Heck Mizoroki butyl cinnamate

Liu, S., Fukuyama, T., Sato, M. and Ryu, I. (2004) Continuous microflow synthesis of butyl cinnamate by a Mizoroki-Heck reaction using a low-viscosity ionic liquid as the recycling reaction medium. Org. Proc. Res. Dev., 8, 477-81. 

Since then, many research groups have described the benefit of ionic liquids as solvents in the Mizoroki-Heck reaction covering a large variety of substrates. Cacchi et al. [22] achieved a stereoselective coupling of aryl iodides and methyl cinnamates in a mixture of molten tetrabutylammonium acetate and bromide. Intramolecular Mizoroki-Heck reactions were conducted in l- -butyl-3-methylimidazolium tetralluoroborate ([BMIm]BF4) using PdCl2 as a precatalyst. Substituted benzofurans were obtained in satisfactory yields [23]. The ionic liquid containing the palladium catalyst could be reused several times with small decrease in activity. 

Mizoroki-Heck couplings of bromo- and chloroarenes were successfully achieved by using the electron-rich benzimidazolylidene palladium complex 2 (Figure 15.1), generated in situ in tetrabutylammonium bromide as solvent [29]. The coupling of 4-chloroacetophenone with butyl acrylate in the presence of 1 mol% 2 yields 93% 4-acetyl-(El-cinnamic ester in 6 h reaction time. Butyl acrylate was also coupled with 2 equiv of bromobenzene leading to the trisubstituted olefin 3,3-diphenylpropenoic acid butyl ester in 91% yield. 

---