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Harnessing single amino acid catalysis: Development of the enantioselective intramolecular Morita-Baylis-Hillman and Rauhut-Currier reactions and studies toward the synthesis of (+)-Sch 642305
by Aroyan, Carrie Elizabeth, Ph.D., Boston College, 2008, 337 pages; AAT 3341012

Abstract (Summary)

The development of two catalytic asymmetric synthetic methods is presented and culminates with studies of their application to the synthesis of a natural product. The intramolecular variant of the Morita-Baylis-Hillman (MBH) reaction has remained almost untouched by asymmetric catalysis. A significant advance in the field is demonstrated with the development of a highly enantioselective intramolecular MBH reaction employing a co-catalytic system of N -methylimidazole (NMI) and pipecolinic acid (Pip). The optimization of various reaction parameters and the use of protic conditions (THF-H 2 O, 3:1) afforded the desired products in up to 82% yield and 80% ee. The extension of this methodology to include the use of vinylogous reaction partners in the Rauhut-Currier (RC) reaction has been achieved, establishing the first highly enantioselective RC reaction. A single amino acid derivative of cysteine, in the presence of potassium tert -butoxide and a critical concentration of water in acetonitrile, was demonstrated to function as a highly selective catalyst providing products in up to 95% ee. Finally, the application of the MBH and RC reactions to the synthesis of complex molecules presents highly useful methodology for the formation of a new C-C bond in the generation of densely functionalized enantiopure products. Preliminary studies toward the application of this methodology to the stereoselective synthesis of (+)-Sch 642305 are described. Examination of the catalyst's ability to dictate the stereoselectivity of the key step ( catalyst control ) and allow the synthesis of both the natural product, and difficult-to-obtain unnatural stereoisomeric analogs, will be the subject of on-going studies.

Indexing (document details)

Advisor:Miller, Scott J.
School:Boston College
School Location:United States -- Massachusetts
Keyword(s):Amino acid catalysis, Morita-Baylis-Hillman reaction, Rauhut-Currier reaction
Source:DAI-B 69/12, Jun 2009
Source type:Dissertation
Subjects:Organic chemistry
Publication Number: AAT 3341012
ISBN:9780549958659
Document URL:http://proquest.umi.com/pqdlink?did=1686173761&Fmt=7&clientI d=79356&RQT=309&VName=PQD
ProQuest document ID:1686173761


 

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