Ionic liquid, 1-n-butyl-3-methylimidazolium bis(trifluoro-methanesulfonyl)imide, resulted in the first catalyst-free aminohalogenation of electron-deficient alkenes

The 2-Ns-based aminohalogenation of α,β-unsaturated ketones has been achieved in an ionic liquid, 1-n-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide {[bmim][N(SO₂CF₃) ₂]}. [Bmim][N(SO₂CF₃)₂] was found to be superior not only to classical organic solvents but also to its counterpart, [bmim][BF₄], which was proven to be successful in the TsNCl ₂-based aminohalogenation but failed to give any product for this reaction. The present process takes the advantage of 2-NsNCl₂ as the stable nitrogen/halogen source in a one-pot operation without the use of any metal catalysts, it is convenient to perform without special protection of inert gases. Eight examples were examined with good to excellent stereoselectivity (1:5 to one isomer) and modest to good chemical yields (53-72%).