(2,5-dioxopyrrolidin-1-yl) (2S)-2-[(2-methylpropan-2-yl)oxycarbonylamino]propanoate

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

Procedure: L-Alanine (3.57 g, 40 mmol) was dissolved in 18.8 ml of Triton B (40 mmol), evaporated to dryness, and the oily residue re-evaporated twice with DMF (30 ml each). The salt obtained was stirred with 11.45 g of Boc-Ala-OSu (40 mmol) in 40 ml DMF, with 4 ml of NMM added, for 20 hours. The solvent was removed and the residue taken up in 10% HOAc (100 ml). The product was extracted into EtOAc (4 times 100 ml), washed twice with a small volume of H2O, dried over Na2SO4, evaporated to a small volume, and treated with petroleum ether until cloudiness developed. A crystalline product formed on storage in the refrigerator overnight: Yield, 8.2 g (76.3%); mp 115°-118°. evaporated to dryness the oily residue re-evaporated twice with DMF (30 ml each) The salt obtained added, for 20 hours The solvent was removed The product was extracted into EtOAc (4 times 100 ml) washed twice with a small volume of H2O dried over Na2SO4 evaporated to a small volume treated with petroleum ether until cloudiness A crystalline product formed on storage in the refrigerator overnight Yield

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

Procedure: L-Alanine (3.57 g, 40 mmol) was dissolved in 18.8 ml of Triton B (40 mmol), evaporated to dryness, and the oily residue re-evaporated twice with DMF (30 ml each). The salt obtained was stirred with 11.45 g of Boc-Ala-OSu (40 mmol) in 40 ml DMF, with 4 ml of NMM added, for 20 hours. The solvent was removed and the residue taken up in 10% HOAc (100 ml). The product was extracted into EtOAc (4 times 100 ml), washed twice with a small volume of H2O, dried over Na2SO4, evaporated to a small volume, and treated with petroleum ether until cloudiness developed. A crystalline product formed on storage in the refrigerator overnight: Yield, 8.2 g (76.3%); mp 115°-118°. evaporated to dryness the oily residue re-evaporated twice with DMF (30 ml each) The salt obtained added, for 20 hours The solvent was removed The product was extracted into EtOAc (4 times 100 ml) washed twice with a small volume of H2O dried over Na2SO4 evaporated to a small volume treated with petroleum ether until cloudiness A crystalline product formed on storage in the refrigerator overnight Yield

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

Procedure: L-Alanine (3.57 g, 40 mmol) was dissolved in 18.8 ml of Triton B (40 mmol), evaporated to dryness, and the oily residue re-evaporated twice with DMF (30 ml each). The salt obtained was stirred with 11.45 g of Boc-Ala-OSu (40 mmol) in 40 ml DMF, with 4 ml of NMM added, for 20 hours. The solvent was removed and the residue taken up in 10% HOAc (100 ml). The product was extracted into EtOAc (4 times 100 ml), washed twice with a small volume of H2O, dried over Na2SO4, evaporated to a small volume, and treated with petroleum ether until cloudiness developed. A crystalline product formed on storage in the refrigerator overnight: Yield, 8.2 g (76.3%); mp 115°-118°. evaporated to dryness the oily residue re-evaporated twice with DMF (30 ml each) The salt obtained added, for 20 hours The solvent was removed The product was extracted into EtOAc (4 times 100 ml) washed twice with a small volume of H2O dried over Na2SO4 evaporated to a small volume treated with petroleum ether until cloudiness A crystalline product formed on storage in the refrigerator overnight Yield

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

Procedure: To a stirred solution of 23 (crude) (0.588 mmol) in CH2Cl2 (2.9 mL) at 0 degrees were added Boc-Ala-OSu (185 mg, 0.647 mmol) and triethylamine (0.18 mL, 1.3 mmol). The mixture was allowed to reach 21° C. slowly, stirring for 16 h at room temperature. The solvent was then evaporated. The mixture was quenched with a saturated ammonium chloride solution and extracted with ethyl acetate, washed with brine, dried (MgSO4) filtered and concentrated. The residue was purified by silica gel column chromatography with gradient of EtOAc (20-60%) in hexanes to afford 24 (140 mg, 49%) as a white solid. LRMS (ESI): calc. 484.1; found 507.2 (MNa)+. to reach 21° C. The solvent was then evaporated The mixture was quenched with a saturated ammonium chloride solution extracted with ethyl acetate washed with brine dried (MgSO4) filtered concentrated The residue was purified by silica gel column chromatography with gradient of EtOAc (20-60%) in hexanes

