A Catalytic Application of Co/Zr Heterobimetallic Complexes: Kumada Coupling of Unactivated Alkyl Halides with Alkyl Grignard Reagents

✍ Scribed by Wen Zhou; Jonathan Wesley Napoline; Christine M. Thomas

• Publisher: John Wiley and Sons
• Year: 2011
• Tongue: English
• Weight: 298 KB
• Volume: 2011
• Category: Article
• ISSN: 1434-1948
• DOI: 10.1002/ejic.201100109

✦ Synopsis

Abstract

Tris(phosphanylamide) early/late heterobimetallic Zr/Co complexes, ClZr(R′NPR~2~)~3~CoI [R′ = __i__Pr, R = Ph (1), R′ = 2,4,6‐trimethylphenyl, R = __i__Pr (2), R′ = R = __i__Pr (3)], have been utilized as catalysts for the cross‐coupling of alkyl halides with n‐octylmagnesium bromide. While yields are consistently higher for alkyl bromide substrates, it is found that these unusual heterobimetallic complexes are also active towards more challenging alkyl chloride substrates. This is particularly interesting in light of the fact that monometallic cobalt complexes are inert towards these substrates, suggesting that Zr also plays a role in catalysis. Radical trapping studies suggest that a one‐electron transfer radical oxidative addition pathway is operative.