| 1.Synthesis and application of Chiral Organocatalysts in the Asymmetric Baylis-Hillman Reaction Chiral catalysts 1-4 were prepared conveniently from amino acids, and applied in asymmetric Baylis-Hillman reaction to study the relationship between catalyst structure and enantioselectivity. The selectivities of asymmetric Baylis-Hillman reaction in PEG(400) were detected, and high yield (up to 88.0%) , moderate selectivities (up to 54.3%) were achieved by using 30 mol% catalyst 3. 2 Synthesis of Novel Chiral Catalysts and their Catalysis in Direct Asymmetric Aldol Reactions 2.1 (4R)-4-(2,4,6-trimethylphenyl)methoxy-(S)-proline, a new chiral catalyst for the asymmetric aldol reaction, was prepared conveniently. Efficient enantioselective catalysis of aldol reactions of various benzaldehydes with acetone in excess of acetone as the solvent was achieved with high yield up to 91.0% and good selectivities (up to 88.5% ee) by using 5 mol% of the catalyst 5. 2.2 (S)-Proline was N-protected using phenylmethoxycarbonyl chloride and then coupled with hydroxylamine by the method of mixed anhydride, giving N-(N-phenylmethoxycarbonyl-(S)-prolyl)-hydroxyl amine, which, after deprotection by catalytic hydrogenolysis, afforded the title compound. This compound efficiently catalyzed the direct asymmetric aldol reaction with the yield up to 90.0% and enantiomeric excess up to 89.5%. |
