Reaction Steps
Prepared according to the general procedure from 2-chloro-hydrocinnamaldehyde and (E)-methyl 4-oxo-4-cyclohexylbut-2-enoate using 0.5 mol % 1 as the catalyst in 76% yield as a single diasteromer (white solid). [α]D20 (c 1.06, CHCl3)=+178.6; mp=87-89° C.; 1H NMR (400 MHz, CDCl3) δ 7.32-7.25 (m, 3H), 7.15-7.13 (m, 2H), 4.98 (d, 1H, J=6.9 Hz), 3.73 (s, 3H), 3.47 (dd, 1H, J=14.3, 4.8 Hz), 3.06 (t. 1H, J=6.3 hz), 2.86-2.81 (m, 1H), 2.67 (dd, 1H, J=14.3, 10.1 Hz), 2.06-2.03 (m, 1H), 1.88-1.83 (m, 5H), 1.28-1.13 (m, 5H); 13C NMR (100 MHz, CDCl3) δ 171.4, 169.6, 170.3, 138.3, 129.1, 128.9, 127.0, 96.2, 52.6, 43.0, 41.0, 40.0, 33.4, 30.2, 30.0, 26.1, 26.0, 25.9; IR (thin film) ν 3086, 3027, 2929, 2854, 1773, 1737, 1452, 1436, 1155, 1056 cm−1; HRMS (ESI) calcd for C20H24O4 [M+Na]+ 351.1566, found 351.1574; 86% ee (3S,4S)-isomer as determined by HPLC(OD-H, 9:1 hexanes/i-PrOH), tr (3S,4S)=8.5 min, tr (3R,4R)=7.7 min.
