(1-bromo-2-methylpropan-2-yl) acetate

Conditions: temp:60.01; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: A solution of bromo-tert-butyl acetate (44.4 mL, 0.275 mol), (S)-leucine methyl ester hydrochloride (50 g, 0.275 mol) and diisopropylethyl amine (191 mL, 1.1 mol) in acetonitrile (400 mL) was stirred at room temperature for 16 hrs and heated at 60° C. for 4 hrs. After completion of the reaction (TLC, hexane-ethyl acetate, 9:1) a small aliquot (5 mL) was taken out and acetonitrile was removed under reduced pressure. Ethyl acetate (100 mL) was added and the solution was washed with water (2×100 mL), 10% aqueous citric acid (100 mL) and water (100 mL). The ethyl acetate extract was dried over sodium sulfate, evaporated under reduced pressure and chromatographed over silica gel column. Elution with 5% ethyl acetate in hexane gave pure N-tert-butyl acetyl-(S)-leucine methyl ester (2) as an oil, [α]D25 -17.2 (c, 2.9, MeOH); 1H NMR (CDCl3): 0.88 (3H, d, J=6.6 Hz), 0.89 (3H, d, J=6.6 Hz), 1.42 (9H, s), 1.48 (2H, m), 1.70 (1H, apparent hept, J=6.6 Hz), 3.24 (2H, ABq, J=18 Hz), 3.29 (1H, t, J=7.2 Hz), 3.68 (3H, s); 13C NMR (CDCl3): 22.34 (CH3), 22.65 (CH3), 24.81 (CH), 28.06 (C(CH3)3), 42.44 (CH2), 49.86 (CH2), 51.74 (OCH3), 59.22 (CH), 81.26 (C), 170.87 (CO), 175.43 (CO). acetonitrile was removed under reduced pressure Ethyl acetate (100 mL) was added the solution was washed with water (2×100 mL), 10% aqueous citric acid (100 mL) and water (100 mL) The ethyl acetate extract was dried over sodium sulfate evaporated under reduced pressure chromatographed over silica gel column Elution with 5% ethyl acetate in hexane

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

Procedure: To a mixture of 3-methylthiopropylamine (30.0 g, 0.285 mol) and sodium bicarbonate (12.0 g, 0.142 mol) in 250 ml of ethanol was added dropwise bromo-t-butyl acetate (27.8 g, 0.142 mol). After 5 hours the ethanol was removed on a rotary evaporator and the residue partitioned between water and chloroform. The chloroform layer was dried, filtered and concentrated to give 36.4 g of crude N-(3-methylthiopropyl)glycine t-butyl ester as an oil. After 5 hours the ethanol was removed on a rotary evaporator the residue partitioned between water and chloroform The chloroform layer was dried filtered concentrated

Conditions: temp:60.01; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: A solution of bromo-tert-butyl acetate (44.4 mL, 0.275 mol), (S)-leucine methyl ester hydrochloride (50 g, 0.275 mol) and diisopropylethyl amine (191 mL, 1.1 mol) in acetonitrile (400 mL) was stirred at room temperature for 16 hrs and heated at 60° C. for 4 hrs. After completion of the reaction (TLC, hexane-ethyl acetate, 9:1) a small aliquot (5 mL) was taken out and acetonitrile was removed under reduced pressure. Ethyl acetate (100 mL) was added and the solution was washed with water (2×100 mL), 10% aqueous citric acid (100 mL) and water (100 mL). The ethyl acetate extract was dried over sodium sulfate, evaporated under reduced pressure and chromatographed over silica gel column. Elution with 5% ethyl acetate in hexane gave pure N-tert-butyl acetyl-(S)-leucine methyl ester (2) as an oil, [α]D25 -17.2 (c, 2.9, MeOH); 1H NMR (CDCl3): 0.88 (3H, d, J=6.6 Hz), 0.89 (3H, d, J=6.6 Hz), 1.42 (9H, s), 1.48 (2H, m), 1.70 (1H, apparent hept, J=6.6 Hz), 3.24 (2H, ABq, J=18 Hz), 3.29 (1H, t, J=7.2 Hz), 3.68 (3H, s); 13C NMR (CDCl3): 22.34 (CH3), 22.65 (CH3), 24.81 (CH), 28.06 (C(CH3)3), 42.44 (CH2), 49.86 (CH2), 51.74 (OCH3), 59.22 (CH), 81.26 (C), 170.87 (CO), 175.43 (CO). acetonitrile was removed under reduced pressure Ethyl acetate (100 mL) was added the solution was washed with water (2×100 mL), 10% aqueous citric acid (100 mL) and water (100 mL) The ethyl acetate extract was dried over sodium sulfate evaporated under reduced pressure chromatographed over silica gel column Elution with 5% ethyl acetate in hexane

