Sintesi e caratterizzazione strutturale di derivati piperidinici e morfolinici chirali

The topic of this thesis concerns the study of catalytic processes for the synthesis of chiral 3,4,5-trisubstituted piperidine and 2,6-disubstituted morpholine. Substrates possessing an α,β-unsaturated ester and a ketone moiety, able to undergo addition/cyclization cascade reactions with different pro-nucleophiles (thiophenols, acetone cyanohydrin and malononitrile), have been evaluated. Chiral and achiral systems for phase-transfer catalysis have been applied as catalysts. Moderate enantiomeric excesses have been obtained for the morpholinic products and good to excellent values for the piperidinic products, by using cyclopeptoids and quaternary ammonium salts derived from Chincona alkaloids as catalysts respectively. Moreover, the absolute configuration of the 3,4,5-trisubstituted piperidines has been determined through quantomechanical simulations of their chirooptical spectra. Finally, the relative configuration of the 2,6-disubstituted morpholines has been assigned through NMR experiments.