(π-Allyl)palladium Complexes Bearing Diphosphinidenecyclobutene Ligands (DPCB): Highly Active Catalysts for Direct Conversion of Allylic Alcohols
journal contributionposted on 20.08.2002, 00:00 by Fumiyuki Ozawa, Hideyuki Okamoto, Seiji Kawagishi, Shogo Yamamoto, Tatsuya Minami, Masaaki Yoshifuji
The (π-allyl)palladium complex bearing an sp2-hybridized phosphorus ligand (DPCB-OMe: 1,2-bis(4-methoxyphenyl)-3,4-bis[(2,4,6-tri-tert-butylphenyl)phosphinidene]cyclobutene) efficiently catalyzes direct conversion of allylic alcohols in the absence of activating agents of alcohols such as Lewis acids. N-Allylation of aniline proceeds at room temperature to afford monoallylated anilines in 90−97% yields. C-Allylation of active methylene compounds is also successful at 50 °C using a catalytic amount of pyridine as a base, giving monoallylation products in 85−95% yields. The catalytic mechanism involving hydrido- and (π-allyl)palladium intermediates has been proposed on the basis of stoichiometric examinations using model compounds of presumed intermediates.
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hydridomonoallylation productsabsencehybridized phosphorus ligandsp 2yieldstoichiometric examinationsallylic alcoholstertDirect ConversionLigandcatalyzemethylene compoundsbutylphenylDPCBbiComplexebasisActive CatalystsintermediateAllylic Alcoholsaniline proceedsLewis acidsBearingagentDiphosphinidenecyclobuteneconversionmechanismpyridinemodel compoundsmonoallylated anilinesroom temperature