Based Organocatalysts in Asymmetric Reductions

As mentioned briefly in Chapter 2, very few publications describing cinchona alkaloid-based asymmetric reduction systems have appeared, despite the importance of this reaction, and they are restricted to the reduction of aromatic ketones. 

This chapter described the cinchona-catalyzed asymmetric oxidation of enones and the reduction of prochiral ketones. 

In contrast to asymmetric oxidation chemistry, cinchona-catalyzed asymmetric reduction reactions have been explored very little, despite the importance of this reaction. Previous reports on this topic are restricted to the reduction of aromatic ketones, and the enantioselectivities achieved to date remain far from satisfactory when compared with metal catalysis. Moreover, Hantsch esters, another type of useful organic hydrides, have not yet been studied in combination with cinchona catalysts. However, as is well known, the structures of cinchona alkaloids are easily modifiable, thus permitting the easy tuning of the reaction course. The successful use of cinchona catalysts for this reaction will therefore likely be reported in the very near future. 

This work was supported by grants KRF-2008-005-J00701 (MOEHRD), Rll-2005-008-00000-0 (SRC program of MEST/KOSEF) and R31-2008-000-10029-0 (WCU program). 

Cinchona-Catalyzed Nucleophilic a-Substitution of Carbonyl Derivatives 

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