(2S)-3-cyclopentyl-2-[(2-methylpropan-2-yl)oxycarbonylamino]propanoic acid

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

Procedure: A mixture of 1.2 g (4.67 mmol) of N-(tert-butoxycarbonyl)-3-cyclopentyl-L-alanine, 540 mg (5 mmol) of benzylalcohol, 675 mg (5 mmol) of 1-hydroxybenzotriazole, 1.152 g (6 mmol) of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride and 0.031 g (0.25 mmol) of 4-dimethylaminopyridine was stirred in 20 ml of dichloromethane for 1 hour and then a further 610 mg (5 mmol) of 4-dimethylaminopyridine were added. After 4 hours the solution was extracted with 2M hydrochloric acid and saturated sodium bicarbonate solution, dried over anhydrous magnesium sulphate and evaporated. The oil obtained was chromatographed on silica gel using ethyl acetate/ petrol (1:6) for the elution to give 1.55 g of N-(tert-butoxycarbonyl)-3-cyclopentyl-L-alanine benzyl ester as a colourless oil; MS: m/e 348 [M+H]. After 4 hours the solution was extracted with 2M hydrochloric acid and saturated sodium bicarbonate solution dried over anhydrous magnesium sulphate evaporated The oil obtained was chromatographed on silica gel for the elution

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

Procedure: A mixture of 1.2 g (4.67 mmol) of N-(tert-butoxycarbonyl)-3-cyclopentyl-L-alanine, 540 mg (5 mmol) of benzyl alcohol, 675 mg (5 mmol) of 1-hydroxybenzotriazole, 1.152 g (6 mmol) of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride and 0.031 g (0.25 mmol) of 4-dimethylaminopyridine was stirred in 20 ml of dichloromethane for 1 hour and then a further 610 mg (5 mmol) of 4-dimethylaminopyridine were added. After 4 hours the solution was extracted with 2M hydrochloric acid and saturated sodium bicarbonate solution, dried over anhydrous magnesium sulphate and evaporated. The oil obtained was chromatographed on silica gel using ethyl acetate/ petrol (1:6) for the elution to give 1.55 g of N-(tert-butoxycarbonyl)-3-cyclopentyl-L-alanine benzyl ester as a colourless oil; MS: m/e 348 [M+H]. After 4 hours the solution was extracted with 2M hydrochloric acid and saturated sodium bicarbonate solution dried over anhydrous magnesium sulphate evaporated The oil obtained was chromatographed on silica gel for the elution

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

Procedure: A mixture of 1.2 g (4.67 mmol) of N-(tert-butoxycarbonyl)-3-cyclopentyl-L-alanine, 540 mg (5 mmol) of benzyl alcohol, 675 mg (5 mmol) of 1-hydroxybenzotriazole, 1.152 g (6 mmol) of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride and 0.031 g (0.25 mmol) of 4-dimethylaminopyridine was stirred in 20 ml of dichloromethane for 1 hour and then a further 610 mg (5 mmol) of 4-dimethylaminopyridine were added. After 4 hours the solution was extracted with 2M hydrochloric acid and saturated sodium bicarbonate solution, dried over anhydrous magnesium sulphate and evaporated. The oil obtained was chromatographed on silica gel using ethyl acetate/ petrol (1:6) for the elution to give 1.55 g of N-(tert-butoxycarbonyl)-3-cyclopentyl-L-alanine benzyl ester as a colourless oil; MS: m/e 348 [M+H]. After 4 hours the solution was extracted with 2M hydrochloric acid and saturated sodium bicarbonate solution dried over anhydrous magnesium sulphate evaporated The oil obtained was chromatographed on silica gel for the elution

