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 concentrated, using toluene to remove residual 2-methoxyethanol azeotropically. 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)max 288 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. concentrationconcentrated
9. customto remove residual 2-methoxyethanol azeotropically
10. customThe crude product (57.3 g) was recrystallized from toluene (450 mL)