THESIS
2023
1 online resource (xiv, 92 pages) : illustrations (some color)
Abstract
Thiamine is a water-soluble vitamin, which through its pyrophosphorylated derivative thiamine
diphosphate (ThDP), serves as an enzyme cofactor in a multitude of biomolecular reactions via
ylide/carbene chemistry. The transient N-heterocyclic carbene (NHC) species generated during
its biocatalysis is an attractive ligand for transition metal catalysts as it can confer on them
enhanced water solubility and potentially novel activity. A water-soluble NHC-Au(I)Cl
complex of thiamine was synthesized by the in situ generation of a thiazolin-2-ylidine carbene
from thiamine hydrochloride in the presence of chloro(dimethylsulfide)gold(I) and was
thoroughly characterized by
1H NMR,
13C NMR and ESI-HRMS. This complex was utilized
as a green catalyst for the A
3 coupling reaction. Its catalytic acti...[
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Thiamine is a water-soluble vitamin, which through its pyrophosphorylated derivative thiamine
diphosphate (ThDP), serves as an enzyme cofactor in a multitude of biomolecular reactions via
ylide/carbene chemistry. The transient N-heterocyclic carbene (NHC) species generated during
its biocatalysis is an attractive ligand for transition metal catalysts as it can confer on them
enhanced water solubility and potentially novel activity. A water-soluble NHC-Au(I)Cl
complex of thiamine was synthesized by the in situ generation of a thiazolin-2-ylidine carbene
from thiamine hydrochloride in the presence of chloro(dimethylsulfide)gold(I) and was
thoroughly characterized by
1H NMR,
13C NMR and ESI-HRMS. This complex was utilized
as a green catalyst for the A
3 coupling reaction. Its catalytic activity matched or exceeded other
common A
3 coupling catalysts while tolerating a broad range of substrates. A new class of
artificial metalloenzymes based on the supramolecular anchoring of ThDP to bacterial enzyme
MenD was envisioned; this system aims to promote asymmetric organometallic catalysis in the
aqueous and chiral environment of the MenD active site. To this end, the synthesis of a ThDP-AuCl
NHC complex was attempted. Attempts at direct synthesis of the complex were not
successful. Several strategies towards the indirect synthesis of the complex via the characterized
thiamine-AuCl NHC complex were attempted instead, but they too did not yield the desired
product. Miscellaneous investigations were conducted which uncovered the relatively
unexplored chemistry of thiazolin-2-ylidine carbene metal complexes, helping to rationalize
some observations of performed experiments.
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