Phosphinocyclodextrins as confining units for catalytic metal centres. Applications to carbon-carbon bond forming reactions.
The capacity of two cavity-shaped ligands, HUGPHOS-1 and HUGPHOS-2, to generate exclusively singly phosphorus-ligated complexes, in which the cyclodextrin cavity tightly wraps around the metal centre, was explored with a number of late transition metal cations. Both cyclodextrin-derived ligands were assessed in palladium-catalysed Mizoroki-Heck coupling reactions between aryl bromides and styrene on one hand, and the rhodium-catalysed asymmetric hydroformylation of styrene on the other hand. The inability of both chiral ligands to form standard bis(phosphine) complexes under catalytic conditions was established by high-pressure NMR studies and shown to have a deep impact on the two carbon-carbon bond forming reactions both in terms of activity and selectivity. For example, when used as ligands in the rhodium-catalysed hydroformylation of styrene, they lead to both high isoselectivity and high enantioselectivity. In the study dealing with the Mizoroki-Heck reactions, comparative tests were carried out with WIDEPHOS, a diphosphine analogue of HUGPHOS-2.
Laboratoire de Chimie Inorganique Moléculaire et Catalyse, Institut de Chimie UMR 7177 CNRS, Université de Strasbourg, 1, rue Blaise Pascal, 67008 Strasbourg Cedex, France.
Matthieu
M
Jouffroy
Laboratoire de Chimie Inorganique Moléculaire et Catalyse, Institut de Chimie UMR 7177 CNRS, Université de Strasbourg, 1, rue Blaise Pascal, 67008 Strasbourg Cedex, France.
Rafael
R
Gramage-Doria
Laboratoire de Chimie Inorganique Moléculaire et Catalyse, Institut de Chimie UMR 7177 CNRS, Université de Strasbourg, 1, rue Blaise Pascal, 67008 Strasbourg Cedex, France.
David
D
Sémeril
Laboratoire de Chimie Inorganique Moléculaire et Catalyse, Institut de Chimie UMR 7177 CNRS, Université de Strasbourg, 1, rue Blaise Pascal, 67008 Strasbourg Cedex, France.
Dominique
D
Armspach
Laboratoire de Chimie Inorganique Moléculaire et Catalyse, Institut de Chimie UMR 7177 CNRS, Université de Strasbourg, 1, rue Blaise Pascal, 67008 Strasbourg Cedex, France.
Dominique
D
Matt
Istituto di Chimica dei Composti OrganoMetallici CNR, via Madonna del Piano, 10, 50019 Sesto Fiorentino, Firenze, Italy.
Werner
W
Oberhauser
Groupe Matière Condensée et Matériaux, UMR 6626 CNRS, Université de Rennes 1, 263, avenue du Général Leclerc, 35042 Rennes Cedex, France.
Loïc
L
Toupet
Heck reaction; asymmetric hydroformylation; cyclodextrin; homogeneous catalysis; palladium; phosphine; rhodium