Ionic liquid media resulted in more efficient regio- and stereoselective aminohalogenation of cinnamic esters

The ionic liquid, butylmethylimidazolium tetrafluoroborate ([Bmim][BF4]), was found to be superior to classical organic solvents for the metal catalyzed regio- and stereoselective aminohalogenation of cinnamic esters. The aminohalogenation reaction of cinnamic esters with p-TsNCl2 proceeded at a faster rate (within 12 h) in the presence of a reduced amount of catalyst (CuOTf, 6.0 mol %). Good yields (76–82%) and excellent regio- and stereoselectivity (one isomer) were achieved for eight examples.