A Polystyrene-Cross-Linking Bisphosphine: Controlled Metal Monochelation and Ligand-Enabled First-Row Transition Metal Catalysis

作者：Iwai Tomohiro; Harada Tomoya; Shimada Hajime; Asano Kiichi; Sawamura Masaya

来源：ACS Catalysis, 2017, 7(3): 1681-1692.

DOI：10.1021/acscatal.6b02988

• immobilized phosphines
• polystyrene
• bisphosphine
• first-row transition metals
• C-N coupling
• C-H/C-Ocoupling
• hydroboration

A polystyrene-cross-linking bisphosphine PSDPPBz was synthesized through radical emulsion copolymer-ization between 4-t-butylstyrene as a monomer and tetraviny-lated 1,2-bis(diphenylphosphino)benzene (DPPBz) as a 4-fold cross-linker. The location of the DPPBz bisphosphine moiety at the branching points of the cross-linked network organic polymer allowed controlled bisphosphine monochelation to transition metals under conditions where homogeneous ligands may form bischelated single metal complexes or multinuclear complexes. PS-DPPBz showed high ligand performance in first-row transition metal catalysis, enabling challenging molecular Alkyl transformations that were not possible through the screening of existing homogeneous ligands. In the Ni-catalyzed amination of aryl chlorides with N-alkyl-substituted primary amines, the substrate scope has been expanded to include 2,6-disubstituted aryl chlorides and N-tertiary-alkyl-substituted primary amines. PS-DPPBz was effective for the Ni-catalyzed C-H/C-O coupling between 1,3-azoles and monocyclic aryl pivalates, which showed poor reactivity in the reported homogeneous catalytic system based on 1,2-bis(dicyclohexylphosphino)ethane (DCYPE). The usefulness of the polymer-cross-linking strategy was also demonstrated in alkene hydroboration reactions catalyzed by Cu or Co.

• 出版日期2017-3