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Polyglycerol‐Supported Chromium‐Salen as a High‐Loading Dendritic Catalyst for Stereoselective Diels–Alder Reactions
Author(s) -
Hajji Chakib,
Roller Sebastian,
Beigi Maryam,
Liese Andreas,
Haag Rainer
Publication year - 2006
Publication title -
advanced synthesis and catalysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.541
H-Index - 155
eISSN - 1615-4169
pISSN - 1615-4150
DOI - 10.1002/adsc.200606168
Subject(s) - chemistry , catalysis , benzaldehyde , chromium , stereoselectivity , ultrafiltration (renal) , polymer chemistry , diels–alder reaction , organic chemistry , ligand (biochemistry) , enantioselective synthesis , chromatography , biochemistry , receptor
In this paper we demonstrate the application of hyperbranched polyglycerol (PG) 3 as a polymeric support for asymmetric catalysis. A new polyglycerol‐supported unsymmetrical salen ligand 4 is described, which was successfully purified by gel permeation chromatography (GPC) or by ultrafiltration. After the insertion of the metal, e.g., chromium, the corresponding polymeric chromium complex was used as catalyst for asymmetric Diels–Alder reactions between Danishefsky’s diene and benzaldehyde. The catalytic activities (up to 98 % conversion) and enantioselectivities (up to 78 % ee ) were comparable to the original catalyst reported by Jacobsen. The soluble polyglycerol‐supported catalysts were recovered by dialysis after the catalytic reactions and were recycled two times to afford identical reactivities as in the first run, with slightly reduced enantioselectivities. Moreover, this polymeric support catalyst showed a high retention (99.02 %) in a continuously operated membrane reactor.