Premium
Enantioselective Catalysis, XII . Synthesis of Bis(phosphane) Palladium and Rhodium Complexes on a Polyethylene Oxide Grafted Polystyrene Matrix (TentaGel) and the Catalytic Behavior of the Rhodium Complexes
Author(s) -
Nagel Ulrich,
Leipold Joachim
Publication year - 1996
Publication title -
chemische berichte
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 0009-2940
DOI - 10.1002/cber.19961290712
Subject(s) - rhodium , chemistry , catalysis , polymer chemistry , tetrafluoroborate , pyrrolidine , ligand (biochemistry) , palladium , medicinal chemistry , organic chemistry , ionic liquid , biochemistry , receptor
A new polymer‐attached rhodium catalyst on a polyethylene oxide‐grafted styrene matrix (TentaGel) is described. The corresponding anchor molecules were prepared by starting from different Boc‐protected chiral pyrrolidinebis(phosphane)Pd complexes. The crystal structure of [3 R ,4 R )‐ N ‐(4‐carboxybutanoyl)‐3,4‐bis(diphenylphosphanyl)pyrrolidine‐ P,P ′]‐diiodopalladium ( 1c ) was determined. The formation of an amide bond between TentaGel and anchor molecules resulted in polymer‐bound Pd bisphosphane complexes. De‐complexation of the Pd with cyanide and reaction of the free polymeric ligand with [Rh(COD) 2 ]BF 4 led to the active hydrogenation catalyst. The influence of different solvents on the swelling volume and the catalytic behavior was tested. The polymer‐bound rhodium complex [(3 R ,4 R )‐ N ‐(1,5‐dioxo‐5‐TentaGel‐amino‐pentyl)‐3,4‐bis (diphenylphosphanyl)pyrrolidine P,P ′] (1,5‐cyclooctadiene)rhodium tetrafluoroborate ( 7 ) has about the same catalytic activity and enantioselectivity as the homogeneous complex [(3 R ,4 R )‐ N ‐( tert ‐butoxycarbonyl)‐3,4‐bis(diphenylphosphanyl)pyrrolidine‐ P,P ′] (1,5‐cyclooctadiene)rhodium tetrafluoroborate ( 9 ) in the same solvent mixture. It is possible to reuse 7 once, then it abruptly loses activity. This behavior remains to be clarified.