Synthesis of 1,2,3-Triazolines

C=C double bonds which are neither strained nor activated by an EWG or EDG react slowly with azides. The reaction may take weeks or even months. The use of high temperatures is restricted as 1,2,3-triazolines are thermally unstable. In such cases, the imine-diazoalkane reaction is a suitable alternative. This method is a versatile route for the preparation of 1,5-substituted triazolines, especially 1,5-diaryltriazolines (848), from the reaction of a SchifTs base and diazomethane under mild conditions 93JHCl 191 . A wide range of substituents can be incorporated from readily available imines. 

There is no general and convenient method for the synthesis of A - and A -triazolines. 

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