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Oxidative C-H Activation: Convergent Fragment-Coupling approaches to Spiroacetals and the Total Synthesis of Clavosolide A

Peh, GuangRong (2016) Oxidative C-H Activation: Convergent Fragment-Coupling approaches to Spiroacetals and the Total Synthesis of Clavosolide A. Doctoral Dissertation, University of Pittsburgh. (Unpublished)

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Abstract

Two one-pot oxidative cyclization strategies to spiroacetals are described herein. The first approach utilizes a Lewis acid-mediated Ferrier reaction for the initial fragment coupling followed by 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ)-initiated oxidative carbon–hydrogen bond cleavage and cyclization. The second approach relies on a Heck cross coupling for fragment assembly followed by a DDQ-mediated dehydrogenation of enol ethers into enones and subsequent acid-induced cyclization. These methods provide mild convergent protocols to spiroketal subunits, which are ubiquitous in natural products, medicinal drugs, and chemical libraries.

Cyclopropane-substituted allylic ethers undergo carbon–hydrogen bond cleavage to form stable oxocarbenium ions upon reaction with DDQ. Significantly, in the presence of an appending nucleophile, facile ring closure occurs to yield highly functionalized tetrahydropyrans with no accompanied cyclopropane scission. This methodology was showcased during the total synthesis of the sponge-derived macrodiolide clavosolide A.


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Details

Item Type: University of Pittsburgh ETD
Status: Unpublished
Creators/Authors:
CreatorsEmailPitt UsernameORCID
Peh, GuangRonggup2@pitt.eduGUP2
ETD Committee:
TitleMemberEmail AddressPitt UsernameORCID
Committee ChairFloreancig, Paul Eflorean@pitt.eduFLOREAN
Committee MemberHorne, W. Sethhorne@pitt.eduHORNE
Committee MemberKoide, Kazunorikoide@pitt.eduKOIDE
Committee MemberHildebrand, Jeffrey D.jeffh@pitt.eduJEFFH
Date: 21 January 2016
Date Type: Publication
Defense Date: 30 September 2015
Approval Date: 21 January 2016
Submission Date: 6 October 2015
Access Restriction: No restriction; Release the ETD for access worldwide immediately.
Number of Pages: 208
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: cyclopropane, carbon–hydrogen bond activation, spiroacetals
Date Deposited: 21 Jan 2016 21:47
Last Modified: 15 Nov 2016 14:30
URI: http://d-scholarship.pitt.edu/id/eprint/26188

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