ethyl (1R,2S)-2-aminocyclopentane-1-carboxylate

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

Procedure: To a solution of cis-ethyl 2-aminocyclopentanecarboxylate (1.57 g, 10 mmol) in 50 mL tetrahydrofuran was added 4-chlorobenzenesulfonyl chloride (3.17 g, 15 mmol) and triethylamine (2.1 mL, 15 mmol). The reaction was stirred at room temperature for 4 h, then diluted into 100 mL diethyl ether and washed with 100 mL water. The organic layer was concentrated and purified by flash chromatography on a 120 g silica gel column with 10 to 40% ethyl acetate in hexane, 20 min gradient, to yield cis-ethyl 2-(4-chlorophenylsulfonamido)cyclopentanecarboxylate (3.05 g, 92%). 1H NMR (400 MHz, CDCl3) δ ppm 7.76-7.80 (2H, m), 7.43-7.47 (2H, m), 5.57 (1 H, d, J=8.56 Hz), 3.91-4.10 (2H, m), 3.70-3.81 (1H, m), 2.74 (1H, dt, J=8.31, 6.55 Hz), 1.64-1.98 (5H, m), 1.44-1.58 (1H, m), 1.18 (3H, t, J=7.05 Hz). LC/MS R.T.=2.00 min; [M+H]+=332.07; [M+Na]+=354.04. washed with 100 mL water The organic layer was concentrated purified by flash chromatography on a 120 g silica gel column with 10 to 40% ethyl acetate in hexane, 20 min gradient

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

Procedure: A solution of cis-ethyl 2-(benzylamino)cyclopentanecarboxylate (2.99 g, 12.1 mmol), prepared according to Bartoli, G. et al., J. Org. Chem., 59:5328-5335, was hydrogenated along with 500 mg 10% palladium on carbon in 20 mL ethanol at 45 psi for 22 h. The reaction was filtered through a 45μ filter and concentrated to give cis-ethyl 2-aminocyclopentanecarboxylate (1.75 g, 92%). 1H NMR (400 MHz, CDCl3) δ ppm 4.14 (2H, q, J=7.13 Hz), 3.53-3.62 (1H, m), 2.75 (1H, td, J=8.37, 6.67 Hz), 1.93-2.11 (1H, m), 1.77-1.92 (3H, m), 1.43-1.62 (2H, m), 1.35 (2H, s), 1.25 (3H, t, J=7.18 Hz). MS [M+H]+=158.24. The reaction was filtered through a 45μ filter concentrated

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

Procedure: To a solution of cis-ethyl 2-aminocyclopentanecarboxylate (1.57 g, 10 mmol) in 50 mL tetrahydrofuran was added 4-chlorobenzenesulfonyl chloride (3.17 g, 15 mmol) and triethylamine (2.1 mL, 15 mmol). The reaction was stirred at room temperature for 4 h, then diluted into 100 mL diethyl ether and washed with 100 mL water. The organic layer was concentrated and purified by flash chromatography on a 120 g silica gel column with 10 to 40% ethyl acetate in hexane, 20 min gradient, to yield cis-ethyl 2-(4-chlorophenylsulfonamido)cyclopentanecarboxylate (3.05 g, 92%). 1H NMR (400 MHz, CDCl3) δ ppm 7.76-7.80 (2H, m), 7.43-7.47 (2H, m), 5.57 (1 H, d, J=8.56 Hz), 3.91-4.10 (2H, m), 3.70-3.81 (1H, m), 2.74 (1H, dt, J=8.31, 6.55 Hz), 1.64-1.98 (5H, m), 1.44-1.58 (1H, m), 1.18 (3H, t, J=7.05 Hz). LC/MS R.T.=2.00 min; [M+H]+=332.07; [M+Na]+=354.04. washed with 100 mL water The organic layer was concentrated purified by flash chromatography on a 120 g silica gel column with 10 to 40% ethyl acetate in hexane, 20 min gradient

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

Procedure: A solution of cis-ethyl 2-(benzylamino)cyclopentanecarboxylate (2.99 g, 12.1 mmol), prepared according to Bartoli, G. et al., J. Org. Chem., 59:5328-5335, was hydrogenated along with 500 mg 10% palladium on carbon in 20 mL ethanol at 45 psi for 22 h. The reaction was filtered through a 45μ filter and concentrated to give cis-ethyl 2-aminocyclopentanecarboxylate (1.75 g, 92%). 1H NMR (400 MHz, CDCl3) δ ppm 4.14 (2H, q, J=7.13 Hz), 3.53-3.62 (1H, m), 2.75 (1H, td, J=8.37, 6.67 Hz), 1.93-2.11 (1H, m), 1.77-1.92 (3H, m), 1.43-1.62 (2H, m), 1.35 (2H, s), 1.25 (3H, t, J=7.18 Hz). MS [M+H]+=158.24. The reaction was filtered through a 45μ filter concentrated