Palladium-catalyzed 1,4-additions

On the other hand, Li et al. reported the first palladium-catalyzed 1,4-addition of terminal alkynes to vinyl ketones in water with high yields (Eq. 4.36).60 At nearly the same time, Chisholm et al. reported such a reaction catalyzed by Rh(acac)(CO)2 (acac = acetylacetonoate) in the presence of /m(o-mcthoxyphcnyl)phosphine in aqueous dioxane... 

Palladium-catalyzed 1,4-additions to conjugated dienes can be divided into two classes (1) non-oxidation reactions that (2) oxidation reactions. In the former class, a palladium(O) catalyst is employed and the first step in the catalytic cycle is often an activation of one of the reactants by its oxidative addition to Pd(0). In the second class, a palladium(II) complex is the active catalyst which oxidizes the substrate diene with formation of Pd(0). Reoxidation of Pd(0) to Pd(II) by an oxidant regenerates the active catalyst. 

Related palladium-catalyzed 1,4-additions of a carbon and an amine function via a carbocyclization of 18 were reported by Grigg (Eq.(20)] [40,41]. In this case, the spriocyclic compound 19 was formed. 

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