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

Procedure: To a mixture of 3-methylthiopropylamine (30.0 g, 0.285 mol) and sodium bicarbonate (12.0 g, 0.142 mol) in 250 ml of ethanol was added dropwise bromo-t-butyl acetate (27.8 g, 0.142 mol). After 5 hours the ethanol was removed on a rotary evaporator and the residue partitioned between water and chloroform. The chloroform layer was dried, filtered and concentrated to give 36.4 g of crude N-(3-methylthiopropyl)glycine t-butyl ester as an oil. After 5 hours the ethanol was removed on a rotary evaporator the residue partitioned between water and chloroform The chloroform layer was dried filtered concentrated

Conditions: temp:60.01; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: A solution of bromo-tert-butyl acetate (44.4 mL, 0.275 mol), (S)-leucine methyl ester hydrochloride (50 g, 0.275 mol) and diisopropylethyl amine (191 mL, 1.1 mol) in acetonitrile (400 mL) was stirred at room temperature for 16 hrs and heated at 60° C. for 4 hrs. After completion of the reaction (TLC, hexane-ethyl acetate, 9:1) a small aliquot (5 mL) was taken out and acetonitrile was removed under reduced pressure. Ethyl acetate (100 mL) was added and the solution was washed with water (2×100 mL), 10% aqueous citric acid (100 mL) and water (100 mL). The ethyl acetate extract was dried over sodium sulfate, evaporated under reduced pressure and chromatographed over silica gel column. Elution with 5% ethyl acetate in hexane gave pure N-tert-butyl acetyl-(S)-leucine methyl ester (2) as an oil, [α]D25 -17.2 (c, 2.9, MeOH); 1H NMR (CDCl3): 0.88 (3H, d, J=6.6 Hz), 0.89 (3H, d, J=6.6 Hz), 1.42 (9H, s), 1.48 (2H, m), 1.70 (1H, apparent hept, J=6.6 Hz), 3.24 (2H, ABq, J=18 Hz), 3.29 (1H, t, J=7.2 Hz), 3.68 (3H, s); 13C NMR (CDCl3): 22.34 (CH3), 22.65 (CH3), 24.81 (CH), 28.06 (C(CH3)3), 42.44 (CH2), 49.86 (CH2), 51.74 (OCH3), 59.22 (CH), 81.26 (C), 170.87 (CO), 175.43 (CO). acetonitrile was removed under reduced pressure Ethyl acetate (100 mL) was added the solution was washed with water (2×100 mL), 10% aqueous citric acid (100 mL) and water (100 mL) The ethyl acetate extract was dried over sodium sulfate evaporated under reduced pressure chromatographed over silica gel column Elution with 5% ethyl acetate in hexane

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

Procedure: To a mixture of 3-methylthiopropylamine (30.0 g, 0.285 mol) and sodium bicarbonate (12.0 g, 0.142 mol) in 250 ml of ethanol was added dropwise bromo-t-butyl acetate (27.8 g, 0.142 mol). After 5 hours the ethanol was removed on a rotary evaporator and the residue partitioned between water and chloroform. The chloroform layer was dried, filtered and concentrated to give 36.4 g of crude N-(3-methylthiopropyl)glycine t-butyl ester as an oil. After 5 hours the ethanol was removed on a rotary evaporator the residue partitioned between water and chloroform The chloroform layer was dried filtered concentrated