Ionic Liquid, 1‐n‐Butyl‐3‐methylimidazolium Bis(trifluoromethanesulfonyl)imide, Resulted in the First Catalyst‐Free Aminohalogenation of Electron‐Deficient Alkenes

Abstract 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 %).