反应详情

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).

1. customcondensed
2. customto provide
3. customin an approximate ratio of 90:10 Crystallization
4. customprovided the pure E-isomer, mp 49°-50° C., [α]D25 -2.2 (c,0.2, methanol)