Studies On The Three-component Aza-Diels-Alder Reaction And The Asymmetric Addition Of Phenylacetylene To Aldehydes

This thesis is composed of three parts:(1) The development of asymmetric organocatalytic tandem reactions is illustrated from its beginning up to the present. The reactions are classified by their single activation steps, and introduced systematically.(2) Pyrrolidine-thiourea, pyrrolidine-tetrazole and imidazolidin-4-one were synthesized from L-proline and L-phenylalanine, respectively. These chiral catalysts and some natural amino acids were used for catalyzing aza-Diels-Alder reaction of methylvinylketone, 4-nitrobenzaldehyde and 4-anisidine or benzyl amine. The results showed that L-proline was the best catalyst for the three-component reactions. The desired 4-piperidone derivatives were obtained in high yield (up to 94%) and good distereoselectivity (up to 29:1 dr) under optimized conditions. A practical solution for preparing the 4-piperidone derivatives was described.(3) A series of chiralβ-hydroxy amide ligands was synthesized by the reaction of benzoyl chloride and chiral amino alcohols which were derived from L-amino acids. Titanium(IV) complexes of these newβ-hydroxy amide ligands were used for catalyzing the enantioselective addition of phenylacetylene to aldehydes. It was found that the enantioselectivity of the reaction is strongly affected by the amount of titanium tetraisopropoxide and the solvents. Chiral ligand synthesized from 2-amino-3-ethyl-1-phenylpentan-3-ol was effective for the asymmetric alkynylation of aldehydes and the propargyl alcohols were obtained in high yields (up to 96%) and high enantiomeric excesses (up to 97%) under optimized conditions.