Methanol → Methyl 3-bromocinnamate, predominantly trans

Reaction equation

[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

Participants

Reactant 3

HCID 887Methanol

HCID 1118Sulfuric Acid

HCID 776461m-Bromocinnamic acid

Product 1

HCID 1482751Methyl 3-bromocinnamate, predominantly transYield 47%

Procedure

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. C10H9BrO2 requires C, 49.82; H, 3.76; Br, 33.14%); Vmax (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, 1683), 161.0 (4.19), 130.0 (9.44), 102.1 (100).