Synthesis of pyrazoles from sulfonyl hydrazone and benzyl acrylate under transition-metal-free conditions

Pyrazoles as an important class of heterocyclic compounds, are widely found in pharmaceuticals and bioactive natural products. Herein we report a [3 + 2] cycloaddition reaction for the synthesis of a series of pyrazoles, with the yield up to 77%. This approach exhibits many notable features, such as convenient operating conditions, excellent functional group compatibility and readily accessible raw materials, providing an alternative route for the construction of pyrazole derivatives. DBU-mediated [3 + 2] cycloaddition reaction for the synthesis of pyrazoles. It is noteworthy that this reaction constructed two new C-N bonds and a new C-C bond at the same time, providing a new door for the construction and functionalization of pyrazole scaffolds.