title: Role of planar chirality of S,N- and P,N-ferrocene ligands in palladium-catalyzed allylic substitutions.
abstract: Palladium-catalyzed asymmetric allylic substitutions using thioether and phosphino derivatives of ferrocenyloxazoline as ligands have been investigated with a focus on studying the role of planar chirality. In allylic alkylation, up to 98% ee and 95% ee were achieved with S,N- and P,N-ligands, respectively. In allylic amination, 97% ee was realized with P,N-ligands in the presence of TBAF. Several palladium allylic complexes were characterized by X-ray diffraction and/or solution NMR. Thioether derivatives of ferrocenyloxazolines with only planar chirality showed lower enantioselectivity in the allylic alkylation except 5c because of the formation of a new chirality on sulfur atom during the coordination of sulfur with palladium. On the other hand, in the planar chiral P,N-ligands without central chirality, (Sp)-11a-c there was no such disturbance and comparatively higher enantioselectivity in both palladium-catalyzed allylic alkylation and amination was provided.
authors.affiliation: State Key Laboratory of Organometallic Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, 354 Fenglin Lu, Shanghai 200032, China.
authors.forename: Shu-Li
authors.initials: SL
authors.lastname: You
authors.forename: Xue-Long
authors.initials: XL
authors.lastname: Hou
authors.forename: Li-Xin
authors.initials: LX
authors.lastname: Dai
authors.forename: Yi-Hua
authors.initials: YH
authors.lastname: Yu
authors.forename: Wei
authors.initials: W
authors.lastname: Xia