Text

theses

Chiral Brønsted acidic small molecules have found widespread applications as organocatalysts from the beginning of this century. Weaker Brønsted acids such as diols and (thio)ureas, typically classified as hydrogen bonding catalysts, and stronger phosphoric acids have proven to be highly effective in a wide range of asymmetric transformations. Chiral carboxylic acids, much less developed than those mentioned above, have recently drawn the attention of organic chemists as complementary Brønsted acid catalysts. Given that the pKa of a chiral carboxylic acid is expected to lie between that of most hydrogen bond donor and chiral phosphoric acid catalysts, it provides new potential to activate a different set of substrates requiring appropriate catalyst acidity. More importantly, by taking advantage of the judicious design of the catalyst structure, the acidity can be largely increased by the stabilization of the corresponding counterion via all kinds of interactions. This dissertation outlines the development of a new type of conjugate-base-stabilized carboxylic acid to solve the problems that have not been addressed by previously existing catalytic systems. In addition, the development of innovative synthetic applications of known chiral phosphoric acids is also detailed. Specific projects include the inter-, intramolecular Povarov reactions of secondary amines, kinetic resolution of indolines, the synthesis of polycyclic amines via an oxidative Povarov approach, the biomimetic enantioselective synthesis of isoindolinones and a dual-catalysis approach to the kinetic resolution of 1,2-diaryl-1,2-diaminoethanes.

ETD_7750

Ph.D.

Includes bibliographical references

by Chang Min

doi:10.7282/T3M90C44

ETD doctoral

The author owns the copyright to this work.