Palladium(II)-Catalyzed Enyne Coupling Reaction Initiated by Acetoxypalladation of Alkynes and Quenched by Protonolysis of the Carbon−Palladium Bond
作者:Ligang Zhao、Xiyan Lu、Wei Xu
DOI:10.1021/jo050121n
日期:2005.5.1
key step in completing the Pd(II) catalytic cycle. The nitrogen-containing ligands, like halides, served to favor the protonolysis of the carbon−palladium bond over the β-H elimination in the Pd(II)-mediated reactions. The intermolecular coupling reactions provide an efficient method for synthesizing γ,δ-unsaturated carbonyls. The intramolecular coupling reactions offer a method to construct a variety
thiyl radical to the alkynyl group followed by radical cyclization of the corresponding vinyl radical onto the O-silyloxime moiety to give cyclic O-silylhydroxylamines in good yields. The reactivity of O-silyloximes in radical cyclization was similar to or even higher than that of O-benzyloximes. Facile removal of the silyl group of the cyclization products leading to hydroxylamines and nitrone formation
Nickel-mediated cyclization of enynes under an atmosphere of carbon dioxide
作者:Masanori Takimoto、Takashi Mizuno、Miwako Mori、Yoshihiro Sato
DOI:10.1016/j.tet.2006.03.121
日期:2006.8
Nickel-mediated carboxylation of α,ω-enyne was investigated. In the presence of a stoichiometric amount of zero-valent nickel complex, enynes having an electron-withdrawing group on alkene reacted with carbon dioxide via intramolecular cyclization to afford cyclic carboxylic acids in good yields. Various heterocyclic compounds were prepared by this carboxylative cyclization protocol. The reaction seems