Effect of counter-cations on aggregation and chiral discrimination: Application to highly diastereo- and enantio-selective syntheses

Different types of short (a few steps), efficient (yields between 65% and 9 5%), highly diastereo- and enantioselective (d.e. or e.e. greater than or e qual to 95%) syntheses of small synthons have been designed using the role of the counter-cation on aggregation and on the chiral discrimination. Thre e chiral auxiliaries will be envisaged: the 8-phenylmenthol (reduction of a n alpha-ketoester, alkylation of the phenylacetate), the hydroxypinanone an d the corresponding iminoglycinate (alkylation of the Li and Li:Mfi enolate s, aldolization of the directly-generated Ti-enolate, catalytic aldolizatio n using P2-Et as base), the oxathiane and corresponding aryl-sulfonium salt s (asymmetric syntheses of mono and di-aryl epoxides, of aryl-carbethoxy cy clopropanes).