Copper complexes substitution

Piperazinothiazoies (2) were obtained by such a replacement reaction, Cu powder being used as catalyst (25. 26). 2-Piperidinothiazoles are obtained in a similar way (Scheme 2) (27). This catalytic reaction has been postulated in the case of benzene derivatives as a nucleophilic substitution on the copper-complexed halide in which the halogen possesses a positive character by coordination (29). For heterocyclic compounds the coordination probably occurs on the ring nitrogen. 

Pyridazines form complexes with iodine, iodine monochloride, bromine, nickel(II) ethyl xanthate, iron carbonyls, iron carbonyl and triphenylphosphine, boron trihalides, silver salts, mercury(I) salts, iridium and ruthenium salts, chromium carbonyl and transition metals, and pentammine complexes of osmium(II) and osmium(III) (79ACS(A)125). Pyridazine N- oxide and its methyl and phenyl substituted derivatives form copper complexes (78TL1979). 

Copper alloys are attacked at high pH. However, attack is usually caused not by elevated pH alone but because of copper complexation by ammonia or substituted ammonium compounds. In fact, copper resists corrosion in caustic solutions. For example, corrosion rates in hot caustic soda may be less than 1 mil/y (0.025 mm/y). 

Available information on the mechanism of cyclocondensation is rather contradictory. According to one hypothesis, both the condensation of aryl halides with copper acetylides and the cyclization occur in the same copper complex (63JOC2163 63JOC3313). An alternative two-stage reaction route has also been considered condensation followed by cyclization (66JOC4071 69JA6464). However, there is no clear evidence for this assumption in the literature and information on the reaction of acetylenyl-substituted acids in conditions of acetylide synthesis is absent. 

The bromo substituent in l-bromo-19-meLhyl-l,l9-dideoxybiladienes- c is not essential for porphyrin formation. When 1-methylbiladiene-ac dihydrobromide or the 1,19-dimethyl-biladienc-ac are heated in refluxing methanol or dimethylformamide in the presence of cop-per(II) salts, the porphyrin copper complexes 13 are formed by oxidative cyclization. The free porphyrins can then be obtained by removal of the copper with acid. A wide range of porphyrins 13 can be prepared by this method. However, a restriction is the accessibility of the starting material with special substitution patterns. 

The use of chiral bis(oxazoline) copper catalysts has also been often reported as an efficient and economic way to perform asymmetric hetero-Diels-Alder reactions of carbonyl compounds and imines with conjugated dienes [81], with the main focus on the application of this methodology towards the preparation of biologically valuable synthons [82]. Only some representative examples are listed below. For example, the copper complex 54 (Scheme 26) has been successfully involved in the catalytic hetero Diels-Alder reaction of a substituted cyclohexadiene with ethyl glyoxylate [83], a key step in the total synthesis of (i )-dihydroactinidiolide (Scheme 30). 

The well-defined copper complexes 94 and 95 (Fig. 2.16) have been used as catalysts for the intermolecular hydroamination of electron-deficient alkenes [Michael acceptors, X=CN, C(=0)Me, C(=0)(0Me)] and vinyl arenes substituted... 

Bis(oxazoline)-copper complexes 158 have been used by Evans group as chiral catalysts for the enantioselective aziridination of olefins.116 Aryl-substituted olefins have been found to be particularly suitable substrates, which can be efficiently converted to A-tosylaziridines with ee of up to 97% (R = Ph... 

The magnesium complex 34 was demetalated with trifluoroacetic acid to produce the H2[pz(A3B1)] (35) (98%) followed by conversion into the corresponding copper complex Cu[pz (A3B x)] (36, 95%) with Cu(II) acetate. Alternatively, Compound 36 can be prepared directly from the magnesium complex 34 by treatment with trifluoroacetic acid in the presence of Cu(II) acetate (72%). All forms of the norbomadiene substituted pz precursors, M[pz (A3Bj)] A = dipropyl, B = benzonorbomadiene M = Mg, H2, Cu, 34-36, have... 

Copper complexes of substituted malonic acids had no influence on the acute toxicity towards adult zebra fish [227], possibly due to stronger chelating groups at the gill epithelia. In contrast, hatching of zebra fish, which is already very sensitive to Cu2+ alone, was delayed in the presence of hydrophobic ra-hexade-cyl malonate, and was not influenced by the less hydrophobic benzyl malonate [227], Overall, it appeared that the toxicity of free Cu2+ and the Cu-hexadecyl malonate complex was additive [227],... 

An EPR and ENDOR investigation of the planar copper complex 63Cu(sal)2 (Fig. 30) substituted into a single crystal of Ni(sal)2 has been reported by Schweiger et al.62,65). The aim of this work was to determine the structure of the internal H-bond occuring in Cu(sal)2, and to draw a detailed picture of the unpaired electron distribution on the... 

Aminated Polystyrene-Copper Complexes as Oxidation Catalysts The Effect of the Degree of Substitution on Catalytic Activity... 

In the following sections we shall discuss (i) the structure and behaviour of the various copper complexes with the ligands listed in scheme 2 (ii) the activities of the polymeric catalysts in comparison with the low molecular weight analogs (iii) the effect of the degree of substitution, a, on the activities of the polymeric catalysts. 

The same complex could be obtained starting from CuC and subsequent substitution of both bridged chlorides by adding hydroxyl ions. Scheme 3 describes the formation and interconversion of both binuclear copper complexes. 

The preparation of cyclopropanes by intermolecular cyclopropanation with acceptor-substituted carbene complexes is one of the most important C-C-bond-forming reactions. Several reviews [995,1072-1074,1076,1077,1081] and monographs have appeared. In recent decades chemists have focused on stereoselective intermolecular cyclopropanations, and several useful catalyst have been developed for this purpose. Complexes which catalyze intermolecular cyclopropanations with high enantiose-lectivity include copper complexes [1025,1026,1028,1029,1031,1373,1398-1400], cobalt complexes [1033-1035], ruthenium porphyrin complexes [1041,1042,1230], C2-symmetric ruthenium complexes [948,1044,1045], and different types of rhodium complexes [955,998,999,1002-1004,1010,1062,1353,1401-1405], Particularly efficient catalysts for intermolecular cyclopropanation are C2-symmetric cop-per(I) complexes, as those shown in Figure 4.20. These complexes enable the formation of enantiomerically enriched cyclopropanes with enantiomeric excesses greater than 99%. Illustrative examples of intermolecular cyclopropanations are listed in Table 4.24. 

In 1995, Backvall and van Koten reported the first example of a catalytic, enantioselective Sn2 substitution of a primary allylic acetate in the presence of a chiral copper complex [28, 29]. 

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