反応 #56563

反応方程式

ethyl 2-methoxyimino-4-bromoacetoacetate

thiourea

→

ethyl 2-methoxyimino-2-(2-aminothiazol-4-yl)acetate hydrobromide

溶媒

ethanol

反応条件

後処理

1. 1
   温度was refluxed for 4 hours
2. 2
   その他to precipitate crystals
3. 3
   ろ過The crystals were collected by filtration
4. 4
   洗浄washed with ethanol
5. 5
   その他dried

実験手順

A solution of ethyl 2-methoxyimino-4-bromoacetoacetate (a mixture of syn and anti isomers) (17.4 g.) and thiourea (5.4 g.) in ethanol (100 ml.) was refluxed for 4 hours. The reaction mixture was allowed to stand in a refrigerator to precipitate crystals. The crystals were collected by filtration, washed with ethanol and dried to give ethyl 2-methoxyimino-2-(2-aminothiazol-4-yl)acetate hydrobromide (anti isomer) (9.5 g.). The filtrate and the washings were put together and concentrated under reduced pressure. Water (100 ml.) was added to the residue and the mixture was washed with ether. The aqueous layer was alkalized with a 28% aqueous solution of ammonia and extracted with ethyl acetate. The extract was washed with water and a saturated aqueous sodium chloride solution and dried over magnesium sulfate. The solvent was distilled off under reduced pressure to give crystalline substance of ethyl 2-methoxyimino-2-(2-aminothiazol-4-yl)acetate (syn isomer), which can be represented as ethyl 2-methoxyimino-2-(2-imino-2,3-dihydrothiazol-4-yl)acetate (syn isomer), (5.2 g.)

出典