Application of backdoor induction of chirality in asymmetric catalysis: enantioselective hydrogenation with rhodium complexes of triphenylphosphine amino acid bioconjugates

Kokan, Zoran (2014) Application of backdoor induction of chirality in asymmetric catalysis: enantioselective hydrogenation with rhodium complexes of triphenylphosphine amino acid bioconjugates. Doctoral thesis, Faculty of Science > Department of Chemistry.

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Abstract

Within this thesis, a total of 73 new ligands based on triphenylphosphine derivatives with aminoacids, short peptides and/or amines, were synthesized. The ligands were divided into three categories (A, B, and C) by the phosphine phenyl ring substitution and denticity. Their in situ prepared Rh(I) complexes were tested as catalysts in the enantioselective hydrogenation of model substrates, methyl-2-acetamidoprop-2-enoate (S1) and methyl-(Z)-2-acetamido-3-phenylprop-2-enoate (S2). Chiral information from distant amino acids is transmitted to the prochiral metal through "backdoor induction" via hydrogen bonding. The obtained maximal enantiomeric excess (ee) is ee(R) = 68 %, ee(S) = 84 % and ee(R) = 81 % using monodentate A, B, and bidentate C ligands, respectively. Pd(II) and Pt(II) complexes of A and B were synthesized as model compounds for examination of ligand interactions. The ligands and their metal complexes were characterized with different analytical methods (1H, 13C, 31P NMR, COSY, NOESY, ESI-MS, MALDI-TOF HRMS, CD, and single crystal X-ray diffraction). The stereochemistry of the hydrogenation products was explained using stereochemical analysis and DFT calculations.

Item Type: Thesis (Doctoral thesis)
Keywords: backdoor induction, enantioselective catalysis, hydrogen bond, chirality, aminoacids, rhodium, triphenylphosphine
Supervisor: Kirin, Srećko
Date: 2014
Number of Pages: 125
Subjects: NATURAL SCIENCES > Chemistry
Divisions: Faculty of Science > Department of Chemistry
Depositing User: mag. bibl. Ana Šafran
Date Deposited: 10 Jul 2014 12:37
Last Modified: 14 Feb 2017 16:51
URI: http://digre.pmf.unizg.hr/id/eprint/2496

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