Palladium-Catalyzed Cascade Reactions of Alkenes, Alkynes, and Allenes

PALLADIUM-CATALYZED CASCADE REACTIONS OF ALKENES, ALKYNES, AND ALLENES 

Catalytic Cascade Reactions, First Edition. Edited by Peng-Fei Xu, Wei Wang. 2014 John Wiley Sons, Inc. Published 2014 by John Wiley Sons, Inc. 

Palladium complexes exist predominantly in several different oxidation states Pd(0), Pd(II), and Pd(IV), although both Pd(I) and Pd(III) are known. Most commonly, the involvement of Pd(0)/Pd(II) complexes as intermediates in palladium-catalyzed transformations has been well established and studied extensively in organic synthesis. Recently, Pd(IV)-mediated transformations have been implicated in many new synthetic methodologies [5]. 

Palladium-catalyzed transformations of alkenes have been studied extensively and developed widely. In general, two distinct types of transformations wiU take place when bond palladium species meet the alkenes. One is the insertion of alkene into the X-Pd bond the other is the nucleophilic attack of the alkenes activated by Pd(II) species. These transformations are known as carbopalladation, aminopaUadation, oxopalladation, and so on, depending on the atom that is involved. How to trap the resnlting palladium species from carbopalladation or other palladium-catalyzed transformations with other reagents will be the key to making a cascade. 

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