Date of Award
Campus Access Dissertation
Chemistry and Biochemistry
Sheryl L Wiskur
This dissertation details our efforts to design and implement mild conditions in which to carry out the Mukaiyama aldol reaction. The design of a bi-functional organic chiral catalyst, which comprises of a Lewis base acetate anion paired with a chiral quaternary ammonium cinchona alkaloid, is discussed. We found that when the addition of a silyl ketene acetyl to benzaldehyde is catalyzed with our bi-functional catalyst, the reaction proceeds through a two step tandem process. The first step involves racemic carbon-carbon bond formation to generate a pair of alkoxide diastereomers. The second step involves a kinetic resolution of these diastereomers via enantioselective silylation. This reaction is the first example of a kinetic resolution of secondary alcohols through a tandem sequence. This work then inspired us to design a `clean-up' reaction: where an asymmetric reaction which generates modest e.e. can be linked in tandem to a kinetic resolution which targets the minor enantiomer, thereby increasing the e.e.of the products which were generated in the first reaction. This design was realized when we were able to increase the e.e.of a homoallylic alcohol generated through the allylboration of benzaldehyde, which gave 80% e.e. This reaction was then treated to a kinetic resolution reaction, in tandem, which involved selective acylation of the minor enantiomer. The combination of both of these reactions resulted in a homoallylic alcohol with an e.e. of 99%, which is higher than the standalone allyboration.
Chapter three talks about the synthesis and characterization of a C2 symmetric bis(oxazolidinyl)pyridine ligand, synthesized from readily available cis amino indanol. Our C2 ligand shows tridentate binding to give 5 coordinate distorted trigonal pyramidal solid state structures with zinc, copper and cadmium chlorides. The bis(oxazolidinyl)pyridine ligand exhibits sufficient flexibility to give both cis and trans tridentate coordination
Patel, S. G.(2010). The Kinetic Resolution of Secondary Alcohols Through A Tandem Enantioselective Silylation and the Synthesis of Bis(Oxazolidinyl)Pyridine Metal-Organic Complexes. (Doctoral dissertation). Retrieved from http://scholarcommons.sc.edu/etd/716