Zinc metal organohalides

The reaction of heterocyclic lithium derivatives with organic halides to form a C-C bond has been discussed in Section 3.3.3.8.2. This cannot, however, be extended to aryl, alkenyl or heteroaryl halides in which the halogen is attached to an sp2 carbon. Such cross-coupling can be successfully achieved by nickel or palladium-catalyzed reaction of the unsaturated organohalide with a suitable heterocyclic metal derivative. The metal is usually zinc, magnesium, boron or tin occasionally lithium, mercury, copper, and silicon derivatives of thiophene have also found application in such reactions. In addition to this type, the Pd-catalyzed reaction of halogenated heterocycles with suitable alkenes and alkynes, usually referred to as the Heck reaction, is also discussed in this section. 

Boronina T, Klabunde KJ, Sergeev G. Destruction of organohalides in water using metal particles carbon tetrachloride/water reactions with magnesium, tin, and zinc. Environ Sci Technol 1995 29 1511-1517. 

In the following, attention will be focussed on the metals magnesium, zinc and lithium respectively in their reactions with organohalides. Unfortunately only in a limited number of the reports on the reactions of those metals, are Barbier reactions involved. 

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