机械化学条件下Mn(OAc)3促进的自由基串联反应研究

In view of the increasing importance of mechanochemistry in organic synthesis, the broad applications of Mn(OAc)3 in free radical reactions and the high efficiency of cascade reaction strategy towards the construction of heterocycles and complex natural products, the present project is to investigate on Mn(OAc)3-promoted free radical cascade reactions under mechanochemical condition... The following two systems will be emphatically studied: (1) The C atom in C=N double bond is to be directly derived via free radical addition-elimination cascade reactions; and some novel carbonyl compounds is to be obtained through hydrolysis of the derived C=N double bond. (2)In the addition reactions of 1,3-dicarbonyl compounds to C=C double bond in chalcone skeleton,the free radical addition position (regioselectivity) and the subsequent cyclization is to be directed by certain fuctioal groups. Moreover, suitable base would be employed as co-catalyst to tune the process of base-initiated Michael addition and Mn(III)-promoted radical addition (chemoselectivity), thus a control on the pathway of this kind of addition-elimination cyclization cascade reaction would be achieved...In addition, solvents and some other transiton metal catalysts such as Ce(NH4)2(NO3)6, Cu(OAc)2 and Co(OAc)2 would be investigated to find out their efficiency or effect on the above systems... Based on the studies on these Mn(OAc)3-promoted free radical cascade reactions under mechanochemical condition, some novel green methods are aimed to be developed for construction of 1,3-dicarbonyl,quinoline and furan moieties.

基于机械化学在有机合成中日益凸显的重要性，Mn(OAc)3在自由基反应中的广泛应用，以及串联反应策略在构建杂环及复杂天然产物等化学过程中的高效性，本项目拟研究机械化学条件下Mn(OAc)3促进的自由基串联反应。.重点研究以下两种体系：（1）通过C=N双键的自由基加成-消除串联反应实现对C=N双键中碳的直接衍生化，并藉由C=N双键的水解衍生出各种新型羰基化合物。（2）以1,3-二羰基化合物对查尔酮骨架中C=C双键的加成反应为对象，通过特定导向基团控制自由基加成的位置（区域选择性）及随后的成环反应；另采用适当的碱作共催化剂，通过控制Michael加成与自由基加成反应进程（化学选择性），来控制该加成-消除成环串联反应路径。同时对比考察溶剂及其它过渡金属对这些反应的影响。.该研究最终旨在通过机械化学条件下Mn(OAc)3促进的自由基串联反应发展出构建1,3-二羰基、喹啉、呋喃等结构的绿色新方法。

基于机械化学在有机合成中日益凸显的重要性，Mn(OAc)3在自由基反应中的广泛应用，以及串联反应策略在构建杂环及复杂天然产物等化学过程中的高效性，本项目研究了机械化学条件下Mn(OAc)3促进的自由基串联反应，主要是通过羰基化合物对芳香亚胺中C=N双键的自由基加成-消除串联反应实现了对C=N双键中碳的直接衍生化，并藉由C=N双键的水解衍生出一些新型羰基化合物。主要问题在于：对于易与C=N双键发生自由基加成-消除串联反应的底物仅局限于1,3-二羰基化合物，而相应的产物由于形成了高度共轭体系，导致对后续C=N双键的水解衍生出相应的羰基化合物比较困难。此外，发展出机械化学条件下通过查尔酮与水合肼的串联反应合成一系列3,5-二苯基-1H-吡唑，以及通过苯胺与二硫化碳的加成反应合成一系列苯基异硫氰酸酯、对称及不对称苯基硫脲的绿色新方法。

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