Lipophilic chiral cobalt (III) complexes of hexaamine ligands: Efficacies as enantioselective hydrogen bond donor catalysts Academic Article

abstract

• 2019 Elsevier B.V. Four known chiral enantiopure octahedral cobalt(III)trichloride salts with aliphatic hexaamine ligands are converted to new CH2Cl2 soluble tris(tetraarylborate)or 3BArf salts (BArf = B(3,5-C6H3(CF3)2)4 in biphasic reactions. These include sepulchrate and sarcophagine complexes in which the hexaamine ligands are bicyclic (Z(CH2NHCH2CH2NHCH2)3Z, Z=N, CX), as well as a truncated sarcophagine in which a missing carbon vertex renders the ligand acyclic and tripodal, with three terminal NH2 groups that define a trigonal C3 symmetric face (CH3C(CH2NHCH2CH2NH2)3). In the presence of tertiary amine bases, these are effective catalysts for two Michael type carbon-carbon bond forming reactions and a related carbon-nitrogen bond forming reaction. However, only the last complex affords significant enantioselectivities (3057% ee). Rationales, and directions for future catalyst optimization, are proposed.

authors

• Gladysz, John

published proceedings

• MOLECULAR CATALYSIS

altmetric score

• 3

author list (cited authors)

• Maximuck, W. J., & Gladysz, J. A.

citation count

• 13

complete list of authors

• Maximuck, William J||Gladysz, John A

publication date

• August 2019

publisher

• Elsevier  Publisher

published in

• Molecular Catalysis  Journal

keywords

• Cobalt
• Enantioselective Catalysis
• Hexaamine Ligands
• Hydrogen Bonding
• Sarcophagine Complexes
• Sepulchrate Complexes
• Werner Complexes

Digital Object Identifier (DOI)

• 10.1016/j.mcat.2019.03.018

start page

• 117

end page

• 124

volume

• 473

URL

• http://dx.doi.org/10.1016/j.mcat.2019.03.018