Reaction Steps
The title compound was prepared according to the general procedure from tert-butyl trans-4-oxo-2-butenoate and trans-N-(4-methoxybenzenesulfonyl)-3-phenylprop-2-en-1-imine using 10 mol % 9 as the catalyst in 70% yield white solid. [α]D20 (c 1.07, CHCl3)=+90.4; mp=139-142° C.; 1H NMR (400 MHz, CDCl3) 8.03 (dd, 21-1, J=6.9, 2.1 Hz), 7.16-7.13 (m, 2H), 7.05-7.00 (m, 4H), 6.60 (dd, 2H, J=8.2, 1.0 Hz), 5.59 (dd, 1H, J=8.1, 6.6 Hz), 3.92 (s, 3H), 3.66 (t, 1H, J=6.9 Hz), 3.49-3.43 (m, 1H), 2.57 (dd, 1H, J=17.3, 6.1 Hz), 1.94 (dd, 1H, J=17.3, 7.5 Hz), 1.41 (s, 9H); 13C NMR (100 MHz, CDCl3) δ 171.0, 169.0, 164.3, 136.9, 131.4, 129.2, 128.9, 128.0, 127.8, 124.5, 114.2, 113.6, 81.1, 56.0, 44.2, 41.9, 32.5, 28.2; IR (thin film) ν 3086, 2976, 1715, 1594, 1496, 1364, 1264, 1167, 1080 cm−1; HRMS (ESI) calcd for C24H27NO6S [M+Na]+ 480.1451, found 480.1456; 97% ee (3S,4S)-isomer as determined by HPLC (AS-H, 9:1 hexanes/i-PrOH), tr (3S,4S)=19.4 min, tr (3R,4R)=14.1 min.