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

Procedure: A mixture of 1.2 g (4.67 mmol) of N-(tert-butoxycarbonyl)-3-cyclopentyl-L-alanine, 540 mg (5 mmol) of benzylalcohol, 675 mg (5 mmol) of 1-hydroxybenzotriazole, 1.152 g (6 mmol) of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride and 0.031 g (0.25 mmol) of 4-dimethylaminopyridine was stirred in 20 ml of dichloromethane for 1 hour and then a further 610 mg (5 mmol) of 4-dimethylaminopyridine were added. After 4 hours the solution was extracted with 2M hydrochloric acid and saturated sodium bicarbonate solution, dried over anhydrous magnesium sulphate and evaporated. The oil obtained was chromatographed on silica gel using ethyl acetate/ petrol (1:6) for the elution to give 1.55 g of N-(tert-butoxycarbonyl)-3-cyclopentyl-L-alanine benzyl ester as a colourless oil; MS: m/e 348 [M+H]. After 4 hours the solution was extracted with 2M hydrochloric acid and saturated sodium bicarbonate solution dried over anhydrous magnesium sulphate evaporated The oil obtained was chromatographed on silica gel for the elution

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

Procedure: A mixture of 1.2 g (4.67 mmol) of N-(tert-butoxycarbonyl)-3-cyclopentyl-L-alanine, 540 mg (5 mmol) of benzylalcohol, 675 mg (5 mmol) of 1-hydroxybenzotriazole, 1.152 g (6 mmol) of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride and 0.031 g (0.25 mmol) of 4-dimethylaminopyridine was stirred in 20 ml of dichloromethane for 1 hour and then a further 610 mg (5 mmol) of 4-dimethylaminopyridine were added. After 4 hours the solution was extracted with 2M hydrochloric acid and saturated sodium bicarbonate solution, dried over anhydrous magnesium sulphate and evaporated. The oil obtained was chromatographed on silica gel using ethyl acetate/ petrol (1:6) for the elution to give 1.55 g of N-(tert-butoxycarbonyl)-3-cyclopentyl-L-alanine benzyl ester as a colourless oil; MS: m/e 348 [M+H]. After 4 hours the solution was extracted with 2M hydrochloric acid and saturated sodium bicarbonate solution dried over anhydrous magnesium sulphate evaporated The oil obtained was chromatographed on silica gel for the elution

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

Procedure: To a solution of (S)-2-(tert-butoxycarbonylamino)-3-cyclopentenylpropanoic acid (56 g, 0.22 mol) in methanol (500 mL) was added Pd/C (23 g, 0.022 mol, 10%). The mixture was stirred under a hydrogen atmosphere (1 atm) at ambient temperature overnight and then filtered through a pad of celite. The filtrate was concentrated under reduced pressure to afford (S)-2-(tert-butoxycarbonylamino)-3-cyclopentylpropanoic acid (55 g, 97% yield) as viscous oil, which was used in the next step without further purification. filtered through a pad of celite The filtrate was concentrated under reduced pressure

Conditions: temp:0.01; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: To a flask charged with compound (S)-2-((tert-butoxycarbonyl)amino)-3-cyclopentylpropanoic acid (55.0 g, 214 mmol) was added THF/DCM (800 mL, 1:1). The solution was cooled to 0° C. and ethyl chloroformate (24.5 mL, 257 mmol) and NMM (28.4 mL, 257 mmol) was added dropwise sequentially. After addition, the mixture was stirred at 0° C. under nitrogen for 1 h. To the other flask charged with N,O-dimethylhydroxylamine HCl (25.0 g, 257 mmol) was added DCM (400 mL). The mixture was cooled to 0° C. and TEA (38.7 mL, 278 mmol) was added. The resulting mixture was transferred into the former reaction flask. The reaction mixture was allowed to warm to ambient temperature and stirred overnight. The reaction was then quenched with water (500 mL) and the two phases were separated. The organic phase was washed with water (500 mL), dried over anhydrous sodium sulfate, and concentrated to afford (S)-tert-butyl (3-cyclopentyl-1-(methoxy(methyl)amino)-1-oxopropan-2-yl)carbamate as colorless oil (60 g, 93% yield), which was used in the next step without further purification. After addition The mixture was cooled to 0° C. to warm to ambient temperature stirred overnight The reaction was then quenched with water (500 mL) the two phases were separated The organic phase was washed with water (500 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 (S)-2-((tert-butoxycarbonyl)amino)-3-(cyclopent-1-en-1-yl)propanoic acid (56 g, 0.22 mol) in methanol (500 mL) was added Pd/C (23 g, 0.022 mol, 10%). The mixture was stirred under a hydrogen atmosphere (1 atm) at ambient temperature overnight and then filtered through a pad of celite. The filtrate was concentrated under reduced pressure to afford (S)-2-((tert-butoxycarbonyl)amino)-3-cyclopentylpropanoic acid (55 g, 97% yield) as viscous oil, which was used in the next step without further purification. filtered through a pad of celite The filtrate was concentrated under reduced pressure

