Enantioselective synthesis and application to the allylic imidate rearrangement of amine-coordinated palladacycle catalysts of cobalt sandwich complexes

Cassar, Doyle J., Ilyashenko, Gennadiy, Ismail, Muhammad, Woods, James, Hughes, David L. and Richards, Christopher J. ORCID: https://orcid.org/0000-0001-7899-4082 (2013) Enantioselective synthesis and application to the allylic imidate rearrangement of amine-coordinated palladacycle catalysts of cobalt sandwich complexes. Chemistry - A European Journal, 19 (52). pp. 17951-17962. ISSN 0947-6539

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Abstract

The reaction of (η5-(N,N-dimethylaminomethyl)cyclopentadien-yl)(η4-tetraphenylcyclobutadiene)cobalt with sodium tetrachloropalladate and (R)-N-acetylphenylalanine gave planar chiral palladacycle di-μ-chloridebis[(η5-(Sp)-2-(N,N-dimethylaminomethyl)cyclopentadienyl,1-C,3′-N)(η4-tetraphenylcyclobutadiene)cobalt]dipalladium [(Sp)-Me2-CAP-Cl] in 92 % ee and 64 % yield. Enantiopurity (>98 % ee) was achieved by purification of the monomeric (R)-proline adducts and conversion back to the chloride dimer. Treatment with AgOAc gave (Sp)-Me2-CAP-OAc which was applied to asymmetric transcyclopalladation (up to 78 % ee). The (R)-N-acetylphenylalanine mediated palladation methodology was applicable also to the corresponding N,N-diethyl (82 % ee, 39 % yield) and pyrrolidinyl (>98 % ee, 43 % yield) cobalt sandwich complexes. A combination of 5 mol % of the latter [(Sp)-Pyrr-CAP-Cl] and AgNO3 (3.8 equiv) is a catalyst for the allylic imidate rearrangement of an (E)-N-aryltrifluoroacetimidate (up to 83 % ee), and this catalyst system is also applicable to the rearrangement of a range of (E)-trichloroacetimidates (up to 99 % ee). This asymmetric efficiency combined with the simplicity of catalyst synthesis provides accessible solutions to the generation of non-racemic allylic amine derivatives.

Item Type:	Article
Uncontrolled Keywords:	asymmetric synthesis,catalysis,metallacycles,palladium,sandwich complexes
Faculty \ School:	Faculty of Science > School of Chemistry Faculty of Science > School of Chemical Sciences and Pharmacy (former - to 2009) Faculty of Science
UEA Research Groups:	Faculty of Science > Research Groups > Synthetic Chemistry (former - to 2017) Faculty of Science > Research Groups > Chemistry of Materials and Catalysis
Depositing User:	Pure Connector
Date Deposited:	25 Jul 2014 15:20
Last Modified:	04 Jul 2023 10:30
URI:	https://ueaeprints.uea.ac.uk/id/eprint/49743
DOI:	10.1002/chem.201302922

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