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- “ Typical experimental procedure for the synthesis of amide catalysts: To a stirred solution of N Cbz‐proline 12 (498 mg, 2.0 mmol) in dichloromethane (10 mL) was successively added (1R, 2S)‐norephedrin (302 mg, 2.0 mmol) in dichloromethane (5 mL) followed by DMAP (12 mg, 0.1 mmol) and DCC (413 mg, 2 mmol) in dichloromethane (5 mL). After stirring for 20 hr at room temperature, the mixture was filtered. The filtrate was successively washed with 1 N HCl, water, saturated NaHCO3, and brine and dried over Na2SO4. Filtration and concentration in vacuo gave white solid, which was chromatographed on silica gel (eluting with Hexane:EtOAc = 1:1) to give 15 (658 mg, 86%) as a white crystal ” . The mixture of amide 15 (1 g, 2.61 mmol) and 10% Pd‐C in MeOH (30 ml) was hydrogenated at 0.3 MPa for 2 hr at room temperature. After filtration, the mixture was concentrated in vacuo. The residue was chromatographed on silica gel (CHC13:MeOH = 9:1) to give 8 (586 mg, 90%) as a white crystal. Data for 8: Rf = 0.40 (CHCl3:CH3OH = 7:1); m.p. 127–128°C; 1H‐NMR (400 MHz, CDCl3) δ: 1.00–1.20 (d, J = 6.9 Hz, 3H, CH 3), 1.65–1.70 (sep, J = 6.5 Hz, 2H, pyrrolidine H4), 1.80–1.90 (sex, J = 5.6 Hz, 1H, one of pyrrolidine H3), 2.05–2.15 (m, 1.H, one of pyrrolidine H3), 2.80–2.87 (m, 1H, one of pyrrolidine H5), 2.92–3.00 (m, 1H, one of pyrrolidine H5), 2.71–3.42 (br s, 1H, OH), 3.73 (q, J = 4.6 Hz, 1H, pyrrolidine H2), 4.21–4.31 (dsep, J d = 29 Hz, J sep = 7.9 Hz, 1H, CHCH3), 4.82 (d, J = 2.9 Hz, 1H, CHOH), 7.25–7.35 (m, 5H, Ph), 7.65 (br d, 1H, amide NH); 13C‐NMR (136 MHz, CDCl3) δ: 14.9, 26.1, 30.6, 47.2, 50.9, 60.4, 76.8, 126.4 (×2), 127.3, 127.9 (×2), 140.8, 175.9; MALDI‐TOF‐MS (matrix, 2,5‐dihydroxybenzoic acid) m/z 271.3 [M] + ; IR (KBr‐solid): 3355, 3311, 2970, 1620, 1529, 1450, 1119, 1000, 700, 571 cm−1; [α]D 22 = − 111.6 (c 1, CHCl3)
- Typical experimental procedure for aldol reaction: The mixture of isobutylaldehyde (142 mg, 1.97 mmol), 8 (97.8 mg, 20 mol%) in acetone was cooled to −40°C and stirred for 48 hr in an nitrogen atmosphere. Saturated aqueous NH4Cl was added, and the mixture was extracted with ethyl acetate. Drying by sodium sulfate followed by concentration in vacuo to give crude product, which was purified by silica gel chromatography to give keto alcohol 17 4c (56.5 mg, 22%) as a colorless liquid. [α]D 22 = +63.4 (c 1, CHCl3)