(S)-Benzyl 2-((S)-2-(tert-butoxycarbonylamino)-4-methylpentanamido)-3-phenylpropanoate

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

Procedure: A 500 mL round bottom flask was charged with 46.52 g (99 mmol) N-tert-Butyloxycarbonyl-L-leucinyl-L-phenylalanine benzyl ester, 340 mL anhydrous methylene chloride (CH2Cl2), and 51 mL trifluoroacetic acid (TFA). The mixture was stirred at room temperature under a nitrogen atmosphere for 3 hours, and then concentrated in vacuo. The residue was azetroped twice with toluene, and carried on. The same 500 mL round bottom flask containing the crude TFA salt was placed under a nitrogen atmosphere and charged with 21.5 g (99 mmol) Boc-L-valine, 13.4 g (99 mmol) HOBT, and 270 mL anhydrous THF. The solution was cooled in an ice/acetone bath and 21.4 g (104 mmol) DCC was added in one portion. The mixture was stirred in the cold for 1 hour, and then warmed to room temperature and stirred overnight. The precipitated DCU was filtered off, and the filtrate was concentrated in vacuo. The residue was taken up in ethyl acetate and washed once with water, once with a 10% solution of citric acid, once with saturated NaHCO3, and once with brine. The organic layer was then dried over Na2SO4, filtered, and concentrated in vacuo. The resultant solid was precipitated from ethanol with H2O to provide 41.96 g (75%) of the title compound. concentrated in vacuo The same 500 mL round bottom flask containing the crude TFA salt The solution was cooled in an ice/acetone bath The mixture was stirred in the cold for 1 hour warmed to room temperature stirred overnight The precipitated DCU was filtered off the filtrate was concentrated in vacuo washed once with water, once with a 10% solution of citric acid, once with saturated NaHCO3 The organic layer was then dried over Na2SO4 filtered concentrated in vacuo The resultant solid was precipitated from ethanol with H2O

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

Procedure: A 500 mL round bottom flask was charged with 46.52 g (99 mmol) N-tert-Butyloxycarbonyl-L-leucinyl-L-phenylalanine benzyl ester, 340 mL anhydrous m ethylene chloride (CH2Cl2), and 51 mL trifluoroacetic acid (TFA). The mixture was stirred at room temperature under a nitrogen atmosphere for 3 hours, and then concentrated in vacuo. The residue was azeotroped twice with toluene, and carried on. The same 500 mL round bottom flask containing the crude TFA salt was placed under a nitrogen atmosphere and charged with 21.5 g (99 mmol) Boc-L-valine, 13.4 g (99 mmol) HOBT, and 270 mL anhydrous THF The solution was cooled in an ice/acetone bath and 21.4 a (104 mmol) DCC was added in one portion. The mixture was stirred in the cold for 1 hour, and then warmed to room temperature and stirred overnight. The precipitated DCU was filtered off, and the filtrate was concentrated in vacuo. The residue was taken up in ethyl acetate and washed once with water, once with a 10% solution off citric acid, once with saturated NaHCO3, and once with brine. The organic layer was then dried over Na2SO4, filtered, and concentrated in vacuo. The resultant solid was precipitated from ethanol with H2O to provide 41.96 g (75%) of the title compound. concentrated in vacuo The residue was azeotroped twice with toluene The same 500 mL round bottom flask containing the crude TFA salt was cooled in an ice/acetone bath The mixture was stirred in the cold for 1 hour warmed to room temperature stirred overnight The precipitated DCU was filtered off the filtrate was concentrated in vacuo washed once with water, once with a 10% solution off citric acid, once with saturated NaHCO3 The organic layer was then dried over Na2SO4 filtered concentrated in vacuo The resultant solid was precipitated from ethanol with H2O

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

Procedure: A 500 mL round bottom flask was charged with 46.52 g (99 mmol) N-tert-Butyloxycarbonyl-L-leucinyl-L-phenylalanine benzyl ester, 340 mL anhydrous m ethylene chloride (CH2Cl2), and 51 mL trifluoroacetic acid (TFA). The mixture was stirred at room temperature under a nitrogen atmosphere for 3 hours, and then concentrated in vacuo. The residue was azeotroped twice with toluene, and carried on. The same 500 mL round bottom flask containing the crude TFA salt was placed under a nitrogen atmosphere and charged with 21.5 g (99 mmol) Boc-L-valine, 13.4 g (99 mmol) HOBT, and 270 mL anhydrous THF The solution was cooled in an ice/acetone bath and 21.4 a (104 mmol) DCC was added in one portion. The mixture was stirred in the cold for 1 hour, and then warmed to room temperature and stirred overnight. The precipitated DCU was filtered off, and the filtrate was concentrated in vacuo. The residue was taken up in ethyl acetate and washed once with water, once with a 10% solution off citric acid, once with saturated NaHCO3, and once with brine. The organic layer was then dried over Na2SO4, filtered, and concentrated in vacuo. The resultant solid was precipitated from ethanol with H2O to provide 41.96 g (75%) of the title compound. concentrated in vacuo The residue was azeotroped twice with toluene The same 500 mL round bottom flask containing the crude TFA salt was cooled in an ice/acetone bath The mixture was stirred in the cold for 1 hour warmed to room temperature stirred overnight The precipitated DCU was filtered off the filtrate was concentrated in vacuo washed once with water, once with a 10% solution off citric acid, once with saturated NaHCO3 The organic layer was then dried over Na2SO4 filtered concentrated in vacuo The resultant solid was precipitated from ethanol with H2O

