ethyl (3S)-3-amino-3-phenylpropanoate

Conditions: temp:20.01; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: In a 25 ml flask, 13.0 g of D-β-phenylalanine ethyl ester was charged under nitrogen, and sodium-potassium alloy (Na : K = 56 : 44 by weight) (0.1 g) was added thereto. The mixture was stirred at 20°C for 3 hours. The reaction mixture was treated as in Example 11 to give 12.1 g of racemic β-phenylalanine ethyl ester. B.P. 95° to 96°C/0.6 mmHg. [α]D25 -0.1° (neat). The reaction mixture was treated as in Example 11

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

Procedure: 9.7 g (51.6 mmol) of ethyl (S)-3-amino-3-phenylpropionate, 8.5 g (51.6 mmol) of 2,3-dimethyl-6,7-dihydro-5H-imidazo[1,2-a]pyridin-8-one and 0.26 g (1.3 mmol) of p-toluenesulfonic acid monohydrate are heated under reflux in 50 ml of toluene in a water separator. After water no longer separates, the reaction mixture is cooled to 0° C. and diluted with 100 ml of tetrahydrofuran. 7.24 g (64.5 mmol) of potassium tert-butoxide are then introduced and the mixture is stirred at room temperature for 16 h. 150 ml of saturated ammonium chloride solution are added to the reaction mixture, the organic phase is separated off and the aqueous phase is extracted with 300 ml of ethyl acetate. The combined organic phases are washed with 250 ml of water, dried over sodium sulfate and evaporated. 13.27 g (88%) of the title compound are isolated as a red-brown oil. An analytical sample is obtained by crystallization using diethyl ether (red solid, m.p. 134° C.). the organic phase is separated off the aqueous phase is extracted with 300 ml of ethyl acetate The combined organic phases are washed with 250 ml of water dried over sodium sulfate evaporated

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

Procedure: 9.7 g (51.6 mmol) of ethyl (S)-3-amino-3-phenylpropionate, 8.5 g (51.6 mmol) of 2,3-dimethyl-6,7-dihydro-5H-imidazo[1,2-a]pyridin-8-one and 0.26 g (1.3 mmol) of p-toluenesulphonic acid monohydrate are heated to reflux in 50 ml of toluene using a water separator. After no more water separates, the reaction mixture is cooled to 0° C. and diluted with 100 ml of tetrahydrofuran. 7.24 g (64.5 mmol) of potassium tert-butoxide are then introduced and the mixture is stirred at room temperature for 16 h. 150 ml of saturated ammonium chloride are added to the reaction mixture, the organic phase is removed and the aqueous phase is extracted with 300 ml of ethyl acetate. The combined organic phases are washed with 250 ml of water, dried over sodium sulphate and evaporated. 13.27 g (88%) of the title compound are isolated as a red-brown oil. An analytical sample is obtained by crystallizing with diethyl ether (red solid, m.p. 134° C.). the organic phase is removed the aqueous phase is extracted with 300 ml of ethyl acetate The combined organic phases are washed with 250 ml of water dried over sodium sulphate evaporated

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

Procedure: 1.89 g (5.77 mmol) of TOTU and 932 μL of N,N-diisopropylethylamine were added at 0° C. to a solution of 3.57 g (5.77 mmol) of (S)-2-(4,4-bis(trifluoromethyl)-3-(4-(3-(2-methylphenyl)ureido)-3-methoxybenzyl)-2, 5-dioxoimidazolidin-1-yl)-2-(2-methylpropyl)acetic acid (prepared from (S)-2-(4,4-bis(trifluoromethyl)-2,5-dioxoimidazolidin-1-yl)-2-(2-methylpropyl)acetic acid and 4-(3-(2-methylphenyl)ureido)-3-methoxybenzyl chloride as described in Example 18f) and 1.11 g (5.77 mmol) of ethyl (S)-3-amino-3-phenylpropionate in 30 mL of absolute DMF. After stirring at room temperature for 1 hour, DMF was removed in vacuo, the residue was taken up in ethyl acetate and the ethyl acetate solution was washed successively with an aqueous KHSO4K2SO4 solution, a saturated NaHCO3 solution and water. After drying the organic phase over sodium sulfate and filtering, the solvent was removed in vacuo and the residue was chromatographed over silica gel using ethyl acetate/heptane (2/3). After concentration of the product fractions, 3.26 g (71%) of the title compound were obtained. DMF was removed in vacuo the ethyl acetate solution was washed successively with an aqueous KHSO4K2SO4 solution After drying the organic phase over sodium sulfate filtering the solvent was removed in vacuo the residue was chromatographed over silica gel

Conditions: temp:20.01; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: In a 25 ml flask, 13.0 g of D-β-phenylalanine ethyl ester was charged under nitrogen, and sodium-potassium alloy (Na : K = 56 : 44 by weight) (0.1 g) was added thereto. The mixture was stirred at 20°C for 3 hours. The reaction mixture was treated as in Example 11 to give 12.1 g of racemic β-phenylalanine ethyl ester. B.P. 95° to 96°C/0.6 mmHg. [α]D25 -0.1° (neat). The reaction mixture was treated as in Example 11

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

Procedure: 9.7 g (51.6 mmol) of ethyl (S)-3-amino-3-phenylpropionate, 8.5 g (51.6 mmol) of 2,3-dimethyl-6,7-dihydro-5H-imidazo[1,2-a]pyridin-8-one and 0.26 g (1.3 mmol) of p-toluenesulfonic acid monohydrate are heated under reflux in 50 ml of toluene in a water separator. After water no longer separates, the reaction mixture is cooled to 0° C. and diluted with 100 ml of tetrahydrofuran. 7.24 g (64.5 mmol) of potassium tert-butoxide are then introduced and the mixture is stirred at room temperature for 16 h. 150 ml of saturated ammonium chloride solution are added to the reaction mixture, the organic phase is separated off and the aqueous phase is extracted with 300 ml of ethyl acetate. The combined organic phases are washed with 250 ml of water, dried over sodium sulfate and evaporated. 13.27 g (88%) of the title compound are isolated as a red-brown oil. An analytical sample is obtained by crystallization using diethyl ether (red solid, m.p. 134° C.). the organic phase is separated off the aqueous phase is extracted with 300 ml of ethyl acetate The combined organic phases are washed with 250 ml of water dried over sodium sulfate evaporated