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Mechanistic Insights into the Palladium‐Catalysed Asymmetric Phosphination of Cyclohexenyl Triflate
Author(s) -
Julienne Delphine,
Delacroix Olivier,
Lohier JeanFrançois,
de OliveiraSantos Jana Sopkova,
Gaumont AnnieClaude
Publication year - 2011
Publication title -
european journal of inorganic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 1434-1948
DOI - 10.1002/ejic.201000987
Subject(s) - chemistry , transmetalation , trifluoromethanesulfonate , reductive elimination , borane , oxidative addition , cationic polymerization , medicinal chemistry , catalytic cycle , adduct , palladium , catalysis , stereochemistry , combinatorial chemistry , organic chemistry
Preliminary results on the mechanism of the asymmetricphosphination involving an achiral alkenyl triflate (cyclohexenyl triflate) and a secondary phosphane–borane, (methyl)phenylphosphane–borane ( 1 ) are reported. A catalytic cycle is proposed based on the variable‐temperature 31 P NMR characterization of the individual steps (oxidative addition, transmetallation and reductive elimination). Each likely intermediate involved in this asymmetric C–P coupling reaction has been identified and characterized. Hence, cationic oxidative addition complex 3 has been readily synthesized and engaged in the stoichiometric reaction with highly enantio‐enriched secondary phosphane–borane ( S P )‐ 1 enabling to isolate the corresponding diastereomerically pure transmetallation adduct ( S , S , R P )‐ 5 . Its structure has been confirmed by X‐ray crystallography. Its decomposition by reductive elimination affords the highly enantio‐enriched coupling product ( S P )‐ 2 . This study also provides information on the origin of the enantioselectivity.