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首页> 外文期刊>Dalton transactions: An international journal of inorganic chemistry >Chiral manganese complexes with pinene appended tetradentate ligands as stereoselective epoxidation catalysts
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Chiral manganese complexes with pinene appended tetradentate ligands as stereoselective epoxidation catalysts

机译：pin烯附加四齿配体的手性锰配合物作为立体选择性环氧化催化剂

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摘要

A novel family of chiral manganese complexes Lambda-1(CF3SO3) and Delta-2(CF3SO3), have been stereoselectively prepared, characterized and studied as epoxidation catalysts. The complexes are structurally related to [Mn-II(CF3SO3)(2)(alpha-MCP)] (MCP = N,N'-dimethyl-N,N'-bis(2-pyridylmethyl)cyclohexane-trans-1,2-diamine),recently reported as a very efficient epoxidation catalyst in combination with peracetic acid. Pinene rings have been fused to the 4 and 5 positions of the two pyridine groups of the ligand, giving rise to complexes where the two labile binding sites of the manganese ion are confined in a better-defined chiral pocket than in the parent [MnII(CF3SO3)(2)(a-MCP)]. Chirality in these complexes arises from the stereochemistry of the trans-diaminocyclohexane ring, from the pinene ring and also from the topological chirality adopted by the ligand upon binding to the manganese ion. While previous studies have demonstrated that small modi. cations in the structure of the MCP ligand result in a dramatic loss of efficiency, Lambda-1(CF3SO3) and Delta-2(CF3SO3) exhibit comparable catalytic activity to [Mn-II(CF3SO3)(2)(alpha-MCP)]. In addition, the complexes exhibit a remarkable stereoselectivity ( up to 46% ee) in the epoxidation of selected substrates. The results reported in this work point towards modi. cation of the 4 and 5 positions of the pyridine groups as a new strategy towards the design of stereoselective versions of this family of highly active and environmentally benign epoxidation catalysts.
机译：新型的手性锰配合物Lambda-1（CF3SO3）和Delta-2（CF3SO3）家族已被立体选择性地制备，表征和研究为环氧化催化剂。该配合物在结构上与[Mn-II（CF3SO3）（2）（α-MCP）]相关（MCP = N，N'-二甲基-N，N'-双（2-吡啶基甲基）环己烷-反式1,2 -二胺），最近报道为与过氧乙酸组合的非常有效的环氧化催化剂。 ene烯环已稠合在配体的两个吡啶基团的4和5位上，形成了络合物，其中锰离子的两个不稳定结合位点被限制在比母体[MnII（ CF3SO3）（2）（a-MCP）]。这些配合物中的手性来自反式-二氨基环己烷环的立体化学，from烯环以及配体与锰离子结合后采用的拓扑手性。虽然以前的研究表明，这种小方法。 MCP配体结构中的阳离子导致效率急剧下降，Lambda-1（CF3SO3）和Delta-2（CF3SO3）表现出与[Mn-II（CF3SO3）（2）（alpha-MCP）相当的催化活性。 。此外，该复合物在所选底物的环氧化中显示出显着的立体选择性（高达46％ee）。在这项工作中报告的结果指向modi。吡啶基的4位和5位阳离子作为设计该系列高活性和环境友好的环氧化催化剂的立体选择形式的新策略。

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