Ethanol → Ethyl 2-(2-thioxo-2,3-dihydrobenzoxazol-5-yl)propionate

Reaction equation

[NH2:1][C:2]1[CH:3]=[C:4]([CH:9]([CH3:15])[C:10]([O:12][CH2:13][CH3:14])=[O:11])[CH:5]=[CH:6][C:7]=1[OH:8].C(O[C:19]([S-])=[S:20])C.[K+].C(O)C>O>[S:20]=[C:19]1[NH:1][C:2]2[CH:3]=[C:4]([CH:9]([CH3:15])[C:10]([O:12][CH2:13][CH3:14])=[O:11])[CH:5]=[CH:6][C:7]=2[O:8]1

Participants

Procedure

A stirred mixture of ethyl 2-(3-amino-4-hydroxyphenyl)propionate (8.4 g.), potassium ethylxanthate (6.33 g.), ethanol (38 ml.) and water (6.5 ml.) was heated under reflux for 4 hours. The solution was evaporated to half volume and diluted with water (65 ml.). The mixture was acidified with 2N-hydrochloric acid and extracted several times with ether. The ethereal solution was washed with water, then dried with anhydrous sodium sulphate, and evaporated to give ethyl 2-(2-thioxo-2,3-dihydrobenzoxazol-5-yl)propionate as an oil. Dry chlorine was passed into a solution of the thione (9 g.) in freshly dried and distilled chloroform (150 ml.) with stirring for 4 hours. The solution was then washed with water, N-sodium hydroxide solution, then water (3x). The dried (Na2SO4) organic solution was evaporated to yield ethyl 2-(2-chloro-5-benzoxazolyl)propionate as a brown oil which was shown to be a single compound by thin layer chromatography.