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- Asymmetric ion-pairing catalysis in chemistry is a type of asymmetric catalysis taking place specifically with charged intermediates or charged reagents. In one type of catalysis ion-pairing exists with a charged and chiral catalyst. The charged catalyst can be cationic or anionic. Catalysis by anionic catalysts is also called asymmetric counteranion-directed catalysis. In the other variation of asymmetric ion-pairing catalysis called anion or cation binding, the chiral catalyst is neutral but binds in a noncovalent way to an intermediate ion pair. Asymmetric ion-pairing catalysis is distinct from other covalent types of catalysis such as Lewis acid catalysis and . It is one of several strategies in enantioselective synthesis and of some relevance to academic research. The first reported example of this type of catalysis is attributed to Dolling, Davis & Grabowski who in 1984 used a chiral cinchonidine based phase transfer catalyst in the synthesis of indacrinone. Important chiral cation scaffolds are quaternary ammonium cations and quaternary phosphonium cations. The first reported example of asymmetric cation-binding catalysis originates from Cram and Sogah who in 1981 used a chiral crown ether in combination with a potassium base in an enantioselective Michael addition. The development of chiral anionic catalysists is a more recent research field. In 2000 Llewellyn, Adamson & Arndtsen used a chiral borate anion in olefin aziridination and cyclopropanation. Another regularly encountered scaffold is a chiral phosphate anion together with iminium, carbocationic or oxocarbenium counterions. Chiral anion phase-transfer catalysis was introduced by Toste in 2007. (en)
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- Asymmetric ion-pairing catalysis in chemistry is a type of asymmetric catalysis taking place specifically with charged intermediates or charged reagents. In one type of catalysis ion-pairing exists with a charged and chiral catalyst. The charged catalyst can be cationic or anionic. Catalysis by anionic catalysts is also called asymmetric counteranion-directed catalysis. In the other variation of asymmetric ion-pairing catalysis called anion or cation binding, the chiral catalyst is neutral but binds in a noncovalent way to an intermediate ion pair. Asymmetric ion-pairing catalysis is distinct from other covalent types of catalysis such as Lewis acid catalysis and . It is one of several strategies in enantioselective synthesis and of some relevance to academic research. (en)
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- Asymmetric ion-pairing catalysis (en)
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