1,3-Dipolar Cycloaddition of Electron-rich Alkynes and Optically Active Allenes in Asymmetric Catalysis

DSpace/Manakin Repository

1,3-Dipolar Cycloaddition of Electron-rich Alkynes and Optically Active Allenes in Asymmetric Catalysis

Show simple item record


dc.contributor.advisor Ready, Joseph M. en
dc.creator Qi, Xiangbing en
dc.date.accessioned 2010-07-12T17:40:03Z en
dc.date.available 2010-07-12T17:40:03Z en
dc.date.issued 2009-09-04 en
dc.identifier.other 760901123 en
dc.identifier.uri http://hdl.handle.net/2152.5/344 en
dc.description.abstract This dissertation includes two parts. The first part focuses on two 1,3-dipolar cycloadditions of electron-rich alkynes. Chapter one describes a copper-promoted cycloaddition reaction of acetylides with diazocarbonyl compounds. This novel cycloaddition offers a direct and efficient approach to the synthesis of pyrazoles. The method is a rare example of an inverse-electron-demand cycloaddition, it represents a conceptually novel approach to this important class of heterocycles. Chapter two investigates a cycloaddition reaction between donor-acceptor cyclopropanes and silyl ynol ethers. Lewis acid promoted ring-opening of donor-acceptor cyclopropanes generates a 1,3-zwitterion; cycloaddition with a silyl ynol ether leads to a general synthesis of cyclopentenones. Substitution is tolerated on the ynol and on all positions of the cyclopropane to give tri-, tetra-, and penta-substituted cyclopentenones in high yield. methyl(methoxyl)aluminumchloride, which is generated from dimethylaluminumchloride by oxidation, appears strong reactivity towards ring-opening of donor-acceptorcyclopropanes and cycloaddition with silyl ynol ethers. This infrequently used species might be extended to other classes of cycloadditions or Lewis acid promoted reactions. The second part describes a new asymmetric catalysis design using optically active allenes as backbone and the application in an asymmetric meso-epoxides opening reaction. Allenes are inherently chiral and can be prepared in optically pure form. They have not been incorporated into ligands or catalysts for asymmetric reactions. Since allenes project functionality differently than either tetrahedral carbon or chiral biaryls, they may create complementary chiral environments. Chapter three demonstrates that optically active, C2-symmetric allene-containing bisphosphine oxides can catalyze the addition of silicon tetrachloride to meso-epoxides with high enantioselectivity. The fact that high asymmetric induction is observed suggests that allenes may represent a new platform for the development other classes of organic catalysts or ligands for asymmetris reactions. en
dc.format.medium Electronic en
dc.format.mimetype application/pdf en
dc.language.iso en en
dc.subject Alkynes en
dc.subject Cyclopropanes en
dc.subject Hydrocarbons, Cyclic en
dc.title 1,3-Dipolar Cycloaddition of Electron-rich Alkynes and Optically Active Allenes in Asymmetric Catalysis en
dc.type.material Text en
dc.type.genre dissertation en
dc.format.digitalOrigin born digital en
thesis.degree.grantor Graduate School of Biomedical Sciences en
thesis.degree.department en
thesis.degree.name Doctor of Philosophy en
thesis.degree.level Ph.D en
thesis.degree.discipline Biological Chemistry en
thesis.date.available 2011-09-04 en

Files in this item

Files Size Format View
qixiangbing.pdf 2.366Mb PDF View/Open

This item appears in the following Collection(s)

Show simple item record

Search DSpace


Advanced Search

Browse

My Account