Chemistry ETDs

Author

Xixi Song

Publication Date

7-6-2012

Abstract

The development of new catalytic reactions, particularly synthetically efficient cascade processes for the facile preparation of important molecular architectures, which otherwise are difficult to access via traditional methods, is of considerable significance. Toward this end, my Ph.D. work focuses on developing new organocatalytic reactions and their applications in organic syntheses. A novel direct organocatalytic stereoselective α-arylation methodology has been discovered. The cross-coupling-like products are assembled using simple enals and various brominated aromatic systems, such as p-bromophenols, bromonaphthols and 3-bromoindoles. The products have been applied in the concise photo-syntheses of [α]-annulated carbazoles. Moreover, an unexpected reaction has been identified with aliphatic enals, and fully developed into a new [3+3] formal cycloaddition cascade reaction, and serves as a powerful approach to polysubstituted arenes from simple enals in a highly regio- and chemo-selective fashion. The Diels-Alder reaction of acetylenic aldehydes has been realized for 'one-pot' synthesis of polysubstituted salicylaldehyde frameworks that were constructed via an unprecedented aminocatalytic Diels-Alder-retro-Diels-Alder cascade from simple alkynals and 2-pyrones. Furthermore, the use of N-protected 3-hydroxy-2-pyridines as dienes leads to catalytic enantioselective Diels-Alder process without subsequent retro-Diels-Alder reaction. A chiral C2 symmetric organocatalyst is found as an effective promoter for the activation and stereo-control of various substituted alkynals.

Language

English

Keywords

organocatalysis, cascade reaction, asymmetric catalysis, aminocatalysis

Document Type

Dissertation

Degree Name

Chemistry

Level of Degree

Doctoral

Department Name

Department of Chemistry and Chemical Biology

First Advisor

Wang, Wei

First Committee Member (Chair)

Wang, Wei

Second Committee Member

Mariano, Patrick

Third Committee Member

Guo, Hua

Fourth Committee Member

Feng, Changjian

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