Under an atmosphere of argon, 1-(4-chlorophenyl)cyclopropanecarboxylic acid (1.57 g, 7.9 mmol, Eq: 1.20) was combined with tetrahydrofuran (70.0 ml) to give a colorless solution. Then EDC (3.09 g, 15.8 mmol, Eq: 2.40), HOBt (2.47 g, 15.8 mmol, Eq: 2.40) and triethylamine (6.66 g, 9.18 ml, 65.8 mmol, Eq: 10.0) was added. (A white suspension was obtained.) The reaction mixture was stirred for 15 min at room temperature. A solution of (2S,4R)-methyl 4-(2-chlorophenylsulfonyl)pyrrolidine-2-carboxylate (2 g, 6.58 mmol, Eq: 1.00) in tetrahydrofuran (14.0 ml) was added dropwise. The reaction was stirred for 3 days at room temperature. The reaction mixture was poured into 75 ml HCl 1M and extracted with 2×100 ml ethyl acetate. The organic layers were washed with 75 ml satd. Na2CO3 solution and 75 ml brine. The organic layer was dried over Na2SO4, filtered and concentrated in vacuo. The crude material was purified by flash chromatography (50 g column, from 0% to 100% ethyl acetate in heptane). The title compound was obtained as a light yellow solid (1.5 g, 47.2%, MS (m/e)=482.3 [M+H+]).
