Olefin cyclopropanation catalyzed by new diiminophosphorane and triiminophosphorane complexes of copper and palladium

Catalytic cyclopropanation of olefins using copper(I) diphosphinoamines

“…More recently Warren et al have reported catalytic cyclopropanation using Cu(I) b-diketiminate: [Me 2 NN]Cu(g 2 -ethylene) complex [13]. Chelating diiminophosphorane and tripodal iminophosphorane copper and palladium complexes have been shown recently to efficiently catalyze the cyclopropanation of activated monosubstituted olefins [14].…”

New copper(I) and silver(I) triazolato-complexes: Synthesis, reactivity and catalytic activity in olefin cyclopropanation

“…Among the others, copper complexes cover a crucial role in this field [5] and both experimental [6] and theoretical [7] studies have been accomplished in order to elucidate the mechanism of olefin cyclopropanation promoted by Cu-based catalysts. A large variety of sp 2 -nitrogen based ligands, such as C 2 -symmetric semicorrins [8], bis(oxazolines) [9], optically active bipyridines [10] polypyrazolylborates [11] and diiminophosphoranes [12], have been used with the aim of enhancing the selectivity. Recently, high enantioselectivities were reached with binaphthyldiimines [13] and chiral bispidines [14].…”

Calixarene‐Derived Mono‐Iminophosphoranes: Highly Efficient Ligands for Palladium‐ and Nickel‐Catalysed Cross‐Coupling

“…However, this representation is only used for the sake of simplicity, theoretical analysis showing that the P À N bond is in fact a single bond reinforced by negative hyperconjugation of the lone pair of the nitrogen atom onto other orbitals centred on the phosphorus atom. [1,2] Iminophosphoranes can bind transition metals via their nitrogen atom, [3][4][5][6][7][8][9][10][11][12] but their binding strength is rather weak in comparison with that of imines. To increase their capacity to form metal complexes, they are often covalently associated with another, stronger donor that enables them to bind as chelate species.…”