- Synthesis of a Family of Highly Substituted Porphyrin Thioethers via Nitro Displacement in 2,3,7,8,12,13,17,18-Octaethyl-5,10,15,20-tetranitroporphyrin
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A series of highly substituted porphyrin thioethers was synthesized from 2,3,7,8,12,13,17,18-octaethyl-5,10,15,20-tetranitroporphyrin (H2OETNP). The reactions proceeded via a SNAr mechanism with a broad range of aromatic thiols in the presence of a base. This is a rapid way to prepare a large variety of meso-substituted porphyrins from only one precursor. Single crystal X-ray analysis revealed that these new porphyrin thioethers are highly distorted, exhibiting conformational properties that are distinctive of both meso-sulfur substitution and steric overcrowding in general. Additionally, denitration of H2OETNP under basic conditions was investigated, yielding products of stepwise desubstitution. This allowed a comparative X-ray crystallographic study to delineate the successive structural effects of an increasing degree of nitro substitution in the complete series of nitro-substituted octaethylporphyrins.
- Kielmann, Marc,Flanagan, Keith J.,Norvai?a, Karolis,Intrieri, Daniela,Senge, Mathias O.
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p. 5122 - 5134
(2017/05/24)
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- Surprising Outcomes of Classic Ring-Expansion Conditions Applied to Octaethyloxochlorin, 3. Schmidt-Reaction Conditions
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The Schmidt reaction (treatment of a ketone with sodium azide and a mineral acid) is an alternative to the Beckmann rearrangement to expand a cyclic ketone to a lactam. However, when applied toward the conversion of a synthetic porphyrin into a derivative containing a nonpyrrolic building block, this approach failed to generate the expected lactam. Instead, by using sulfuric acid as a catalyst, a novel heptaethyl-2-hydroxy-chlorin-3-one was formed, structurally characterized, and its mechanism of formation deduced. The work demonstrates how the extraordinary structural stability of the porphyrin macrocycle redirects the reactivity patterns of classic ring-expansion reactions. By using hydrochloric acid as a catalyst, a somewhat regioselective chlorination of the meso-positions of the oxochlorin was observed. The halogenation sites were determined spectroscopically and by X-ray crystallography of selected derivatives. The regioselectivity of the halogenation was computationally rationalized. This method is superior to alternative halogenation methods for the regioselective generation of 5-chloro-, 10-chloro-, and 5,10-dichlorooxochlorins.
- Li, Ruoshi,Zeller, Mathias,Bruhn, Torsten,Brückner, Christian
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p. 1835 - 1842
(2017/04/21)
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- Paley's watchmaker analogy and prebiotic synthetic chemistry in surfactant assemblies. Formaldehyde scavenging by pyrroles leading to porphyrins as a case study
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The formation of elaborate molecules is regarded as an essential first step in prebiotic chemistry, but how such transformations could spontaneously occur, particularly in dilute aqueous conditions, remains poorly understood. Here, micromolar concentrations of a 3,4-dialkylpyrrole and excess formaldehyde in aqueous micellar solution (pH 7) at 25 or 50 °C were found to give good yield (up to 40%) of the lipophilic octaalkylporphyrin. The reaction occurs despite a mean occupancy number of ～0.1 pyrrole molecules/micelle, and 1 of 10 000 micelles initially containing the requisite 4 pyrrole molecules to form the porphyrin assuming a (random) Poisson distribution. Yields of up to 13% were observed in large, unilamellar phosphatidylcholine vesicles, wherein there are ～15 000 pyrrole molecules per vesicle membrane. Double-labeling crossover experiments (of 3,4-diethylpyrrole and 3,4-dimethylpyrrole) examined by mass spectrometry revealed facile exchange processes of reactive constituents among both micelle and vesicle surfactant assemblies. Together, the exchange of pyrrolic reactants among micelles and the thermodynamic driving force for tetrapyrrole formation overcome the apparent statistical odds against reaction. The fruitful exchange, accumulation and reaction of minute quantities of reactants in aqueous-surfactant assemblies suggest a general means for formation of prebiotically valuable constituents, even when the statistical odds at the outset are overwhelmingly improbable.
- Alexy, Eric J.,Hintz, Carl W.,Hughes, Hubert M.,Taniguchi, Masahiko,Lindsey, Jonathan S.
