Investigations in Enantioselective Catalysis. Development of Novel Asymmetric Organocatalytic Reactions

Citation

Borths, Christopher J. (2005) Investigations in Enantioselective Catalysis. Development of Novel Asymmetric Organocatalytic Reactions. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/bhq4-ep12. https://resolver.caltech.edu/CaltechETD:etd-07072004-222212

Abstract

A new strategy for the catalysis of organic transformations using iminium ion activation has been developed. Using this strategy, the first asymmetric organocatalytic Diels-Alder reaction has been developed. This methodology has demonstrated the possibility of an imidazolidinone salt to function as an effective asymmetric catalyst for a wide variety of chemical transformations.

The iminium ion activation strategy has also proved successful for conjugate additions, and an asymmetric organocatalytic Mukaiyama-Michael reaction has been developed using the principles of LUMO-lowering catalysis. A more reactive and selective chiral imidazolidinone catalyst was developed, and this secondary amine has extended the range of transformations possible with iminium ion catalysis.

Progress has been made towards the development of an enantioselective organocatalytic alpha-oxidation of ketones. Proline catalysis has been demonstrated to effectively catalyze the asymmetric alpha-oxidation of cyclohexanone, but extension of this methodology to other ketones has not been successful. These studies have further demonstrated the utility of proline as a catalyst, and provide a platform for the extension of HOMO-raising catalysis to other organic transformations.

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