Design, synthesis and testing of new chiral sulfide catalysts for Corey-Chaykovsky reaction

Abstract

<div lang="en" class="abs"><p class="abs_header">Abstract</p><p>The first part of this monograph discusses the asymmetric, ylide based, reagent controlled epoxidations. Both different chiral ylides and epoxidation processes, stoichiometric and catalytic, are reviewed.</p><p>In the following part, new chiral sulfide catalysts were discovered as enantioselective catalysts for the Corey-Chaykovsky reaction (epoxidation of aldehydes via sulfonium ylides). Using a crystal structure of an oxazolidine derivative as a starting point, a thiazolidine ligand family was designed, synthesized and finally employed as catalysts in the asymmetric epoxidation of benzaldehyde. The ligands were prepared starting from L-valine, L-<em>tert</em>-leucine, D-penicillamine and L-cysteine. The differently tuned thiazolidine ligands were demonstrated to catalyze the formation of <em>trans</em>-stilbene oxide with varying enantioselectivities. On the basis of these results, a mechanistic rationale for the asymmetric induction was presented. The results heavily demonstrated the importance of ring rigidity as an affecting factor in the enantioselectivity of the tested thiazolidines.</p></div>