The palladium (II) acetate promoted 6-endo-trig cyclization of 1,1-dialkyl-2-silyloxy-1,5-dienes.

Development, Scope, and Mechanism of the Palladium-Catalyzed Intramolecular Hydroalkylation of 3-Butenyl β-Diketones

“…For these reasons, we believed that the β-diketone moiety of 3 would be sufficiently nucleophilic to attack the pendant olefin in the presence of 4 . By analogy with the Pd(II)-mediated cyclization of 3-butenyl silyl enol ethers (eq 2), we expected that reaction of 3 with 4 would occur via an initial 5- exo -trig cyclization followed by β-hydride elimination and olefin displacement to form 2-acetyl-3-methyl-2-cyclopentenone and a Pd(0) complex (Scheme ). We reasoned that the β-diketone moiety, in contrast to the silyl enol ether functionality, would tolerate the conditions required for in situ oxidation of Pd(0), and if these conditions were met, the Pd(II)-catalyzed oxidative alkylation of an unactivated olefin would be realized.…”

“…In the presence of a suitable oxidant, Pd(II) complexes catalyze the oxidative amination, alkoxylation, and hydroxylation of unactivated olefins with heteroatom nucleophiles. In a similar manner, palladium(II) complexes mediate the oxidative alkylation of unactivated olefins with stabilized carbon nucleophiles such as a malonate anion or silyl enol ether (eq 2). , However, efficient Pd(II)-catalyzed oxidative alkylation has been largely precluded by the incompatibility of the nucleophile with the stoichiometric oxidant and/or the Pd(II) complex , and silyl dienol ethers .…”