A New and Efficient Procedure for Bi(OTf)3-Promoted [3+2] Cycloaddition of N-Tosylaziridines to Yield Imidazolines

[3+2] Cycloaddition of a series of substituted N-tosylaziridines with various nitriles promoted by Bi(OTf)3 is described for the synthesis of substituted imidazolines under mild reaction conditions. The procedure works well over a range of substrates to give the corresponding products in good to excellent yields (up to 99 %).