Lanthanides–pybox: An Excellent Combination for Highly Enantioselective Electrophilic α-Amination of Acyclic β-Keto Esters. Isolation of Ternary Pybox/Ln/β-Keto Ester Complexes

Àlex Pericas, Rubén Jiménez, Albert Granados, Alexandr Shafir, Adelina Vallribera, Anna Roglans, Elies Molins

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7 Citations (Scopus)

Abstract

© 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim High enantioselection is obtained in α-amination of acyclic β-keto esters in the presence of lanthanide triflates and pybox ligands. The Eu3+ complexes proved more active than those with Yb3+ and La3+ and high dependence of ee on the type and steric bulk of the ester group was observed. Excellent results were achieved using a combination of europium triflate with ligand L4 (diphenyl-pybox). Preparation of ternary complexes (8) [(L4)(β-keto ester enolate)Ln (OTf)2] was accomplished. Complexes 8 and [(L4)(β-keto ester)Ln (OTf)2]+, identified by ESI-MS, are proposed as key intermediates of the α-amination reaction.
Original languageEnglish
Pages (from-to)4305-4312
JournalChemistrySelect
Volume1
Issue number14
DOIs
Publication statusPublished - 1 Jan 2016

Keywords

  • lanthanides
  • pybox ligands
  • ternary reaction intermediates
  • α-amination
  • β-keto esters

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