Butanoic acid, 2-(hydroxyimino)-3-oxo-, 1,1-dimethylethyl ester, (Z)-

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:

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:-30.01; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: In 15 ml of acetonitrile was dissolved 1.07 g of tert-butyl 2-hydroxyimino-3-oxobutyrate, followed by addition of 2.8 ml of triethylamine. Then, 2.5 ml of chlorotrimethylsilane was added dropwise with ice-cooling and the mixture was stirred at 20°-25° C. for 1.5 hours, after which it was concentrated under reduced pressure. The residue was suspended in 15 ml of tetrahydrofuran and the suspension was filtered in a nitrogen gas stream to remove insolubles. This filtrate containing tert-butyl 2-trimethylsilyloxyimino-3-trimethylsilyloxy-3-butenoate was cooled to -30° C. and 0.46 ml of sulfuryl chloride was added dropwise. After the temperature of the system was increased to 20° C., the reaction mixture was concentrated under reduced pressure. The concentrate was chromatographed on a silica gel column and elution was carried out with 100 ml of hexane-ether (1:1, v/v). The eluate was concentrated under reduced pressure to give 1.08 g of tert-butyl 4-chloro-2-hydroxyimino-3-oxobutyrate. Yield 85.2%. cooling after which it was concentrated under reduced pressure the suspension was filtered in a nitrogen gas stream to remove insolubles This filtrate containing tert-butyl 2-trimethylsilyloxyimino-3-trimethylsilyloxy-3-butenoate 0.46 ml of sulfuryl chloride was added dropwise After the temperature of the system was increased to 20° C. the reaction mixture was concentrated under reduced pressure The concentrate was chromatographed on a silica gel column and elution The eluate was concentrated under reduced pressure

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

Procedure: To a suspension of tert-butyl 2-hydroxyimino-3-oxobutyrate (46.8 g) and potassium carbonate (51.8 g) in ethyl acetate (70 ml) and N,N-dimethylformamide (70 ml) was added 2,2,2-trichloroethyl chloroacetate (56.5 g), and the mixture was stirred at 45° to 48° C. for 3.5 hours. After the insoluble inorganic substance was filtered off, to the filtrate were added water and ethyl acetate. The separated ethyl acetate solution was washed with water and a saturated aqueous sodium chloride, followed by drying over magnesium sulfate. Removal of the solvent gave tert-butyl 2-(2,2,2-trichloroethoxycarbonylmethoxyimino)-3-oxobutyrate (84.9 g). After the insoluble inorganic substance was filtered off, to the filtrate were added water and ethyl acetate The separated ethyl acetate solution was washed with water by drying over magnesium sulfate Removal of the solvent

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

Procedure: To a suspension of tert-butyl 2-hydroxyimino-3-oxobutyrate (46.8 g) and potassium carbonate (51.8 g) in ethyl acetate (70 ml) and N,N-dimethylformamide (70 ml) was added 2,2,2-trichloroethyl chloroacetate (56.5 g), and the mixture was stirred at 45° to 48° C. for 3.5 hours. After the insoluble inorganic substance was filtered off, to the filtrate were added water and ethyl acetate. The separated ethyl acetate solution was washed with water and a saturated aqueous sodium chloride, followed by drying over magnesium sulfate. Removal of the solvent gave tert-butyl 2-(2,2,2-trichloroethoxycarbonylmethoxyimino)-3-oxobutyrate (84.9 g). After the insoluble inorganic substance was filtered off, to the filtrate were added water and ethyl acetate The separated ethyl acetate solution was washed with water by drying over magnesium sulfate Removal of the solvent

Conditions: temp:40.01; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: To a suspension of tert-butyl 2-hydroxyimino-3-oxobutyrate (56.4 g) and potassium carbonate (62.4 g) in ethyl acetate (300 ml) and N,N-dimethylformamide (60 ml) was added benzyl chloroacetate (60 g), and the mixture was stirred at 40° C. for 7 hours. The reaction mixture was poured into ice-water (1000 ml), and the separated organic layer was washed twice with a saturated aqueous solution of sodium chloride and then dried over magnesium sulfate. Removal of the solvent gave tert-butyl 2-benzyloxycarbonylmethoxyimino-3-oxobutyrate (96.3 g) as an oil. the separated organic layer was washed twice with a saturated aqueous solution of sodium chloride dried over magnesium sulfate Removal of the solvent