(3R)-3-[(2-methylpropan-2-yl)oxycarbonylamino]butanoic acid

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

Procedure: To a solution of (R)-3-tert-butoxycarbonylamino-butyric acid (150 mg, 0.74 mmol) and HATU (309 mg, 0.81 mmol) in DMF (2 mL) was added pyrrolidine (0.19 mL, 2.21 mmol). The resultant yellow reaction mixture was stirred at room temperature overnight then quenched with water and extracted with EtOAc (2×). The combined organics were washed with water (3×) and brine then dried over MgSO4 and concentrated to afford ((R)-1-methyl-3-oxo-3-pyrrolidin-1-yl-propyl)-carbamic acid tert-butyl ester as a colorless oil which was used without further purification. then quenched with water extracted with EtOAc (2×) The combined organics were washed with water (3×) and brine then dried over MgSO4 concentrated

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

Procedure: To a solution of (R)-3-tert-butoxycarbonylamino-butyric acid (150 mg, 0.74 mmol) and HATU (309 mg, 0.81 mmol) in DMF (2 mL) was added pyrrolidine (0.19 mL, 2.21 mmol). The resultant yellow reaction mixture was stirred at room temperature overnight then quenched with water and extracted with EtOAc (2×). The combined organics were washed with water (3×) and brine then dried over MgSO4 and concentrated to afford ((R)-1-methyl-3-oxo-3-pyrrolidin-1-yl-propyl)-carbamic acid tert-butyl ester as a colorless oil which was used without further purification. then quenched with water extracted with EtOAc (2×) The combined organics were washed with water (3×) and brine then dried over MgSO4 concentrated

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

Procedure: A solution of (3R)-3-[(tert-butoxycarbonyl)amino]butanoic acid (1 g, 5 mmol) in acetonitrile (40 mL) was treated with 1-[3-(dimethylamino)propyl]-3-ethylcarbodiimide hydrochloride (EDC; 1.05 g, 5.5 mmol), 1-hydroxybenzotriazole (HOBt; 810 mg, 6 mmol), N,O-dimethylhydroxylamine hydrochloride (1.0 g, 10 mmol) and triethylamine (1.4 mL) and stirred at room temperature for 2 d. The solution was evaporated and the residue purified by flash chromatography on a Biotage® system (silica gel, 40-90% ethyl acetate/hexane gradient) to yield the desired product as a colorless viscous oil. MS 269.1 (M+Na). The solution was evaporated the residue purified by flash chromatography on a Biotage® system (silica gel, 40-90% ethyl acetate/hexane gradient)

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

Procedure: A solution of (3R)-3-[(tert-butoxycarbonyl)amino]butanoic acid (1 g, 5 mmol) in acetonitrile (40 mL) was treated with 1-[3-(dimethylamino)propyl]-3-ethylcarbodiimide hydrochloride (EDC; 1.05 g, 5.5 mmol), 1-hydroxybenzotriazole (HOBt; 810 mg, 6 mmol), N,O-dimethylhydroxylamine hydrochloride (1.0 g, 10 mmol) and triethylamine (1.4 mL) and stirred at room temperature for 2 d. The solution was evaporated and the residue purified by flash chromatography on a Biotage® system (silica gel, 40-90% ethyl acetate/hexane gradient) to yield the desired product as a colorless viscous oil. MS 269.1 (M+Na). The solution was evaporated the residue purified by flash chromatography on a Biotage® system (silica gel, 40-90% ethyl acetate/hexane gradient)

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

Procedure: To a solution of (R)-3-(tert-butoxycarbonylamino)butanoic acid (4.30 g, 21.16 mmol) in DMF (20 mL) and DCM (20.00 mL) was added EDC (4.46 g, 23.27 mmol) and HOBt (4.21 g, 27.5 mmol). The mixture was stirred at rt for 15 min, then N,O-dimethylhydroxylamine hydrochloride (3.10 g, 31.7 mmol) was added, followed by TEA (5.90 mL, 42.3 mmol) dropwise. The resulting light yellow suspension was stirred at rt for 7 hr. The reaction was quenched with addition of water (100 mL). The mixture was extracted with EtOAc (2×). The combined EtOAc extracts were washed with water (2×), 0.3 M aqueous KHSO4, saturated aqueous NaHCO3 (2×), saturated aqueous NaCl (2×), dried over Na2SO4, filtered and concentrated to give (R)-tert-butyl 4-(methoxy(methyl)amino)-4-oxobutan-2-ylcarbamate (2.48 g, 10.1 mmol, 47.6% yield) as a pale yellow solid. 1H NMR (400 MHz, CDCl3) δ ppm 5.32 (s, 1H), 4.14-3.96 (m, 1H), 3.68 (s, 3H), 3.18 (s, 3H), 2.71 (dd, J=15.6, 4.6 Hz, 1H), 2.61-2.49 (m, 1H), 1.41 (d, J=17.2 Hz, 9H), 1.24 (d, J=6.7 Hz, 3H). The resulting light yellow suspension was stirred at rt for 7 hr The reaction was quenched with addition of water (100 mL) The mixture was extracted with EtOAc (2×) The combined EtOAc extracts were washed with water (2×), 0.3 M aqueous KHSO4, saturated aqueous NaHCO3 (2×), saturated aqueous NaCl (2×) dried over Na2SO4 filtered concentrated

