I. Studies Toward the Synthesis of Echinodithianic Acid and II. The Temperature Dependent NMR Spectrum of Methyl N-Acetylsarcosinate
Date of Award:
Doctor of Philosophy (PhD)
Chemistry and Biochemistry
Richard K. Olsen (Committee Chair)
Richard K. Olsen
Approaches to the preparation of echinodithianic acid (5) from 2,5-dicarbomethoxy-1,4-dithiane (1) were not successful, due to the inability to carboxylate or carboalkoxylate 1 at carbons 2 and 5. Studies toward the synthesis of 5 utilizing methyl 2-acetamidoacrylate (8) have been investigated. The electrophilic addition of sulfur dichloride to 8 yielded bis-(2-acetamido-2-carbo-methoxyvin-1-yl) sulfide, while the addition of thiocyanogen chloride to 8 produced methyl 2-acetamido-3-thiocyanato-acrylate.
As electrophilic additions of unsymmetrical dipolar reagents to methyl 2-acetamidoacrylate (8) are not reported in the literature, the addition of hydrogen bromide to 8 was studied to determine the orientation effect of the acetamido group.
Methyl 2-acetamido-2-bromopropionate (69) was found to be the kinetically favored adduct, while under equilibrium conditions the Michael addition product, methyl 2-acetamido-3-bromopropionate (68), was favored.
The rates of exchange of the acetyl (a) and the N-methyl (b) protons from the cis to the trans form of methyl N-acetylsarcosinate (72) were measured by a total NMR lineshape method and found to be the same within the limits of the experimental method. Thermodynamic activation parameters are reported.
From these data it was concluded that the exchanges of each of the four types of protons (a, b, c, d) in 72 depend solely on hindered rotation about the amide C-N bond.
Love, Alan LeRoy, "I. Studies Toward the Synthesis of Echinodithianic Acid and II. The Temperature Dependent NMR Spectrum of Methyl N-Acetylsarcosinate" (1971). All Graduate Theses and Dissertations. 7213.
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