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In an inert atmosphere glovebox, samarium (III) trifluoromethanesulfonate (1.20 g, 2.0 mmol) was added to a flame-dried 250 mL 3-neck round bottom flask fitted with a glass stopper, a septum, and a vacuum hose adapter followed by powdered 4 Å molecular sieves (4.0 g). Following removal from the glove-box, the reaction was placed under nitrogen and (S)-phenylalanine methyl amide (8.91 g, 50 mmol) was added as a solution in 80 mL of tetrahydrofuran immediately followed by freshly distilled (77° C., 14 mmHg, Vigreaux collumn) clear, colorless 5-methylfurfural (3.98 mL, 40 mmol). After stirring for 29 hours at room temperature, the reaction mixture was filtered through a plug of silica with dichloromethane, concentrated and purified by silica gel chromatography (1:1 ethyl acetate:hexanes) to afford the title compound as a clear, colorless oil in 46% yield (4.93 g, 18.2 mmol) and the faster eluting (2R, 5S) isomer as a pale yellow oil in 38% yield (4.10 g, 15.2 mmol). IR (film) 3482, 3325, 2922, 2862, 1695, 1563, 1495, 1477, 1453, 1402, 1326, 1267, 1218, 1098, 1021, 1006, 956.8, 938.9, 791.1, 734.4, 701.5 cm−1; 1H NMR (300 MHz, CDCl3) δ 7.26 (m, 5H, PhH), 6.11 (m, 1H, CHCHCCH3), 5.89 (m, 1H, CHCHCCH3 ), 5.19 (s, 1H, NCHN), 3.79 (dd, J=7.2, 4.5 Hz, 1H, CHCONMe), 3.26 (dd, J=14.4, 4.5 Hz, 1H, one of CH2Ph), 3.09 (dd, J=14.1, 7.5 Hz, 1H, one of CH2Ph), 2.64 (s, 3H, NCH3), 2.21 (s, 3H, ArCH3), 2.10 (br s, 1H, NH); 13C NMR (75 MHz, CDCl3) δ 173.9, 153.5, 148.5, 137.3, 129.6, 128.9, 127.0, 111.2, 106.6, 71.3, 60.5, 37.8, 27.4, 14.0; HRMS (CI) exact mass calc'd for (C16H18N2O2) requires m/z 270.1368, found m/z 270.1368. [α]D=−156.5 (g=1.0, CHCl3). The enantiopurity of the catalyst was confirmed (>99% ee) by HPLC analysis (AD column, 5% isopropanol in hexanes, 1 mL/min, 254 nm); (2S, 5S) isomer tr=22.9 min, (2S, 5R) isomer tr=25.7 min. The relative stereochemistry of catalyst 5 was confirmed by NOE studies.

1. customround bottom flask fitted with a glass stopper
2. customremoval from the glove-box
3. distillationby freshly distilled (77° C., 14 mmHg, Vigreaux collumn) clear
4. filtrationthe reaction mixture was filtered through a plug of silica with dichloromethane
5. concentrationconcentrated
6. custompurified by silica gel chromatography (1:1 ethyl acetate:hexanes)