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Studies towards the total synthesis of ionomycin Daynard, Timothy S.
Abstract
An optically pure precursor to ionomycin (1) consisting of the thirty two carbon backbone and protected functional groups of the target molecule was synthesized by the coupling of two subunits between C₁₅ and C₁₆ via the Suzuki reaction. An enantioselective route to the C₁₁-C₁₅ fragment 57 was developed. This unit was coupled to the C₁-C₁₀ fragment 53 to provide the left half 162a (C₁-C₁₅) of the target molecule. Hydroboration of this 2-methyl terminal alkene with 9-BBN generated an asymmetric center at C₁₄ and provided the alkylborane moiety necessary for the Suzuki coupling reaction. The resulting alkylborane was reacted with the alkenyl iodide fragment 200 (C1₆-C₃₂) in the presence of the palladium catalyst PdCI₂(dppf) and sodium hydroxide to afford the coupled products 203a,b in 79% yield with the stereochemistry about the double-bond exclusively E and as a 57:43 mixture of epimers about C₁₄.
Item Metadata
Title |
Studies towards the total synthesis of ionomycin
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Creator | |
Publisher |
University of British Columbia
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Date Issued |
1998
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Description |
An optically pure precursor to ionomycin (1) consisting of the thirty two carbon
backbone and protected functional groups of the target molecule was synthesized by
the coupling of two subunits between C₁₅ and C₁₆ via the Suzuki reaction.
An enantioselective route to the C₁₁-C₁₅ fragment 57 was developed. This unit
was coupled to the C₁-C₁₀ fragment 53 to provide the left half 162a (C₁-C₁₅) of the target
molecule. Hydroboration of this 2-methyl terminal alkene with 9-BBN generated an
asymmetric center at C₁₄ and provided the alkylborane moiety necessary for the Suzuki
coupling reaction. The resulting alkylborane was reacted with the alkenyl iodide
fragment 200 (C1₆-C₃₂) in the presence of the palladium catalyst PdCI₂(dppf) and sodium
hydroxide to afford the coupled products 203a,b in 79% yield with the stereochemistry
about the double-bond exclusively E and as a 57:43 mixture of epimers about C₁₄.
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Extent |
10561915 bytes
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Genre | |
Type | |
File Format |
application/pdf
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Language |
eng
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Date Available |
2009-06-19
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Provider |
Vancouver : University of British Columbia Library
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Rights |
For non-commercial purposes only, such as research, private study and education. Additional conditions apply, see Terms of Use https://open.library.ubc.ca/terms_of_use.
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DOI |
10.14288/1.0061544
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URI | |
Degree | |
Program | |
Affiliation | |
Degree Grantor |
University of British Columbia
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Graduation Date |
1998-11
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Campus | |
Scholarly Level |
Graduate
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Aggregated Source Repository |
DSpace
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Item Media
Item Citations and Data
Rights
For non-commercial purposes only, such as research, private study and education. Additional conditions apply, see Terms of Use https://open.library.ubc.ca/terms_of_use.