Novel Synthetic Methodology Utilizing Fluorous Phases as a Liquid Screen

在本项目中，我们研究了“相位消失法”。我们最近开发的这种新方法利用了氟相的独特性质。PV法利用试剂在氟相中的扩散，是一种非常简单的方法，不需要任何滴漏斗、加热/冷却浴和温度计。对PV法合适的溶剂的检查表明，FC-72(全氟己烷)是一种出色的含氟溶剂。首先用Br2考察了烯烃的溴化反应；该反应在2天内完成，以68-97%的产率生成相应的二溴，而轻轻搅拌溴层，注意不要将三层混合，反应在4小时内完成，产率相似(88-91%)。我们还进行了各种有机反应，包括芳基甲醚与BBr3的脱甲基化，醇与PbR3或SOBr3的溴化，以及芳香族化合物与SnCl4的Friedel-Craft酰化反应。结果表明，该方法以较高的产率得到了相应的产物。用一个非常简单的多指玻璃装置成功地在Friedel-Craft酰化反应中平行合成了PV方法，一次提供了四种类型的芳香酮，高产率(-85%)。在FC-72的这个项目中，我们发现这种溶剂有弱点。也就是说，FC-72的回收非常不完整，因为它的高挥发性，在平行合成过程中，我们有时会遇到产品的污染。为了克服这些问题，我们再次寻找了比FC-72更适合于PV法的氟溶剂，发现全氟聚醚(Galden)是一种更好的溶剂。

In this project, we studied "the Phase-Vanishing(PV) Method". This novel method that we developed recently utilizes unique properties of the fluorous phase. The PV method, which capitalizes on the diffusion of reagents through the fluorous phase, is very simple methodology, and does not need any dropping funnels, heating/cooling baths, and thermometers. Inspection of suitable solvent for the PV method reveals that FC-72(perfluorohexanes) is an outstanding fluorous solvent. Firstly we examined bromination of olefins with Br2 ; this reaction finished in 2 days with standing to afford corresponding dibromide in 68-97% yields, while gentle stirring of the bromine layer, taking care not to mix the three layers, the reaction completed in 4 hours giving similar yields (88-91%). We also carried out various organic reactions including demethylations of aryl methyl ethers with BBr_3, bromination of alcohols with PBr_3 or SOBr_3, and the Friedel-Crafts acylations of aromatic compounds with SnCl_4 using the PV method, and showed that the method gave corresponding products in good yields. A parallel synthesis of the PV method in the Friedel-Crafts acylations using a very simple multi-fingered glass apparatus is also performed successfully, providing four types of aromatic keteones in high yield (64-85%) at once. During this project with FC-72 we have found that the solvent has weak points. Namely, the recovery of FC-72 is invaluably incomplete due to its high volatility, and in the parallel synthesis we sometimes faced contamination of products. In order to overcome these problems, we searched again more suitable fluorous solvents for the PV method than FC-72, and found that perfluoropolyethers (Galden) are a superior solvent.