Graduation Year

2022

Document Type

Dissertation

Degree

Ph.D.

Degree Name

Doctor of Philosophy (Ph.D.)

Degree Granting Department

Chemistry

Major Professor

Xiaodong Michael Shi, Ph.D.

Committee Member

James Leahy, Ph.D.

Committee Member

Jianfeng Cai, Ph.D.

Committee Member

Libin Ye, Ph.D.

Keywords

Alkene Oxyarylation, Alkyne arylation, Alkyne Difunctionalization, Electrochemistry, Gold Catalysis, Ligand Assisted Oxidative Addition

Abstract

This dissertation mainly contains three parts: 1) the study of ligand assisted gold oxidative addition toward aryl iodide to achieve the alkene difunctionalization. 2) The selective arylation reaction via electrochemical anode oxidation promoted gold redox chemistry. 3) The π acid reactivity of gold redox chemistry under electrochemistry conditions.

In the first part, the gold-catalyzed intermolecular oxyarylation of alkene is reported. This work employed the oxidative addition of aryl iodide to Me-DalphosAu+ for the formation of Au(III)-Ar intermediate. The better binding ability of alkene over O nucleophiles ensured the success of intermolecular oxyarylation, giving desired products with broad substrate scope and high efficiency. “One-pot” converting of methoxy group into other nucleophiles allowed achieving alkene difunctionalization with C-N, C-S, and C-C bonds construction under mild conditions.

In the second part, The combination of ArB(OH)2 transmetallation with cationic gold(I) [LAu]+ and electrochemical anodic oxidation (EAO) approach was successfully developed for the preparation of AuIII-Ar intermediate for the first time. This in-situ generated aryl gold intermediate gave rapid and controllable transmetallation with ArB(OH)2 or alkyne followed by reductive elimination to generate either di-aryl coupling or sp2-sp Sonogashira-type coupling products under mild conditions with no need of external oxidants. This study significantly extended the versatility of electrochemical approach in promoting gold redox catalysis.

In the third part, the combination of gold π acid reactivity and electrochemical anode oxidation promoted gold(I/III) redox catalysis was reported for the first time. With the utility of aryl hydrazine HOTf salt as carbon source, we avoided the generation of reactive L-Au(I)-Ar intermediate in the reaction pathway. The reaction was successfully carried out under mild conditions without any external oxidant, and both alkene and alkyne di-functionalization were received under mild conditions with excellent functional group compatibility and regioselectivity.

In summary, we explored two new strategies for achieving gold redox chemistry in a catalytic version. Both the oxidative addition approach and the electrochemistry oxidation pathway showed excellent reactivity under mild conditions and have a broad substrate scope. These newly developed strategy will definitely facilitate more useful transformations in gold redox chemistry.

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