Cesium Salts in Organic Synthesis: A Review

The excellent advantages of cesium such as short reaction times, small amount of reagent used, high yields of the products, milder reaction conditions, and easy work-up procedures counter balanced its higher cost. From the last two decades, the use of cesium salts has received an increasing interest in numerous varieties of synthetic conversions. Today, the use of cesium salts has reached the industrial acceptance. For example, palladium catalyzed coupling reactions like the Suzuki coupling or the Buchwald amination reactions use the cesium salts. However, cesium salts are also utilized in direct nucleophilic substitution reactions since they have replaced the standard bases. This is the first review in this area which exclusively deals with recent developments in Cs salt promoted reactions with special focus on mechanistic aspects as well as on the recent applications in drug synthesis. Today, cesium carbonate (Cs2CO3), cesium fluoride (CsF), cesium acetate (CsOAc) and cesium hydroxide monohydrate (CsOH·H2O) are the most frequently used cesium compounds in the organic synthesis.