NEW CHIRAL PROLINE-BASED CATALYSTS FOR SILICON AND ZIRCONIUM OXIDES-PROMOTED ASYMMETRIC BIGINELLI REACTION
DOI:
https://doi.org/10.1007/4339Keywords:
hydroxyproline, silica oxide, zirconium oxide, asymmetric catalysis, Biginelli reaction, nanosized oxide.Abstract
4-Hydroxy-(2S)-prolines bearing 3,4-dihydro-2H-1,4-benzoxazine or 1,2,3,4-tetrahydroquinoline fragments were synthesized and studied as chiral catalysts in the Biginelli reaction. The target product ethyl 6-methyl-2-oxo-4-phenyl-1,2,3,4-tetrahydropyrimidine-5-carboxylate was obtained with 54% enantiomeric excess (ee). An increase in ee values of the reaction product up to 76% was observed in the presence of nanosized oxides SiO2–ZrO2 as heterogeneous promoters.
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Published
2018-06-04
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Original Papers