Dissertation Information for Cheryl K. Eidell NAME: - Cheryl K. Eidell
DEGREE:
- Ph.D.
DISCIPLINE:
- Chemistry
SCHOOL:
- Emory University (USA) (2001)
ADVISORS: - Albert Padwa
COMMITTEE MEMBERS: - Frank E. McDonald - David Goldsmith
MPACT Status: Fully Complete
Title: The preparation and Diels-Alder cycloaddition of 2-amino and 2-amidofurans: Application toward alkaloid synthesis
Abstract: "The synthesis of 2-amino- and amido-furans for use in Diels-Alder cycloadditions was explored. Three novel methods for amido-furan formation were developed utilizing either Pummerer conditions, iminium salt formation, or diazo decomposition reactions. The various substituted amido-furans generated were found to undergo facile Diels-Alder reactions to give interesting azapolycyclic systems applicable to natural product synthesis.
Thio- and oxa-substituted furans were synthesized by generating a thionium or oxonium ion which was trapped intra molecularly via an oxygen atom of an adjacent amide carbonyl. When a dienophile was connected via a carbon chain to the amido functionality, the amido-thio-furan or amido-oxa-furan underwent an intramolecular Diels-Alder reaction followed by nitrogen assisted ring opening of the initial oxa-bridged cycloadduct. For the amido-oxa-furans, elimination produced an aromatized product, while a 1,2-thiomethyl shift occurred for the amido-thio-furan cycloadducts. This cascade methodology was showcased in the formal synthesis of (±)-erysotrine and the synthesis of the core of (±)-mesembrine.
In situ formation of amino-isobenzofurans was accomplished using stable iminium salts generated from an intramolecular attack of carbon atoms bearing suitable leaving groups by neighboring oxygen atoms of amide carbonyls. A variety of leaving groups, such as bromides, mesylates, and triflates, were employed in the salt formation. Upon treatment with base, the iminium salts were deprotonated to reveal the amino-isobenzofuran which was immediately trapped with various dienophiles in both an inter- and intramolecular fashion. This methodology provided facile entry into the benzophenanthridine core.
The third method developed for amido-furan synthesis involved the rhodium catalyzed decomposition of á-diazo imides which generated a push-pull carbonyl ylide. A rapid 1,4-hydrogen transfer occurred to provide an amido-substituted furanone. Acylation of the furanones gave amido-furans which could be trapped with various dienophiles."
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MPACT Scores for Cheryl K. Eidell A = 0
C = 0
A+C = 0
T = 0
G = 0
W = 0
TD = 0
TA = 0
calculated 2008-04-10 16:12:31
Advisors and Advisees Graph
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