Acylpalladation

Negishi E, Tan Z (2005) Diastereoselective, Enantioselective, and Regioselective Carbo-alumination Reactions Catalyzed by Zirconocene Derivatives. 8 139-176 Negishi E, Wang G, Zhu G (2006) Palladium-Catalyzed Cyclization via Carbopalladation and Acylpalladation. 19 1-48... 

The scope of reaction has been further extended to allylic electrophiles. An extensive investigation of the intramolecular acylpalladation has been performed in a series of < -iodoalkenylbenzenes with both terminal and internal double bonds and 1-iodo-substituted 1,4-, 1,5-, or 1,6-dienes. ... 

The other strategy requires dienes or enynes containing allylic or propargylic ester fragments. The main pathway in this case involves the formation of allylpalladium intermediates, which perform carbapalladation of double or triple bonds with subsequent acylpalladation forming two cycles, and termination by palladium hydride elimination or other usual trapping pathways (Scheme for example, in the following examples in Scheme 22. ... 

The cyclization of enynes containing propargylic carbonate fragment involves allene intermediate, which takes part in intramolecular acylpalladation by endo-frig-modc to give a six-membered ring (Scheme 23). " ... 

Cyclization at an enolate center can successfully compete with acylpalladation of G=G bonds (Equation (42)). ... 

These reactions may as well occur in the termination stages of cascade reactions, for example, involving intramolecular acylpalladation (Scheme 30) or intramolecular Heck reaction Equation (49). ... 

Negishi E, Wang G, Zhu G (2006) Palladium-Catalyzed Cyclization via Carbopalladation and Acylpalladation. 19 1-48... 

Cyclic acylpalladation. Another major subtopic of carbopalladation is acylpalladation. In the mid-1960s, two seemingly independent papers were published by J. Tsuji [24] and P.R. Hughes [25,26]. The former reported a perfectly alternating copolymerization of norbornadiene with CO (Scheme 8), while the latter described two related Pd-catalyzed carbonylation cyclizations shown in Scheme 9. 

Although the Pd-catalyzed alkene-CO copolymerization reaction must involve a series of acylpalladation reactions, it is outside the scope of this chapter. And, the readers are referred to recent reviews and pertinent references cited therein [27-29]. As such, the cyclic carbonylation reactions of dienes were of limited synthetic utility because of difficulties in controlling regiochemistry and other aspects of importance in fine chemicals synthesis. Whatever the reasons might have been, little had been reported further until the 1980s. 

Development of cyclic acylpalladation of halodienes and haloarylalkenes during the 1983-1985 period [10,30] (Scheme 10) proved to be a breakthrough triggering many subsequent investigations both by the authors group and by others including W. Oppolzer, R. Grigg, and K. Yamamoto. The two discrete cyclic acypalladation reactions shown in Eqs. 1 and 2 of Scheme 10 have been conveniently termed Type I and Type II cyclic acyl-... 

In addition to a couple of reviews focused on results obtained in the authors group [38,39], a comprehensive book on organopalladium chemistry for organic synthesis [40] contains two dozens or so chapters on cyclic car-bopalladation and cyclic acylpalladation. Thus, its Part IV (pi 123-1659) on carbopalladation contains reviews of cyclic carbopalladation on the synthe-... 

Table 1 Effect of ring size ont he competition between cyclic carbopalladation and cyclic acylpalladation in the presence of CO...

Ring size Substrate Cyclic carbopalladation Cyclic acylpalladation... 

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