Organozinc reagents uncatalyzed

Uncatalyzed Cross-Coupling Reactions of Organozinc Reagents I 291... 

Scheme 4.23 Uncatalyzed cross-couplings of organozinc reagents with activated electrophiles [103, 104],...

Whereas uncatalyzed substitution reactions of organozinc compounds are limited to very reactive electrophiles, metal-transmetallated organozinc compounds are able to perform substitution reactions on various electrophiles. In the case of conjugated electrophiles, these zinc copper reagents can follow a Sn2 or Sn2 mechanism. 

The uncatalyzed reaction of acid chlorides with organozincs is sluggish and inefS-cient. It is often complicated by side reactions and leads usually to low yields of the desired acylation products. In contrast, the CuCN 2LiCl-mediated acylation of various zinc reagents affords ketones in excellent yields. The reaction of the zinc-copper reagent 328 obtained by the direct zinc insertion to the iodide 329 followed by a transmetallation with CuCN 2LiCl reacts with benzoyl chloride at 25 °C leading to the ketone 330 in 85% yield [52b]. The functionalized benzylic bromide 331... 

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