Ruthenium-bipyridine complex catalyzed C–H alkenylation of arylpyrazole derivatives

Abstract

Direct dehydrogenative alkenylation of N-arylpyrazoles by acrylates has proven to be efficient under Ru(II) carboxylate complexes SPS-BPY and SPS-DB-BPY catalyst along with $$\hbox {Cu(OAc)}_{2}{\cdot }\hbox {H}_{2}\hbox {O}$$ as an oxidant. The reaction was found to be atom-economical and was characterized by a number of substituted N-arylpyrazoles with excellent chemoselectivity. The reaction allowed a direct alkenylation to be performed under the eco-friendly solvent system. The diverse functional group tolerance of this protocol opened up a new insight to the use of ruthenium(II) bipyridine complexes as a productive method for the oxidative heterocoupling of N-arylpyrazole. Synopsis Ruthenium(II)-Bipyridine catalyst was used for directive C–C alkenylation of arylpyrazoles and aryloxazolines under additive- and co-catalyst-free mild conditions. The comprehensive substrate scope and high chemoselectivity make the protocol versatile. The method prevents the formation of homo-coupled byproducts thereby challenging the traditional alkenylation reactions and opens up a new genre in ruthenium catalysis.