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Manganese-promoted rearrangement of alkynyl carbonyls to allenyl carbonyls with emphasis on asymmetric induction using chiral bases

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Date Issued:
2004
Summary:
The conversion of alkynyl carbonyls to allenyl carbonyls via manganese mediated coordinations followed by a based-catalyzed isomerization was carried out using a range of chiral and achiral amine bases. In this work we employed HPLC equipped with a chiral column to determine the enantiomeric excess. Deuterium labeling experiments suggested that the alkyne/allene rearrangement reaction involved an intermediate cumenolate. We also demonstrated that the reaction required a ligand on manganese for an amine base to be used catalytically. Phosphines were tested as a possible ligand because they are neutral two electron donors that binds to transition metals through their lone pairs. It was observed that the rate of the reaction decreased from 24hr to 3hr by use of phosphine as a ligand. It was also confirmed that amine base with pKa lower then DBU (pKa = 13.6) would not carry out the isomerization. Chiral amidine and chiral DBU derivatives were synthesized to carry out the isomerization enantioselectively. Alkoxy base were also used in isomerization that demonstrated enantioselectivity.
Title: Manganese-promoted rearrangement of alkynyl carbonyls to allenyl carbonyls with emphasis on asymmetric induction using chiral bases.
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Name(s): Khoram, Anita
Florida Atlantic University, Degree grantor
Lepore, Salvatore D., Thesis advisor
Charles E. Schmidt College of Science
Department of Chemistry and Biochemistry
Type of Resource: text
Genre: Electronic Thesis Or Dissertation
Issuance: monographic
Date Issued: 2004
Publisher: Florida Atlantic University
Place of Publication: Boca Raton, FL
Physical Form: application/pdf
Extent: 110 p.
Language(s): English
Summary: The conversion of alkynyl carbonyls to allenyl carbonyls via manganese mediated coordinations followed by a based-catalyzed isomerization was carried out using a range of chiral and achiral amine bases. In this work we employed HPLC equipped with a chiral column to determine the enantiomeric excess. Deuterium labeling experiments suggested that the alkyne/allene rearrangement reaction involved an intermediate cumenolate. We also demonstrated that the reaction required a ligand on manganese for an amine base to be used catalytically. Phosphines were tested as a possible ligand because they are neutral two electron donors that binds to transition metals through their lone pairs. It was observed that the rate of the reaction decreased from 24hr to 3hr by use of phosphine as a ligand. It was also confirmed that amine base with pKa lower then DBU (pKa = 13.6) would not carry out the isomerization. Chiral amidine and chiral DBU derivatives were synthesized to carry out the isomerization enantioselectively. Alkoxy base were also used in isomerization that demonstrated enantioselectivity.
Identifier: 9780496261994 (isbn), 13158 (digitool), FADT13158 (IID), fau:10019 (fedora)
Degree granted: Thesis (M.S.)--Florida Atlantic University, 2004.
Collection: FAU Electronic Theses and Dissertations Collection
Note(s): Charles E. Schmidt College of Science
Subject(s): Carbonyl compounds--Synthesis
Organic compounds--Synthesis
Allene
Alkenes
Methathesis (Chemistry)
Isomerism
Held by: Florida Atlantic University Libraries
Persistent Link to This Record: http://purl.flvc.org/fcla/dt/13158
Sublocation: Digital Library
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Owner Institution: FAU
Is Part of Series: Florida Atlantic University Digital Library Collections.