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dc.contributor.authorLuan, Yien_US
dc.date.accessioned2015-08-07T03:18:41Z
dc.date.available2015-08-07T03:18:41Z
dc.date.issued2013
dc.date.submitted2013
dc.identifier.other(ALMA)contemp
dc.identifier.urihttps://hdl.handle.net/2144/12810
dc.descriptionThesis (Ph.D.)--Boston University PLEASE NOTE: Boston University Libraries did not receive an Authorization To Manage form for this thesis or dissertation. It is therefore not openly accessible, though it may be available by request. If you are the author or principal advisor of this work and would like to request open access for it, please contact us at open-help@bu.edu. Thank you.en_US
dc.description.abstractβ-amino esters are useful building blocks for the synthesis of biologically active β-amino carbonyl compounds. We developed a three-component condensation reaction for directly accessing β-amino esters using diazo esters, arylboranes, and carbamoyl imines. Catalyzed by Cu(II) salts, the reaction affords the corresponding isocyanate Mannich product: one that can be easily trapped in situ by other nucleophiles. The overall Mannich condensation is an α,α-disubstituted enolate addition to imines. The reaction was rendered asymmetric using (-)-phenylmenthol ester in good yields and selectivities. The tetrahydrochromeno polycyclic core is a characteristically unique structure among the large number of biologically active phenolic compounds isolated from nature. We have developed an iron-catalyzed tandem rearrangementlhetero-Diels--Alder approach to access tetrahydrochromeno heterocycles. The process can occur as a homodimerization and cycloaddition process using electron-rich dienophiles. Deuterium labeling and mechanistic studies revealed a hydride shift and ortho-quinone methide cycloaddition reaction pathway. Short route synthesis of (±)-dependensin using the homodimerization approach has also been demonstrated. The enantioselective addition of vinyl- and aryl boronates to ortho-quinone methides would result in compounds with a benzylic chiral carbon center. This methodology could readily be utilized in the synthesis of a variety of natural products, such as (+)-cochinchinenene B- D, myristinin A, (-)-(S)-4-methoxy-dalbergione and (+)-mimosifoliol. We have developed a novel enantioselective addition ofboronates to orthoquinone methides catalyzed by chiral biphenols. Substituted 2-styryl phenols were obtained in good yields (up to 95%) and high enantiomeric ratios (up to 98:2) in presence of 10 mol % of 3,3'-Br2-BINOL. A two-step synthesis of (S)-4-Methoxy-dalbergione is achieved in good yield and selectivity. Dihydronaphthalene derivatives are useful starting materials for the synthesis of biologically active cyclic molecules. We developed a new enantioselective [4 + 2] cycloaddition reaction, which uses alkenyl boronate as the dienophile. The reaction is dual catalyzed by a chiral Bmnsted acid and an achiral Lewis acid. The 1,2-dihydronaphthalene products are obtained in high yields, diastereoselectivities and enantioselectivities.en_US
dc.language.isoen_US
dc.publisherBoston Universityen_US
dc.titleExpanding the reactivity of metal- and boron-mediated asymmetric mutli-component condensation reactionsen_US
dc.typeThesis/Dissertationen_US
etd.degree.nameDoctor of Philosophyen_US
etd.degree.leveldoctoralen_US
etd.degree.disciplineChemistryen_US
etd.degree.grantorBoston Universityen_US


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