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|Title:||The Design and Utility of Chiral Derivatizing Agents|
|Author(s):||Robertson, Michael Wayne|
|Department / Program:||Chemistry|
|Degree Granting Institution:||University of Illinois at Urbana-Champaign|
|Abstract:||A variety of chloroformates derived from aryl perfluoroalkyl secondary carbinols were utilized as chiral derivatizing agents for asymmetric primary amines, secondary alcohols and several primary carbinols. The chromatographic behavior and nuclear magnetic resonance properties of selected diastereomeric carbamates and carbonates derived from several chloroformates and a number of amines and alcohols are reported. Several chloroformates exhibited favorable properties as manifested by the facile chromatographic separation of a number of derived diastereomeric carbamates, and a discussion of the reasons underlying enhanced chromatographic resolution of carbamate diastereomers is presented. In addition, several chloroformates were effectively applied as NMR chiral derivatizing agents in a manner that allowed for the convenient determination of enantiomeric purity and absolute configuration of various asymmetric primary amines and secondary carbinols. The resolution and assignment of absolute configuration of several chiral chloroformates is presented along with a discussion of the enhanced stability of chloroformates derived from aryl perfluoroalkyl secondary alcohols.
An examination of the kinetically controlled partial resolution of a number of chloroformates with R-(+)-1-(1-naphthyl)ethyl amine was conducted. A consistent preferential formation of one carbamate diastereomer of a predictable, general stereochemisty was found. The extent of diastereoselectivity in the kinetic resolution of 2-(2-methoxy-phenyl)-1,1,1-trifluoroethyl chloroformate with R-(+)-1-(1-napthyl)ethyl amine was examined as a function of solvent, tertiary amine and triethyl-amine stoichometry and a discussion of the possible origin of the observed stereo-differentiation in those reactions is presented.
The kinetically controlled partial resolution of a series of alkyl aryl and perhalalkyl aryl secondary alcohols with R-(+)-3-(2-methoxy-phenyl)-1,1,1-trifluoropropyl chloroformate was examined and a general correlation found for the stereochemistry of the reactants and products. An opposite sense of diastereoselectivity was found for the reaction of aryl alkyl and aryl perhaloalkyl carbinols with a given chloroformate and a rationale of the possible origin of this reversed selectivity is proposed.
The chromatographic resolution of five aryl-2-pyrrolidones, via the derived diastereomeric ureides, was examined utilizing R-(-)-1-(1-naphthyl)ethyl isocyanate as the chiral derivatizing agent. A discussion of some factors thought to be responsible for the observed facile chromatographic separation of the diastereomeric derivatives is presented. In addition, a number of aryl alkyl acetamides were derivatized with the same chiral isocyanate and the preliminary results of the NMR and chromatographic properties of the derived diastereomeric ureides is presented.
An improved synthesis of (alpha)-trifluoromethylphenylacetic acid is reported that is considerably more convenient than the currently existing methods for the synthesis of this functionalized carboxylic acid. The chromatographic properties of several diasteromeric amides derived from (alpha)-trifluoromethylphenylacetic acid are reported.
Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 1981.
|Date Available in IDEALS:||2014-12-13|