R. Chinchilla, P. Mazón, C. Nájera
Sep 6, 2004
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0
Influential Citations
22
Citations
Journal
Tetrahedron-asymmetry
Abstract
Abstract Dimeric ammonium salts derived from cinchonidine or cinchonine and a bridging (anthracen-9,10-yl)dimethyl moiety bearing different counter-anions are used as chiral phase-transfer catalysts in the asymmetric alkylation reaction of a benzophenone-imine tert -butyl glycinate. The counterion generally has a great influence on the final enantioselectivity, the tetrafluoroborate or hexafluorophosphate anion giving place to higher ee’s compared to the chloride or bromide anions. The more noticeable differences are generally observed when the hexafluorophosphate salts of O -allylated dimeric catalysts are employed.