ethyl 4-bromo-2-methoxyimino-3-oxobutanoate

Conditions: temp:0.00; pressure:0.00; stir:

Conditions: temp:0.00; pressure:0.00; stir:

Conditions: temp:0.00; pressure:0.00; stir:

Conditions: temp:0.00; pressure:0.00; stir:

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: 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.) was refluxed for 4 hours to precipitate crystals The crystals were collected by filtration washed with ethanol dried

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: 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.) was refluxed for 4 hours to precipitate crystals The crystals were collected by filtration washed with ethanol dried

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: 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 and cooled in refrigerator to precipitate crystals. The crystals were collected by filtration, washed with ethanol and dried to give ethyl 2-methoxyimino-2-(2-amino-1,3-thiazol-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 sodium chloride aqueous solution and dried over magnesium sulfate. The solvent was distilled off under reduced pressure to give crystalline substance of ethyl 2-methoxyimino-2-(2-amino-1,3-thiazol-4-yl)acetate (syn isomer) (5.2 g.). was refluxed for 4 hours cooled in refrigerator to precipitate crystals The crystals were collected by filtration washed with ethanol dried

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: 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 and cooled in refrigerator to precipitate crystals. The crystals were collected by filtration, washed with ethanol and dried to give ethyl 2-methoxyimino-2-(2-amino-1,3-thiazol-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 sodium chloride aqueous solution and dried over magnesium sulfate. The solvent was distilled off under reduced pressure to give crystalline substance of ethyl 2-methoxyimino-2-(2-amino-1,3-thiazol-4-yl)acetate (syn isomer) (5.2 g.). was refluxed for 4 hours cooled in refrigerator to precipitate crystals The crystals were collected by filtration washed with ethanol dried

Conditions: temp:50.01; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: A mixture of ethyl 2-methoxyimino-4-bromoacetoacetate (a mixture of syn and anti isomers) (7.6 g.), O-ethyl thiocarbamate (3.0 g.) and dimethylacetamide (5 ml.) was stirred for 3 hours at 50° C. Ethyl acetate (50 ml.) was added to the reaction mixture and the resulting mixture was washed with water and with a saturated sodium chloride aqueous solution and dried over magnesium sulfate. Ethyl acetate was distilled off to give crystalline residue. The residue was washed with diisopropyl ether to give ethyl 2-methoxyimino-2-(2-oxo-2,3-dihydro-1,3-thiazol-4-yl)acetate (syn isomer) (2.35 g.). the resulting mixture was washed with water and with a saturated sodium chloride aqueous solution dried over magnesium sulfate Ethyl acetate was distilled off to give crystalline residue The residue was washed with diisopropyl ether

Conditions: temp:50.01; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: A mixture of ethyl 2-methoxyimino-4-bromoacetoacetate (a mixture of syn and anti isomers) (7.6 g.), O-ethyl thiocarbamate (3.0 g.) and dimethylacetamide (5 ml.) was stirred for 3 hours at 50° C. Ethyl acetate (50 ml.) was added to the reaction mixture and the resulting mixture was washed with water and with a saturated sodium chloride aqueous solution and dried over magnesium sulfate. Ethyl acetate was distilled off to give crystalline residue. The residue was washed with diisopropyl ether to give ethyl 2-methoxyimino-2-(2-oxo-2,3-dihydro-1,3-thiazol-4-yl)acetate (syn isomer) (2.35 g.). the resulting mixture was washed with water and with a saturated sodium chloride aqueous solution dried over magnesium sulfate Ethyl acetate was distilled off to give crystalline residue The residue was washed with diisopropyl ether

Conditions: temp:50.01; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: Thioacetamide (3.8 g.) was added to a solution of ethyl 2-methoxyimino-4-bromoacetoacetate (a mixture of syn and anti isomers) (12.6 g.) in ethanol (50 ml.) and the mixture was stirred for 5 hours at 50° C. Ethanol was distilled off under reduced pressure and water was added to the residue. The resulting mixture was extracted with ethyl acetate. The extract was in turn washed with water, a sodium bicarbonate aqueous solution and a saturated sodium chloride aqueous solution and dried over magnesium sulfate. The solvent was distilled off under reduced pressure to give ethyl 2-methoxyimino-2-(2-methyl-1,3-thiazol-4-yl)acetate (a mixture of syn and anti isomers) (9.0 g.). Ethanol was distilled off under reduced pressure and water was added to the residue The resulting mixture was extracted with ethyl acetate washed with water a sodium bicarbonate aqueous solution and a saturated sodium chloride aqueous solution and dried over magnesium sulfate The solvent was distilled off under reduced pressure

Conditions: temp:50.01; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: Thioacetamide (3.8 g.) was added to a solution of ethyl 2-methoxyimino-4-bromoacetoacetate (a mixture of syn and anti isomers) (12.6 g.) in ethanol (50 ml.) and the mixture was stirred for 5 hours at 50° C. Ethanol was distilled off under reduced pressure and water was added to the residue. The resulting mixture was extracted with ethyl acetate. The extract was in turn washed with water, a sodium bicarbonate aqueous solution and a saturated sodium chloride aqueous solution and dried over magnesium sulfate. The solvent was distilled off under reduced pressure to give ethyl 2-methoxyimino-2-(2-methyl-1,3-thiazol-4-yl)acetate (a mixture of syn and anti isomers) (9.0 g.). Ethanol was distilled off under reduced pressure and water was added to the residue The resulting mixture was extracted with ethyl acetate washed with water a sodium bicarbonate aqueous solution and a saturated sodium chloride aqueous solution and dried over magnesium sulfate The solvent was distilled off under reduced pressure