 10.9 mmol) was added and the reaction mixture was stirred at room temperature for 1 h. The flask was again cooled to 0° C. and DCM (11 mL) and pyridine (2.6 mL, 33 mmol) were added. Stirring was continued for 50 min and 2,6-dimethyl-phenylamine (1.33 g, 10.9 mmol) was then added. The reaction mixture was stirred at room temperature for 1.5 h and concentrated to dryness. The residue was dissolved in ethanol (30 mL) and 1,2-ethylenediamine (3.3 mL, 49 mmol) was added. The reaction mixture was heated at reflux for 2 h, allowed to cool to room temperature, stirred for 2 d, and concentrated. Water (50 mL) was added to the residue and the precipitate was collected, rinsed well with water, and dried to yield the titled compound (1.904 g, 70% yield). MS (ESI/Cl): mass calcd. for C15H16N2O, 240.1; m/z found, 241.1 [M+H]+. 1H NMR (400 MHz, CD3OD): 7.76 (d, J=8.8 Hz, 2H), 7.10 (s, 3H), 6.72 (d, J=8.8 Hz, 2H), 2.24 (s, 6H).

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