Methanol → Methyl 3-bromocinnamate, predominantly trans

反応式

[Br:1][C:2]1[CH:3]=[C:4](/[CH:8]=[CH:9]/[C:10]([OH:12])=[O:11])[CH:5]=[CH:6][CH:7]=1.S(=O)(=O)(O)O.[CH3:18]O>>[Br:1][C:2]1[CH:3]=[C:4](/[CH:8]=[CH:9]/[C:10]([O:12][CH3:18])=[O:11])[CH:5]=[CH:6][CH:7]=1

参加物

反応物 3

HCID 887Methanol

HCID 1118Sulfuric Acid

HCID 776461m-Bromocinnamic acid

生成物 1

HCID 1482751Methyl 3-bromocinnamate, predominantly trans収率 47%

実験手順

A solution of trans-3-(3-bromophenyl)-2-propenoic acid (0.405 mol) in methanol (300 ml) was treated with conc. sulfuric acid (6.0 ml) and heated under reflux for 10 h. The cooled mixture was filtered to afford the title compound (46.14 g, 47%) as brilliant white crystals, m.p. 53°-55° C. (Found: C, 50.10; H, 3.58; Br; 33.21. C10 H9BrO2 requires C, 49.82; H, 3.76; Br, 33.14%); νmax (nujol)/cm-1 1730.5, 1715.0, 1644; δH (270 MHz) 3.81 (3H, s, OCH3); 6.43 (1H, d, 2-H, 3J2,3 =16.2 Hz); 7.25 (1H, t, 5'-H, Jo =7.8 Hz); 7.43 (1H, dt, 4'-H, Jo =7.9, Jm =1.0 Hz); 7.50 (1H, dt, 6'-H, Jo =7.9, Jm =1.0 Hz); 7.60 (1H, d, 3-H, 3J3,2 =16.2 Hz); 7.66 (1H, t, 2'-H, Jm =1.7 Hz). δC (67.8 MHz) 51.8 (OCH3); 123.0 (3'-C); 133.0 (4'-C); 136.4 (1'-C); 143.1 (3-C); 166.9 (CO2Me). Remaining signals lie in the range 119.3-130.7 ppm; m/z 242.0, 240.0 (46.67, 47.64, M+), 211.0, 209.0 (72.69, 74.00), 182.9, 180.9 (15.67, 16.83), 161.0 (4.19), 130.0 (9.44), 102.1 (100).