Alkylzinc compounds alkylation

A wide variety of typical anionic initiators is described for the polymerization of PMVK. Grignard reagents are used as well as complexes formed of alkylaluminum or alkylzinc compounds with alkali metal alkyls (so called -ate complexes ). Alkali metal initiators and alkoxides are also described. Some examples are given in Table 5. 

Development of new methodologies for formation of carbon-carbon bonds has been one of the major tasks in organic chemistry. Obviously, organometallic compounds, particularly zinc derivatives, have found great use in such reactions. During the past several years, there have been several significant reports of nickel- and palladium-catalyzed reactions of dialkylzincs and alkylzinc halides with alkyl halides of diverse structure. A detailed account of most of these studies can be found in a recent review by Knochel et al,246... 

The alkylzinc halides formed in this reaction are white crystalline compounds which are rarely isolated and which decompose to the dialkyl compounds when heated. Good results are obtained on use of primary or secondary alkyl iodides (sometimes mixed with the bromides). The reaction is carried out in an atmosphere of nitrogen or carbon dioxide. 

Yields are normally 50-84% but are lower if the two groups R are secondary alkyl cadmium compounds.360 Aryl and alkyl bromides are more suitable than the iodides for this reaction.361 Alkylcadmiums are usually preferred to alkylzincs because of their less ready reaction with carbonyl groups. The preparation of 1-phenyl-3-eicosanone3 62 from stearoyl chloride and bisphenethyl-cadmium provides an example ... 

Pd-catalyzed alkylation with alkylzincs and alkylmagnesiums has been applied to the synthesis of natural products and related compounds of biochemical interest, as exemplified in Scheme 6. 

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