科研之友
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摘要
Six amino-alcohol modified beta-cyclodextrins CD-1 similar to CD-6 were synthesized by nucleophilic substitution from mono(6-O-p-tolylsulfonyl)-beta-cyclodextrin with the yields of 34%similar to 58%, and were verified by H-1 NMR, C-13 NMR and ESI-MS techniques. These beta-cyclodextrin derivatives were applied to the asymmetric epoxidation of trans-chalcone by H2O2. And the results implied that the dosage of the beta-cyclodextrin derivatives and the structure of the modified group had an important effect on the enantioselectivity in the reaction. Among them, CD-1 exhibited the best performance in the asymmetric epoxidation of trans-chalcone employed H2O2 and NaHCO3 as oxidant, and 25.7% ee value was obtained, It were showed from the spectra of 2D-H-1 ROESY NMR that, CD-1 could form inclusion complex with trans-chalcone and self-inclusion existed in all the beta-cyclodextrin derivatives CD-1 similar to CD-6, which affected the enhancement of the ee value. And the two kinds of inclusion complexes were confirmed by quantum chemistry calculation too.
