Cinchona Alkaloids in Asymmetric Phase-Transfer Catalysis

Cinchona Alkaloids in Asymmetric Phase-Transfer Catalysis 

Cinchona alkaloids, of course, have occupied the central position in the design of chiral PTCs. By employing a simple chemical transformation of the tertiary amine ofthe natural cinchona alkaloids to the corresponding quaternary ammonium salts, using active halides (e.g., aryl-methyl halides), a basic series of PTCs can be readily prepared. Cinchona alkaloid-derived PTCs have proved their real value in many types of catalytic asymmetric synthesis, including a-alkylation of modified a-amino acids for the synthesis of higher-ordered a-amino acids [2], a-alkylation of 

Asymmetric Phase Transfer Catalysis. Edited by Keiji Maraoka Copyright 2008 WILEY-VCH GmbH Co. KGaA, Weinheim ISBN 978-3-527-31842-1 

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