Direct dehydrative N-Pyridinylation of amides, the interrupted Bischler-Napieralski reaction, and the enantioselective total synthesis and arylative dimerization of aspidosperma alkaloids
Name
861616020-MIT.pdf
Description
Full printable version
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50.71 MB
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Checksum (MD5)
c6c43f12a91d6e9fc51847b8742c1f29
Author(s)
Medley, Jonathan William
Advisor(s)
Mohammad Movassaghi.
Date Issued
2013
Publisher
Massachusetts Institute of Technology
Abstract
I. Direct Dehydrative N-Pyridinylation of Amides A method for the single-step N-pyridinylation of secondary amides is described. The process involves electrophilic activation of secondary amides with trifluoromethanesulfonic anhydride in the presence of 2-fluoropyridine followed by introduction of a pyridine N-oxide derivative and warming to afford the corresponding N-pyridinyl tertiary amide derivatives. The structure of activated amide intermediates is probed through in situ monitoring, and a mechanism supported by in situ monitoring and deuterium labeling experiments is discussed. II. Synthesis of Spirocyclic Indolines by Interruption of the Bischler-Napieralski Reaction The development of a versatile method for the synthesis of spirocyclic pyrrolidinoindolines is described. Treatment of N-acyltryptamines with trifluoromethanesulfonic anhydride-2-chloropyridine reagent combination affords highly persistent spiroindoleninium ions, which are selectively trapped intra- and intermolecularly by various nucleophiles. III. A Concise and Versatile Double-Cyclization Strategy for the Highly Stereoselective Synthesis and Novel Arylative Dimerization of Aspidosperma Alkaloids A strategy for the concise, stereoselective synthesis of aspidosperma alkaloids and related structures via a common putative diiminium ion intermediate is described. The approach enables the dimerization of aspidosperma-type structures at the sterically hindered C2-position. The diiminium intermediate is prepared in situ from an enantioenriched [alpha]-quaternary 2- chlorotryptamine lactam through a stereoselective electrophilic double-cyclization cascade. The key C5-quaternary stereocenter is secured via successive diastereoselective [alpha]-alkylations of pseudoephenamine crotonamide.
Description
Thesis (Ph. D. in Organic Chemistry)--Massachusetts Institute of Technology, Dept. of Chemistry, 2013.
Cataloged from PDF version of thesis. Vita.
Includes bibliographical references.
Subjects
Chemistry.
MIT Department
Massachusetts Institute of Technology. Department of Chemistry
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