A novel ligand-free palladium catalytic system with SO3H-functional ionic liquids as cocatalyst for amidocarbonylation reaction

Effects of Lewis acid BF3·OEt2, and Brønsted acids TsOH, CF3COOH, H3PO4, and HClO4 as cocatalyst respectively on the ligand-free palladium-catalyzed amidocarbonylation were investigated. SO3H-functional ionic liquids 1-methyl-3-(4-sulfonic acid)butylimidazolium hydrosulfate [MIm(CH2)4SO3H][HSO4] and 1-methyl-3-(4-sulfonic acid)butylimidazolium triflate [MIm(CH2)4SO3H][OTf] were firstly employed as cocatalysts instead of these Lewis acid and Brønsted acids. By using a ligand-free and weak corrosive catalyst in situ prepared form PdBr2, LiBr·H2O, and [MIm(CH2)4SO3H][OTf], the amidocarbonylation of benzaldehyde, acetamide, and CO could proceed smoothly and afford N-acetyl-α-phenylglycine with yield of 58% in [C6mim]PF6 medium.