Phase-transfer catalysis conditions cinchona alkaloid-derived catalyst

Enantioselective introduction of a side chain to glycine involves alkylation of 14, of 15, and a bomanesultam derivative under solid-liquid phase transfer catalysis conditions. Chiral catalysts serving in the alkylation of iV-protected glycine esters include the quatemized cinchona alkaloid 16. Another method involves alkylation of 17 (both enantiomers are available). 

Phase-transfer catalysis is one of the most practical synthetic methodologies because of its operational simplicity and mild reaction conditions, which enable applications in industrial syntheses as a sustainable green chemical process. As reviewed in this chapter, diverse Cinchona alkaloid-derived quaternaiy ammonium salts have been developed via the modification of Cinchona alkaloids based on steric or electronic factors as highly efficient chiral PTC catalysts and successfully applied in various asymmetric organic reactions. Despite the successful development and application of these catalysts, some problems remain to be addressed. Although Cinchona alkaloids have unique structural features, resulting in the availability of four... 

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