ethyl 3-amino-2-hydroxybenzoate

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

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

Procedure: To a solution of 1-(benzyloxycarbonyl)azetidine-3-carboxylic acid (2.4 g) in dichloride methane (15 ml) was added 1-hydroxybenzotriazole (1.48 mg, 11 mmol), diisopropylethylamine (4 g, 30 mmol) and 1-ethly-3-(3-dimethylaminopropyl)carbodiimide hydrochloric (2 g, 11 mmol). The mixture was stirred at room temperature for 30 min. Then ethyl 3-amino-2-hydroxybenzoate (700 mg, 4 mmol) was added. The mixture was stirred at room temperature for 2 h. To the resulting mixture, water (10 ml) was added and hydrochloride acid (1N) to pH=3, then extracted with ethyl acetate (100 ml×4). The organic phase was washed with sodium bicarbonate (saturated) and brine and concentrated, dried with sodium sulfate. The crude was purified by column chromatography (silica gel, petroleum ether/ethyl acetate=20:1). 820 mg of benzyl 3-(2-hydroxy-3-(methoxycarbonyl)phenylcarbamoyl)azetidine-1-carboxylate was obtained. Yield 52%. LC-MS (ESI) m/z: 385 (M+1)+. The mixture was stirred at room temperature for 2 h hydrochloride acid (1N) to pH=3, then extracted with ethyl acetate (100 ml×4) The organic phase was washed with sodium bicarbonate (saturated) and brine concentrated dried with sodium sulfate The crude was purified by column chromatography (silica gel, petroleum ether/ethyl acetate=20:1)

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

Procedure: To a stirred solution of ethyl 3-amino-2-hydroxybenzoate (0.601 g, 3.6 mmol) and pyridine (0.633 g, 8 mmol) in anhydrous dichloromethane (20 mL) was added dropwise a solution of benzyl 2-(chlorocarbonyl)pyrrolidine-1-carboxylate (1.12 g, 4 mmol) in anhydrous dichloromethane (5 mL). After the addition, the mixture was stirred at room temperature overnight. The mixture was diluted with dichloromethane, washed with water (30 mL×3), 1N hydrochloric acid (30 mL×3), brine (30 mL), dried over anhydrous sodium sulfate, and concentrated to give benzyl 2-(2-hydroxy-3-(methoxycarbonyl)phenylcarbamoyl)pyrrolidine-1-carboxylate (1.43 g). LC-MS (ESI) m/z: 399 (M+1)+. After the addition washed with water (30 mL×3), 1N hydrochloric acid (30 mL×3), brine (30 mL) dried over anhydrous sodium sulfate concentrated

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

Procedure: To a solution of ethyl ester 3.6 g (20 mmol) of step 2 in dimethylformamide 30 mL was added K2CO3 5.5 g (40 mmol), followed by stirring at room temperature for 10 min. Dibromoethane 1.9 mL (22 mmol) was added dropwise to the reaction mixture which was then stirred for 3 hours under reflux. The reaction mixture was cooled to room temperature, concentrated in a vacuum, diluted with ethylacetate, and washed with a saturated sodium bicarbonate solution and a saturated NaCl solution. The resulting residue was dried over magnesium sulfate and concentrated in a vacuum to afford 3.7 g of the title compound (yield 89%). was then stirred for 3 hours under reflux The reaction mixture was cooled to room temperature concentrated in a vacuum diluted with ethylacetate washed with a saturated sodium bicarbonate solution The resulting residue was dried over magnesium sulfate concentrated in a vacuum

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

Procedure: To a solution of ethyl ester 3.6 g (20 mmol) of step 2 in dimethylformamide 30 mL was added K2CO3 5.5 g (40 mmol), followed by stirring at room temperature for 10 min. Dibromoethane 1.9 mL (22 mmol) was added dropwise to the reaction mixture which was then stirred for 3 hours under reflux. The reaction mixture was cooled to room temperature, concentrated in a vacuum, diluted with ethylacetate, and washed with a saturated sodium bicarbonate solution and a saturated NaCl solution. The resulting residue was dried over magnesium sulfate and concentrated in a vacuum to afford 3.7 g of the title compound (yield 89%). was then stirred for 3 hours under reflux The reaction mixture was cooled to room temperature concentrated in a vacuum diluted with ethylacetate washed with a saturated sodium bicarbonate solution The resulting residue was dried over magnesium sulfate concentrated in a vacuum

