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

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

Procedure: L-Cysteine methyl ester hydrochloride was acylated with N-(tert-butoxycarbonyl)-D-serine by using in an analogous manner the procedure described in Example 1(e) to yield N-[N-(tert-butoxycarbonyl)-D-seryl]-L-cysteine methyl ester as white crystals of m.p. 105°-106° C.

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

Procedure: To a stirred solution of N-t-butoxycarbonyl-D-serine (10.0 g, 48.7 mol) in N,N-dimethylformamide (150 mL) at about 0° C. was added sodium hydride (4.0 g, 60% dispersion in mineral oil, 99.84 mmol) portionwise. The mixture was stirred for about 30 minutes, and then a solution of 1,3-dichloro-5-chloromethyl-benzene (9.5 mL, 48.7 mmol) in ethyl ether (40 mL) was added. The reaction was allowed to slowly warm to room temperature overnight. The reaction was then quenched with 1N NaOH, the mixture extracted three times with dichloromethane. The combined organic layers were then washed three times with water, 1N, HCl, dried over anhydrous magnesium sulfate, filtered and concentrated in vacuo to give crude product. The original basic aqueous layer was then acidified to about pH 4 with HCl, and the mixture was extracted three times with dichloromethane. These three organic layers were combined and washed three times each with water and brine then dried over anhydrous magnesium sulfate, filtered and concentrated in vacuo to give an additional 620 mg of crude product. Both product fractions were combined and purified by silica gel chromatography using 5% methanol/chloroform as eluent and yielded the title compound of part 1-E (12.39 g, 70%): −APcl MS (M−1)− 363, (M−3)− 361; 1H NMR=400 MHz (CDCl3) δ: 7.13 (arom, s, 3H), 5.42 (NH, d, 1H), 4.50 (CHCO2H, m, 1H), 4.45 (PhCH2O, s, 2H), 3.82 (CH2OBz, d of d, 2H), 1.43 (BOC, s, 9H). The reaction was then quenched with 1N NaOH the mixture extracted three times with dichloromethane The combined organic layers were then washed three times with water, 1N, HCl dried over anhydrous magnesium sulfate filtered concentrated in vacuo to give crude product the mixture was extracted three times with dichloromethane washed three times each with water and brine then dried over anhydrous magnesium sulfate filtered concentrated in vacuo to give an additional 620 mg of crude product purified by silica gel chromatography

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

Procedure: D-serine (25 g, 238 mmol) and triethylamine (35 mL, 250 mmol) were dissolved in water (400 mL), and Boc2O (50 g, 230 mmol) was added thereto and stirred at room temperature for 20 hours. The reaction mixture was washed with ethyl acetate (200 mL×2). The aqueous layer was acidified with 2 mol/L HCl to pH 2 and extracted with ethyl acetate (200 mL×5). The organic extract was dried over sodium sulfate anhydride. Sodium sulfate was filtered off and the solvent was removed by evaporation under reduced pressure to give Boc-D-Ser (44.4 g, 91%) as a colorless oil. Resulting Boc-D-Ser (44.4 g, 216 mmol) was dissolved in DMF (500 mL) and the mixture was cooled in an ice bath to 0° C. and then, NaH (18.4 g, 460 mmol) was added thereto in several portions. The mixture was stirred at 0° C. for 2 hours, and a solution of 3,5-bis(trifluoromethyl)benzyl bromide (42 mL, 230 mmol) in DMF (100 mL) was added dropwise thereto for a period of 30 min. After stirring at 0° C. for 2 hours and at room temperature for 20 hours, the reaction was stopped by adding water (1 L) thereto. The mixture was washed with hexane (250 mL×2) and acidified with 2 mol/L HCl to pH 2. After extracting with ethyl acetate (250 mL×4), the organic extract was washed with water and saturated brine in order and dried over sodium sulfate anhydride. Sodium sulfate was filtered off and the solvent was removed by evaporation under reduced pressure to give (2R)-3-(3,5-bis(trifluoromethyl)benzyloxy)-2-tert-butoxycarbonylaminopropionic acid (76.6 g, 82%) as a pale brown oil. for a period of 30 min After stirring at 0° C. for 2 hours and at room temperature for 20 hours The mixture was washed with hexane (250 mL×2) After extracting with ethyl acetate (250 mL×4) the organic extract was washed with water and saturated brine in order dried over sodium sulfate anhydride Sodium sulfate was filtered off the solvent was removed by evaporation under reduced pressure

