Synthesis of chiral titanium-containing phosphinoamide ligands for enantioselective heterobimetallic catalysis

TETRAHEDRON

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Article

Ence, Chloe C.¹  Walker, Whitney K.¹  Stokes, Ryjul W.¹  Martinez, Erin E.¹  Sarager, Spencer M.¹  Smith, Stacey J.¹  Michaelis, David J.¹ 

[1] Brigham Young Univ, Dept Chem & Biochem, Provo, UT 84602 USA

关键词: Phosphinoamide ligand;    Heterobimetallic catalyst;    Enantioselective;    Allylic amination;    Palladium;   

DOI  :  10.1016/j.tet.2019.04.063

来源: Elsevier

【 摘 要 】

The synthesis of six chiral titanium-containing phosphinoamide ligands is discussed. These ligands assemble chiral heterobimetallic Pd-Ti complexes, enable enantioselective intramolecular allylic aminations with hindered amine nucleophiles and achieve selectivity up to 53% ee. Mechanistic studies demonstrate the reversibility of the enantio-determining C-N bond forming step, which leads to a gradual increase in the % ee of the reaction over time. These results represent a rare example of enan-tioselective heterobimetallic catalysis and suggest that these new ligands could find broad application in enantioselective transition metal catalysis. (C) 2019 Elsevier Ltd. All rights reserved.

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