New 1,3-dipolar cycloaddition/dehydrogenation of azomethines ylides and azodicarboxylates: direct and effective construction of unsaturated 1,2,4-triazolines

The first K2CO3-catalyzed 1,3-dipolar cycloaddition/dehydrogenation of azodicarboxylates with azomethines was developed and a wide range of unsaturated 1,2,4-triazolines have been successfully prepared in good yields (up to 93%).