Emulsion Catalysis in Lewis Acid-Catalyzed Organic Reactions

Emulsion Catalysis in Lewis Acid-Catalyzed Organic Reactions 

In 1998, a new type of catalyst named Lewis acid surfactant combined catalyst (LASC) was described by Kobayshi and coworkers. They found that LASC can act both as a Lewis acid to activate the substrate molecules and as a surfactant to form emulsions in water. The high efficiency of LASC was generally applicable for various organic transformations. 

The LASC-catalyzed reaction is also appHcable to transformations using organometaUics. By using the LASCs, Kobayshi and coworkers have attained Lewis 

Similarly, Friedel-Crafts reactions of indoles with electron-defident olefins were catalyzed by Sc(DS)j [30]. Not only enones but also a-nitrostyrene was successfully used as the acceptor in this reaction. It is noteworthy that soHd substrates such as indole and a-nitrostyrene as well as hquid ones reacted smoothly. The author daimed that it was the first example of a Lewis acid-catalyzed Friedel-Crafts-type reaction of an aromatic compounds in water. 

Wang et al. [53] have reported the synthesis of a new primary-secondary diamine catalyst containing a long alkyl chain and its application to the Michael addition of malonates to a,b-unsaturated ketones in water which was not successful earlier. This asymmetric Michael addition process was found to be effective 

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Emulsion Catalysis in Lewis Acid-CatalYzed Organic Reactions I 299... 

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