An exceptional P-H phosphonite: biphenyl-2,2'-bisfenchylchlorophosphite and derived ligands (BIFOPs) in enantioselective copper-catalyzed 1,4-additions |
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Authors: | Kop-Weiershausen T Lex J Neudörfl J-M Goldfuss B |
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Affiliation: | Institut für Organische Chemie, Universit?t zu K?ln, Greinstrasse 4, 50939 K?ln, Germany. t.kop-weiershausen@uni-koeln.de |
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Abstract: | Biphenyl-2,2'-bisfenchol (BIFOL) based chlorophosphite, BIFOP-Cl, exhibits surprisingly high stabilities against hydrolysis as well as hydridic and organometallic nucleophiles. Chloride substitution in BIFOP-Cl proceeds only under drastic conditions. New enantiopure, sterically demanding phosphorus ligands such as a phosphoramidite, a phosphite and a P-H phosphonite (BIFOP-H) are hereby accessible. In enantioselective Cu-catalyzed 1,4-additions of ZnEt2 to 2-cyclohexen-1-one, this P-H phosphonite (yielding 65% ee) exceeds even the corresponding phosphite and phosphoramidite. |
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