methyl (2S)-2-[[(2S)-2-[(2-methylpropan-2-yl)oxycarbonylamino]propanoyl]amino]propanoate

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

Procedure: To a solution of LiOH.H2O (275 mg, 6.56 mmol) in a mixture of solvents MeOH:H2O (10.9 mL:3.6 mL) was added Boc-Ala-Ala-OMe (1.2 g, 4.38 mmol) and stirred for 4 hours at r.t. The solution was acidified to pH 2 with saturated aqueous solution of citric acid and the mixture was extracted with EtOAc (3×20 mL). The organic layer was dried over Na2SO4 and concentrated under vacuum to give the desired product Boc-Ala-Ala-OH as a highly viscous and hygroscopic oil in quantitative yields (1.14 g). The product was taken for further reactions directly without any purification. the mixture was extracted with EtOAc (3×20 mL) The organic layer was dried over Na2SO4 concentrated under vacuum

Conditions: temp:25.01; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: To a cold (−15° C.) solution of Boc-Ala-OH (1.034 g, 5.47 mmol) and NMM (901 μl, 8.20 mmol) in THF (15 mL) was added ECF (538 μl, 5.63 mmol) under N2 atmosphere and vigorously stirred. After 2 min of stirring, a solution of methyl alaninate hydrochloride (840 mg, 6.01 mmol) in a mixture of solvents THF:DMF (4 mL:3 mL) was added to the reaction mixture followed by NMM (1.5 mL, 13.67 mmol) and stirred. After 10 min the mixture was warmed to 25° C. and stirred for further 8 h. THF was removed under reduced pressure and the resulting viscous solution was diluted with water (10 mL) and thoroughly extracted with ethyl acetate. The combined organic extracts were washed with saturated citric acid (10 mL), saturated NaHCO3 (10 mL) and dried over by Na2SO4 and concentrated under reduced pressure to give a residue, which was purified by silica gel flash column chromatograph (EtOAc:Hexane—3:17) to give the desired product as a solid (m.p. 107-108° C.) in good yields (1.48 g, 98.6%). (TLC:EtOAc:Hexanes 7:3—Rf—0.55). After 2 min of stirring stirred stirred for further 8 h THF was removed under reduced pressure the resulting viscous solution was diluted with water (10 mL) thoroughly extracted with ethyl acetate The combined organic extracts were washed with saturated citric acid (10 mL), saturated NaHCO3 (10 mL) dried over by Na2SO4 concentrated under reduced pressure to give a residue, which was purified by silica gel flash column chromatograph (EtOAc:Hexane—3:17)

Conditions: temp:25.01; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: To a cold (−15° C.) solution of Boc-Ala-OH (1.034 g, 5.47 mmol) and NMM (901 μl, 8.20 mmol) in THF (15 mL) was added ECF (538 μl, 5.63 mmol) under N2 atmosphere and vigorously stirred. After 2 min of stirring, a solution of methyl alaninate hydrochloride (840 mg, 6.01 mmol) in a mixture of solvents THF:DMF (4 mL:3 mL) was added to the reaction mixture followed by NMM (1.5 mL, 13.67 mmol) and stirred. After 10 min the mixture was warmed to 25° C. and stirred for further 8 h. THF was removed under reduced pressure and the resulting viscous solution was diluted with water (10 mL) and thoroughly extracted with ethyl acetate. The combined organic extracts were washed with saturated citric acid (10 mL), saturated NaHCO3 (10 mL) and dried over by Na2SO4 and concentrated under reduced pressure to give a residue, which was purified by silica gel flash column chromatograph (EtOAc:Hexane—3:17) to give the desired product as a solid (m.p. 107-108° C.) in good yields (1.48 g, 98.6%). (TLC:EtOAc:Hexanes 7:3—Rf—0.55). After 2 min of stirring stirred stirred for further 8 h THF was removed under reduced pressure the resulting viscous solution was diluted with water (10 mL) thoroughly extracted with ethyl acetate The combined organic extracts were washed with saturated citric acid (10 mL), saturated NaHCO3 (10 mL) dried over by Na2SO4 concentrated under reduced pressure to give a residue, which was purified by silica gel flash column chromatograph (EtOAc:Hexane—3:17)

