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Updated: Jun 29, 2025

Palladium N-Heterocyclic Carbene Complexes: Synthesis from Benzimidazolium Salts and Catalytic Activity in Carbon-carbon Bond-forming Reactions
Published on: July 30, 2017
Palladium-catalyzed C-C bond cleavage of N-cyclopropyl acylhydrazones
Hiroki Fujioka1, Motohiro Yasui1, Shohei Hamada2
1Kobe Pharmaceutical University, Motoyamakita, Higashinada, Kobe 658-8558, Japan. masa-u@kobepharma-u.ac.jp.
Abstract:
Despite their utility as directing groups, the C-C bond cleavage of cyclopropanes utilizing hydrazones has not been explored. Herein, Pd-catalyzed C-C bond cleavage reaction of N-cyclopropyl acylhydrazones, followed by cycloisomerization to yield pyrazoles, has been developed. The protocol enables the synthesis of various α-pyrazole carbonyl compounds, which have a potential of biological activity. Control experiments and DFT calculations suggest that β-carbon elimination of a stable 6-membered chelate palladium complex occurs, generating a conjugated azine as a reaction intermediate for the following cycloisomerization.
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