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

Procedure: To a solution of 2-hydroxy-3-nitrobenzoic acid ethyl ester 8.4 g (40 mmol) of step 1 in methanol 100 mL was added 5% Pd/C 0.84 g, after which the reactor was filled hydrogen gas, followed by stirring at room temperature for 5 hrs. Ammoniumformate 0.5 g was added to the reaction mixture before re-filling with hydrogen gas and re-stirring at room temperature for 24 hrs. The catalyst was removed by celite filtration, followed by vacuum concentration to afford the title compound 7.2 g (yield 99%). re-stirring at room temperature for 24 hrs The catalyst was removed by celite filtration followed by vacuum concentration

Conditions: temp:60.01; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: To a solution of ethyl 3-amino-2-hydroxybenzoate (500 mg), sodium hydrogen carbonate (927 mg) and benzyltributylammonium bromide (983 mg) in chloroform (10 ml) was added dropwise chloroacetyl chloride (374 mg) in chloroform (3 ml) under ice bath cooling. The reaction mixture was stirred at ambient temperature for 1 hour and at 60° C. for 2 hours. To the reaction mixture was added dropwise chloroacetyl chloride (312 mg) in chloroform (3 ml) under ice bath cooling and stirred at 60° C. for 2 hours. After the reaction mixture was concentrated in vacuo, the residue was diluted with chloroform and saturated sodium hydrogen carbonate aqueous solution. The organic layer was separated and washed with brine. The solution was dried over magnesium sulfate and concentrated in vacuo to give ethyl 2H-1,4-benzoxazin-3-one-8-carboxylate (460 mg). cooling cooling stirred at 60° C. for 2 hours After the reaction mixture was concentrated in vacuo the residue was diluted with chloroform and saturated sodium hydrogen carbonate aqueous solution The organic layer was separated washed with brine The solution was dried over magnesium sulfate concentrated in vacuo

Conditions: temp:60.01; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: To a solution of ethyl 3-amino-2-hydroxybenzoate (500 mg), sodium hydrogen carbonate (927 mg) and benzyltributylammonium bromide (983 mg) in chloroform (10 ml) was added dropwise chloroacetyl chloride (374 mg) in chloroform (3 ml) under ice bath cooling. The reaction mixture was stirred at ambient temperature for 1 hour and at 60° C. for 2 hours. To the reaction mixture was added dropwise chloroacetyl chloride (312 mg) in chloroform (3 ml) under ice bath cooling and stirred at 60° C. for 2 hours. After the reaction mixture was concentrated in vacuo, the residue was diluted with chloroform and saturated sodium hydrogen carbonate aqueous solution. The organic layer was separated and washed with brine. The solution was dried over magnesium sulfate and concentrated in vacuo to give ethyl 2H-1,4-benzoxazin-3-one-8-carboxylate (460 mg). cooling cooling stirred at 60° C. for 2 hours After the reaction mixture was concentrated in vacuo the residue was diluted with chloroform and saturated sodium hydrogen carbonate aqueous solution The organic layer was separated washed with brine The solution was dried over magnesium sulfate concentrated in vacuo

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

Procedure: To a solution of 1-(benzyloxycarbonyl)azetidine-3-carboxylic acid (2.4 g) in dichloride methane (15 ml) was added 1-hydroxybenzotriazole (1.48 mg, 11 mmol), diisopropylethylamine (4 g, 30 mmol) and 1-ethly-3-(3-dimethylaminopropyl)carbodiimide hydrochloric (2 g, 11 mmol). The mixture was stirred at room temperature for 30 min. Then ethyl 3-amino-2-hydroxybenzoate (700 mg, 4 mmol) was added. The mixture was stirred at room temperature for 2 h. To the resulting mixture, water (10 ml) was added and hydrochloride acid (1N) to pH=3, then extracted with ethyl acetate (100 ml×4). The organic phase was washed with sodium bicarbonate (saturated) and brine and concentrated, dried with sodium sulfate. The crude was purified by column chromatography (silica gel, petroleum ether/ethyl acetate=20:1). 820 mg of benzyl 3-(2-hydroxy-3-(methoxycarbonyl)phenylcarbamoyl)azetidine-1-carboxylate was obtained. Yield 52%. LC-MS (ESI) m/z: 385 (M+1)+. The mixture was stirred at room temperature for 2 h hydrochloride acid (1N) to pH=3, then extracted with ethyl acetate (100 ml×4) The organic phase was washed with sodium bicarbonate (saturated) and brine concentrated dried with sodium sulfate The crude was purified by column chromatography (silica gel, petroleum ether/ethyl acetate=20:1)

