反应详情

The crude 2-(4-bromophenyl-4-(cyanomethyl)-5-methyloxazole (assume 0.22 mol) was combined with 2-methoxyethanol (630 mL) and 85% solid KOH (74.6 g, 1.33 mol) in water (360 mL) was added to the reaction. The mixture was heated to reflux for 3 h, cooled, quenched with 2 M HCl (500 mL), and extracted with CH2Cl2. The organic layer was dried (MgSO4), and the solvent removed in vacuo, using toluene to azeotropically remove residual 2-methoxyethanol. The crude product (57.3 g) was recrystallized from toluene (450 mL) to give 39.8 g (60%) of 2-(4-bromophenyl)-5-methyl-4-oxazoleacetic acid as an off-white powder: Rf=0.23 in 10% MeOH/CH2Cl2; 1H NMR (500 MHz, CDCl3) 9.00 (br s, 1H), 7.85-7.83 (m, 2H), 7.58-7.56 (m, 2H), 3.62 (s, 3H), 2.36 (s, 3H); 13C (125 MHz, CDCl3) 173.8, 159.0, 146.2, 132.0, 129.1, 127.6, 125.9, 124.7, 31.5, 10.2; IR (CHCl3) 2923, 1699, 1641, 1481, 1428, 1306, 1234, 1010, 829, 727 cm−1; UV (EtOH)max288 nm (19626).

1. additionwas added to the reaction
2. temperatureThe mixture was heated
3. temperatureto reflux for 3 h
4. temperaturecooled
5. customquenched with 2 M HCl (500 mL)
6. extractionextracted with CH2Cl2
7. dry with materialThe organic layer was dried (MgSO4)
8. customthe solvent removed in vacuo
9. customThe crude product (57.3 g) was recrystallized from toluene (450 mL)