Abstract

We developed an approach to the β-thioenamide linkage contained in the S-(2-aminovinyl)cysteine (avCys) residue of thioviridamide.1,2 Kinetic and thermodynamic control of radical additions of thiols to ynamides were studied for the formation of β-thioenamide linkage. Thiyl radicals are electrophilic and ynamides are electron-rich alkynes. This complementary polarity of the radical and acceptor increases the likelihood of a successful radical addition reaction. Because little is known about these types of compounds (β-thioenamides), we were unsure what kinds of yields and stereoselectivities (cis vs. trans) to expect. The adduct stability is another issue to consider. Fortunately, under typical radical addition conditions, the two separable isomers (cis and trans) are formed in good yield. Selective formation of kinetic (cis) and thermodynamic (trans) isomers are controlled by reaction time and equivalents of thiol. We converted the kinetic isomer to the thermodynamic isomer to confirm that isomerization can occur under the reaction conditions. Alkyl and aryl thiols including cysteine-derived thiols with different ynamides were used in this process.

Degree

MS

College and Department

Physical and Mathematical Sciences; Chemistry and Biochemistry

Rights

http://lib.byu.edu/about/copyright/

Date Submitted

2008-12-22

Document Type

Thesis

Handle

http://hdl.lib.byu.edu/1877/etd2773

Keywords

thiyl radical addtion, cis and trans isomers, kinetic and thermodynamic adducts

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