Ionic Liquid, 1‐n‐Butyl‐3‐methylimidazolium Bis(trifluoromethanesulfonyl)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 TsNCl₂‐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 %).