(2S)-3-cyano-2-[(2-methylpropan-2-yl)oxycarbonylamino]propanoic acid

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

Procedure: A solution of dicyclohexylcarbodiimide (DCC, 8.3 g, 40 mmol) in acetone (100 ml) was added dropwise a suspension of Boc-asparagine (9.3 g, 40 mmol) in pyridine (50 mL) at 0° C. under nitrogen. The reaction mixture was stirred at ambient temperature for 3 h. The mixture was filtered and the filtrate was concentrated. The residue was dissolved in dichloromethane (400 mL) and the solution was washed with 2 N aqueous HCl (20 mL×3) and brine (200 mL), dried over anhydrous sodium sulfate, and concentrated to afford (S)-2-(tert-butoxycarbonylamino)-3-cyanopropanoic acid (5.5 g, 56% yield), which was used directly without further purification. The mixture was filtered the filtrate was concentrated The residue was dissolved in dichloromethane (400 mL) the solution was washed with 2 N aqueous HCl (20 mL×3) and brine (200 mL) dried over anhydrous sodium sulfate concentrated

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

Procedure: Sequentially HATU (1.21 g, 3.20 mmol) and DIEA (1.35 mL, 7.8 mmol) were added to a 0° C. solution of (S)-2-(tert-butoxycarbonylamino)-3-cyanopropanoic acid and (S)-2-amino-N-((S)-3-(cyclopent-1-en-1-yl)-1-((R)-2-methyloxiran-2-yl)-1-oxopropan-2-yl)-3-(4-methoxyphenyl)propanamide (TFA salt, 2.1 mmol) in DMF (20 mL). The reaction mixture was allowed to warm to ambient temperature and stirred for 3 h. EtOAc (100 mL) and water (100 mL) was added. The aqueous layer was extracted with EtOAc (50 mL×3). The combined organic phases were washed with brine (200 mL×3), dried over anhydrous sodium sulfate, and concentrated. The residue was purified by flash column chromatography on silica gel (EtOAc/hexane=1:2) to afford tert-butyl ((S)-3-cyano-1-(((S)-1-(((S)-3-(cyclopent-1-en-1-yl)-1-((R)-2-methyl oxiran-2-yl)-1-oxopropan-2-yl)amino)-3-(4-methoxyphenyl)-1-oxopropan-2-yl)amino)-1-oxopropan-2-yl)carbamate (590 mg, 45% yield). The aqueous layer was extracted with EtOAc (50 mL×3) The combined organic phases were washed with brine (200 mL×3) dried over anhydrous sodium sulfate concentrated The residue was purified by flash column chromatography on silica gel (EtOAc/hexane=1:2)

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

Procedure: A solution of dicyclohexylcarbodiimide (DCC, 8.3 g, 40 mmol) in acetone (100 ml) was added dropwise a suspension of Boc-asparagine (9.3 g, 40 mmol) in pyridine (50 mL) at 0° C. under nitrogen. The reaction mixture was stirred at ambient temperature for 3 h. The mixture was filtered and the filtrate was concentrated. The residue was dissolved in dichloromethane (400 mL) and the solution was washed with 2 N aqueous HCl (20 mL×3) and brine (200 mL), dried over anhydrous sodium sulfate, and concentrated to afford (S)-2-(tert-butoxycarbonylamino)-3-cyanopropanoic acid (5.5 g, 56% yield), which was used directly without further purification. The mixture was filtered the filtrate was concentrated The residue was dissolved in dichloromethane (400 mL) the solution was washed with 2 N aqueous HCl (20 mL×3) and brine (200 mL) dried over anhydrous sodium sulfate concentrated

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

Procedure: Sequentially HATU (1.21 g, 3.20 mmol) and DIEA (1.35 mL, 7.8 mmol) were added to a 0° C. solution of (S)-2-(tert-butoxycarbonylamino)-3-cyanopropanoic acid and (S)-2-amino-N-((S)-3-(cyclopent-1-en-1-yl)-1-((R)-2-methyloxiran-2-yl)-1-oxopropan-2-yl)-3-(4-methoxyphenyl)propanamide (TFA salt, 2.1 mmol) in DMF (20 mL). The reaction mixture was allowed to warm to ambient temperature and stirred for 3 h. EtOAc (100 mL) and water (100 mL) was added. The aqueous layer was extracted with EtOAc (50 mL×3). The combined organic phases were washed with brine (200 mL×3), dried over anhydrous sodium sulfate, and concentrated. The residue was purified by flash column chromatography on silica gel (EtOAc/hexane=1:2) to afford tert-butyl ((S)-3-cyano-1-(((S)-1-(((S)-3-(cyclopent-1-en-1-yl)-1-((R)-2-methyl oxiran-2-yl)-1-oxopropan-2-yl)amino)-3-(4-methoxyphenyl)-1-oxopropan-2-yl)amino)-1-oxopropan-2-yl)carbamate (590 mg, 45% yield). The aqueous layer was extracted with EtOAc (50 mL×3) The combined organic phases were washed with brine (200 mL×3) dried over anhydrous sodium sulfate concentrated The residue was purified by flash column chromatography on silica gel (EtOAc/hexane=1:2)

