benzyl (2S)-2-[(2-methylpropan-2-yl)oxycarbonylamino]-3-phenylpropanoate

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

Procedure: To a solution of N-t-butoxycarbonyl-L-phenylalanine benzyl ester (1 g) in methylene chloride (10 ml) is added aluminum chloride (1 g) in anisole (12 ml), and the mixture is stirred at room temperature for 2 hours. The reaction mixture is poured into an aqueous sodium hydrogen carbonate solution and filtered to remove insoluble material. The filtrate is washed with methylene chloride, acidified to pH 2.5 with hydrochloric acid, and adsorbed on high porous polymer HP-20 (manufactured by Mitsubishi Chemical Co., Ltd.). After washing with water, the resin is washed with methanol. Concentration of the methanol eluent gives crystals of L-phenylalanine (0.3 g) melting at 270° C. Yield: 54%. filtered to remove insoluble material The filtrate is washed with methylene chloride After washing with water the resin is washed with methanol

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

Procedure: Benzyl (2S)-2-(tert-butoxycarbonylamino)-3-phenyl-propanoate (12.8 g, 36 mmol) was stirred in HCl, 2 M in diethyl ether (90 mL) and HCl, 4 M in dioxane (18 mL) and the resulting mixture was stirred overnight at room temperature. The mixture was then diluted with hexanes (100 mL) and filtered to collect the title compound (7.98 g, 76%) as a fine white powder. 1H NMR (CD3OD, 400 MHz): δ (ppm) 7.40-7.15 (m, 10H), 5.23 (s, 2H), 4.36-4.31 (m, 1H), 3.26-3.12 (m, 2H). filtered to collect the title compound (7.98 g, 76%) as a fine white powder

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

Procedure: To a stirred solution of Boc-Phe-OH (10 g, 37.7 mmoL) in DMF (50 mL) was added potassium carbonate (7.81 g, 56.5 mmol) followed by benzyl chloride (4.55 mL, 39.6 mmol) and the resulting suspension was stirred at 60° C. for 3 d. The mixture was diluted with water (400 mL) and extracted with ethyl acetate (75 mL, 2×25 mL). The combined organics were washed with brine (200 mL), water (3×100 mL) and brine (50 mL). The organic phase was dried over anhydrous sodium sulfate, filtered and concentrated then chromatographed on silica gel eluting with 0%-20% ethyl acetate in hexanes. The product-containing fractions were concentrated in vacuo giving the title compound (12.84 g, 95%) as a white solid. extracted with ethyl acetate (75 mL, 2×25 mL) The combined organics were washed with brine (200 mL), water (3×100 mL) and brine (50 mL) The organic phase was dried over anhydrous sodium sulfate filtered concentrated then chromatographed on silica gel eluting with 0%-20% ethyl acetate in hexanes The product-containing fractions were concentrated in vacuo

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

Procedure: To a solution of N-t-butoxycarbonyl-L-phenylalanine benzyl ester (1 g) in methylene chloride (10 ml) is added aluminum chloride (1 g) in anisole (12 ml), and the mixture is stirred at room temperature for 2 hours. The reaction mixture is poured into an aqueous sodium hydrogen carbonate solution and filtered to remove insoluble material. The filtrate is washed with methylene chloride, acidified to pH 2.5 with hydrochloric acid, and adsorbed on high porous polymer HP-20 (manufactured by Mitsubishi Chemical Co., Ltd.). After washing with water, the resin is washed with methanol. Concentration of the methanol eluent gives crystals of L-phenylalanine (0.3 g) melting at 270° C. Yield: 54%. filtered to remove insoluble material The filtrate is washed with methylene chloride After washing with water the resin is washed with methanol

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

Procedure: Benzyl (2S)-2-(tert-butoxycarbonylamino)-3-phenyl-propanoate (12.8 g, 36 mmol) was stirred in HCl, 2 M in diethyl ether (90 mL) and HCl, 4 M in dioxane (18 mL) and the resulting mixture was stirred overnight at room temperature. The mixture was then diluted with hexanes (100 mL) and filtered to collect the title compound (7.98 g, 76%) as a fine white powder. 1H NMR (CD3OD, 400 MHz): δ (ppm) 7.40-7.15 (m, 10H), 5.23 (s, 2H), 4.36-4.31 (m, 1H), 3.26-3.12 (m, 2H). filtered to collect the title compound (7.98 g, 76%) as a fine white powder

