Development of new transition metal catalyzed C-C bond forming reactions and their application toward natural product synthesis

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dc.contributor.advisorKrische, Michael J.en
dc.contributor.committeeMemberAnslyn, Eric V.en
dc.contributor.committeeMemberSiegel, Dionicio R.en
dc.contributor.committeeMemberBrodbelt, Jennifer S.en
dc.contributor.committeeMemberLiu, Hung-Wenen
dc.creatorHassan, Abbasen
dc.date.accessioned2012-01-27T22:00:43Zen
dc.date.accessioned2017-05-11T22:23:54Z
dc.date.available2012-01-27T22:00:43Zen
dc.date.available2017-05-11T22:23:54Z
dc.date.issued2011-12en
dc.date.submittedDecember 2011en
dc.date.updated2012-01-27T22:01:37Zen
dc.descriptiontexten
dc.description.abstractIn Michael J. Krische research group we are developing new transition metal catalyzed Carbon-Carbon (C-C) forming reactions focusing on atom economy and byproduct free, environmental friendly approaches. We have developed a broad family of C-C bond forming hydrogenations with relative and absolute stereocontrol which provide an alternative to stoichiometric organometallic reagents in certain carbonyl and imine additions. Inspiring from the group work my goal was to develop new reactions, extend the scope of our group chemistry and their application towards synthesis of biologically active natural products. I have been part of enantioselective Rh catalyzed Aldol reaction of vinyl ketones to different aldehydes. Also, we have found that iridium catalyzed transfer hydrogenation of allylic acetates in the presence of aldehydes or alcohols results in highly enantioselective carbonyl allylation under the conditions of transfer hydrogenative. Based on this reactivity a concise enantio- and diastereoselective synthesis of 1,3-polyols was achieved via iterative chain elongation and bidirectional iterative asymmetric allylation was performed, which enables the rapid assembly of 1,3-polyol substructures with exceptional levels of stereocontrol. The utility of this approach stems from the ability to avoid the use of chirally modified allylmetal reagents, which require multistep preparation, and the ability to perform chain elongation directly from the alcohol oxidation level. This approach was utilized for the total synthesis of (+)-Roxaticin from 1,3-propanediol in 20 longest linear steps and a total number of 29 manipulations. Further, advancements were made in iridium catalyzed C-C bond formation under transfer hydrogenation. While methallyl acetate does not serve as an efficient allyl donor, the use of more reactive leaving group in methallyl chloride compensate for the shorter lifetime of the more highly substituted olefin π-complex. Based on this insight into the requirements of the catalytic process, highly enantioselective Grignard-Nozaki-Hiyama methallylation is achieved from the alcohol or aldehyde oxidation levels. Also, a catalytic method for enantioselective vinylogous Reformatsky- type aldol addition was developed in which asymmetric carbonyl addition occurs with equal facility from the alcohol or aldehyde oxidation level. Good to excellent levels of regioselectivity and uniformly high levels of enantioselectivity were observed across a range of alcohols and aldehydes.en
dc.description.departmentChemistryen
dc.format.mimetypeapplication/pdfen
dc.identifier.slug2152/ETD-UT-2011-12-4837en
dc.identifier.urihttp://hdl.handle.net/2152/ETD-UT-2011-12-4837en
dc.language.isoengen
dc.subjectHydrogenation C-C bond formationen
dc.subjectTransfer hydrogenation C-C bond formationen
dc.subjectTotal synthesisen
dc.subjectRoxaticinen
dc.subjectAldol reactionen
dc.subjectEnantioselective vinylogous aldol-Reformatsky reactionen
dc.subjectEnantioselective Grignard Nozaki-Hiyama Methallylationen
dc.titleDevelopment of new transition metal catalyzed C-C bond forming reactions and their application toward natural product synthesisen
dc.type.genrethesisen

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