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p. 10025 - 10031
(2015/10/12)
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- Syntheses of highly distorted meso-trifluoromethyl-substituted β-octaalkylporphyrins
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Treatment of 5,5′-d icarboxy-3,3′,4,4′-tetraalkyl-2,2′-dipyrromethanes with trifluoroacetic acid and subsequent oxidation resulted in formation of meso-trifluoromethy l-substituted β-octaalkylporphyrins. The structura l characterizations and the spectrosc
- Suzuki, Masaaki,Ishii, Shuto,Hoshino, Tyuji,Neya, Saburo
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supporting information
p. 1563 - 1565
(2015/02/19)
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- The exhaustive reduction of formylporphyrins to methylporphyrins using dimethylformamide/water as reductant under microwave irradiation
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The reduction of meso-formyl derivatives of 5,15-diaryl- and 5,10,15-triphenylporphyrin (and their nickel(II) complexes) to the corresponding meso-methyl porphyrins is achieved in high yield by microwave heating of the substrate in dimethylformamide (DMF)
- Fletcher, Sarah J.,Harper, Shannon R.,Arnold, Dennis P.
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p. 200 - 208
(2014/05/20)
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- Microwave-assisted Piloty-Robinson synthesis of 3,4-disubstituted pyrroles
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(Chemical Equation Presented) The synthesis of N-acyl 3,4-disubstituted pyrroles can be accomplished directly from hydrazine and an aldehyde via a Piloty-Robinson pyrrole synthesis. The use of microwave radiation for the cyclization and pyrrole formation
- Milgram, Benjamin C.,Eskildsen, Katrine,Richter, Steven M.,Scheidt, W. Robert,Scheidt, Karl A.
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p. 3941 - 3944
(2008/02/01)
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- Phenyl-substituted porphyrins. 1. Synthesis of meso-phenyl-substituted porphyrins
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A method was developed for the synthesis of a series of meso-phenyl-substituted octaalkylporphyrins with various numbers of phenyl groups at various positions. Some of their properties were studied.
- Syrbu,Lyubimova,Semeikin
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p. 1262 - 1270
(2007/10/03)
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- Dissociation kinetics of copper and cobalt complexes with sterically distorted porphyrins
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The dissociation kinetics of the cobalt and copper complexes with octaethylporphyrin, its 5-phenyl, 5,15-diphenyl, and 5,10,15,20-tetraphenyl derivatives, and dodecaphenylporphyrin in acetic acid with small additions of trifluoroacetic acid were studied. In this series of complexes, the steric distortion of the tetrapyrrole macrocycle sequentially increases, which results in a regular decrease in the kinetic stability of the metal porphyrins: The dissociation rate increases by three orders of magnitude.
- Kuvshinova,Kuz'min,Dudkina,Pukhovskaya,Semeikin,Golubchikov
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p. 133 - 136
(2007/10/03)
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- Tripyrrin - The missing link in the series of oligopyrrolic ligands
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The first derivative of the hitherto elusive tripyrrin 2 was prepared and characterized; the X-ray structural analysis of its trifluoracetato-palladium(II) complex 7 displays a highly flexible N3 ligand.
- Broering,Brandt
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p. 499 - 500
(2007/10/03)
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- Structure-stability relationships of phthalocyanine copper complexes
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The influence of NO2, Br, and COOH function substituents in various positions of Cu(II)Pc on the reactivity of the latter concerning the dissociation of the metal - nitrogen bonds in proton donor solvents is discussed.
- Sokolova,Lomova,Klueva,Suslova,Mayzlish,Shaposhnikov
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p. 775 - 785
(2007/10/03)
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- Kinetics of Complex Formation of Sterically Distorted Porphyrins with Copper Acetate in Pyridine and Dimethylformamide
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The kinetics of complex formation of octaethylporphine, 5-monophenyloctaethylporphyrin, 5,15-diphenyloctaethylporphyrin, 5,10,15,20-tetraphenyloctaethylporphyrin, and dodecaphenylporphyrin with copper acetate in pyridine and dimethylformamide was studied.
- Dudkina,Shatunov,Kuvshinova,Pukhovskaya,Semeikin,Golubchikov
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p. 1955 - 1960
(2007/10/03)
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- Synthesis and Crystal Structures of Cofacial Bisoctaethylchlorins as Structural Models for the Special Pair
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Covalently linked bistetrapyrrole systems can be used to mimic structurally the arrangement of the two special pair bacteriochlorophylls in the bacterial photosynthetic reaction center. Such models require a cofacial arrangement of the two tetrapyrrole units with some overlap of the π systems and intramolecular stabilization by aggregation of the two macrocycles. Using the McMurry reaction for the coupling of metallo formyloctaethylchlorins, covalently linked cofacial bischlorins were prepared and characterized by spectroscopy and single crystal X-ray crystallography. Coupling of Ni(II)5-formyloctaethylchlorin yielded a (Z)-ethene-bridged bischlorin with cofacial orientation of the subunits stabilized by intramolecular π-π interactions that structurally resembles the situation found for the special pair in bacterial reaction centers. In addition, two different atropisomers of the respective (E)-ethene-bridged bischlorin were formed. Use of Cu(II)5-formyloctaethylchlorin yielded similar products, however a crystal structure showed a (Z)-ethene-bridged bischlorin without intramolecular stabilization via aggregation effects. The bischlorins are easily oxidized to mixed chlorin-porphyrin species.
