Cascade carbopalladation arene termination

Termination of cascade carbopalladation sequences by arylation can play a major role in systems that form a reasonably long-lived palladium intermediate and contain a suitably functionalized arene moiety in the vicinity of the organopalladium function. In particular, neopentylpalladium intermediates have been found to intramolecularly attack an adjacent arene moiety. For example, iodoarenes 149 with electron-withdrawing substituents in the... 

Brase S, de Meijere A (2002) Palladium-Catalyzed Cascade Carbopalladation Termination with Alkenes, Arenes, and Related jr-Bond Systems. In Negishi E, de Meijere A (eds) Handbook of Organopalladium Chemistry for Organic Synthesis. Wiley, New York, p 1369... 

IV.3.1 Palladium-Catalyzed Cascade Carbopalladation Termination with Alkenes, Arenes, and Related ir-Bond Systems... 

Erase, S. and de Meijere, A. (2002) Palladium-catalyzed tandem and cascade carbopalladation -termination with alkenes, arenes and related jr-compounds, mHandbook of Organo-Palladium Chemistry (ed. E.-i. Negishi), John WUey Sons Inc., New York, pp. 1369 05. 

Domino or cascade reactions provide valuable approaches, especially to various carbo- and heterocyclic systems with three, four, or even more annelated rings. The Heck reaction has successfully been employed in various inter-inter-, intra-inter-, inter-intra-, as well as all-intramolecular reaction cascades, hi this section, the termination of these processes by alkenes, arenes, and related ir-bond systems such as alkynes and allenes will be described. A cascade Heck reaction is considered to consist of an oxidative addition of a heteroatom-carbon bond to palladium (starter), carbopalladation of a nonaromatic carbon-carbon double or triple bond without immediate dehydropalladation (relay), one, two, or more fimher car-bopalladation(s) of a carbon-carbon double or triple bond, and eventually ensuing dehydropalladation. Crucial for a cascade reaction of this kind to occur is the blockage or retardation of a dehydropalladation at one of the intermediate stages by using 1,1-disubsti-tuted alkenes and appropriately substimted cycloalkenes, bicycloalkenes, or alkynes as relays since they give kinetically stable alkyl- or alkenylpalladium intermediates, respectively. 

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