Cinchona electronic factor

The asymmetric phase-transfer epoxidation of ( )-a, 3-unsaturated sulfones has recently been achieved by Dorow and coworker using N-anthracenylmethyl cinchona alkaloid derivatives as catalysts and KOC1 as an oxidant at low temperature [23]. The screening of several etheral functional groups at the C9( O) position of the catalyst moiety indicated that the steric size and the electronic factor of the ether substituent has a significant effect on both the reaction conversion and the enantioselectivity. 

The same group also reported the several evidence, which can strongly support their hypothesis of the electronic factor in the cinchona PTCs [21]. First, bcnzylations... 

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... 

Different factors determining the regioselectivity have been discussed These include steric and electronic contributions of the chiral cinchona ligands, substrates, and solvent effects, which all depend on each other. 

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