Asymmetric epoxidation of olefins catalyzed by Ti(salan) complexes using aqueous hydrogen peroxide as the oxidant*
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چکیده
Ti(salan) complexes were found to be efficient catalysts for asymmetric epoxidation with aqueous hydrogen peroxide as the oxidant. In the presence of pH 7.4 phosphate buffer, the reaction of various conjugate olefins proceeded smoothly to afford the corresponding epoxides in high yield with high enantioselectivity, even on a multigram scale. Ti(salan) complexes could be prepared from Ti(OiPr)4 and the corresponding salan ligand and directly used without isolation and purification.
منابع مشابه
Oxidation catalysis of Nb(salan) complexes: asymmetric epoxidation of allylic alcohols using aqueous hydrogen peroxide as an oxidant.
Several optically active Nb(salan) complexes were synthesized, and their oxidation catalysis was examined. A dimeric mu-oxo Nb(salan) complex that was prepared from Nb(OiPr)(5) and a salan ligand was found to catalyze the asymmetric epoxidation of allylic alcohols using a urea-hydrogen peroxide adduct as an oxidant with good enantioselectivity. However, subsequent studies of the time course of ...
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