be retained by macro-ring strain produced by 5,5′-linkage of biphenyls even without 6,6′-substituents on biphenyls. The Pd(II)-2d complex as catalyst showed high catalytic activity and enantioselectivity for asymmetricWacker-typecyclization of allylphenols.
Polymer-Supported 2,2′-Bis(oxazolin-2-yl)-1,1′-binaphthyls (Boxax): Immobilized Chiral Ligands for Asymmetric Wacker-Type Cyclizations
作者:Yasuhiro Uozumi、Heiko Hocke
DOI:10.1055/s-2002-35603
日期:——
,1'-binaphthyl (boxax) ligands were anchored on various polymer supports including PS-PEG, PS, PEGA, and MeO-PEG via selective monofunctionalization at the 6-position of the binaphthyl backbone. Palladium(II) complexes of the supported boxax ligands catalyzed Wacker-type cyclization of 2-(2,3-dimethyl-2-butenyl)phenol to give 2-methyl-2-isopropenyl-2,3-dihydrobenzofuran with up to 96% ee.
Chelation-Induced Axially Chiral Palladium Complex System with Tetraoxazoline Ligands for Highly Enantioselective Wacker-Type Cyclization
作者:Yong Jian Zhang、Feijun Wang、Wanbin Zhang
DOI:10.1021/jo701469y
日期:2007.11.1
A new family of chelation-induced axiallychiral palladium complexes by using biphenyl ligands 2 with four identical chiral oxazoline groups at four ortho positions has been developed. Although there is no axialchirality in ligands 2 due to the molecular symmetry, when they chelated with one or two palladium ions, the axialchirality could be induced by destroying the molecular symmetry. Significantly
Design and Preparation of 3,3‘-Disubstituted 2,2‘-Bis(oxazolyl)-1,1‘-binaphthyls (boxax): New Chiral Bis(oxazoline) Ligands for Catalytic Asymmetric Wacker-Type Cyclization
promoted by the oxazolyl groups. The 3,3'-disubstituted boxax ligands showed much higher enantioselectivity than the 3,3'-unsubstituted ones in the palladium(II)-catalyzed Wacker-typecyclization of an o-allylphenol. The cyclization of (E)-2-(2-methyl-2-butenyl)phenol (10) in the presence of a cationic palladium catalyst coordinated with (S)-2,2'-bis(4,4-dimethyloxazol-2-yl)-3,3'-bis(methoxycarbonyl)-1
Palladium-Carbene Catalysts for Aerobic, Intramolecular Wacker-Type Cyclisation Reactions
作者:Kilian Muñiz
DOI:10.1002/adsc.200404172
日期:2004.10
A catalyst derived from in situ complexation of N-heterocyclic carbenes to palladium bistrifluoroacetate promotes efficient intramolecularWacker-typecyclisationreactions under aerobic conditions. A variety of 2-allylphenols undergo oxidative conversion to dihydrobenzofurans.