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

Procedure: Iodomethane (2.18 ml, 35.01 mmol) was added to a mixture of (S)-2-(tert-butoxycarbonylamino)-3-cyanopropanoic acid (5.00 g, 23.34 mmol) and DBU (3.67 ml, 24.51 mmol) in toluene (20 mL) at rt. The reaction was stirred at 50 C for 2 days. Water (20 mL), saturated KHSO4 (20 mL) and ethyl acetate (50 mL) were added. The organic layer was separated, washed with brine and dried over sodium sulfate. After removal of solvent, the residue was purified by chromatography (hexane:Ethyl acetate=2:1) to give the (S)-methyl-2-(tert-butoxycarbonylamino)-3-cyanopropanoate as white solid (4.6 g, 86%). 1H NMR (400 MHz, d6-DMSO) δ7.64 (d, J=8.8 Hz, 1H), 4.39 (m, 1H), 3.66 (s, 3H), 2.96 (dd, J=16.8 Hz & 5.1 Hz, 1H), 2.85 (dd, J=16.8 Hz & 5.2 Hz, 1H), 1.40 (s, 9H). The organic layer was separated washed with brine dried over sodium sulfate After removal of solvent the residue was purified by chromatography (hexane:Ethyl acetate=2:1)

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

Procedure: A solution of dicyclohexylcarbodiimide (DCC, 8.3 g, 40 mmol) in acetone (100 ml) was added dropwise a suspension of Boc-asparagine (9.3 g, 40 mmol) in pyridine (50 mL) at 0° C. under nitrogen. The reaction mixture was stirred at ambient temperature for 3 h. The mixture was filtered and the filtrate was concentrated. The residue was dissolved in dichloromethane (400 mL) and the solution was washed with 2 N aqueous HCl (20 mL×3) and brine (200 mL), dried over anhydrous sodium sulfate, and concentrated to afford (S)-2-(tert-butoxycarbonylamino)-3-cyanopropanoic acid (5.5 g, 56% yield), which was used directly without further purification. The mixture was filtered the filtrate was concentrated The residue was dissolved in dichloromethane (400 mL) the solution was washed with 2 N aqueous HCl (20 mL×3) and brine (200 mL) dried over anhydrous sodium sulfate concentrated

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

Procedure: Sequentially HATU (1.21 g, 3.20 mmol) and DIEA (1.35 mL, 7.8 mmol) were added to a 0° C. solution of (S)-2-(tert-butoxycarbonylamino)-3-cyanopropanoic acid and (S)-2-amino-N-((S)-3-(cyclopent-1-en-1-yl)-1-((R)-2-methyloxiran-2-yl)-1-oxopropan-2-yl)-3-(4-methoxyphenyl)propanamide (TFA salt, 2.1 mmol) in DMF (20 mL). The reaction mixture was allowed to warm to ambient temperature and stirred for 3 h. EtOAc (100 mL) and water (100 mL) was added. The aqueous layer was extracted with EtOAc (50 mL×3). The combined organic phases were washed with brine (200 mL×3), dried over anhydrous sodium sulfate, and concentrated. The residue was purified by flash column chromatography on silica gel (EtOAc/hexane=1:2) to afford tert-butyl ((S)-3-cyano-1-(((S)-1-(((S)-3-(cyclopent-1-en-1-yl)-1-((R)-2-methyl oxiran-2-yl)-1-oxopropan-2-yl)amino)-3-(4-methoxyphenyl)-1-oxopropan-2-yl)amino)-1-oxopropan-2-yl)carbamate (590 mg, 45% yield). The aqueous layer was extracted with EtOAc (50 mL×3) The combined organic phases were washed with brine (200 mL×3) dried over anhydrous sodium sulfate concentrated The residue was purified by flash column chromatography on silica gel (EtOAc/hexane=1:2)