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Stage #1: With lithium hexamethyldisilazane In tetrahydrofuran at -20℃; for 0.333333 h; Stage #2: at -20℃; for 2 h;
To a SOLUTION OF TERT-BUTYL 2, 4-DIOXOPIPERIDINE-1-CARBOXYLATE (1.92 g, 9.0 MMOL), in dry THF (65 mL) and cooled TO-20°C under nitrogen, lithium bis (trimethylsilyl) amide (LIHMDS) (27 mL of 1 M solution in THF) was added dropwise. After 20 min stirring, 2.53 mL (4.9 g, 31.3 MMOL) of iodoethane were added and the solution was stirred at-20°C for 2 hours. The reaction mixture was poured in 5percent aq KHS04 and extracted with DCM (x2). The collected organic layers were washed with water, dried over NA2SO4 and evaporated to dryness. The residue was purified by column chromatography (N-HEXANE/ETOAC 1: 1) affording 1.4 G of target product (5.8 mmol, 64percent). ESI (+) MS: m/z 242 (MH+),
64%
Stage #1: With lithium hexamethyldisilazane In tetrahydrofuran at -20℃; for 0.333333 h; Stage #2: at -20℃; for 2 h;
Example 12 Preparation of ter-butyl 5-ETHYL-2, 4-DIOXOPIPERIDINE-1-CARBOXYLATE To a solution of tert-butyl 2, 4-dioxopiperidine-1-carboxylate (1.92 G, 9.0 MMOL), IN dry THF (65 mL) and cooled TO-20°C under nitrogen, lithium bis (trimethylsilyl) amide (LIHMDS) (27 mL of 1 M solution in THF) was added dropwise. After 20 min stirring, 2.53 mL (4. 9 g, 31.3 MMOL) of iodoethane were added and the solution was stirred AT-20°C for 2 hours. The reaction mixture was poured in 5percent aq KHS04 and extracted with DCM (x2). The collected organic layers were washed with water, dried over NA2SO4 and evaporated to dryness. The residue was purified by column chromatography (n-Hexane/EtOAc 1: 1) affording 1.4 G of target product (5.8 mmol, 64percent).
64%
Stage #1: With lithium hexamethyldisilazane In tetrahydrofuran at 20℃; for 0.333333 h; Stage #2: at -20℃; for 2 h; Stage #3: With potassium hydrogensulfate; water In tetrahydrofuran
EXAMPLE 13 Preparation of 5-ethylpiperidine-2,4-dione To a solution of tert-butyl 2,4-dioxopiperidine-1-carboxylate (1.92 g, 9.0 mmol), in dry THF (65 mL) and cooled to -20° C. under nitrogen, lithium bis(trimethylsilyl)amide (LiHMDS) (27 mL of 1 M solution in THF) was added dropwise. After 20 min stirring, 2.53 mL (4.9 g, 31.3 mmol) of iodoethane were added and the solution was stirred at -20° C. for 2 hours. The reaction mixture was poured in 5percent aq KHSO4 and extracted with DCM (*2). The collected organic layers were washed with water, dried over Na2SO4 and evaporated to dryness. The residue was purified by column chromatography (n-hexane/EtOAc 1:1) affording 1.4 g of 5-ethyl-2,4-dioxo-piperidine-1-carboxylic acid tert-butyl ester (5.8 mmol, 64percent); ESI (+) MS: m/z 242 (MH+).
To a SOLUTION OF TERT-BUTYL 2, 4-DIOXOPIPERIDINE-1-CARBOXYLATE (1.92 g, 9.0 MMOL), in dry THF (65 mL) and cooled TO-20C under nitrogen, lithium bis (trimethylsilyl) amide (LIHMDS) (27 mL of 1 M solution in THF) was added dropwise. After 20 min stirring, 2.53 mL (4.9 g, 31.3 MMOL) of iodoethane were added and the solution was stirred at-20C for 2 hours. The reaction mixture was poured in 5% aq KHS04 and extracted with DCM (x2). The collected organic layers were washed with water, dried over NA2SO4 and evaporated to dryness. The residue was purified by column chromatography (N-HEXANE/ETOAC 1: 1) affording 1.4 G of target product (5.8 mmol, 64%). ESI (+) MS: m/z 242 (MH+),
64%
Example 12 Preparation of ter-butyl 5-ETHYL-2, 4-DIOXOPIPERIDINE-1-CARBOXYLATE To a solution of tert-butyl 2, 4-dioxopiperidine-1-carboxylate (1.92 G, 9.0 MMOL), IN dry THF (65 mL) and cooled TO-20C under nitrogen, lithium bis (trimethylsilyl) amide (LIHMDS) (27 mL of 1 M solution in THF) was added dropwise. After 20 min stirring, 2.53 mL (4. 9 g, 31.3 MMOL) of iodoethane were added and the solution was stirred AT-20C for 2 hours. The reaction mixture was poured in 5% aq KHS04 and extracted with DCM (x2). The collected organic layers were washed with water, dried over NA2SO4 and evaporated to dryness. The residue was purified by column chromatography (n-Hexane/EtOAc 1: 1) affording 1.4 G of target product (5.8 mmol, 64%).
64%
EXAMPLE 13 Preparation of 5-ethylpiperidine-2,4-dione To a solution of tert-butyl 2,4-dioxopiperidine-1-carboxylate (1.92 g, 9.0 mmol), in dry THF (65 mL) and cooled to -20 C. under nitrogen, lithium bis(trimethylsilyl)amide (LiHMDS) (27 mL of 1 M solution in THF) was added dropwise. After 20 min stirring, 2.53 mL (4.9 g, 31.3 mmol) of iodoethane were added and the solution was stirred at -20 C. for 2 hours. The reaction mixture was poured in 5% aq KHSO4 and extracted with DCM (*2). The collected organic layers were washed with water, dried over Na2SO4 and evaporated to dryness. The residue was purified by column chromatography (n-hexane/EtOAc 1:1) affording 1.4 g of 5-ethyl-2,4-dioxo-piperidine-1-carboxylic acid tert-butyl ester (5.8 mmol, 64%); ESI (+) MS: m/z 242 (MH+).
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