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New Chiral Calixsalen Chromium Complexes: Recyclable Asymmetric Catalysts
Author(s) -
Zulauf Anaïs,
Mellah Mohamed,
Schulz Emmanuelle
Publication year - 2010
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201001012
Subject(s) - catalysis , ethylenediamine , bimetallic strip , epoxide , chromium , cyclohexane , chemistry , selectivity , diamine , polymer chemistry , nucleophile , polymer , derivative (finance) , organic chemistry , combinatorial chemistry , financial economics , economics
A chiral N , N ′‐bis(salicylidene)ethylenediamine (salen) polymer has been prepared by a condensation reaction between a thiophenedisalicyladehyde derivative and ( S , S )‐cyclohexane‐1,2‐diamine. This polymeric compound was demonstrated to possess a cyclic structure with two to five repetitive units. The addition of chromium(II) salts led to the generation of a chiral catalyst that could be recovered as an insoluble powder. The performance of this new calixsalen‐type catalyst was examined in various transformations, particularly in its ability to promote nucleophilic epoxide ring opening under heterogeneous conditions. The target products were obtained in high yields and with improved selectivity compared with those obtained by using analogous linear polymers. The arrangement of the catalytic sites in the cyclic structure is probably more suitable for the necessary cooperative bimetallic pathway of this demanding reaction. The catalyst could be successfully recycled. This approach represents the first use of calixsalen complexes under heterogeneous catalytic conditions.