Dimethylformamide → 6-bromo-2-(4-hydroxy-3,5-dimethylphenyl)quinazolin-4(3H)-one

Beteiligte Stoffe

Reaktionsschritte

To a solution of 4-hydroxy-3,5-dimethylbenzoic acid (2.00 g, 12.0 mmol) in CH2Cl2 (60.2 mL) cooled to 0-5° C. was added oxalyl chloride (1.47 mL, 16.8 mmol) followed by dropwise addition of DMF (93.3 μL, 1.20 mmol). The mixture was stirred for 1.25 h, the volatiles were removed under vacuum to give crude acid chloride, which was used immediately without further purification. A mixture of 2-amino-5-bromobenzamide (1.99 g, 9.23 mmol) and the acid chloride (crude residue described above) in THF (92.3 mL) was stirred at room temperature for 17 h, then heated at reflux for 4 h. The volatiles were removed under vacuum, the residue was triturated with EtOAc, and filtered to afford the amide (3.02 g, 90%) as a yellow solid. A mixture of the amide (3.01 g, 8.29 mmol), 2 M NaOH (20.0 mL), water (40.0 mL), and MeCN (20.0 mL) was heated at reflux for 15 h, cooled to 5° C., and neutralized with 2 M aqueous HCl. After stirring for 30 min, the white solid was filtered, triturated with acetone, and filtered again to afford 6-bromo-2-(4-hydroxy-3,5-dimethylphenyl)quinazolin-4(3H)-one (2.28 g, 80%). Selected data: 1H NMR (300 MHz, DMSO-d6) δ 8.18 (d, J=2.29 Hz, 1H), 7.93 (dd, J=8.72, 2.42 Hz, 1H), 7.86 (s, 2H), 7.63 (d, J=8.70 Hz, 1H), 5.75 (s, 1H), 2.24 (s, 6H); MS (APCI) m/z 346 [M+H]+.

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