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

Procedure: To a solution of (S)-2-(tert-butoxycarbonylamino)-3-cyclopentenylpropanoic acid (56 g, 0.22 mol) in methanol (500 mL) was added Pd/C (23 g, 0.022 mol, 10%). The mixture was stirred under a hydrogen atmosphere (1 atm) at ambient temperature overnight and then filtered through a pad of celite. The filtrate was concentrated under reduced pressure to afford (S)-2-(tert-butoxycarbonylamino)-3-cyclopentylpropanoic acid (55 g, 97% yield) as viscous oil, which was used in the next step without further purification. filtered through a pad of celite The filtrate was concentrated under reduced pressure

Conditions: temp:0.01; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: To a flask charged with compound (S)-2-((tert-butoxycarbonyl)amino)-3-cyclopentylpropanoic acid (55.0 g, 214 mmol) was added THF/DCM (800 mL, 1:1). The solution was cooled to 0° C. and ethyl chloroformate (24.5 mL, 257 mmol) and NMM (28.4 mL, 257 mmol) was added dropwise sequentially. After addition, the mixture was stirred at 0° C. under nitrogen for 1 h. To the other flask charged with N,O-dimethylhydroxylamine HCl (25.0 g, 257 mmol) was added DCM (400 mL). The mixture was cooled to 0° C. and TEA (38.7 mL, 278 mmol) was added. The resulting mixture was transferred into the former reaction flask. The reaction mixture was allowed to warm to ambient temperature and stirred overnight. The reaction was then quenched with water (500 mL) and the two phases were separated. The organic phase was washed with water (500 mL), dried over anhydrous sodium sulfate, and concentrated to afford (S)-tert-butyl (3-cyclopentyl-1-(methoxy(methyl)amino)-1-oxopropan-2-yl)carbamate as colorless oil (60 g, 93% yield), which was used in the next step without further purification. After addition The mixture was cooled to 0° C. to warm to ambient temperature stirred overnight The reaction was then quenched with water (500 mL) the two phases were separated The organic phase was washed with water (500 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 (S)-2-((tert-butoxycarbonyl)amino)-3-(cyclopent-1-en-1-yl)propanoic acid (56 g, 0.22 mol) in methanol (500 mL) was added Pd/C (23 g, 0.022 mol, 10%). The mixture was stirred under a hydrogen atmosphere (1 atm) at ambient temperature overnight and then filtered through a pad of celite. The filtrate was concentrated under reduced pressure to afford (S)-2-((tert-butoxycarbonyl)amino)-3-cyclopentylpropanoic acid (55 g, 97% yield) as viscous oil, which was used in the next step without further purification. filtered through a pad of celite The filtrate was concentrated under reduced pressure

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

Procedure: A mixture of 1.2 g (4.67 mmol) of N-(tert-butoxycarbonyl)-3-cyclopentyl-L-alanine, 540 mg (5 mmol) of benzyl alcohol, 675 mg (5 mmol) of 1-hydroxybenzotriazole, 1.152 g (6 mmol) of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride and 0.031 g (0.25 mmol) of 4-dimethylaminopyridine was stirred in 20 ml of dichloromethane for 1 hour and then a further 610 mg (5 mmol) of 4-dimethylaminopyridine were added. After 4 hours the solution was extracted with 2M hydrochloric acid and saturated sodium bicarbonate solution, dried over anhydrous magnesium sulphate and evaporated. The oil obtained was chromatographed on silica gel using ethyl acetate/ petrol (1:6) for the elution to give 1.55 g of N-(tert-butoxycarbonyl)-3-cyclopentyl-L-alanine benzyl ester as a colourless oil; MS: m/e 348 [M+H]. After 4 hours the solution was extracted with 2M hydrochloric acid and saturated sodium bicarbonate solution dried over anhydrous magnesium sulphate evaporated The oil obtained was chromatographed on silica gel for the elution