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Fluorous mixture synthesis of four stereoisomers of the C21-C40 fragment of tetrafibricin and efforts towards total synthesis of tetrafibricin

zhang, kai (2011) Fluorous mixture synthesis of four stereoisomers of the C21-C40 fragment of tetrafibricin and efforts towards total synthesis of tetrafibricin. Doctoral Dissertation, University of Pittsburgh. (Unpublished)

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Abstract

Efforts towards the synthesis of natural product tetrafibricin and its stereoisomers are described. Retrosynthesis of the framework of tetrafibricin gives 6 fragments, C1-C8, C9-C13, C14-C20, C21-C30, C31-C34 and C35-C40. Chapter 2 describes the fluorous mixture synthesis of four stereoisomers of the C21¨CC40 fragment with the aid of fluorous tagging to encode configurations at C37 and C33. After demixing and detagging, the isomers were found to have substantially identical 1H NMR spectra. However, there were some small but reliable differences in their 13C NMR spectra. Chapter 3 describes efforts towards total synthesis of tetrafibricin. After making the 6 fragments, different sequences of fragment coupling by a series of Julia-Kocienski reactions were attempted. First the alkylation of dithiane C9-C13 with iodide C14-C20 provided C9-C20 carbon skeleton. Then the first Julia-Kocienski olefination with sulfone C21-C30 and aldehyde C9-C20 gave olefin C9-C30, which was then advanced to aldehyde to attempt another Julia-Kocienski olefination. Fragment C31-C40 was also achieved by Julia-Kocienski olefination of sulfone C35-C40 with aldehyde C31-C34. Then the two big parts, aldehyde C9-C30 and sulfone C31-C40, were coupled together to afford fragment C9-C40 by Julia-Kocienski olefination. Finally, Horner-Wadsworth-Emmons olefination of phosphonate C1-C8 with aldehyde C9-C40 provided C1-C40 to achieve the whole carbon framework of tetrafibricin.

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Details

Item Type: University of Pittsburgh ETD
Status: Unpublished
Creators/Authors:
CreatorsEmailPitt UsernameORCID
zhang, kaikaz8@pitt.eduKAZ8
ETD Committee:
TitleMemberEmail AddressPitt UsernameORCID
Committee ChairCurran, Dennis Pcurran@pitt.eduCURRAN
Committee MemberDay, Billy Wbday@pitt.eduBDAY
Committee MemberFloreancig, Paulflorean@pitt.eduFLOREAN
Committee MemberNelson, Scottsgnelson@pitt.eduSGNELSON
Date: 1 July 2011
Date Type: Completion
Defense Date: 21 January 2011
Approval Date: 1 July 2011
Submission Date: 23 March 2011
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: fibrinogen; fluorous mixture synthesis; Kocienski¨CJulia reaction; quasiisomers; tetrafibricin
Other ID: http://etd.library.pitt.edu/ETD/available/etd-03232011-110626/, etd-03232011-110626
Date Deposited: 10 Nov 2011 19:32
Last Modified: 15 Nov 2016 13:37
URI: http://d-scholarship.pitt.edu/id/eprint/6572

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