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Palladium-Catalyzed ortho C–H Activation/Arylation of 7-Arylpyrazolo[1,5- a ]pyridines: Synthesis of Biaryl-Substituted Mono- and Bipyrazolo[1,5- a ]pyridines with AIEE Properties

Year: 2026

Type: article

Abstract: High Resolution Image Download MS PowerPoint Slide In this study, we present a facile synthetic methodology for the synthesis of 7-(2-biaryl)-substituted pyrazolo[1,5- a ]pyridines directly from 7-arylpyrazolo[1,5- a ]pyridines via palladium-mediated ortho -C–H activation/arylation. This transformation can be readily accomplished under both catalytic and stoichiometric conditions, facilitated by the intrinsic directing ability of the pyrazolo[1,5- a ]pyridine scaffold. Through the stoichiometric reactions, key 7-phenylpyrazolo[1,5- a ]pyridine-derived palladacycles bearing acetate or trifluoroacetate ligands were isolated and structurally characterized by X-ray crystallography. To gain mechanistic insight into the C–H bond cleavage step, both parallel and intermolecular kinetic isotope effect (KIE) studies were conducted, providing evidence in support of the proposed reaction pathway. Finally, the developed methodology enables the practical synthesis of 7,7′-bis(2-biaryl)-substituted 3,3′-bipyrazolo[1,5- a ]pyridines via an intermolecular C–H/C–H cross-coupling reaction, affording a new class of aggregation-induced enhanced emission (AIEE)-active luminogens.

Source: Organometallics

DOI: 10.1021/acs.organomet.5c00472

Authors: Lin-En Zeng, Yi-Hua Jiang, Pei-Shen Xiao, Hsi-Min Kao, Jean-Ho Chu

Institution: National Taitung University

Language: English

Topic: Catalytic C–H Functionalization Methods

Subfield: Organic Chemistry

Field: Chemistry

Domain: Physical Sciences

Open Access status: hybrid

Estimated APC paid: $4,500

Funders: Academia Sinica, National Taiwan Normal University, National Science and Technology Council