956903-05-2Relevant articles and documents
P-Stereogenic trifluoromethyl derivatives of josiphos: Synthesis, coordination properties, and applications in asymmetric catalysis
Buergler, Jonas F.,Niedermann, Katrin,Togni, Antonio
, p. 632 - 640 (2012)
Intermolecular nucleophilic substitution of a CF3 group of bis(trifluoromethyl)phosphanes by a lithiated Ugi's amine (4) affords both diastereoisomers of the corresponding P-stereogenic trifluoromethylphosphanes 6 and 7. Separation of the isomers by column chromatography on silica gel followed by substitution of the dimethylamino group with phosphanes or pyrazoles yields the bidentate P^P (9 and 10) or P^N ligands (12 and 13) without epimerization at the stereogenic phosphorus center. The coordination properties of these bidentate ligands were investigated on the basis of crystal structures of the corresponding palladium and rhodium complexes. IR spectroscopic measurements of rhodium-carbonyl complexes 16-23 indicated the strongly electronic-withdrawing character of these phosphanes. The catalytic potential of these ligands was demonstrated in the rhodium-catalyzed hydrogenation of olefins as well as in the palladium-catalyzed allylic alkylation reaction, where high activities and enantioselectivities were observed. CF3, more than just a simple substituent: Intra- and intermolecular nucleophilic substitutions of a CF 3 group in bis(trifluoromethyl)phosphanes were used in the preparation of bidentate ferrocenyl ligands bearing a P-stereogenic trifluoromethylphosphanyl group. High activities and enantioselectivities were achieved in rhodium-catalyzed olefin hydrogenation reactions and in palladium-catalyzed allylic alkylation reactions using these ligands. Copyright