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

Procedure: To a solution of 1-(benzyloxycarbonyl)azetidine-3-carboxylic acid (2.4 g) in dichloride methane (15 ml) was added 1-hydroxybenzotriazole (1.48 mg, 11 mmol), diisopropylethylamine (4 g, 30 mmol) and 1-ethly-3-(3-dimethylaminopropyl)carbodiimide hydrochloric (2 g, 11 mmol). The mixture was stirred at room temperature for 30 min. Then ethyl 3-amino-2-hydroxybenzoate (700 mg, 4 mmol) was added. The mixture was stirred at room temperature for 2 h. To the resulting mixture, water (10 ml) was added and hydrochloride acid (1N) to pH=3, then extracted with ethyl acetate (100 ml×4). The organic phase was washed with sodium bicarbonate (saturated) and brine and concentrated, dried with sodium sulfate. The crude was purified by column chromatography (silica gel, petroleum ether/ethyl acetate=20:1). 820 mg of benzyl 3-(2-hydroxy-3-(methoxycarbonyl)phenylcarbamoyl)azetidine-1-carboxylate was obtained. Yield 52%. LC-MS (ESI) m/z: 385 (M+1)+. The mixture was stirred at room temperature for 2 h hydrochloride acid (1N) to pH=3, then extracted with ethyl acetate (100 ml×4) The organic phase was washed with sodium bicarbonate (saturated) and brine concentrated dried with sodium sulfate The crude was purified by column chromatography (silica gel, petroleum ether/ethyl acetate=20:1)

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

Procedure: To a stirred solution of ethyl 3-amino-2-hydroxybenzoate (0.601 g, 3.6 mmol) and pyridine (0.633 g, 8 mmol) in anhydrous dichloromethane (20 mL) was added dropwise a solution of benzyl 2-(chlorocarbonyl)pyrrolidine-1-carboxylate (1.12 g, 4 mmol) in anhydrous dichloromethane (5 mL). After the addition, the mixture was stirred at room temperature overnight. The mixture was diluted with dichloromethane, washed with water (30 mL×3), 1N hydrochloric acid (30 mL×3), brine (30 mL), dried over anhydrous sodium sulfate, and concentrated to give benzyl 2-(2-hydroxy-3-(methoxycarbonyl)phenylcarbamoyl)pyrrolidine-1-carboxylate (1.43 g). LC-MS (ESI) m/z: 399 (M+1)+. After the addition washed with water (30 mL×3), 1N hydrochloric acid (30 mL×3), brine (30 mL) dried over anhydrous sodium sulfate concentrated

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

Procedure: To a stirred solution of ethyl 3-amino-2-hydroxybenzoate (0.601 g, 3.6 mmol) and pyridine (0.633 g, 8 mmol) in anhydrous dichloromethane (20 mL) was added dropwise a solution of benzyl 2-(chlorocarbonyl)pyrrolidine-1-carboxylate (1.12 g, 4 mmol) in anhydrous dichloromethane (5 mL). After the addition, the mixture was stirred at room temperature overnight. The mixture was diluted with dichloromethane, washed with water (30 mL×3), 1N hydrochloric acid (30 mL×3), brine (30 mL), dried over anhydrous sodium sulfate, and concentrated to give benzyl 2-(2-hydroxy-3-(methoxycarbonyl)phenylcarbamoyl)pyrrolidine-1-carboxylate (1.43 g). LC-MS (ESI) m/z: 399 (M+1)+. After the addition washed with water (30 mL×3), 1N hydrochloric acid (30 mL×3), brine (30 mL) dried over anhydrous sodium sulfate concentrated