Stereoselectivity induced by support confinement effects. Aza-pyridinoxazolines: A new family of C1-symmetric ligands for copper-catalyzed enantioselective cyclopropanation reactions

  1. García, J.I. 1
  2. Jiménez-Osés, G. 1
  3. López-Sánchez, B. 1
  4. Mayoral, J.A. 1
  5. Vélez, Andrea . 1
  1. 1 Universidad de Zaragoza
    info

    Universidad de Zaragoza

    Zaragoza, España

    ROR https://ror.org/012a91z28

Revista:
Dalton Transactions

ISSN: 1477-9226

Año de publicación: 2010

Volumen: 39

Número: 8

Páginas: 2098-2107

Tipo: Artículo

DOI: 10.1039/B919274C SCOPUS: 2-s2.0-76749118894 WoS: WOS:000274405200030 GOOGLE SCHOLAR

Otras publicaciones en: Dalton Transactions

Resumen

Aza-pyridinoxazoline ligands, a new class of C1-symmetric ligands, are described and tested in the heterogeneous enantioselective catalysis of a cyclopropanation reaction, with the aim of improving surface confinement effects by the clay support on the reaction stereoselectivity. In the case of trans/cis diastereoselectivity, these surface effects lead to a systematic reversal of selectivity, cis-cyclopropanes being favored. Regarding the enantioselectivities, support confinement has a positive effect in the case of major cis-cyclopropane products, leading to moderate enantioselectivity values (60% ee). A theoretical (DFT) mechanistic study is carried out to explain the origin of the enantioselectivity in the homogeneous phase at a molecular level, and to get insights on the geometries of the key intermediates and transition structures. © 2010 The Royal Society of Chemistry.