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

Procedure: Boc-(L)-Ala-(L)-Ala-OMe was prepared as follows. Boc-(L)-Ala-OH (2.06 g, 10.63 mmol) was dissolved in distilled dichloromethane (5 mL). To the resulting solution was added H2N-(L)-Ala-OMe (0.996 g, 9.67 mmol) in 5 mL of distilled dichloromethane. Dicyclohexylcarbodiimide (abbr. DCC; 2.19 g, 10.63 mmol) was dissolved in 3 mL distilled dichloromethane and added to the solution. Dicyclohexylurea (abbr. DCU) precipitation was noted immediately after DCC addition. Triethylamine (3 mL, 21.52 mmol) and additional distilled dichloromethane (4 mL) were added to the reaction mixture. The reaction proceeded for a total of three hours, when TLC analysis indicated consumption of H2N-(L)-Ala-OMe starting material and formation of a new component. DCU precipitation was promoted by storing the reaction at −20° C. The precipitate was filtered through a Buchner funnel and rinsed with cold dichloromethane. The combined filtrate and rinses were dried under vacuum and purified by Silica chromatography to yield dipeptide Boc-(L)-Ala-(L)-Ala-OMe (2.03 g, 7.14 mmol, 74%). 1H-NMR (chloroform-d) δ (ppm): 1.34 (d, J=14.1 Hz, 3H); 1.38 (d, J=14.3 Hz, 3H); 1.40 (s, 9H); 3.73 (s, 3H); 4.14 (s-broad, 1H); 4.55 (quintet, J=14.5 Hz, 1H); 4.97 (s-broad, 1H); 6.59 (s-broad, 1H). distilled dichloromethane added to the solution Dicyclohexylurea (abbr. DCU) precipitation after DCC addition were added to the reaction mixture proceeded for a total of three hours, when TLC analysis consumption of H2N-(L)-Ala-OMe starting material and formation of a new component DCU precipitation the reaction at −20° C The precipitate was filtered through a Buchner funnel rinsed with cold dichloromethane The combined filtrate and rinses were dried under vacuum purified by Silica chromatography

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

Procedure: Boc-(L)-Ala-(L)-Ala-OMe was prepared as follows. Boc-(L)-Ala-OH (2.06 g, 10.63 mmol) was dissolved in distilled dichloromethane (5 mL). To the resulting solution was added H2N-(L)-Ala-OMe (0.996 g, 9.67 mmol) in 5 mL of distilled dichloromethane. Dicyclohexylcarbodiimide (abbr. DCC; 2.19 g, 10.63 mmol) was dissolved in 3 mL distilled dichloromethane and added to the solution. Dicyclohexylurea (abbr. DCU) precipitation was noted immediately after DCC addition. Triethylamine (3 mL, 21.52 mmol) and additional distilled dichloromethane (4 mL) were added to the reaction mixture. The reaction proceeded for a total of three hours, when TLC analysis indicated consumption of H2N-(L)-Ala-OMe starting material and formation of a new component. DCU precipitation was promoted by storing the reaction at −20° C. The precipitate was filtered through a Buchner funnel and rinsed with cold dichloromethane. The combined filtrate and rinses were dried under vacuum and purified by Silica chromatography to yield dipeptide Boc-(L)-Ala-(L)-Ala-OMe (2.03 g, 7.14 mmol, 74%). 1H-NMR (chloroform-d) δ (ppm): 1.34 (d, J=14.1 Hz, 3H); 1.38 (d, J=14.3 Hz, 3H); 1.40 (s, 9H); 3.73 (s, 3H); 4.14 (s-broad, 1H); 4.55 (quintet, J=14.5 Hz, 1H); 4.97 (s-broad, 1H); 6.59 (s-broad, 1H). distilled dichloromethane added to the solution Dicyclohexylurea (abbr. DCU) precipitation after DCC addition were added to the reaction mixture proceeded for a total of three hours, when TLC analysis consumption of H2N-(L)-Ala-OMe starting material and formation of a new component DCU precipitation the reaction at −20° C The precipitate was filtered through a Buchner funnel rinsed with cold dichloromethane The combined filtrate and rinses were dried under vacuum purified by Silica chromatography

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

Procedure: To a solution of LiOH.H2O (275 mg, 6.56 mmol) in a mixture of solvents MeOH: H2O (10.9 mL: 3.6 mL) was added Boc-Ala-Ala-OMe (1.2 g, 4.38 mmol) and stirred for 4 hours at r.t. The solution was acidified to pH 2 with saturated aqueous solution of citric acid and the mixture was extracted with EtOAc (3×20 mL). The organic layer was dried over Na2SO4 and concentrated under vacuum to give the desired product Boc-Ala-Ala-OH as a highly viscous and hygroscopic oil in quantitative yields (1.14 g). The product was taken for further reactions directly without any purification. the mixture was extracted with EtOAc (3×20 mL) The organic layer was dried over Na2SO4 concentrated under vacuum

Conditions: temp:25.01; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: To a cold (−15° C.) solution of Boc-Ala-OH (1.034 g, 5.47 mmol) and NMM (901 μl, 8.20 mmols) in THF (15 ml) was added ECF (538 μl, 5.63 mmols) under N2 atmosphere and vigorously stirred. After 2 min of stirring, a solution of methyl alaninate hydrochloride (840 mg, 6.01 mmols) in a mixture of solvents THF:DMF (4 mL: 3 mL) was added to the reaction mixture followed by NMM (1.5 ml, 13.67 mmols) and stirred. After 10 min the mixture was warmed to 25° C. and stirred for further 8 h. THF was removed under reduced pressure and the resulting viscous solution was diluted with water (10 mL) and thoroughly extracted with ethyl acetate. The combined organic extracts were washed with saturated citric acid (10 mL), saturated NaHCO3 (10 mL) and dried over by Na2SO4 and concentrated under reduced pressure to give a residue, which was purified by silica gel flash column chromatograph (EtOAc:Hexane—3:17) to give the desired product as a solid (m.p. 107-108° C.) in good yields (1.48 g, 98.6%). (TLC:EtOAc:Hexanes 7:3—Rf—0.55). After 2 min of stirring stirred stirred for further 8 h THF was removed under reduced pressure the resulting viscous solution was diluted with water (10 mL) thoroughly extracted with ethyl acetate The combined organic extracts were washed with saturated citric acid (10 mL), saturated NaHCO3 (10 mL) dried over by Na2SO4 concentrated under reduced pressure to give a residue, which was purified by silica gel flash column chromatograph (EtOAc:Hexane—3:17)

