Csp2-N bond formation via ligand-free Pd-catalyzed oxidative coupling reaction of N-tosylhydrazones and indole derivatives.

In a fresh approach to the synthesis of N-vinylazoles, a ligand-free palladium catalytic system was found to promote the Csp(2)-N bond-forming reaction utilizing N-tosylhydrazones and N-H azoles. This process shows functional group tolerance; di-, tri-, and tetrasubstituted N-vinylazoles were obtained in high yields. Under the optimized conditions, the reaction proceeds with high stereoselectivity depending on the nature of the coupling partners.