Effect of Additives on Chemoselectivity and Diastereoselectivity in the Catalytic Epoxidation of Chiral Allylic Alcohols with Hydrogen Peroxide and Binuclear Manganese Complexes
journal contributionposted on 06.02.2009, 00:00 by Hamdullah Kilic, Waldemar Adam, Paul L. Alsters
The catalytic oxidations of chiral allylic alcohols 2 by manganese complexes of the cyclic triamine 1,4,7-trimethyl-1,4,7-triazacyclononane (tmtacn) 1 and hydrogen peroxide as oxygen donor in the presence of co-catalyst are investigated to understand the factors that affect the catalyst selectivity. Chemoselectivity and diastereoselectivity of catalyst 1 are significantly affected by the structure of the allylic alcohol and the nature and amount of co-catalyst. More pronounced is the influence of the amount of added molar equivalents of H2O2 (20−110 mol % with respect to the substrate). Our present results reflect the complex redox chemistry of the Mn catalyst 1/H2O2/co-catalyst system in the early phase of the alkene oxidation.