Asymmetric catalysis Atom economy

The development of highly efficient asymmetric catalysts is one of the most intensively investigated research fields today.1 Catalytic asymmetric reactions are extremely powerful in terms of the practicality and atom economy.2 The power of asymmetric catalysis is rapidly growing, so as to be applicable to syntheses of natural products with complex structures. We call total syntheses using catalytic asymmetric reactions in key steps catalytic asymmetric total syntheses . In this chapter, we describe our recent success in catalytic asymmetric total syntheses of (-)-strychnine and fostriecin. Both of the total syntheses involve catalytic asymmetric carbon-carbon bond forming reactions using bifunctional catalysts developed in our group3 as key steps. 

Sustainable Catalysis Without Metals or Other Endangered Elements, Parts 1 and 2 deal with catalysts that do not possess a metal centre as part of their structure. After an introductory chapter. Chapters 2-4 cover non-asymmetric acid and base catalysis. The subsequent chapters (5-24) deal with asymmetric organocatalysis as this area has exploded in importance over the last 20 years. Again, catalysts that contain endangered elements e.g. phosphorus) have been excluded and authors were asked to highlight any examples that have other sustainable features (use of green solvent, high atom economy, etc.). 

The aldol reaction is an important carbon-carbon bond-forming method for constructing p-hydroxy carbonyl compounds in which new stereogenic centers are created. Especially, regio- and stereoselective aldol reactions are the most useful for organic synthesis of complex molecular skeletons [11-15]. From a viewpoint of atom economy, an aldol reaction via direct formation of an enolate with a catalytic amoimt of base is highly desired, and high Brpnsted basicity of the alkaline-earth metal compounds is suitable for this purpose. In recent researches on chiral alkaline-earth metal catalysis, direct-type asymmetric aldol and related reactions have been developed. 

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