Cross-coupling organomagnesium compounds

Transition metal-catalyzed cross-coupling reaction has become the most important method for the formation of aryl-aryl bonds. The reaction of aryl halides and sulfonates with organomagnesium compounds is usually referred... 

Catalysed cross-coupling of organomagnesium compounds with vinylic and aryl halides... 

Palladium-catalysed cross-coupling of organomagnesium compounds with alkyl halides is rarely useful (e.g. see [36]), but a satisfactory nickel-catalysed coupling with a neopentyl halide has been reported recently [37] ... 

Catalysed reactions of organomagnesium compounds, such as the alkylmagnesiation reactions noted in Section 4.1 and the cross-coupling reactions noted in Section 8.1, may also involve other organometallic compounds as intermediates, but only stoichiometric reactions are included here. 

We have shown for the first time 12 that not only c/oso-carboranes, but also iodo-nido-7,8-dicarbaundecaborates containing an iodine atom in the polyhedral skeleton or in the pentagonal plane of the polyhedron enter into cross-coupling reactions with organomagnesium and organozinc compounds catalyzed by palladium complexes. It is known that ifo-7,8-dicarbaundecaborates are strong BH-acids (pKa = 21.1), due to the presence of the axial hydrogen atom. 

The cross-coupling reaction of (36) and (37) (Scheme 15) with organomagnesium compounds occurs in a similar way, and differs from those above, only in that m these compounds the iodine atom is bonded to the pentacoordinated boron atom in the pentagonal plane. Cross-coupling reactions of organomagnesium compounds with polyhedral B-iodo-substituted compounds containing pentacoordinated boron atoms were previously unknown. 

In contrast to organomagnesium compounds, organozinc compounds do not metallatc w t/o-7,8-dicar baundecaborates. In this case the cross-coupling reaction between iodo-m t/o-7,8-dicarbaundecaborates (35-37) and organozinc compounds in the presence of palladium catalysts proceeds in the corresponding mcfo-7,8-dicarbaundecaborate anion ... 

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