QUICK scheme strong form

In this section, only examples of Mizoroki-Heck reactions where a proper addition of the cr -aryl- or a -alkeny Ipalladium(II) complex to a double bond of an alkene or alkyne occurs are considered. As a consequence, an often-met deviation from the classic Mizoroki-Heck mechanism, the so-called cyclopalladation, will not be treated in further detail [12, 18]. However, as it is of some importance, especially in heterocycle formation and mainly because it will be encountered later during polycyclization cases, it shall be mentioned briefly below. Palladacycles are assumed to be intermediates in intramolecular Mizoroki-Heck reactions when j3-elimination of the formed intermediate cannot occur. These are frequently postulated as intermediates during intramolecular aryl-aryl Mizoroki-Heck reactions under dehydrohalogenation (Scheme 6.1). The reactivity of these palladacycles is strongly correlated to their size. Six-membered and larger palladacycles quickly undergo reductive elimination, whereas the five-membered species can, for example, lead to Mizoroki-Heck-type domino or cascade processes [18,19]. 

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