Manganese catalysed asymmetric cis-dihydroxylation with H2O2
作者:Johannes W. de Boer、Wesley R. Browne、Syuzanna R. Harutyunyan、Laura Bini、Theodora D. Tiemersma-Wegman、Paul L. Alsters、Ronald Hage、Ben L. Feringa
DOI:10.1039/b808355j
日期:——
High turnover enantioselectivealkenecis-dihydroxylation is achieved with H2O2 catalysed by manganese based complexes containing chiral carboxylato ligands.
Mechanism of Cis-Dihydroxylation and Epoxidation of Alkenes by Highly H<sub>2</sub>O<sub>2</sub> Efficient Dinuclear Manganese Catalysts
作者:Johannes W. de Boer、Wesley R. Browne、Jelle Brinksma、Paul L. Alsters、Ronald Hage、Ben L. Feringa
DOI:10.1021/ic7003613
日期:2007.8.1
the in situ formation of bis(micro-carboxylato)-bridged dinuclear manganese(III) complexes. Tuning of the activity of the catalyst by variation in the carboxylate ligands is dependent on both the electron-withdrawing nature of the ligand and on steric effects. By contrast, the cis-diol/epoxide selectivity is dominated by steric factors. The role of solvent, catalyst oxidation state, H2O, and carboxylic
在羧酸的存在下,复合物[Mn(IV)2(micro-O)3(tmtacn)2] 2+(1,其中tmtacn = N,N',N''-三甲基-1,4,7-已显示出三氮杂环壬烷)在以H 2 O 2作为末端氧化剂催化烯烃氧化为相应的顺式二醇和环氧化物方面非常有效。相对于烯烃的顺式-二羟基化或环氧化,催化体系的选择性显示出取决于所用的羧酸。尤其是在顺式-二羟基化反应中,可以实现较高的周转率(吨> 2000),使用2,6-二氯苯甲酸可使迄今为止报道的第一行过渡金属和烯烃的顺式-二羟基化反应的吨数最高。终端氧化剂(H2O2)具有很高的效率。高活性和选择性归因于双(微羧基)桥联的双核锰(III)配合物的原位形成。通过改变羧酸酯配体来调节催化剂的活性既取决于配体的吸电子性质,又取决于空间效应。相反,顺式二醇/环氧化物的选择性受空间因素支配。结合形态分析和同位素标记研究,探讨了溶剂的作用,催化剂的氧化态,H2