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

Procedure: To a solution of LiOH.H2O (275 mg, 6.56 mmol) in a mixture of solvents MeOH:H2O (10.9 mL:3.6 mL) was added Boc-Ala-Ala-OMe (1.2 g, 4.38 mmol) and stirred for 4 hours at r.t. The solution was acidified to pH 2 with saturated aqueous solution of citric acid and the mixture was extracted with EtOAc (3×20 mL). The organic layer was dried over Na2SO4 and concentrated under vacuum to give the desired product Boc-Ala-Ala-OH as a highly viscous and hygroscopic oil in quantitative yields (1.14 g). The product was taken for further reactions directly without any purification. the mixture was extracted with EtOAc (3×20 mL) The organic layer was dried over Na2SO4 concentrated under vacuum

Conditions: temp:25.01; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: To a cold (−15° C.) solution of Boc-Ala-OH (1.034 g, 5.47 mmol) and NMM (901 μl, 8.20 mmol) in THF (15 mL) was added ECF (538 μl, 5.63 mmol) under N2 atmosphere and vigorously stirred. After 2 min of stirring, a solution of methyl alaninate hydrochloride (840 mg, 6.01 mmol) in a mixture of solvents THF:DMF (4 mL:3 mL) was added to the reaction mixture followed by NMM (1.5 mL, 13.67 mmol) and stirred. After 10 min the mixture was warmed to 25° C. and stirred for further 8 h. THF was removed under reduced pressure and the resulting viscous solution was diluted with water (10 mL) and thoroughly extracted with ethyl acetate. The combined organic extracts were washed with saturated citric acid (10 mL), saturated NaHCO3 (10 mL) and dried over by Na2SO4 and concentrated under reduced pressure to give a residue, which was purified by silica gel flash column chromatograph (EtOAc:Hexane—3:17) to give the desired product as a solid (m.p. 107-108° C.) in good yields (1.48 g, 98.6%). (TLC:EtOAc:Hexanes 7:3—Rf—0.55). After 2 min of stirring stirred stirred for further 8 h THF was removed under reduced pressure the resulting viscous solution was diluted with water (10 mL) thoroughly extracted with ethyl acetate The combined organic extracts were washed with saturated citric acid (10 mL), saturated NaHCO3 (10 mL) dried over by Na2SO4 concentrated under reduced pressure to give a residue, which was purified by silica gel flash column chromatograph (EtOAc:Hexane—3:17)

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

Procedure: Boc-(L)-Ala-(L)-Ala-OMe was prepared as follows. Boc-(L)-Ala-OH (2.06 g, 10.63 mmol) was dissolved in distilled dichloromethane (5 mL). To the resulting solution was added H2N-(L)-Ala-OMe (0.996 g, 9.67 mmol) in 5 mL of distilled dichloromethane. Dicyclohexylcarbodiimide (abbr. DCC; 2.19 g, 10.63 mmol) was dissolved in 3 mL distilled dichloromethane and added to the solution. Dicyclohexylurea (abbr. DCU) precipitation was noted immediately after DCC addition. Triethylamine (3 mL, 21.52 mmol) and additional distilled dichloromethane (4 mL) were added to the reaction mixture. The reaction proceeded for a total of three hours, when TLC analysis indicated consumption of H2N-(L)-Ala-OMe starting material and formation of a new component. DCU precipitation was promoted by storing the reaction at −20° C. The precipitate was filtered through a Buchner funnel and rinsed with cold dichloromethane. The combined filtrate and rinses were dried under vacuum and purified by Silica chromatography to yield dipeptide Boc-(L)-Ala-(L)-Ala-OMe (2.03 g, 7.14 mmol, 74%). 1H-NMR (chloroform-d) δ (ppm): 1.34 (d, J=14.1 Hz, 3H); 1.38 (d, J=14.3 Hz, 3H); 1.40 (s, 9H); 3.73 (s, 3H); 4.14 (s-broad, 1H); 4.55 (quintet, J=14.5 Hz, 1H); 4.97 (s-broad, 1H); 6.59 (s-broad, 1H). distilled dichloromethane added to the solution Dicyclohexylurea (abbr. DCU) precipitation after DCC addition were added to the reaction mixture proceeded for a total of three hours, when TLC analysis consumption of H2N-(L)-Ala-OMe starting material and formation of a new component DCU precipitation the reaction at −20° C The precipitate was filtered through a Buchner funnel rinsed with cold dichloromethane The combined filtrate and rinses were dried under vacuum purified by Silica chromatography