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

Procedure: A 500 mL round bottom flask was charged with 46.52 g (99 mmol) N-tert-Butyloxycarbonyl-L-leucinyl-L-phenylalanine benzyl ester, 340 mL anhydrous methylene chloride (CH2Cl2), and 51 mL trifluoroacetic acid (TFA). The mixture was stirred at room temperature under a nitrogen atmosphere for 3 hours, and then concentrated in vacuo. The residue was azetroped twice with toluene, and carried on. The same 500 mL round bottom flask containing the crude TFA salt was placed under a nitrogen atmosphere and charged with 21.5 g (99 mmol) Boc-L-valine, 13.4 g (99 mmol) HOBT, and 270 mL anhydrous THF. The solution was cooled in an ice/acetone bath and 21.4 g (104 mmol) DCC was added in one portion. The mixture was stirred in the cold for 1 hour, and then warmed to room temperature and stirred overnight. The precipitated DCU was filtered off, and the filtrate was concentrated in vacuo. The residue was taken up in ethyl acetate and washed once with water, once with a 10% solution of citric acid, once with saturated NaHCO3, and once with brine. The organic layer was then dried over Na2SO4, filtered, and concentrated in vacuo. The resultant solid was precipitated from ethanol with H2O to provide 41.96 g (75%) of the title compound. concentrated in vacuo The same 500 mL round bottom flask containing the crude TFA salt The solution was cooled in an ice/acetone bath The mixture was stirred in the cold for 1 hour warmed to room temperature stirred overnight The precipitated DCU was filtered off the filtrate was concentrated in vacuo washed once with water, once with a 10% solution of citric acid, once with saturated NaHCO3 The organic layer was then dried over Na2SO4 filtered concentrated in vacuo The resultant solid was precipitated from ethanol with H2O

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

Procedure: A 500 mL round bottom flask was charged with 46.52 g (99 mmol) N-tert-Butyloxycarbonyl-L-leucinyl-L-phenylalanine benzyl ester, 340 mL anhydrous m ethylene chloride (CH2Cl2), and 51 mL trifluoroacetic acid (TFA). The mixture was stirred at room temperature under a nitrogen atmosphere for 3 hours, and then concentrated in vacuo. The residue was azeotroped twice with toluene, and carried on. The same 500 mL round bottom flask containing the crude TFA salt was placed under a nitrogen atmosphere and charged with 21.5 g (99 mmol) Boc-L-valine, 13.4 g (99 mmol) HOBT, and 270 mL anhydrous THF The solution was cooled in an ice/acetone bath and 21.4 a (104 mmol) DCC was added in one portion. The mixture was stirred in the cold for 1 hour, and then warmed to room temperature and stirred overnight. The precipitated DCU was filtered off, and the filtrate was concentrated in vacuo. The residue was taken up in ethyl acetate and washed once with water, once with a 10% solution off citric acid, once with saturated NaHCO3, and once with brine. The organic layer was then dried over Na2SO4, filtered, and concentrated in vacuo. The resultant solid was precipitated from ethanol with H2O to provide 41.96 g (75%) of the title compound. concentrated in vacuo The residue was azeotroped twice with toluene The same 500 mL round bottom flask containing the crude TFA salt was cooled in an ice/acetone bath The mixture was stirred in the cold for 1 hour warmed to room temperature stirred overnight The precipitated DCU was filtered off the filtrate was concentrated in vacuo washed once with water, once with a 10% solution off citric acid, once with saturated NaHCO3 The organic layer was then dried over Na2SO4 filtered concentrated in vacuo The resultant solid was precipitated from ethanol with H2O

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

Procedure: A 500 mL round bottom flask was charged with 46.52 g (99 mmol) N-tert-Butyloxycarbonyl-L-leucinyl-L-phenylalanine benzyl ester, 340 mL anhydrous methylene chloride (CH2Cl2), and 51 mL trifluoroacetic acid (TFA). The mixture was stirred at room temperature under a nitrogen atmosphere for 3 hours, and then concentrated in vacuo. The residue was azetroped twice with toluene, and carried on. The same 500 mL round bottom flask containing the crude TFA salt was placed under a nitrogen atmosphere and charged with 21.5 g (99 mmol) Boc-L-valine, 13.4 g (99 mmol) HOBT, and 270 mL anhydrous THF. The solution was cooled in an ice/acetone bath and 21.4 g (104 mmol) DCC was added in one portion. The mixture was stirred in the cold for 1 hour, and then warmed to room temperature and stirred overnight. The precipitated DCU was filtered off, and the filtrate was concentrated in vacuo. The residue was taken up in ethyl acetate and washed once with water, once with a 10% solution of citric acid, once with saturated NaHCO3, and once with brine. The organic layer was then dried over Na2SO4, filtered, and concentrated in vacuo. The resultant solid was precipitated from ethanol with H2O to provide 41.96 g (75%) of the title compound. concentrated in vacuo The same 500 mL round bottom flask containing the crude TFA salt The solution was cooled in an ice/acetone bath The mixture was stirred in the cold for 1 hour warmed to room temperature stirred overnight The precipitated DCU was filtered off the filtrate was concentrated in vacuo washed once with water, once with a 10% solution of citric acid, once with saturated NaHCO3 The organic layer was then dried over Na2SO4 filtered concentrated in vacuo The resultant solid was precipitated from ethanol with H2O