Transition‐Metal‐Free Chichibabin‐Type Coupling of Halo‐azaarenes with Grignard reagents

Jiang, Qian; Fang, Ling; Li, Yanhui; Wang, Jian; Li, Jing‐Hua

doi:10.1002/slct.202300780

Cited by 2 publications

(1 citation statement)

References 44 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…2-Phenylpyridines and 2,2′-bipyridines are widely used ligands for photocatalysts of Ir(III) and Ru(II) . To obtain alkyl- and arylpyridines, Minisci reactions of pyridines; transition metal-catalyzed couplings of halopyridines (Suzuki–Miyaura, Negishi, Kumada–Tamao–Corriu, Kochi–Fürstner reactions, and Ni-catalyzed reductive coupling reactions developed by Weix et al) or 2-pyridyl ammonium salts; C–H arylations, alkylations, and alkenylations of pyridines; BF 3 -promoted additions of Grignard or alkynyllithium reagents to pyridines followed by rearomatizations; and S N Ar reactions of Grignard reagents toward 4-cyanopyridines (assisted by BF 3 ), halopyridines (assisted by triphosgene), or pyridine-2-sulfinate were developed. 2,2′-Bipyridines were prepared by reductive coupling of chloropyridines , and phosphorus ligand coupling .…”

Section: Introductionmentioning

confidence: 99%

Purple Light-Promoted Coupling of Bromopyridines with Grignard Reagents via SET

Lei,

Wang,

et al. 2024

J. Org. Chem.

View full text Add to dashboard Cite

Alkyl- and arylpyridines and 2,2′-bipyridines are conventionally prepared by Minisci reactions of pyridines and transition metal-catalyzed coupling reactions of halopyridines. Herein, purple light-promoted radical coupling reactions of 2- or 4-bromopyridines with Grignard reagents in Et2O or a mixture of Et2O and tetrahydrofuran in regular glassware without the need for a transition metal catalyst were disclosed for the first time. Methyl, primary and secondary alkyl, cycloalkyl, aryl, heteroaryl, pyridyl, and alkynyl Grignard reagents were compatible with the protocol. As a result, alkyl- and arylpyridines and 2,2′-bipyridines were easily prepared. Single electron transfer from the Grignard reagent to bromopyridine was stimulated by purple light. An electron extruded from the dimerization of the Grignard reagent worked as the catalyst. Light on/off experiments indicated that constant irradiation was required for product formation. Studies of radical clock substrates verified the involvement of a pyridyl radical from bromopyridine and the noninvolvement of an alkyl or aryl radical from the Grignard reagent. The available proof supports a photoinduced SRN mechanism for the new coupling reactions.

show abstract

Section: Introductionmentioning

confidence: 99%

Purple Light-Promoted Coupling of Bromopyridines with Grignard Reagents via SET

Lei,

Wang,

et al. 2024

J. Org. Chem.

View full text Add to dashboard Cite

show abstract

One-Flow Operation via 4-Bromopyridine Enables Flash Synthesis of AChE Inhibitor

Nagaki,

Soutome,

Kimuro

et al. 2023

Synthesis

View full text Add to dashboard Cite

4-Bromopyridine is a building block that can be converted into valuable compounds, but due to its low stability, it is commercially available in the form of hydrochloride salt. Therefore, the hydrochloride salt is usually desalted with a basic aqueous solution and dried before organic reaction. In this study, to simplify the preparation and reaction procedure of 4-bromopyridine, multiple operations, desalting with a base, separation of the aqueous layer, and subsequent halogen-lithium exchange reaction, were integrated into a single flow reaction. The reaction sequence was completed within 20 seconds and the yields were higher than the conventional methods. We believe this is because the subsequent reaction can be performed immediately after the generation of 4-bromopyridine, which is unstable under ambient conditions

show abstract

Transition‐Metal‐Free Chichibabin‐Type Coupling of Halo‐azaarenes with Grignard reagents

Cited by 2 publications

References 44 publications

Purple Light-Promoted Coupling of Bromopyridines with Grignard Reagents via SET

Purple Light-Promoted Coupling of Bromopyridines with Grignard Reagents via SET

One-Flow Operation via 4-Bromopyridine Enables Flash Synthesis of AChE Inhibitor

Contact Info

Product

Resources

About