Reaction Steps
Prepared according to the general procedure from 2-chloro-hydrocinnamaldehyde and (E)-methyl 4-oxo-4-phenylbut-2-enoate using 0.5 mol % 1 as the catalyst in 91% yield as a 8:1 mixture of diastereomers (white solid). [α]D20 (c 1.16, CHCl3)=+130.4; mp=103-106° C.; 1H NMR (400 MHz, CDCl3) δ 7.67-7.61 (m, 2H), 7.41-7.27 (m, 6H), 7.27-7.17 (m, 2H), 5.82 (d, 1H, J=7.0 Hz), 5.75* (d, 1H, J=5.7 Hz), 3.77 (s, 3H), 3.69* (s, 3H), 3.61-3.58* (m, 1H), 3.56 (dd, 1H, J=14.3, 4.6 Hz), 3.42-3.37* (m, 1H), 3.32-3.28 (m, 1H), 3.17* (dd, 1H, J=13.8, 5.7 Hz), 3.04-2.99 (m, 1H), 2.92* (dd, 1H, J=13.8, 9.2 Hz), 2.77 (dd, 1H, J=14.3, 10.1 Hz); 13C NMR (100 MHz, CDCl3) δ 170.8, 168.9, 152.6, 138.2, 131.8, 129.8, 129.4, 129.2, 129.0, 128.8, 127.4, 127.1, 125.0, 98.1, 95.9, 52.9, 52.8, 42.8, 42.3, 41.2, 40.6, 35.5, 33.4; IR (thin film) ν 3061, 3028, 2952, 1777, 1733, 1496, 1448, 1173, 1069 cm−1; HRMS (ESI) calcd for C20H18O4 [M+Na]+ 345.1097, found 345.1094; >99% ee (3S,4S)-isomer as determined by HPLC (AD-H, 9:1 hexanes/i-PrOH), tr (3S,4S)=32.4 min, tr (3R,4R)=20.3 min.
