Transition Metal-Mediated Alkenylations, Arylations, and Alkynylations

Halogens or O-bound leaving groups, however, also can be detached from the sp2-hybridized C atom of an alkene or an aromatic compound. 

The most important substrates for substitutions of this type are alkenyl and aryl triflates, bromides, or iodides (Sections 16.1-16.4). The most important organometallic compounds to be introduced into the substrates contain Cu, Mg, B, Zn or Sn. The metal-bound C atom can be sp2-, sp2-, or. sp-hybridized in these compounds, and each of these species, in principle, is capable of reacting with unsaturated substrates. Organocopper compounds often (Section 16.1, 16.2), but not always substitute without the need for a catalyst (Section 16.4.5). Grignard compounds substitute in the presence of catalytic amounts of Ni complexes (Section 16.3), while organoboron (Section 16.4.2), organozinc (Section 16.4.3) and organotin (Section 16.4.4) compounds are typically reacted in the presence of Pd complexes (usually Pd(PPhj)4). 

In Section 16.5, a few other C,C coupling reactions of alkenes and of aromatic compounds, which contain an sp2—OTf, an sp2—Br, or an sp2—Cl bond, will be discussed because these C,C couplings and the preceding ones are closely related mechanistically. These substrates, however, react with metal-free alkenes. Palladium complexes again serve as the catalysts. 

Bruckner R (author), Harmata M (editor) In Organic Mechanisms - Reactions, Stereochemistry and Synthesis Chapter DOI 10.1007/978-3-642-03651-4 16, Springer-Verlag Berlin Heidelberg 2010 

16 Transition Metal-Mediated Alkenylations, Arylations, and Alkynylations 

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