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Applications of Iridium-Catalyzed Isomerization Claisen Rearrangements (ICR) to Complex Molecule Synthesis

Stevens, Benjamin Dawson (2007) Applications of Iridium-Catalyzed Isomerization Claisen Rearrangements (ICR) to Complex Molecule Synthesis. Doctoral Dissertation, University of Pittsburgh. (Unpublished)

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The iridium-catalyzed isomerization Claisen rearrangement (ICR) methodology developed in theNelson group has provided access to a broad range of diastereomerically enricheddisubstituted unsaturated aldehydes. Allylsilyl aldehydes produced by the ICR reaction havebeen further elaborated into substrates for highly diastereoselective intramolecular Hosomi-Sakurai annulation reactions. The Sakurai annulation has proven to be particularly powerfulwhen carried out in tandem with intramolecular aldol or Mannich reactions to form complexfused ring systems. An attempted strategic application of this methodology to the synthesis ofthe Rauwolfia alkaloids reserpine and yohimbine is detailed.Vinyl boronic esters have been demonstrated to be effective precursors for the ICRreaction providing diastereomerically enriched boronic aldehydes. The potential forintramolecular chelation between the newly formed aldehyde and proximal boronic ester hasbeen investigated. The boron functionality has proven to be useful for accessing alkoxy- andaryl-substituted compounds that are typically unavailable from the ICR reaction. A synthesis ofthe plant growth inhibitor penieone has been explored in order to demonstrate the practicalapplication of this methodology to complex molecule construction.


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Item Type: University of Pittsburgh ETD
Status: Unpublished
CreatorsEmailPitt UsernameORCID
Stevens, Benjamin Dawsonbes7@pitt.eduBES7
ETD Committee:
TitleMemberEmail AddressPitt UsernameORCID
Committee ChairNelson, Scott Gsgnelson@pitt.eduSGNELSON
Committee MemberDay, Billy Wbday@pitt.eduBDAY
Committee MemberCurran, Dennis Pcurran@pitt.eduCURRAN
Committee MemberWipf, Peterpwipf@pitt.eduPWIPF
Date: 19 September 2007
Date Type: Completion
Defense Date: 21 March 2007
Approval Date: 19 September 2007
Submission Date: 23 November 2006
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: Diastereoselective ring formation; Isomerization; Penienone; Sakurai; Yohimbine; Intramolecular aldol; Reserpine; Intramolecular Mannich; Claisen rearrangement; Boron chelation
Other ID:, etd-11232006-121146
Date Deposited: 10 Nov 2011 20:05
Last Modified: 15 Nov 2016 13:52


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