Graduation Year

2017

Document Type

Thesis

Degree

M.S.

Degree Name

Master of Science (M.S.)

Degree Granting Department

Chemistry

Major Professor

X. Michael Shi, Ph.D.

Committee Member

Shengqian Ma, Ph.D.

Committee Member

Jianfeng Cai, Ph.D.

Keywords

gold, enol, catalysis, alkynylation, acetylide, cascade

Abstract

Au(I) catalysis has recently emerged as a powerful tool for the realization of a broad range of organic transformations. Despite this rapid development, attaining selectivity and maintaining catalyst stability remain significant challenges. Rational ligand design, such as the employment of NHC or TA ligands, has been used to confront these issues. This thesis focuses on the use of Au(I) catalysts bearing these ligands for the selective hydroalkynylation of enol ethers. By employing a TA-Au stabilized catalyst, [(OAr)3PAu(TA-H)]OTf, the intermolecular hydroalkynylation of enol ethers, a substrate that is well-known to promote decomposition of the gold cation, was efficiently achieved. As an expansion of this reaction, the NHC-Au catalyst, IPrAuNTf2, was utilized in a multicomponent system to promote the tandem hydroalkynylation of enol ethers formed in-situ via the cycloisomerization of alkynols. Further exploration of this tandem reaction revealed that IPrAuNTf2 catalyzes a cascade ring-expansion of the alkynylated heterocycles to form oxepines. The mechanistic and synthetic insight obtained from these developed reactions has the potential to be applied towards future studies in gold catalysis.

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