Generation of Onium Carbanion

Since asymmetric phase-transfer catalysts normally contain highly hpophilic chiral organic frameworks, and are reluctant to enter the aqueous phase, the Makosza interfacial mechanism seems plausible. 

Clearly, the area of the interface and the basicity of the inorganic salt affect the amount of available onium carbanion. Notably, an excessively hpophilic phase-transfer catalyst would hardly access the interface, and consequently the use of such a catalyst would result in an insuffident reaction. 

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