In 2022,Norman, Jacob P.; Larson, Nathaniel G.; Entz, Emily D.; Neufeldt, Sharon R. published an article in Journal of Organic Chemistry. The title of the article was 《Unconventional Site Selectivity in Palladium-Catalyzed Cross-Couplings of Dichloroheteroarenes under Ligand-Controlled and Ligand-Free Systems》.Safety of 2-Bromo-5-methylpyridine The author mentioned the following in the article:
This work represents the first highly selective method with a broad scope for C4-coupling of dihalogenated N-heteroarenes such as 2,4-dichloropyridine, 2,4-dichloroquinoline, 3,5-dichloro-4-phenylpyridazine, etc. where selectivity is clearly under ligand control. Under the optimized conditions, diverse substituted 2,4-dichloropyridines and related compounds undergo cross-coupling to form C4-C(sp2) and C4-C(sp3) bonds using organoboron, -zinc, and -magnesium reagents such as p-methoxyphenylboronic acid, cyclopentylmagnesium bromide, benzothiophenylzinc chloride, etc. The synthetic utility of this method is highlighted in multistep syntheses that combine C4-selective cross-coupling with subsequent nucleophilic aromatic substitution reactions. The majority of the products herein (71%) have not been previously reported, emphasizing the ability of this methodol. to open up underexplored chem. space. Remarkably, this work finds that ligand-free “”Jeffery”” conditions enhance the C4 selectivity of Suzuki coupling by an order of magnitude (>99:1). These ligand-free conditions enable the first C5-selective cross-couplings of 2,5-dichloropyridine and 2,5-dichloropyrimidine. In the experimental materials used by the author, we found 2-Bromo-5-methylpyridine(cas: 3510-66-5Safety of 2-Bromo-5-methylpyridine)
2-Bromo-5-methylpyridine(cas: 3510-66-5) belongs to pyridine. Pyridines form stable salts with strong acids. Pyridine itself is often used to neutralize acid formed in a reaction and as a basic solvent. Safety of 2-Bromo-5-methylpyridine