tert-butyl (2S)-2-(2-methoxy-2-oxoethyl)pyrrolidine-1-carboxylate

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

Procedure: A solution of (S)-2-carboxymethyl-pyrrolidine-1-carboxylic acid tert-butyl ester (2.00 g) in methanol (1.32 ml)/acetonitrile (40 ml) was treated with N,N-diisopropylethylamine (1.78 ml). Trimethylsilyldiazomethane, (2M, 8.73 ml) was added dropwise and the resulting mixture was stirred at room temperature, under argon for 24 h. The mixture was diluted with ethyl acetate, washed with 2M HCl, saturated aqueous sodium hydrodgen carbonate, brine then dried (magnesium sulfate). The solvent was removed under reduced pressure to afford the title compound (2.10 g) washed with 2M HCl, saturated aqueous sodium hydrodgen carbonate, brine then dried (magnesium sulfate) The solvent was removed under reduced pressure

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

Procedure: A solution of (S)-2-carboxymethyl-pyrrolidine-1-carboxylic acid tert-butyl ester (2.00 g) in methanol (1.32 ml)/acetonitrile (40 ml) was treated with N,N-diisopropylethylamine (1.78 ml). Trimethylsilyldiazomethane (2M, 8.73 ml) was added dropwise and the resulting mixture was stirred at room temperature, under argon for 24 h. The mixture was diluted with ethyl acetate, washed with 2M HCl, saturated aqueous sodium hydrogen carbonate, brine then dried (magnesium sulfate). The solvent was removed under reduced pressure to afford the title compound (2.10 g) washed with 2M HCl, saturated aqueous sodium hydrogen carbonate, brine then dried (magnesium sulfate) The solvent was removed under reduced pressure

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

Procedure: A solution of (S)-2-carboxymethyl-pyrrolidine-1-carboxylic acid tert-butyl ester (2.00 g) in methanol (1.32 ml)/acetonitrile (40 ml) was treated with N,N-diisopropylethylamine (1.78 ml). Trimethylsilyldiazomethane (2M, 8.73 ml) was added dropwise and the resulting mixture was stirred at room temperature, under argon for 24 h. The mixture was diluted with ethyl acetate, washed with 2M HCl, saturated aqueous sodium hydrogen carbonate, brine then dried (magnesium sulfate). The solvent was removed under reduced pressure to afford the title compound (2.10 g) washed with 2M HCl, saturated aqueous sodium hydrogen carbonate, brine then dried (magnesium sulfate) The solvent was removed under reduced pressure

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

Procedure: tert-Butyl (2S)-2-(2-methoxy-2-oxoethyl)-1-pyrrolidinecarboxylate (8.35 g, 34.3 mmol) was dissolved in 150 mL MeOH. Aqueous NaOH (50 mL, 1 M) was added and the reaction mixture was allowed to stand overnight. After concentration in vacuo to ca. 100 mL, the solution was added to 300 mL water and extracted with ether (2×). The carboxylate solution was acidified to pH 2 with 12 N HCl and extracted with ether (2×). The aqueous layer was saturated with salt and extracted a third time with ether. The combined organic layers were washed with water, brine and dried over MgSO4. Filtration and concentration provided the title acid as a white solid (7.28 g, 31.7 mmol, 92.6%): 1H NMR (300 MHz, CDCl3, mixture of rotamers) δ 4.16 (bs, 1H), 3.37 (bs, 2H), 3.0–2.8 (bs, 1H), 2.36 (dd, J=9.3, 15.3 Hz, 1H), 2.2–2.0 (m, 1H), 1.9–1.7 (m, 4H), 1.48 (s, 9H) ppm. After concentration in vacuo to ca. 100 mL the solution was added to 300 mL water extracted with ether (2×) extracted with ether (2×) extracted a third time with ether The combined organic layers were washed with water, brine dried over MgSO4 Filtration and concentration

