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Application of Diels-Alder reactions of 2-(N-acylamino)-1,3-dienes toward the total synthesis of stenineBoren, Brant Clayton 17 February 2005 (has links)
Natural products continue to influence society at large as many drugs are of
natural product origin. Consequently, the development and study of new chemical
reactions that lead to the efficient preparation of natural products is a central goal in
organic chemistry today. To this end, we have investigated the reactivity and
stereoselectivity of cyclic 2-(N-acylamino)-1,3-dienes toward a total synthesis of
stenine. Chapter I describes the isolation and characterization of stenine, in addition to
comparing five published total syntheses of stenine.
Chapter II discusses synthetic and theoretical investigations of cyclic 2-(Nacylamino)-
1,3-dienes. We have shown that vinylazepenes react with Nphenylmaleimide
to afford exo cycloadducts exclusively. Previous studies of
vinylpiperidenes revealed a preference for endo selectivity. We confirmed the
contrasting stereoselectivity by X-ray analysis of compounds i and ii.
The stereoselectivity of vinylazepenes, vinylcycloalkenes, and vinyl piperidenes
in Diels-Alder reactions varies depending on the detailed structure of the diene. In
collaboration with Dr. Daniel Singleton and Jennifer Hirschi, DFT calculations were
utilized to study model reactions of these dienes to provide insight into controlling the
stereochemistry of this class of Diels-Alder reactions.
Chapter III describes the synthesis of compounds such as iv and v that were
utilized in intra and intermolecular Diels-Alder approaches toward the synthesis of
stenine. We demonstrated that intermediate viii could be constructed from vinyl
stannane vii in ten steps via an intermolecular Diels-Alder reaction of v and dimethyl
fumarate (vi). Finally, we propose a synthetic plan for the completion of stenine from
advanced intermediate viii.
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