Porphyrin copper

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. 

Copper is markedly different in its reactivity compared to iron. In porphyrins copper is totally buried. Due to the rigid structure of the porphyrins, where no twisting of the ligands is possible no reactivity with oxygen is seen. Hence, copper porphyrin-complexes display no superoxide dismutase activity In biological systems copper is essentially coordinated to nitrogen or sulphur. In octahedral Jahn-Teller distorted Cu(II) complexes a tetragonal distortion of the octahedron, usually an extension... 

Porphyrin, octaethyl-, copper complex cyclic voltammetry, 4, 399 <73JA5140)... 

The formation of porphyrins from 1,19-dideoxybi)enes-/r can be achieved starting either from the 1-methyl derivatives or from l,19-dideoxybilene-Z>-l,19-dicarboxylic acid esters. In the first case the desired methine bridge of the porphyrin stems from the 1-methyl group whereas in the latter case orthoformates have to be added in the condensation step as a precursor for the methine unit. The 1-methyl- and also 1,19-dimethyl-l,19-dideoxybilene- > salts can be cy-clized to the corresponding porphyrins with copper(II) acetate in methanol.56 However, when the bilenes contain /i-acceptor substituents, the yields of porphyrins obtained by this method are very low.57... 

Of great importance for porphyrin chemistry is the introduction of carbon substituents by Vilsmeier formylation100 or Friedel-Crafts acylation.100 The introduced substituents allow further carbon-chain elongations and other transformations so that interesting porphyrin derivatives can be synthesized. The Vilsmeier formylation of copper octaethylporphyrin (5) takes place at themethine position. The copper can then be easily removed by treatment with acid.105... 

Similar results are observed in the conjugative addition of CH-acidic methylene compounds with the metal derivatives of 2-nitro-5,10,15.20-tetraphenylporphyrin (6). The nickel porphyrin 6 (M = Ni) yields with an excess of dimethyl malonate the cyclopropane derivative 7 whereas the copper porphyrin 6 (M — Cu) forms with two equivalents of malononitrile the bisadduct 8.111... 

Cyclopropane-fused chlorins are formed in good yields from copper porphyrins with ethyl diazoacetatc in benzene in the presence of copper(I) iodide.200,21 In the case of copper oc-taethylporphyrin 10, which gives a diastereomeric mixture of cyclopropane adducts 11, ethyl me o-porphyrincarboxylate 12 and a geminally dialkylated chlorin 13 (a rearrangement product of the cyclopropane chlorin 11) are observed as minor byproducts.200... 

Complexes III and IV have Fe-porphyrin prosthetic groups (hemes), complex IV also contains copper atoms which are involved in electron transport. Complexes I, III, and IV use the energy of electron transport to pump protons out of the matrix so as to maintain a pH gradient and an electrical potential difference across the inner membrane required for ATP synthesis (see below and Appendix 3). It is important to remember that all dehydrogenations of metabolic substrates remove two protons as well as two electrons and that a corresponding number of protons are consumed in the final reduction of dioxygen (Figures 5, 6). 

Organometallic porphyrin complexes containing the late transition elements (from the nickel, copper, or zinc triads) are exceedingly few. In all of the known examples, either the porphyrin has been modified in some way or the metal is coordinated to fewer than four of the pyrrole nitrogens. For nickel, copper, and zinc the 4-2 oxidation state predominates, and the simple M"(Por) complexes are stable and resist oxidation or modification, thus on valence grounds alone it is easy to understand why there are few organometallic examples. The exceptions, which exist for nickel, palladium, and possibly zinc, are outlined below. Little evidence has been reported for stable organometallic porphyrin complexes of the other late transision elements. 

Chemical analysis revealed that commercial food grade copper chlorophyllin is not a single, pure compound, but is a complex mixture of structurally distinct porphyrins, chlorin, and non-chlorin compounds with variable numbers of mono-, di-, and tri- carboxylic acid that may be present as either sodium or potassium salts. Although the composition of different chlorophyllin mixtures may vary, two compounds are commonly found in commercial chlorophyllin mixtures trisodium Cu (II) chlorin Cg and disodium Cu (II) chlorin which differ in the number of... 

Similar to the intramolecular insertion into an unactivated C—H bond, the intermolecular version of this reaction meets with greatly improved yields when rhodium carbenes are involved. For the insertion of an alkoxycarbonylcarbene fragment into C—H bonds of acyclic alkanes and cycloalkanes, rhodium(II) perfluorocarb-oxylates 286), rhodium(II) pivalate or some other carboxylates 287,288 and rhodium-(III) porphyrins 287 > proved to be well suited (Tables 19 and 20). In the era of copper catalysts, this reaction type ranked as a quite uncommon process 14), mainly because the yields were low, even in the absence of other functional groups in the substrate which would be more susceptible to carbenoid attack. For example, CuS04(CuCl)-catalyzed decomposition of ethyl diazoacetate in a large excess of cyclohexane was reported to give 24% (15%) of C/H insertion, but 40% (61 %) of the two carbene dimers 289). 

In general, for a particular metal state, metallophthalocyanines are more difficult to demetallate than are metalloporphyrins (the central hole is marginally smaller in the phthalocyanine ligand). Thus, copper(II) phthalocyanine, dissolved in concentrated sulfuric acid, is precipitated unchanged when the solution is poured into ice/water. However, metallochlorins are demetallated more readily than the corresponding metalloporphyrins (basicity chlorin < porphyrin). 

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