Epoxidation of olefins by dendritic catalysts

Abstract

<P>POLYAMINOAMIDO (PAMAM) DENDRIMER WAS, FOR THE FIRST TIME, GRAFTED FROM THE INITIAL AMINO GROUP OF MESOPOROUS SBA-15 THAT HAS BEEN PRETREATED WITH AMINOPROPYLTRIETHOXYSILANE. AMINO CONTENT ANALYSIS INDICATES THAT AT LEAST THE FIRST TWO GENERATIONS OF DENDRIMER CAN BE PROPAGATED. THIS NOVEL ZEOLITE SUPPORTED DENDRIMER WAS EMPLOYED TO ANCHOR MN(SALEN) COMPLEX THROUGH A MULTI-STEP METHOD BY THE REACTION BETWEEN TERMINAL AMINO GROUP AND 2,6-DIFORMYL-4-TERT-BUTYLPHENOL. MN(SALEN) COMPLEX CATALYSTS ANCHORED ON SBA-15 SUPPORTED DENDRIMER GIVES VERY HIGH YIELD (64%) AND ENANTIOMERIC EXCESS (55%) FOR STYRENE EPOXIDATION IN THE PRESENCE OF M-CPBA/NMO AS THE OXIDANT. THE DISPERSION OF ACTIVE MN(III)SALEN COMPLEX AND THE NUMBER OF DENDRIMER GENERATION ARE FOUND TO BE OF IMPORTANCE FOR ENHANCED YIELD AND ENANTIOSELECTIVITY. </P>