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

Procedure: To a stirred solution of Boc-Phe-OH (10 g, 37.7 mmoL) in DMF (50 mL) was added potassium carbonate (7.81 g, 56.5 mmol) followed by benzyl chloride (4.55 mL, 39.6 mmol) and the resulting suspension was stirred at 60° C. for 3 d. The mixture was diluted with water (400 mL) and extracted with ethyl acetate (75 mL, 2×25 mL). The combined organics were washed with brine (200 mL), water (3×100 mL) and brine (50 mL). The organic phase was dried over anhydrous sodium sulfate, filtered and concentrated then chromatographed on silica gel eluting with 0%-20% ethyl acetate in hexanes. The product-containing fractions were concentrated in vacuo giving the title compound (12.84 g, 95%) as a white solid. extracted with ethyl acetate (75 mL, 2×25 mL) The combined organics were washed with brine (200 mL), water (3×100 mL) and brine (50 mL) The organic phase was dried over anhydrous sodium sulfate filtered concentrated then chromatographed on silica gel eluting with 0%-20% ethyl acetate in hexanes The product-containing fractions were concentrated in vacuo

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

Procedure: To a solution of N-t-butoxycarbonyl-L-phenylalanine benzyl ester (1 g) in methylene chloride (10 ml) is added aluminum chloride (1 g) in anisole (12 ml), and the mixture is stirred at room temperature for 2 hours. The reaction mixture is poured into an aqueous sodium hydrogen carbonate solution and filtered to remove insoluble material. The filtrate is washed with methylene chloride, acidified to pH 2.5 with hydrochloric acid, and adsorbed on high porous polymer HP-20 (manufactured by Mitsubishi Chemical Co., Ltd.). After washing with water, the resin is washed with methanol. Concentration of the methanol eluent gives crystals of L-phenylalanine (0.3 g) melting at 270° C. Yield: 54%. filtered to remove insoluble material The filtrate is washed with methylene chloride After washing with water the resin is washed with methanol

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

Procedure: To a solution of N-(tert-butoxycarbonyl)-L-phenylalanine (30.0 g, 113 mmol) and benzyl alcohol (14.0 mL, 136 mmol) in methylene chloride (200 mL), were added successively 4-dimethylaminopyridine (1.38 g, 11.3 mmol) and WSCI.HCl (26.0 g, 136 mmol) under ice-cooling, and the mixture was stirred for 63 hr while gradually raising the temperature to room temperature. The solvent was distilled away from the reaction solution under reduced pressure, and water (200 mL) was added to the residue. The mixture was extracted with ethyl acetate (400 mL). The obtained extract solution was washed with 0.5N hydrochloric acid, water, saturated aqueous sodium hydrogencarbonate solution, water and saturated brine (each 200 mL), and dried (anhydrous magnesium sulfate) and concentrated under reduced pressure. The obtained residue was recrystallized from hexane to give the title compound (33.1 g, 82%) as white crystals. cooling The solvent was distilled away from the reaction solution under reduced pressure, and water (200 mL) was added to the residue The mixture was extracted with ethyl acetate (400 mL) The obtained extract solution was washed with 0.5N hydrochloric acid, water, saturated aqueous sodium hydrogencarbonate solution, water and saturated brine (each 200 mL), and dried (anhydrous magnesium sulfate) concentrated under reduced pressure The obtained residue was recrystallized from hexane

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

Procedure: Benzyl (2S)-2-(tert-butoxycarbonylamino)-3-phenyl-propanoate (12.8 g, 36 mmol) was stirred in HCl, 2 M in diethyl ether (90 mL) and HCl, 4 M in dioxane (18 mL) and the resulting mixture was stirred overnight at room temperature. The mixture was then diluted with hexanes (100 mL) and filtered to collect the title compound (7.98 g, 76%) as a fine white powder. 1H NMR (CD3OD, 400 MHz): δ (ppm) 7.40-7.15 (m, 10H), 5.23 (s, 2H), 4.36-4.31 (m, 1H), 3.26-3.12 (m, 2H). filtered to collect the title compound (7.98 g, 76%) as a fine white powder

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

Procedure: To a stirred solution of Boc-Phe-OH (10 g, 37.7 mmoL) in DMF (50 mL) was added potassium carbonate (7.81 g, 56.5 mmol) followed by benzyl chloride (4.55 mL, 39.6 mmol) and the resulting suspension was stirred at 60° C. for 3 d. The mixture was diluted with water (400 mL) and extracted with ethyl acetate (75 mL, 2×25 mL). The combined organics were washed with brine (200 mL), water (3×100 mL) and brine (50 mL). The organic phase was dried over anhydrous sodium sulfate, filtered and concentrated then chromatographed on silica gel eluting with 0%-20% ethyl acetate in hexanes. The product-containing fractions were concentrated in vacuo giving the title compound (12.84 g, 95%) as a white solid. extracted with ethyl acetate (75 mL, 2×25 mL) The combined organics were washed with brine (200 mL), water (3×100 mL) and brine (50 mL) The organic phase was dried over anhydrous sodium sulfate filtered concentrated then chromatographed on silica gel eluting with 0%-20% ethyl acetate in hexanes The product-containing fractions were concentrated in vacuo