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

Procedure: D-serine (25 g, 238 mmol) and triethylamine (35 mL, 250 mmol) were dissolved in water (400 mL), and Boc2O (50 g, 230 mmol) was added thereto and stirred at room temperature for 20 hours. The reaction mixture was washed with ethyl acetate (200 mL×2). The aqueous layer was acidified with 2 mol/L HCl to pH 2 and extracted with ethyl acetate (200 mL×5). The organic extract was dried over sodium sulfate anhydride. Sodium sulfate was filtered off and the solvent was removed by evaporation under reduced pressure to give Boc-D-Ser (44.4 g, 91%) as a colorless oil. Resulting Boc-D-Ser (44.4 g, 216 mmol) was dissolved in DMF (500 mL) and the mixture was cooled in an ice bath to 0° C. and then, NaH (18.4 g, 460 mmol) was added thereto in several portions. The mixture was stirred at 0° C. for 2 hours, and a solution of 3,5-bis(trifluoromethyl)benzyl bromide (42 mL, 230 mmol) in DMF (100 mL) was added dropwise thereto for a period of 30 min. After stirring at 0° C. for 2 hours and at room temperature for 20 hours, the reaction was stopped by adding water (1 L) thereto. The mixture was washed with hexane (250 mL×2) and acidified with 2 mol/L HCl to pH 2. After extracting with ethyl acetate (250 mL×4), the organic extract was washed with water and saturated brine in order and dried over sodium sulfate anhydride. Sodium sulfate was filtered off and the solvent was removed by evaporation under reduced pressure to give (2R)-3-(3,5-bis(trifluoromethyl)benzyloxy)-2-tert-butoxycarbonylaminopropionic acid (76.6 g, 82%) as a pale brown oil. for a period of 30 min After stirring at 0° C. for 2 hours and at room temperature for 20 hours The mixture was washed with hexane (250 mL×2) After extracting with ethyl acetate (250 mL×4) the organic extract was washed with water and saturated brine in order dried over sodium sulfate anhydride Sodium sulfate was filtered off the solvent was removed by evaporation under reduced pressure

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

Procedure: To a stirred solution of N-t-butoxycarbonyl-D-serine (10.0 g, 48.7 mol) in N,N-dimethylformamide (150 mL) at about 0° C. was added sodium hydride (4.0 g, 60% dispersion in mineral oil, 99.84 mmol) portionwise. The mixture was stirred for about 30 minutes, and then a solution of 1,3-dichloro-5-chloromethyl-benzene (9.5 mL, 48.7 mmol) in ethyl ether (40 mL) was added. The reaction was allowed to slowly warm to room temperature overnight. The reaction was then quenched with 1N NaOH, the mixture extracted three times with dichloromethane. The combined organic layers were then washed three times with water, 1N, HCl, dried over anhydrous magnesium sulfate, filtered and concentrated in vacuo to give crude product. The original basic aqueous layer was then acidified to about pH 4 with 1N HCl, and the mixture was extracted three times with dichloromethane. These three organic layers were combined and washed three times each with water and brine then dried over anhydrous magnesium sulfate, filtered and concentrated in vacuo to give an additional 620 mg of crude product. Both product fractions were combined and purified by silica gel chromatography using 5% methanol/chloroform as eluent and yielded the title compound of part 1-E (12.39 g, 70%): −APcl MS (M−1)− 363, (M−3)− 361; 1H NMR=400 MHz (CDCl3) δ: 7.13 (arom, s, 3H), 5.42 (NH, d, 1H), 4.50 (CHCO2H, m, 1H), 4.45 (PhCH2O, s, 2H), 3.82 (CH2OBz, d of d, 2H), 1.43 (BOC, s, 9H). The reaction was then quenched with 1N NaOH the mixture extracted three times with dichloromethane The combined organic layers were then washed three times with water, 1N, HCl dried over anhydrous magnesium sulfate filtered concentrated in vacuo to give crude product the mixture was extracted three times with dichloromethane washed three times each with water and brine then dried over anhydrous magnesium sulfate filtered concentrated in vacuo to give an additional 620 mg of crude product purified by silica gel chromatography

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

Procedure: To a solution of N-Boc-(D)-serine (452 9, 2.2026 mol) in a mixture of THF (7 L) and DMF (3 L) at about 0° C. was added potassium tert-butoxide solution (515.8 g, 4.5963 mol). The reaction mixture was stirred at about 0° C. for about 30 min., then 2,4-difluorobenzyl bromide (456.5 g, 2.2051 mol) was added. After warming to room temperature, the reaction mixture was concentrated in vacua to remove the THF. Partitioned the reaction mixture between 4.5 L H2O and 4.5 L IPE. Separated the layers and adjusted the pH of the aqueous layer with 1 N HCl to about 3. The aqueous layer was extracted twice with 4 L each of IPE. The organic solution was dried over Na2SO4, and concentrated in vacuo to yield a yellow waxy solid (518.0 g, yield: 70.9 %). 1H-NMR (CDCl3) δ1.44 (s, 9H), 3.73 (m, 1H), 3.94 (d, 1H), 4.44 (br s, 1H), 4.54 (s, 2H), 5.34 (m, 1H), 6.78 (m, 1H), 6.84 (m, 1H), 7.30 (m, 1H). After warming to room temperature the reaction mixture was concentrated in vacua to remove the THF Partitioned the reaction mixture between 4.5 L H2O and 4.5 L IPE Separated the layers The aqueous layer was extracted twice with 4 L each of IPE The organic solution was dried over Na2SO4 concentrated in vacuo

