Reaktionsschritte
In a fashion similar to that described in Example 4, α-hexylcinnamaldehyde dimethyl acetal and dimethyl L-tartrate were condensed to provide a mixture of (E)-and (Z)-(4R,5R)-2-(1-hexyl-2-phenyl-1-ethenyl)-4,5-dicarbomethoxy-1,3-dioxolane in an approximate ratio of 90:10 Crystallization provided the pure E-isomer, mp 49°-50° C., [α]D25 -2.2 (c, 0.2, methanol). 1H-NMR (CDCl3) δ7.35-7.26 (5H,m), 6.74 (1H,s), 5.84 (1H,s) 4.86 (1H, d, J=4.4 Hz), 4.70 (1H, d, J=4.4 Hz), 3.85 (3H,s), 3.80 (3H,s), 2.34-2.27 (2H,m), 1.58-1.55 (2H,m), 1.37-1.26 (6H,m), 0.93-0.87 (3H,m), IR (KBr) 2900, 2840, 1730, 1430, 1340, 1200, 1100, 1060, 1030, 980, 950, 915, 870, 790, 750, 730, 690 cm-1. MS m/e (% abundance) 305 (4), 292 (17), 291 (100), 145 (18), 142 (25), 131 (73), 129 (76), 128 (26), 117 (74), 116 (17), 115 (51), 104 (29), 91 (57), 59 (31), 41 (25).