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

Procedure: To a solution of compound 14 (0.907 g, 2.93 mmol) at 0 degrees in THF (3 mL) and under nitrogen was slowly added 1M borane tetrahydrofuran complex (11.73 mL, 11.73 mmol). The yellow solution was then stirred for 50 minutes at room temperature. It was cooled to 0 degrees and then slowly quenched with methanol (approx. 4 mL). After 10 minutes of stirring at room temperature the reaction solution was concentrated under reduced pressure to a yellow, gummy solid and dried under a high vacuum pump. The crude amine 5 was then dissolved in DCM (15 mL) at zero degrees and to this was added BOC-Ala-OSu (0.839 g, 2.93 mmol) followed by triethylamine (0.898 mL, 6.45 mmol). The reaction was stirred at zero degrees for 1 hour and at room temperature for 16 hours. The solvent was then removed under reduced pressure and the residue partitioned between ethyl acetate and saturated NH4Cl. The layers were separated and the ethyl acetate phase washed further with saturated NH4Cl and then brine, dried over Na2SO4, filtered and concentrated. The residue was absorbed onto silica gel and then purified by silica gel chromatography using a 40M Biotage column with a gradient of 20 to 60% ethyl acetate and hexanes to give compound 6 (0.718 g, 51%) as a white crusty solid. LRMS (ESI): calc. 484.1; found 385.1 (MH-Boc)+, 507.2 (MNa)+. at 0 degrees It was cooled to 0 degrees slowly quenched with methanol (approx. 4 mL) After 10 minutes of stirring at room temperature the reaction solution was concentrated under reduced pressure to a yellow, gummy solid dried under a high vacuum pump The crude amine 5 was then dissolved in DCM (15 mL) at zero degrees The reaction was stirred at zero degrees for 1 hour and at room temperature for 16 hours The solvent was then removed under reduced pressure the residue partitioned between ethyl acetate and saturated NH4Cl The layers were separated the ethyl acetate phase washed further with saturated NH4Cl brine, dried over Na2SO4 filtered concentrated The residue was absorbed onto silica gel purified by silica gel chromatography

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

Procedure: (S)-2,5-Dioxopyrrolidin-1-yl 2-(tert-butoxycarbonylamino)propanoate (130 mg, 0.45 mmol) was added to amine 5 (110 mg, 0.35 mmol) and Et3N (94.4 mg, 130 μL, 0.93 mmol) in DCM (2 mL) and DMF (0.2 mL) and the mixture was stirred at room temperature for 36 h. DCM was added followed by 1N HCl and the organic layer was separated and washed with H2O, then with saturated NaHCO3, dried over MgSO4, filtered and concentrated. The crude material was purified by chromatography (Biotage, 25+S column) eluting with 0-50% EtOAc/hexanes. Compound 6 was obtained in 49% yield as a white solid. LRMS (ESI): calc. 484.5; found 507.1 (MNa)+. the organic layer was separated washed with H2O with saturated NaHCO3, dried over MgSO4 filtered concentrated The crude material was purified by chromatography (Biotage, 25+S column) eluting with 0-50% EtOAc/hexanes

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

Procedure: H-Glu(OBzl)-OH (7.0 g, 29.5 mmol) was finely ground in a mortar and pestle and then stirred with 8.88 g (32.3 mmol) of Boc-Ala-OSu for 48 hours in 250 ml DMF in the presence of 6 ml N-methylmorpholine (NMM). Some more NMM was added to maintain the reaction slightly basic during the reaction. The solvent was evaporated and the residue partitioned between 30 ml ethyl acetate and 500 ml H2O containing 2 ml of 10% H2SO4. The organic layer was then washed three times with water, dried(Na2SO4) and evaporated to dryness. The product was taken up in a small volume of ether and treated with a large volume of petroleum ether. A white amorphous solid was obtained which was homogeneous on tlc: Yield, 11.0 g (91.5%); mp 84°-88°; [α]D25 = -8.08° (c l, DMF). to maintain the reaction slightly basic during the reaction The solvent was evaporated the residue partitioned between 30 ml ethyl acetate and 500 ml H2O containing 2 ml of 10% H2SO4 The organic layer was then washed three times with water, dried(Na2SO4) evaporated to dryness treated with a large volume of petroleum ether A white amorphous solid was obtained which Yield

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

Procedure: The desired compound was prepared from 28.9 g of Boc-Pro-Arg(NO2)-OBzl, 150 ml of 4N HCl-AcOEt, 8 ml of Et3N and 16.3 g of Boc-Ala-OSu in the same manner as in Example 8-(1).