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

Procedure: To a stirred solution of N-t-butoxycarbonyl-D-serine (10.0 g, 48.7 mol) in N,N-dimethylformamide (150 mL) at about 0 ° C. was added sodium hydride (4.0 g, 60% dispersion in mineral oil, 99.84 mmol) portionwise. The mixture was stirred for about 30 minutes, and then a solution of 1,3-dichloro-5-chloromethyl-benzene (9.5 mL, 48.7 mmol) in ethyl ether (40 mL) was added. The reaction was allowed to slowly warm to room temperature overnight. The reaction was then quenched with 1N NaOH, the mixture extracted three times with dichloromethane. The combined organic layers were then washed three times with water, 1N HCl, dried over anhydrous magnesium sulfate, filtered and concentrated in vacuo to give crude product. The original basic aqueous layer was then acidified to about pH 4 with 1N HCl, and the mixture was extracted three times with dichloromethane. These three organic layers were combined and washed three times each with water and brine then dried over anhydrous magnesium sulfate, filtered and concentrated in vacuo to give an additional 620 mg of crude product. Both product fractions were combined and purified by silica gel chromatography using 5% methanol/chloroform as eluent and yielded the title compound of part 1-E (12.39 g, 70%): −APcl MS (M−1)− 363, (M−3)− 361; 1H NMR=400 MHz (CDCl3) 67 : 7.13 (arom, s, 3H), 5.42 (NH, d, 1H), 4.50 (CHCO2H, m, 1H), 4.45 (PhCH2O, s, 2H), 3.82 (CH2OBz, d of d, 2H), 1.43 (BOC, s, 9H). The reaction was then quenched with 1N NaOH the mixture extracted three times with dichloromethane The combined organic layers were then washed three times with water, 1N HCl dried over anhydrous magnesium sulfate filtered concentrated in vacuo to give crude product the mixture was extracted three times with dichloromethane washed three times each with water and brine then dried over anhydrous magnesium sulfate filtered concentrated in vacuo to give an additional 620 mg of crude product purified by silica gel chromatography

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

Procedure: To a stirred solution of N-t-butoxycarbonyl-D-serine (10.0 g, 48.7 mol) in N,N-dimethylformamide (150 mL) at about 0 ° C. was added sodium hydride (4.0 g, 60% dispersion in mineral oil, 99.84 mmol) portionwise. The mixture was stirred for about 30 minutes, and then a solution of 1,3-dichloro-5-chloromethyl-benzene (9.5 mL, 48.7 mmol) in ethyl ether (40 mL) was added. The reaction was allowed to slowly warm to room temperature overnight. The reaction was then quenched with 1N NaOH, the mixture extracted three times with dichloromethane. The combined organic layers were then washed three times with water, 1N HCl, dried over anhydrous magnesium sulfate, filtered and concentrated in vacuo to give crude product. The original basic aqueous layer was then acidified to about pH 4 with 1N HCl, and the mixture was extracted three times with dichloromethane. These three organic layers were combined and washed three times each with water and brine then dried over anhydrous magnesium sulfate, filtered and concentrated in vacuo to give an additional 620 mg of crude product. Both product fractions were combined and purified by silica gel chromatography using 5% methanol/chloroform as eluent and yielded the title compound of part 1-E (12.39 g, 70%): −APcl MS (M−1)− 363, (M−3)− 361; 1H NMR=400 MHz (CDCl3) 67 : 7.13 (arom, s, 3H), 5.42 (NH, d, 1H), 4.50 (CHCO2H, m, 1H), 4.45 (PhCH2O, s, 2H), 3.82 (CH2OBz, d of d, 2H), 1.43 (BOC, s, 9H). The reaction was then quenched with 1N NaOH the mixture extracted three times with dichloromethane The combined organic layers were then washed three times with water, 1N HCl dried over anhydrous magnesium sulfate filtered concentrated in vacuo to give crude product the mixture was extracted three times with dichloromethane washed three times each with water and brine then dried over anhydrous magnesium sulfate filtered concentrated in vacuo to give an additional 620 mg of crude product purified by silica gel chromatography