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

Procedure: tert-Butyl (2S)-2-(2-methoxy-2-oxoethyl)-1-pyrrolidinecarboxylate (8.35 g, 34.3 mmol) was dissolved in 150 mL MeOH. Aqueous NaOH (50 mL, 1 M) was added and the reaction mixture was allowed to stand overnight. After concentration in vacuo to ca. 100 mL, the solution was added to 300 mL water and extracted with ether (2×). The carboxylate solution was acidified to pH 2 with 12 N HCl and extracted with ether (2×). The aqueous layer was saturated with salt and extracted a third time with ether. The combined organic layers were washed with water, brine and dried over MgSO4. Filtration and concentration provided the title acid as a white solid (7.28 g, 31.7 mmol, 92.6%): 1H NMR (300 MHz, CDCl3, mixture of rotamers) δ 4.16 (bs, 1H), 3.37 (bs, 2H), 3.0–2.8 (bs, 1H), 2.36 (dd, J=9.3, 15.3 Hz, 1H), 2.2–2.0 (m, 1H), 1.9–1.7 (m, 4H), 1.48 (s, 9H) ppm. After concentration in vacuo to ca. 100 mL the solution was added to 300 mL water extracted with ether (2×) extracted with ether (2×) extracted a third time with ether The combined organic layers were washed with water, brine dried over MgSO4 Filtration and concentration

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

Procedure: A solution of (S)-2-carboxymethyl-pyrrolidine-1-carboxylic acid tert-butyl ester (2.00 g) in methanol (1.32 ml)/acetonitrile (40 ml) was treated with N,N-diisopropylethylamine (1.78 ml). Trimethylsilyldiazomethane, (2M, 8.73 ml) was added dropwise and the resulting mixture was stirred at room temperature, under argon for 24 h. The mixture was diluted with ethyl acetate, washed with 2M HCl, saturated aqueous sodium hydrodgen carbonate, brine then dried (magnesium sulfate). The solvent was removed under reduced pressure to afford the title compound (2.10 g) washed with 2M HCl, saturated aqueous sodium hydrodgen carbonate, brine then dried (magnesium sulfate) The solvent was removed under reduced pressure

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

Procedure: A solution of (S)-2-carboxymethyl-pyrrolidine-1-carboxylic acid tert-butyl ester (2.00 g) in methanol (1.32 ml)/acetonitrile (40 ml) was treated with N,N-diisopropylethylamine (1.78 ml). Trimethylsilyldiazomethane, (2M, 8.73 ml) was added dropwise and the resulting mixture was stirred at room temperature, under argon for 24 h. The mixture was diluted with ethyl acetate, washed with 2M HCl, saturated aqueous sodium hydrodgen carbonate, brine then dried (magnesium sulfate). The solvent was removed under reduced pressure to afford the title compound (2.10 g) washed with 2M HCl, saturated aqueous sodium hydrodgen carbonate, brine then dried (magnesium sulfate) The solvent was removed under reduced pressure

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

Procedure: A solution of (S)-2-carboxymethyl-pyrrolidine-1-carboxylic acid tert-butyl ester (2.00 g) in methanol (1.32 ml)/acetonitrile (40 ml) was treated with N,N-diisopropylethylamine (1.78 ml). Trimethylsilyldiazomethane (2M, 8.73 ml) was added dropwise and the resulting mixture was stirred at room temperature, under argon for 24 h. The mixture was diluted with ethyl acetate, washed with 2M HCl, saturated aqueous sodium hydrogen carbonate, brine then dried (magnesium sulfate). The solvent was removed under reduced pressure to afford the title compound (2.10 g) washed with 2M HCl, saturated aqueous sodium hydrogen carbonate, brine then dried (magnesium sulfate) The solvent was removed under reduced pressure

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

Procedure: tert-Butyl (2S)-2-(2-methoxy-2-oxoethyl)-1-pyrrolidinecarboxylate (8.35 g, 34.3 mmol) was dissolved in 150 mL MeOH. Aqueous NaOH (50 mL, 1 M) was added and the reaction mixture was allowed to stand overnight. After concentration in vacuo to ca. 100 mL, the solution was added to 300 mL water and extracted with ether (2×). The carboxylate solution was acidified to pH 2 with 12 N HCl and extracted with ether (2×). The aqueous layer was saturated with salt and extracted a third time with ether. The combined organic layers were washed with water, brine and dried over MgSO4. Filtration and concentration provided the title acid as a white solid (7.28 g, 31.7 mmol, 92.6%): 1H NMR (300 MHz, CDCl3, mixture of rotamers) δ 4.16 (bs, 1H), 3.37 (bs, 2H), 3.0–2.8 (bs, 1H), 2.36 (dd, J=9.3, 15.3 Hz, 1H), 2.2–2.0 (m, 1H), 1.9–1.7 (m, 4H), 1.48 (s, 9H) ppm. After concentration in vacuo to ca. 100 mL the solution was added to 300 mL water extracted with ether (2×) extracted with ether (2×) extracted a third time with ether The combined organic layers were washed with water, brine dried over MgSO4 Filtration and concentration