Development of catalytic organic reactions in aqueous media

近年来，利用水作为反应溶剂在合成有机化学中受到了相当大的关注。首先，与通常用于有机反应的有机溶剂相比，水是一种廉价、安全、环保的溶剂。水的使用将减少有害有机溶剂的使用，是绿色化学的一个重要研究课题。其次，在含水反应中，使用前不需要干燥溶剂、底物和试剂。因此，可以减少干燥剂、能量和时间的消耗。第三，水具有独特的物理和化学性质，通过利用这些性质，可以实现在有机溶剂中无法达到的反应性或选择性。尽管目前已经开发出各种高效的水中催化体系，但仍有许多类型的反应难以在水中进行。本研究的目的是在水介质中开发高效的催化有机反应。以下是研究期间获得的主要结果。(1)开发了可用于水中各种反应的高疏水性聚合物负载酸催化剂。(2)研究了钯催化烯丙醇在水中的烯丙基取代反应。(3)发现Fe（III）离子在水介质中对非对映选择性Mukaiyama醛醇反应有效。(4)研究了硅烯醇醚在水介质中的催化不对称羟甲基化反应。(5)研究了水合腙在水中的催化不对称mannich型反应。(6)实现了功能化低聚芳烃的两步重复合成。建立了水-四氢呋喃混合溶剂体系合成该化合物的有效方法。

Recently, use of water as a reaction solvent has received considerable attention in synthetic organic chemistry for several reasons. First, water is a cheap, safe, and environmentally benign solvent when compared with organic solvents, which are normally used for organic reactions. Use of water will reduce the use of harmful organic solvents and is regarded as an important research topic in green chemistry. Second, in aqueous reactions, it is unnecessary to dry solvents, substrates, and reagents before use. Thus, consumption of drying agents, energy, and time can be reduced. Third, water has unique physical and chemical properties, and by utilizing these it would be possible to realize reactivity or selectivity that cannot be attained in organic solvents.Although various efficient catalytic systems in water have been developed so far, there are still many types of reactions which are difficult to carry out in water. The aim of this research is to develop efficient catalytic organic reactions in aqueous media.The following are the main results obtained during the research period.(1) Highly hydrophobic polymer-supported acid catalysts that can be used for various reactions in water were developed.(2) Palladium-catalyzed allylic substitution reactions of allyl alcohols in water were developed.(3) It was found that Fe(III) ion was effective for diastereoselective Mukaiyama aldol reactions in aqueous media.(4) Catalytic asymmetric hydroxymethylation of silyl enol ethers in aqueous media was developed.(5) Catalytic asymmetric Mannich-type reactions of hydrazones in water were developed.(6) Two-step repetitive synthesis of functionalized oligoarenes was achieved. The efficient methods for the synthesis using a water-THF mixed solvent system were developed.