The Application Of Immobilized Chiral Catalysts In The Asymmetric Aldol Reactions

1. Synthesis of Immobilized Chiral Catalysts and Application in the Asymmetric Aldol Reactions Merrifield resin supported (4R)-hydroxy-(2S)-proline, PMBHA resin supported (4S)-hydroxy-(2S)-proline, silica supported ethyl cellulose-(2S)-proline-ZnCl2 and β-cyclodextrin immobilized (4S)-phenoxy-(2S)-proline were synthesized. The catalytic abilities of four catalysts on the asymmetric Aldol reactions between acetone and various aromatic aldehydes were studied. The ee value of the reaction between acetone and o-nitro benzaldehyde catalyzed by β-cyclodextrin immobilized (4S)-phenoxy-(2S)-proline was 83.4%. The catalyst could be recycled by simple filtration and reused for four times, while the yields decreased appreciably and the value of ee remained steadiness. 2. Design,Synthesis and Application of Small Organic Molecular Catalysts in Asymmetric Baylis-Hillman Reactions Four new chiral organic catalysts (21a, 21b, 23 and 29) were synthesized from natural L-phenylalanine and L-proline, respectively. The influence of the structure of catalysts on the asymmetric Baylis-Hillman reaction was studied elementarily. The product of methyl vinyl ketone and o-nitro benzaldehyde catalyzed by 29 was obtained in 89.7% yield with 18.1% ee.