反应详情

A suspension of 4-amino-2-bromo-5-methylthiazole hydrobromide (50 mM, 13.7 g) in acetic anhydride (100 ml) was treated dropwise with pyridine (10 ml) while cooling in an ice bath. After stirring for 1 hour the reaction mixture was poured onto 20% aqueous sodium acetate (1 l) and the aqueous solution extracted with dichloromethane (3 × 500 ml.). The combined organic layers were dried and evaporated under reduced pressure to give an oil which crystallised on trituration with ether. The crude product was recrystallised from ethanol to give the 4-acetamido-2-bromo-5-methylthiazole (11.7 g, 50%). mp 129°. (Found: C, 31.15; H, 3.15; N, 12.3. C6H7BrN2OS requires: C, 30.6; H, 3.0; N, 11.9%).

1. temperaturewhile cooling in an ice bath
2. extractionthe aqueous solution extracted with dichloromethane (3 × 500 ml.)
3. customThe combined organic layers were dried
4. customevaporated under reduced pressure
5. customto give an oil which
6. customcrystallised on trituration with ether
7. customThe crude product was recrystallised from ethanol