Cross coupling reactions 3-pyridylzinc bromide

Additionaly, less reactive atyl triflates react with arylzincs by method A furnishing the biaryls in excellent yields. Once again, the triflate involving reaction was accomplished in the presence of lithium chloride or bromide as mediators. These in situ generate appropriate more reactive aryl bromides or chlorides from the parent triflate, and thus accelerate the cross-coupling reaction with arylzinc. For instance, the reaction of 2-pyridylzinc chloride (145) with 3-methylpyridyl triflate (146) gave 3-methyl-2,2 -bipyridin (147) in 98% yield [51], respectively. Scheme 13. 

Preparation and Cross-Coupling of2-Pyhdyl and 3-Pyridylzinc Bromides 83 Table 3.33 Steric effect on cross-coupling reaction. 

In 2010, Andreas Leitner and coworkers [174] at BASF reported the preparation of a very stable 2-pyridylzinc bromide (an sp organometallic nucleophile) on a multi-kilogram scale using Rieke technology and its application in the Negishi-Baba cross-coupling reaction. 

Preparation and Cross-Coupling of2-Pyridyl and 3-Pyridylzinc Bromides 85 Table 3.35 Coupling reactions of P2 P6 with heteroaryl halides. 

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