Copper complexes Schiff base

In 1966, Nozaki et al. reported that the decomposition of o-diazo-esters by a copper chiral Schiff base complex in the presence of olefins gave optically active cyclopropanes (Scheme 58).220 221 Following this seminal discovery, Aratani et al. commenced an extensive study of the chiral salicylaldimine ligand and developed highly enantioselective and industrially useful cyclopropanation.222-224 Since then, various complexes have been prepared and applied to asymmetric cyclo-propanation. In this section, however, only selected examples of cyclopropanations using diazo compounds are discussed. For a more detailed discussion of asymmetric cyclopropanation and related reactions, see reviews and books.17-21,225... 

In situ photoacoustic spectroscopy has been used to study the redox process on the surface of an electrode using copper metal in alkaline solution. The values of copper(II) Schiff base complexes " absorbed on optically transparent thin-layer electrodes (OTTLE) have been... 

Many examples of asymmetric induction are known in carbene chemistry. For instance, copper(II)-Schiff base complexes catalyze the enantioselective cyclopropanation of 1,1-diphenyl-ethylene by ethyl diazoacetate (7) to give ethyl 2,2-diphenylcyclopropanecarboxylate in up to 65/0 e.e. [30]. 

Losada, J., I. Del Peso, and L. Beyer (2001). Electrochemical and spectroelectro-chemical properties of copper(II) Schiff-base complexes. Irwrg. Chim. Acta 321, 107-115. 

PAMAM GO Schiff base drug complex Chloropyridylimine- platinum(ll) Chloropyridylimine- copper(ll) Schiff base Pt complex Cancer n.a. Yes No 324... 

Chiral copper (I) semicorrin complex Chiral copper(II) Schiff base complex... 

The very different basicities of water and of ammonia lead to different reactivity patterns for iSNlcb base hydrolyses of cobalt(iii) compounds. The latest contribution in this area has been a study of base hydrolysis of a series of complexes [Co(NH3)6(RNHa)] + in liquid ethylenediamine. The basicity or solvating power of the solvent determines the form of the rate law for substitutions at copper(ii)-Schiff base complexes. The term corresponding to solvolysis is, of course, only significant for solvents with an affinity for copper(ii). ... 

Oxidative dimerisation of 2-naphthols to l,l -bis-2,2 -naphthol (BINOL) derivatives has been studied extensively. Copper(ii) catalyst under molecular oxygen has shown broad versatility in this transformation. Copper(ii)-Schiff base complexes reveal good catalytic activity in the dimerisation of 2-naphthols with low catalyst loading. This catalyst system is not so effective for substrates bearing electron-withdrawing substituents. " Cu(OH)Cl(TMEDA) is stable and shows good catalytic activity even for electron-poor naphthols... 

Mixed 6),Af-donor ligands such as Schiff bases are of interest in that they provide examples not only of square-planar coordination but also, in the solid state, examples of square-pyramidal coordination by dimerization (Fig. 28.6(b)). A similar situation occurs in the bis-dimethylglyoximato complex, which dimerizes by sharing oxygen atoms, though the 4 coplanar donor atoms are all nitrogen atoms. Copper(II) carboxylates are easily obtained by crystallization from aqueous solution or, in the case of the higher carboxylates, by precipitation with the appropriate acid from ethanolic solutions... 

The major developments of catalytic enantioselective cycloaddition reactions of carbonyl compounds with conjugated dienes have been presented. A variety of chiral catalysts is available for the different types of carbonyl compound. For unactivated aldehydes chiral catalysts such as BINOL-aluminum(III), BINOL-tita-nium(IV), acyloxylborane(III), and tridentate Schiff base chromium(III) complexes can catalyze highly diastereo- and enantioselective cycloaddition reactions. The mechanism of these reactions can be a stepwise pathway via a Mukaiyama aldol intermediate or a concerted mechanism. For a-dicarbonyl compounds, which can coordinate to the chiral catalyst in a bidentate fashion, the chiral BOX-copper(II)... 

The conformation of Schiff-base complexes of copper(IT) a stereo-electronic view. H. S. Maslen and T. N. Waters, Coord. Chem. Rev., 1975,17,137-176 (127). 

John E, Bott A, Green M. Preparation and biodistribution of copper-67 complexes with tetradentate Schiff-base ligands. J Pharm Sci 1994 83 587-590. 

Partial hydrolysis of a potentially heptadentate Schiff-base tripodal ligand derived from tris-(2-aminoethyl)amine and 2-hydroxyacetophenone, induced by copper(II) salts, was reported and the final copper(II) complex (377) was characterized.333 Using salicylaldehyde as a co-ligand, with a copper(II) complex (378), catalytic epoxidation was demonstrated 334... 

Asymmetric ring-opening of saturated epoxides by organocuprates has been studied, but only low enantioselectivities (< 15% ee) have so far been obtained [49, 50]. Muller et al., for example, have reported that the reaction between cyclohexene oxide and MeMgBr, catalyzed by 10% of a chiral Schiff base copper complex, gave trans-2-methylcyclohexanol in 50% yield and with 10% ee [50]. 

A number of structurally very different copper complexes were employed as catalysts. The copper complex of binaphthol-derived phosphoramidite 32 and the Schiff base complex 53 (derived from salicylaldehyde and phenylglycine) gave promising results in a screening reaction between 52 and MeMgBr, and 53 was chosen as the candidate for optimization. The effect of solvent (THF or Et20),... 

Of the other possible structures (95) of the condensation product, the Schiff s base (CXXX) is not resolvable, nor, because of the tautomeric nature of the guanidine system, is the four-membered ring compound (CXXXI). A compound of the improbable structure (CXXXII) should yield a copper complex, which the condensation products failed to do. 

The i.r. and n.m.r. spectra of copper(ii) dithizonate together with other physicochemical data indicate that the complex is dimeric with structure (201). " The Schiff bases S-methyl-N-isopropylidenedithiocarbazate (NSH) and S-methyl-7V-(2-pyridyl)methylenedithiocarbazate (NNSH) form the square-... 

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