Palladium-Catalyzed Cross-Coupling with Acyl Halides and Related Electrophiles

1 Palladium-Catalyzed Cross-Coupling with Acyl Halides and Related Electrophiles 

coordinatively unsaturated active palladium catalyst, PdL2, is produced via dissociation of the ligands, which then reacts with acyl halide to give the acylpalladium intermediate. Since deinsertion of CO of the acylpalladium derivatives may occur simul-taneously, the next step, transmetallation (so-called metathesis), is the most crucial for the efficiency of the overall reaction. A variety of organometallic compounds, such as boron, aluminum, copper, zinc, mercury, silicon, tin, lead, zirconium, and bismuth, are used as the partner in this coupling reaction without loss of CO. In this section, the important features of the cross-coupling reactions of a variety of organometallic compounds with acyl halides and related electrophiles are discussed. 

Handbook of Organopalladium Chemistry for Organic Synthesis, Edited by Ei-ichi Negishi ISBN 0-471-31506-0 2002 John Wiley Sons, Inc. 

When organozinc halides are synthesized in situ by the reaction of organic halides with zinc metal or the zinc-copper couple, DME or benzene-DMA can be used as the solvent. In the case of organozinc halides prepared by transmetallation of 

Organozinc compounds can be prepared by direct metallation of organic halides with zinc metal. The procedure makes the coupling reaction more convenient. A mixture of alkyl halide, acyl chloride, and zinc metal upon stirring in the presence of palladium catalyst at room temperature gives the desired ketone.f - While direct metallation can be carried out efficiently when the zinc-copper couple is used in some cases, the presence of copper ion sometimes prevents the coupling reaction with acyl chloride.f  

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