de Boer Johannes W, Brinksma Jelle, Browne Wesley R, Meetsma Auke, Alsters Paul L, Hage Ronald, Feringa Ben L
Department of Organic and Molecular Inorganic Chemistry, Stratingh Institute, University of Groningen, Nijenborgh 4, 9747 AG Groningen, The Netherlands.
J Am Chem Soc. 2005 Jun 8;127(22):7990-1. doi: 10.1021/ja050990u.
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.
描述了羧酸促进下，以[MnIV2O3(tmtacn)2]2+ 1为催化剂、H2O2为氧化剂的烯烃顺式二羟基化和环氧化反应。在助催化水平下使用羧酸不仅能有效抑制1固有的过氧化氢酶活性，还能调节催化剂的选择性。光谱研究和X射线分析证实，这种调控源于催化过程中原位形成的羧酸盐桥连双核配合物，例如2 {[MnIII2O(CCl3CO2)2(tmtacn)2]2+}和3 {[MnII2(OH)(CCl3CO2)2(tmtacn)2]+}。首次证明了通过所使用的羧酸盐配体调节双核锰基催化剂的选择性和活性的可能性。据我们所知，体系1/2,6 - 二氯苯甲酸（顺式环辛二醇的周转数高达2000）是迄今为止报道的活性最高的无锇顺式二羟基化催化剂。
