Organozinc compounds cross-coupling reactions

The cross-coupling reaction of thiomethylpyrimidines 99 with organozinc compounds 100 in the presence of palladium was found to produce pyrimidines 101 in good to excellent yields <00SL905>. 

Recent notable improvements by Knochel and co-workers include iron-catalyzed cross-coupling reactions of various acid chlorides 148 with dialkylzinc reagents (Equation (24))324 as well as the iron-catalyzed arylation of aroyl cyanides 149 with Grignard reagents (Equation (25)).3 5 In the first case Knochel s reaction conditions tolerate ester groups on the organozinc compounds, while in the latter case ester, aryl alkyl ether, cyano, and chloro functionalities on the aromatic moieties are compatibles with the reaction conditions. 

D. Cross-coupling Reactions of Organozinc Compounds in the Presence of... 

The past decade has seen extensive development of cross-coupling reactions of organozinc compounds and organic halides catalyzed by nickel or palladium catalysts. Although nickel-based catalysts are more reactive with respect to the organic halide partner, the number of failures with these catalysts and the greater selectivity realized with palladium-based catalysts have resulted in the almost exclusive use of the latter group of catalysts for these reactions. 

Organozinc Compounds in the Cross-coupling Reaction with Iodo-carboranes... 

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. 

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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