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

Procedure: A solution of N—BOC-D-serine (2.00 g, 9.75 mmol) in DMF (25 ml) was cooled to 0° C. under nitrogen atmosphere and sodium hydride (60% in mineral oil) (0.82 g, 20.47 mmol) was added portionwise over 15 minutes. After stirring at 0° C. for 30 minutes, 4-fluorobenzyl bromide (1.82 g, 9.75 mmol) in DMF (5 ml) was added. The ice bath was removed and the reaction mixture was stirred at room temperature overnight. The reaction mixture was partitioned between EtOAc (100 ml) and water (50 ml). The aqueous phase was separated and washed with DCM (2×50 ml). The organic washings were discarded. The aqueous layer was acidified with 5% citric acid aqueous solution and back-extracted with DCM (2×100 ml). The combined organic portions were washed with brine (50 ml), dried (MgSO4) and concentrated in vacuo to yield the title compound as pale yellow oil. The ice bath was removed the reaction mixture was stirred at room temperature overnight The reaction mixture was partitioned between EtOAc (100 ml) and water (50 ml) The aqueous phase was separated washed with DCM (2×50 ml) back-extracted with DCM (2×100 ml) The combined organic portions were washed with brine (50 ml) dried (MgSO4) concentrated in vacuo

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

Procedure: A solution of N—BOC-D-serine (2.00 g, 9.75 mmol) in DMF (25 ml) was cooled to 0° C. under nitrogen atmosphere and sodium hydride (60% in mineral oil) (0.82 g, 20.47 mmol) was added portionwise over 15 minutes. After stirring at 0° C. for 30 minutes, 4-fluorobenzyl bromide (1.82 g, 9.75 mmol) in DMF (5 ml) was added. The ice bath was removed and the reaction mixture was stirred at room temperature overnight. The reaction mixture was partitioned between EtOAc (100 ml) and water (50 ml). The aqueous phase was separated and washed with DCM (2×50 ml). The organic washings were discarded. The aqueous layer was acidified with 5% citric acid aqueous solution and back-extracted with DCM (2×100 ml). The combined organic portions were washed with brine (50 ml), dried (MgSO4) and concentrated in vacuo to yield the title compound as pale yellow oil. The ice bath was removed the reaction mixture was stirred at room temperature overnight The reaction mixture was partitioned between EtOAc (100 ml) and water (50 ml) The aqueous phase was separated washed with DCM (2×50 ml) back-extracted with DCM (2×100 ml) The combined organic portions were washed with brine (50 ml) dried (MgSO4) concentrated in vacuo

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

Procedure: To an ice-cooled solution of N-BOC-D-serine (10 g, 48.7 mmol) in methylene chloride (50 ml) was added N,N′-diisopropyl-O-tert-butylisourea (35 ml, 3.5 M) via addition funnel, over 30 min. The reaction mixture was maintained at 0° C. for 2 hrs and then warmed to room temperature over night. The material was again cooled to 0° C. and a second portion of N,N′-diisopropyl-O-tert-butylisourea (28 ml, 3.5 M) was added. The material was stirred for 2 hrs at 0° C. and then warmed again to room temperature over night. Purification by flash silica gel chromatography using (20%) ethyl acetate/hexanes as eluant gave O-tert-butyl-N-BOC-D-serine (7.97 g) as a viscous oil which solidified on standing. via addition funnel warmed to room temperature over night The material was again cooled to 0° C. warmed again to room temperature over night Purification by flash silica gel chromatography

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

Procedure: To a solution of N-Boc-(D)-serine (452 g, 2.2026 mol) in a mixture of THF (7 L) and DMF (3 L) at about 0° C. was added potassium tert-butoxide solution (515.8 g, 4.5963 mol). The reaction mixture was stirred at about 0° C. for about 30 min., then 2,4-difluorobenzyl bromide (456.5 g, 2.2051 mol) was added. After warming to room temperature, the reaction mixture was concentrated in vacuo to remove the THF. The reaction mixture was partitioned between 4.5 L H2O and 4.5 L IPE. The layers were saparated and the pH of the aqueous layer was adjusted with 1 N HCl to about 3. The aqueous layer was extracted twice with 4 L each of IPE. The organic solution was dried over Na2SO4, and concentrated in vacuo to yield a yellow waxy solid (518.0 g, yield: 70.9%). 1H-NMR (CDCl3) δ 1.44 (s, 9H), 3.73 (m, 1H), 3.94 (d, 1H), 4.44 (br s, 1H), 4.54 (s, 2H), 5.34 (m, 1H), 6.78 (m, 1H), 6.84 (m, 1H), 7.30 (m, 1H). After warming to room temperature the reaction mixture was concentrated in vacuo to remove the THF The reaction mixture was partitioned between 4.5 L H2O and 4.5 L IPE The aqueous layer was extracted twice with 4 L each of IPE The organic solution was dried over Na2SO4 concentrated in vacuo