| 新的钌环丙烷化催化体系的探索(Ⅱ) 氮膦配体立体化学结构控制顺反比选择性的初步研究 | |
| The Exploration of Novel Ruthenium Catalytic System for Cyclopropanation ?Preliminary Investigation on Selectivity of Trans:Cis Controlled by Stereochemistry of N,P-ligand | |
| 摘要: 本文研究了一个新的钌催化的苯乙烯环丙烷化反应催化体系。当该催化体系用三氟甲磺酸银预处理后其催化的环丙烷化反应产物的顺反比接近1:1,且顺式产物略微占优。这在环丙烷化反应中是不多见的。我们用分子力学/动力学对该催化体系进行了模拟。结果表明键能并非是决定产物顺反比的主要因素。但是对于非键能来说,由于中间体M1与苯乙烯作用生成顺式产物时的范德华作用非常强,它弥补了由静电能所引起的能量上的不利因素。所以总能量对生成顺式产物较为有利。但是由于生成顺式产物与反式产物的总能量差别不大(2.5kcal·mol-1),所以环丙烷化产物的顺反比接近1:1。这是氮膦配体立体化学结构控制产物选择性的结果。 | |
| 关键词: 环丙烷化反应 分子力学/动力学 卡宾 | |
| 基金项目: | |
| Abstract: A novel ruthenium catalytic system with 1R,2Rcyclohexyl N2P2 as ligand for the asymmetric cyclopropanation of styrene was investigated. Abnormal trans:cis phenomenon was found when the catalytic system was pretreated with AgOTf (silver triflate). The trans:cis is near 1:1, but the cis products has a little advantage. The molecular mechanics/dynamics were used to study this phenomenon. The geometric energies of two approaching states, which resulting in trans and cis products were compared. The results reveal that the energy of valence terms is not the major factor to decide the trans:cis ratio of cyclopropanation products because the difference on the energy of valence terms is very little (about 0.2kcal·mol-1). The theoretical calculation by molecular mechanics was in agreement to this result. But as for energy of nonbonding terms, the interaction of Van der waals between intermediate M1 and styrene to give the cis products is so strong (-0.73 kcal·mol-1) that it offsets the disadvantage caused by elcetrostatic energy. So the total energy of interaction between M1 and styrene is favorable to give cis products. But the difference of total energy for interaction of M1 and styrene to give trans and cis products is small. It is about 2.5kcal·mol-1. This ensures the trans:cis ratio of cyclopropanation products is near 1:1, which is consistent with experimental results and decided by stereochemistry of N,Pligand. | |
| Keywords: cyclopropanation molecular mechanics/dynamics carbene | |
| 投稿时间：2001-01-12 修订日期：2001-04-16 | |
| 摘要点击次数: 1405 | |
| 全文下载次数: 1964 | |
| 李琛,周丹红,姚小泉,刘秀梅,陆世维,韩秀文,包信和.新的钌环丙烷化催化体系的探索(Ⅱ) 氮膦配体立体化学结构控制顺反比选择性的初步研究[J].无机化学学报,2001,17(4):507-512. | |
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