title: cis-Dihydroxylation and epoxidation of alkenes by [Mn(2)O(RCO(2))(2)(tmtacn)(2)]: tailoring the selectivity of a highly H(2)O(2)-efficient catalyst.
abstract: The carboxylic acid promoted cis-dihydroxylation and epoxidation of alkenes catalyzed by [MnIV2O3(tmtacn)2]2+ 1 employing H2O2 as oxidant is described. The use of carboxylic acids at cocatalytic levels not only is effective in suppressing the inherent catalase activity of 1, but also enables the tuning of the catalyst's selectivity. Spectroscopic studies and X-ray analysis confirm that the control arises from the in situ formation of carboxylate-bridged dinuclear complexes, for example, 2 {[MnIII2O(CCl3CO2)2(tmtacn)2]2+} and 3 {[MnII2(OH)(CCl3CO2)2(tmtacn)2]+}, during catalysis. For the first time, the possibility to tune, through the carboxylate ligands employed, both the selectivity and activity of dinuclear Mn-based catalysts is demonstrated. To our knowledge, the system 1/2,6-dichlorobenzoic acid (up to 2000 turnover numbers for cis-cyclooctanediol) is the most active Os-free cis-dihydroxylation catalyst reported to date.
authors.affiliation: Department of Organic and Molecular Inorganic Chemistry, Stratingh Institute, University of Groningen, Nijenborgh 4, 9747 AG Groningen, The Netherlands.
authors.forename: Johannes W
authors.initials: JW
authors.lastname: de Boer
authors.forename: Jelle
authors.initials: J
authors.lastname: Brinksma
authors.forename: Wesley R
authors.initials: WR
authors.lastname: Browne
authors.forename: Auke
authors.initials: A
authors.lastname: Meetsma
authors.forename: Paul L
authors.initials: PL
authors.lastname: Alsters
authors.forename: Ronald
authors.initials: R
authors.lastname: Hage
authors.forename: Ben L
authors.initials: BL
authors.lastname: Feringa