Efficient chemical fixation of CO2 promoted by a bifunctional Ag2WO4/Ph3P system
Efficient chemical fixation of CO2 promoted by a bifunctional Ag2WO4/Ph3P system
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双功能 Ag2WO4/Ph3P 系统促进 CO2 的高效化学固定
DOI：
10.1039/c3gc42406e
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发表时间：
2014-01-01
期刊：
影响因子：
9.8
通讯作者：
He, Liang-Nian
中科院分区：
文献类型：
--
作者：
Song, Qing-Wen;Yu, Bing;He, Liang-Nian
通过炔丙醇和 CO2 的羧化组装，开发了一种有效的异质银催化反应，用于构建α-亚甲基环状碳酸酯基序。这种 CO2 固定方案在室温、无溶剂条件下仅用 1 mol% Ag2WO4 和 2 mol% PPh3 以及大气 CO2 即可顺利进行，以环境友好、低能耗的方式以及简单的操作程序。值得注意的是，通过独特的化学选择性，可以实现高达 98% 的碳酸盐分离产率。此外，Ag2WO4对炔丙底物和CO2的双重活化能力是基于银阳离子和钨酸根阴离子的协同催化机制而提出的。炔丙醇和CO2羧化环化的回收试验表明，该催化剂可重复使用至少4次，并保持较高的催化活性和选择性。特别是，它允许直接有效地应用于各种带有环外烯烃和氨基甲酸酯的恶唑烷酮的一锅合成，在交替引入伯胺或仲胺时，以中等至高产率进行合成。
An efficient heterogeneous silver-catalyzed reaction for construction of the a-methylene cyclic carbonate motif was developed through carboxylative assembly of propargyl alcohols and CO2. Such a CO2 fixation protocol proceeded smoothly with only 1 mol% of Ag2WO4 and 2 mol% of PPh3 as well as atmospheric CO2 at room temperature under solvent-free conditions, in an environmentally benign and low energy manner along with an easy operating procedure. Notably, up to 98% isolated yields of carbonates could be attained with exclusive chemo-selectivity. In addition, the dual activation capacity of Ag2WO4 towards both the propargylic substrate and CO2 is based on which cooperative catalytic mechanism by the silver cation and the tungstate anion is proposed. Recycling trials on carboxylative cyclization of propargyl alcohols and CO2 illustrate that the catalyst can be reused at least 4 times with retention of high catalytic activity and selectivity. Especially, it allows the direct and effective application in the one-pot synthesis of various oxazolidinones bearing exocyclic alkenes and carbamates in moderate to high yields upon the alternative introduction of primary or secondary amines.