Kumada coupling pyridines

Mono-substitution was also realized when one equivalent of 2-thienyhnagnesium bromide was allowed to react with 2,5-dichloropyridine, furnishing thienylpyridine 40 [45]. Furthermore, the Kumada coupling of 5-(2,2 -bithienyl)magnesium bromide (41) with 4-bromopyridine proceeded in refluxing ether to give 4-[5-(2-bithien-2 -yl )]pyridine (42) [46]. 

Kumada reactions. Polyfunctional pyridines can be prepared by Pd(0)-catalyzed cross-coupling of functionalized arylmagnesium halides with chloro- or bromopyridines at temperatures as low as 40 C, e.g., Scheme 114... 

The Kumada reaction has been used for the preparation of polyfunctionalized pyridines. In one example, Grignard reagent 82 was coupled to pyridyl derivative 81 using palladium catalysis to afford 83 in excellent yield [28]. 

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