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

Procedure: To a stirred suspension of (R)-3-aminobutanoic acid (2.415 g, 23.42 mmol) in dioxane (15 mL) and water (15.00 mL) was added TEA (4.90 mL, 35.1 mmol) dropwise. To the resulting light brown solution cooled at 0° C. was added portionwise di-tert-butyl carbonate (4.69 g, 26.9 mmol). The mixture was then stirred at rt for 16 hr. The reaction mixture was partitioned between water (80 mL) and EtOAc (80 mL). The separated aqueous layer was washed with EtOAc and acidified with 1 M aqueous KHSO4 to pH=3 and extracted with EtOAc (2×). The combined EtOAc extracts were washed with saturated aqueous NaCl (2×), dried over Na2SO4, filtered and concentrated to give (R)-3-(tert-butoxycarbonylamino)butanoic acid (4.301 g, 21.16 mmol, 90% yield) as a pale yellow solid. 1H NMR (400 MHz, CDCl3) δ ppm 4.92 (s, 1H), 4.14-3.96 (m, 2H), 2.56 (d, J=5.2 Hz, 2H), 1.45 (s, 9H), 1.25 (d, J=6.9 Hz, 3H). The reaction mixture was partitioned between water (80 mL) and EtOAc (80 mL) The separated aqueous layer was washed with EtOAc extracted with EtOAc (2×) The combined EtOAc extracts were washed with saturated aqueous NaCl (2×) dried over Na2SO4 filtered concentrated

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

Procedure: To a stirred suspension of (R)-3-aminobutanoic acid (2.415 g, 23.42 mmol) in dioxane (15 mL) and water (15.00 mL) was added TEA (4.90 mL, 35.1 mmol) dropwise. To the resulting light brown solution cooled at 0° C. was added portionwise di-tert-butyl carbonate (4.69 g, 26.9 mmol). The mixture was then stirred at rt for 16 hr. The reaction mixture was partitioned between water (80 mL) and EtOAc (80 mL). The separated aqueous layer was washed with EtOAc and acidified with 1 M aqueous KHSO4 to pH=3 and extracted with EtOAc (2×). The combined EtOAc extracts were washed with saturated aqueous NaCl (2×), dried over Na2SO4, filtered and concentrated to give (R)-3-(tert-butoxycarbonylamino)butanoic acid (4.301 g, 21.16 mmol, 90% yield) as a pale yellow solid. 1H NMR (400 MHz, CDCl3) δ ppm 4.92 (s, 1H), 4.14-3.96 (m, 2H), 2.56 (d, J=5.2 Hz, 2H), 1.45 (s, 9H), 1.25 (d, J=6.9 Hz, 3H). The reaction mixture was partitioned between water (80 mL) and EtOAc (80 mL) The separated aqueous layer was washed with EtOAc extracted with EtOAc (2×) The combined EtOAc extracts were washed with saturated aqueous NaCl (2×) dried over Na2SO4 filtered concentrated

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

Procedure: To a solution of (R)-3-tert-butoxycarbonylamino-butyric acid (150 mg, 0.74 mmol) and HATU (309 mg, 0.81 mmol) in DMF (2 mL) was added pyrrolidine (0.19 mL, 2.21 mmol). The resultant yellow reaction mixture was stirred at room temperature overnight then quenched with water and extracted with EtOAc (2×). The combined organics were washed with water (3×) and brine then dried over MgSO4 and concentrated to afford ((R)-1-methyl-3-oxo-3-pyrrolidin-1-yl-propyl)-carbamic acid tert-butyl ester as a colorless oil which was used without further purification. then quenched with water extracted with EtOAc (2×) The combined organics were washed with water (3×) and brine then dried over MgSO4 concentrated

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

Procedure: tert-Butyl(R)-4-((S)-4-(4-chlorophenyl)-4-hydroxy-3,3-dimethylpiperidin-1-yl)-4-oxobutan-2-ylcarbamate was prepared from (S)-4-(4-chlorophenyl)-3,3-dimethylpiperidin-4-ol and Boc-D-beta-homoalanine using the conditions described in Example 1, Step 2. MS (ESI+)=425.1 (M+H)+.

