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Enantioselective β-functionalization of enals via N-heterocyclic carbene catalysis

Date

2015

Authors

White, Nicholas Andrew, author
Rovis, Tomislav, advisor
Kennan, Alan J., committee member
Chen, Eugene Y.-X., committee member
Williams, Robert M., committee member
Kipper, Matt J., committee member

Journal Title

Journal ISSN

Volume Title

Abstract

A series of δ-nitroesters were synthesized through the N-heterocyclic carbene catalyzed coupling of enals and nitroalkenes. The asymmetric coupling of these substrates via the homoenolate pathway afford δ-nitroesters in good yield, diastereoselectivity, and enantioselectivity. This methodology allows for the rapid synthesis of δ-lactams. Using this approach, we synthesized the pharmaceutically relevant piperidines paroxetine and femoxetine. A novel single-electron oxidation pathway for the N-heterocyclic carbene generated Breslow intermediate has been developed. Nitroarenes have been shown to transfer an oxygen from the nitro group to the β-position of an enal in an asymmetric fashion to generate β-hydroxy esters. This reaction affords desired β-hydroxy ester products in good yield and enantioselectivity and tolerates a wide range of enal substrates. A dimerization of aromatic enals to form 3,4-disubstituted cyclopentanones has been investigated. Using a single-electron oxidant, aromatic enals couple to form cyclopenanone products in good yield, good enantioselectivity, and excellent diastereoselectivity. A cross coupling has also been developed to afford non-symmetrical cyclopentanone products.

Description

Includes bibliographical references.
2015 Fall.

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Subject

asymmetric
carbene
catalysis
organic

Citation

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