反应详情

6.2 g of N-(4-phenyl-thiazol-2-yl)-oxamic acid (prepared from the ethyl ester by hydrolyzing with aqueous potassium acetate and liberating the acid with dilute hydrochloric acid), in 25 ml of dry toluene, are heated with 20 ml of oxalyl chloride for 2 hours at 60° C. After distilling off the excess oxalyl chloride under reduced pressure, a solution of 5 ml of ethylene glycol monomethyl ether, 3.5 ml of triethylamine and 20 ml of toluene is added dropwise. The mixture is stirred for a further 3 hours at room temperature and is then left to stand overnight. The precipitate is filtered off, washed with methanol and water and recrystallized from ethanol. 3.7 g of the compound of the formula I, with R1 =C6H5 and R2 =CH2CH2OCH3, of melting point 118°-120° C., are obtained.

1. distillationAfter distilling off the excess oxalyl chloride under reduced pressure
2. additiona solution of 5 ml of ethylene glycol monomethyl ether, 3.5 ml of triethylamine and 20 ml of toluene is added dropwise
3. waitis then left
4. waitto stand overnight
5. filtrationThe precipitate is filtered off
6. washwashed with methanol and water
7. customrecrystallized from ethanol