Henry reaction catalyzed by copper(I) complexes of a new pyridine‐containing macrocyclic ligand

Abstract

The synthesis and characterization of copper(I) complexes of the novel pyridine-containing macrocyclic ligand (PC-L) and their use as catalysts in the Henry reaction are reported. The pyridine-based 12-membered tetraaza macrocyclic (PC-L) ligand 1 can be obtained in good overall yield (85%) from commercially available starting materials. The Cu(I) complexes showed good catalytic activities in the Henry reaction of different aldehydes and nitroalkanes. Remarkable diastereoselectivity was observed when isatine was reacted with nitroethane under catalytic conditions.

Continuous flow asymmetric cyclopropanation reactions using Cu(i) complexes of Pc-L* ligands supported on silica as catalysts with carbon dioxide as a carrier

“…Extensive effort has been made to develop new methods which combine the ease of catalyst recovery of the heterogeneous systems with the higher performances in terms of activity and selectivity obtained with homogeneous catalysts. [1][2][3][4][5] A few years ago, our group reported the synthesis and characterisation of copper(I) complexes of pyridine containing tetraazamacrocyclic ligands Pc-L* 6 and results on their use as catalysts in asymmetric cyclopropanation reactions in the homogeneous phase. 7,8 Recently, in order to improve our catalytic system, we have developed new supported hydrogenbonded (SHB) chiral Pc-L* copper(I) complexes on different ordered and non-ordered silicas.…”

Asymmetric cyclopropanation of olefins catalysed by Cu(i) complexes of chiral pyridine-containing macrocyclic ligands (Pc-L*)

“…5,6 The synthesized ligands were used to prepare the corresponding paramagnetic metal ion complexes, after introduction of the appropriate pendant arms on the nitrogen atoms. 5 A few years ago, our group reported the synthesis and characterisation of copper(I) complexes of new pyridine containing tetraazamacrocyclic ligands 7 and preliminary results on their use as catalysts in asymmetric cyclopropanation reactions. 8 These ligands combine the advantages of macrocyclic polyamines and those of aminopyridine ligands.…”

Catalytic Applications of Pyridine‐Containing Macrocyclic Complexes

“…The Henry (or nitroaldol) reaction can be considered to be among the most valuable C–C bond‐forming reactions, because all of the atoms of the starting reagents are carried through to the formed product . Copper(I) complexes of non‐chiral Pc‐L ligands showed good efficiency in promoting the coupling of nitroalkanes with electron‐poor – and to a lesser extent also electron‐rich – aromatic aldehydes under mild conditions . Surprisingly, very good catalytic activities were also observed with the related silver(I) complexes, and to the best of our knowledge this was the first report in which silver(I) complexes were used to promote the Henry reaction (Scheme ) …”