Ruthenium diacetate-catalysed oxidative alkenylation of C–H bonds in air: synthesis of alkenyl N-arylpyrazoles

Ru(OAc)2(p-cymene) catalyses the directed dehydrogenative alkenylation of N-aryl pyrazoles by styrene and alkyl acrylates in the presence of a catalytic or stoichiometric amount of Cu(OAc)2·H2O in air; the acetic acid solvent plays a key role. With arene electron-donating groups, ruthenium-catalysed ortho-dialkenylation with alkyl acrylates can be obtained. A new method to generate the oxidative homocoupling of N-phenylpyrazole is provided with the Ru(OAc)2(p-cymene) catalyst.