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Homogeneous and Supported Copper Complexes of Cyclic and Open‐Chain Polynitrogenated Ligands as Catalysts of Cyclopropanation Reactions
Author(s) -
Adrián F.,
Burguete M. I.,
Fraile J. M.,
García J. I.,
García J.,
GarcíaEspaña E.,
Luis S. V.,
Mayoral J. A.,
Royo A. J.,
Sánchez M. C.
Publication year - 1999
Publication title -
european journal of inorganic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 1434-1948
DOI - 10.1002/(sici)1099-0682(199912)1999:12<2347::aid-ejic2347>3.0.co;2-7
Subject(s) - cyclopropanation , chemistry , ethyl diazoacetate , catalysis , copper , ligand (biochemistry) , counterion , amine gas treating , styrene , polymer chemistry , combinatorial chemistry , organic chemistry , polymer , copolymer , ion , biochemistry , receptor
Cu I and Cu II complexes of cyclic and open‐chain polyaza compounds have been tested as catalysts in the benchmark cyclopropanation reaction of styrene with ethyl diazoacetate. In general, only small amounts of copper are needed to promote the reaction. The catalytic activity depends on the structure of the ligand, e.g. amine–amides are more efficient than polyamines, and on the oxidation state of copper, Cu II being more active than Cu I . Given that Cu I is the active species, these changes of behavior must be related to the stabilities of the complexes. The nature of the counterion also has a noticeable influence on the catalytic activity, the role of which is discussed. XAS measurements suggest the formation of oligomeric species. Some of the chiral ligands lead to small enantiomeric excesses. Open‐chain ligands can easily be supported on organic polymers and their complexes can be used as catalysts. Furthermore, cyclic and acyclic complexes can be supported on clays by cation exchange and the solids obtained tend to promote the reaction with a decrease in the trans / cis ratio.