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Catalytic Asymmetric Synthesis of β-Lactones and Application to the Total Synthesis of (-)-Pironetin

Shen, Xiaoqiang (2008) Catalytic Asymmetric Synthesis of β-Lactones and Application to the Total Synthesis of (-)-Pironetin. Doctoral Dissertation, University of Pittsburgh. (Unpublished)

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The Al-triamine complex catalyzed acyl halide-aldehyde cyclocondensation (AAC) reactions, developed previously by the Nelson group, have been extended to asymmetric AAC reactions of alkyl-substituted ketenes with structurally diverse aldehydes. By using of 2nd generation Al-triamine complex as catalyst, benzotrifluoride as solvent, the disubstituted β-lactones were synthesized in high yields and excellent enantioselectivities from readily available starting materials.Another conceptionally different methodology has also been developed to synthesize enantioenriched β-lactones. The concept of double activation has been applied in this reaction technology to accelerate the β-lactones formation. By using of cinchona alkaloids to activate ketenes, and at the same time utilizing of lithium salts to activate aldehydes, Wynberg's [2+2] cycloaddition protocol has been greatly expanded to a variety of aldehydes. Stereoenriched β-lactones derived from either Al-triamine or cinchona alkaloids catalyzed asymmetric acyl halide-aldehyde cyclocondensation (AAC) have been untilized in natural product synthesis. An asymmetric total synthesis of the antitumor agent pironetin was pursued using β-lactone templates for establishing all the requisite stereochemical relationships.


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Item Type: University of Pittsburgh ETD
Status: Unpublished
CreatorsEmailPitt UsernameORCID
Shen, Xiaoqiangxis7@pitt.eduXIS7
ETD Committee:
TitleMemberEmail AddressPitt UsernameORCID
Committee ChairNelson, Scott G
Committee MemberDoemling, Alexander S
Committee MemberCurran, Dennis P
Committee MemberFloreancig, Paul E
Date: 29 January 2008
Date Type: Completion
Defense Date: 23 August 2007
Approval Date: 29 January 2008
Submission Date: 8 October 2007
Access Restriction: No restriction; Release the ETD for access worldwide immediately.
Institution: University of Pittsburgh
Schools and Programs: Dietrich School of Arts and Sciences > Chemistry
Degree: PhD - Doctor of Philosophy
Thesis Type: Doctoral Dissertation
Refereed: Yes
Uncontrolled Keywords: β-Lactones; Asymmetric Catalysis; Pironetin; Total Synthesis
Other ID:, etd-10082007-193252
Date Deposited: 10 Nov 2011 20:02
Last Modified: 15 Nov 2016 13:50


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