Acyl halides with organozinc compounds

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 ... 

Palladium-catalyzed coupling reactions of organozinc compounds with acyl halides are the fastest and mildest among the known methods using a variety of organometallic compounds. 

The Negishi cross-coupling reaction is the nickel- or palladium-catalyzed coupling of organozinc compounds with various halides or triflates (aryl, alkenyl, all nyl, and acyl). 

Pd-catalyzed cross-coupling reactions of organozinc compounds with alkenyl and aryl halides can be carried out under mild conditions and are the fastest among all reactions using various organometallics. The reaction with acyl hahdes is not an exception. Usually, the reaction is completed at lower than room temperature within a couple of hours [38,251 - 25 3]. As organozinc compounds are coordinatively unsaturated and sterically less bulky, the transmetallation step is facilitated [29] ... 

Organozinc addition reactions to unsaturated systems lead to an intermediate zinc compound which is in most cases further hydrolyzed to give the corresponding protonated organic compound. This intermediate can also be trapped by reaction with electrophiles (see Electrophile) (E+) such as aldehydes, acyl chlorides, organic halides, silyl halides, and so on. Depending on the nature of the electrophile (see... 

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