34 CH203 Fall 2014 Lecture 34 November 24.pdf

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The Garuganin and Garugamblin Diarylether Heptanoids: TotalSynthesis and Determination of Chiral Properties Using DynamicNMRZhi-Qiang Zhu, M. Quamar Salih, Edward Fynn, Alex D. Bain,*, and Christopher M. Beaudry*,

Department of Chemistry, Oregon State University, 153 Gilbert Hall, Corvallis, Oregon 97331, United StatesDepartment of Chemistry and Chemical Biology, McMaster University, Hamilton, Ontario L8S 4M1, Canada

*S Supporting Information

ABSTRACT: The synthesis of the garuganin and garugamblin diarylether heptanoids using an intramolecular Ullmann couplingis reported. Alkene stereoisomers, vinylogous ester regioisomers, and -diketone congeners are also synthesized. The chiralproperties and free energies of activation for racemization of the garuganin and garugamblin diarylether heptanoids andcongeners are determined using dynamic NMR methods. A combination of techniques including coalescence measurements, lineshape analysis, and selective inversion experiments are used to measure racemization barriers. None of the garuganin orgarugamblin diarylether heptanoids are chiral, despite their reported specic rotation values.

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CH3

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A-B

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H3C

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2ocarbocation 3o carbocation


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CH3

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567(8(; S )9*96G:) ,(


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567(8(; S ,( *B( 967(8(E

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RuCl3

PhPh

PhPh


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567(8(; S ,(


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567(8(; S )9*96G:) ,( BG

34 CH203 Fall 2014 Lecture 34 November 24.pdf

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Transcript of 34 CH203 Fall 2014 Lecture 34 November 24.pdf