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

Procedure: A solution of (3R)-3-[(tert-butoxycarbonyl)amino]butanoic acid (1 g, 5 mmol) in acetonitrile (40 mL) was treated with 1-[3-(dimethylamino)propyl]-3-ethylcarbodiimide hydrochloride (EDC; 1.05 g, 5.5 mmol), 1-hydroxybenzotriazole (HOBt; 810 mg, 6 mmol), N,O-dimethylhydroxylamine hydrochloride (1.0 g, 10 mmol) and triethylamine (1.4 mL) and stirred at room temperature for 2 d. The solution was evaporated and the residue purified by flash chromatography on a Biotage® system (silica gel, 40-90% ethyl acetate/hexane gradient) to yield the desired product as a colorless viscous oil. MS 269.1 (M+Na). The solution was evaporated the residue purified by flash chromatography on a Biotage® system (silica gel, 40-90% ethyl acetate/hexane gradient)

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

Procedure: To a solution of (R)-3-(tert-butoxycarbonylamino)butanoic acid (4.30 g, 21.16 mmol) in DMF (20 mL) and DCM (20.00 mL) was added EDC (4.46 g, 23.27 mmol) and HOBt (4.21 g, 27.5 mmol). The mixture was stirred at rt for 15 min, then N,O-dimethylhydroxylamine hydrochloride (3.10 g, 31.7 mmol) was added, followed by TEA (5.90 mL, 42.3 mmol) dropwise. The resulting light yellow suspension was stirred at rt for 7 hr. The reaction was quenched with addition of water (100 mL). The mixture was extracted with EtOAc (2×). The combined EtOAc extracts were washed with water (2×), 0.3 M aqueous KHSO4, saturated aqueous NaHCO3 (2×), saturated aqueous NaCl (2×), dried over Na2SO4, filtered and concentrated to give (R)-tert-butyl 4-(methoxy(methyl)amino)-4-oxobutan-2-ylcarbamate (2.48 g, 10.1 mmol, 47.6% yield) as a pale yellow solid. 1H NMR (400 MHz, CDCl3) δ ppm 5.32 (s, 1H), 4.14-3.96 (m, 1H), 3.68 (s, 3H), 3.18 (s, 3H), 2.71 (dd, J=15.6, 4.6 Hz, 1H), 2.61-2.49 (m, 1H), 1.41 (d, J=17.2 Hz, 9H), 1.24 (d, J=6.7 Hz, 3H). The resulting light yellow suspension was stirred at rt for 7 hr The reaction was quenched with addition of water (100 mL) The mixture was extracted with EtOAc (2×) The combined EtOAc extracts were washed with water (2×), 0.3 M aqueous KHSO4, saturated aqueous NaHCO3 (2×), saturated aqueous NaCl (2×) dried over Na2SO4 filtered concentrated

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

Procedure: To a stirred suspension of (R)-3-aminobutanoic acid (2.415 g, 23.42 mmol) in dioxane (15 mL) and water (15.00 mL) was added TEA (4.90 mL, 35.1 mmol) dropwise. To the resulting light brown solution cooled at 0° C. was added portionwise di-tert-butyl carbonate (4.69 g, 26.9 mmol). The mixture was then stirred at rt for 16 hr. The reaction mixture was partitioned between water (80 mL) and EtOAc (80 mL). The separated aqueous layer was washed with EtOAc and acidified with 1 M aqueous KHSO4 to pH=3 and extracted with EtOAc (2×). The combined EtOAc extracts were washed with saturated aqueous NaCl (2×), dried over Na2SO4, filtered and concentrated to give (R)-3-(tert-butoxycarbonylamino)butanoic acid (4.301 g, 21.16 mmol, 90% yield) as a pale yellow solid. 1H NMR (400 MHz, CDCl3) δ ppm 4.92 (s, 1H), 4.14-3.96 (m, 2H), 2.56 (d, J=5.2 Hz, 2H), 1.45 (s, 9H), 1.25 (d, J=6.9 Hz, 3H). The reaction mixture was partitioned between water (80 mL) and EtOAc (80 mL) The separated aqueous layer was washed with EtOAc extracted with EtOAc (2×) The combined EtOAc extracts were washed with saturated aqueous NaCl (2×) dried over Na2SO4 filtered concentrated