- Kalisch, Werner W.,Senge, Mathias O.,Ruhlandt-Senge, Karin
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p. 312 - 323
(2007/10/03)
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- Macrocycles containing five pyrrole subunits: The iso-oxopentaphyrin system
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Reaction of a 1,9-diformyl-5-dipyrroketone (11) with a tripyrrane (12) affords a novel pentapyrrolic macrocycle (13) characterized as an iso-oxopentaphyrin (λmax 787 nm). Along with the iso-oxopentaphyrin, small amounts of oxophlorin (20) and porphyrin (21) are also produced. Mechanistic implications are discussed.
- Khoury, Richard G.,Jaquinod, Laurent,Nguyen, Liem T.,Smith, Kevin M.
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p. 113 - 119
(2007/10/03)
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- A novel synthetic route to sapphyrins
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New methodology has been developed for the synthesis of so-called sapphyrins, pentapyrrolic 'expanded porphyrins'. An efficient approach involving acid-catalyzed condensation of 1,19-diunsubstituted a,c-biladienes and 3,4-dialkylpyrrole-2-carbaldehydes eliminates the preparation of bipyrrolic intermediates and allows the synthesis of sapphyrins with an unsymmetrical array of peripheral substituents. The β-substitution pattern of 2,3,13,17-tetraethyl-7,8,12,18,22,23-hexamethylsapphyrin has been unambiguously confirmed by single crystal X-ray crystallography. 1H NMR spectra of the dication salts of sapphyrins are strongly dependent upon the counterions, and the pattern of resonances observed in solution is related to the stacking interactions between the macrocycles.
- Paolesse, Roberto,Licoccia, Silvia,Spagnoli, Mariangela,Boschi, Tristano,Khoury, Richard G.,Smith, Kevin M.
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p. 5133 - 5137
(2007/10/03)
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- Metalloporphyrin mixed-valence π-cation radicals: Solution stability and properties
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Solution equilibria and optical spectra of several metallooctaethylporphyrin π-cation radicals have been examined in methylene chloride solution. The several π-cation radical species, [M(OEP.)]Y (M = Cu, Ni, Zn, Pd, or VO; Y = ClO4- or SbCl6-), are found to dimerize to form [M(OEP.)]22+. These dimeric species are characterized by the appearance of a new, strongly concentration-dependent near-infrared absorption band. This band is found in the region of 900-960 nm for all compounds except for the vanadyl complex which absorbs farther to the red at 1375 nm. The equilibrium constants for the dimerization reaction (2[M(OEP.)]+ (K(D)) [M(OEP.)]22+) have been evaluated from multiple-wavelength, concentration-dependent absorption data. Equimolar solutions of these π-cation radicals and their analogous neutral M(OEP) derivatives react to form new binuclear species, [M(OEP(./2)]2+, in which the single radical electron is delocalized over both porphyrin rings. These new species, for which we suggest the term 'mixed-valence' π-cation radical and which bear a formal relationship to the oxidized special pair of photosynthetic reaction centers, also display a near-infrared absorption band. The near-IR band is however distinctly different from that of the π-cation radical dimers. Equilibrium constants for the formation of these new species (M(OEP) + [M(OEP.)]+ (K(MV)) [M(OEP(./2)]2+), have also been determined. The values of K(MV) are 10-100-fold larger than the analogous dimerization constant K(D). Values of ΔH and ΔS have been obtained for both equilibrium processes. The variations in K(MV) and K(D) values are largely the consequence of entropy differences that probably result from a much stronger solvation of the π-cation radical compared to the neutral porphyrin.
- Brancato-Buentello, Kristin E.,Kang, Seong-Joo,Scheidt, W. Robert
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p. 2839 - 2846
(2007/10/03)
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- Synthesis of meso-13C and 15N labelled octaethylporphyrin and optimisation of the 'symmetrical' route to octaalkylporphyrins
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A simplified synthesis of octaalkylporphyrins from aldehydes is described and was used to prepare meso-13C and 15N labelled octaethylporphyrin.
- Rohrer,Ocampo,Callot
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p. 923 - 925
(2007/10/02)
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- Nonionic superbase-promoted synthesis of oxazoles and pyrroles: Facile synthesis of porphyrins and α-C-acyl amino acid esters
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The reaction of acyl chlorides or acid anhydrides with isocyanoacetates in the presence of the superior strong nonionic base P(MeNCH2CH2)3N (1) gave oxazoles in 98-99% yield. Treatment of the oxazoles with HCl-MeOH gave α-
- Tang,Verkade
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p. 7793 - 7802
(2007/10/02)
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- Porphyrin synthesis from nitrocompounds
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A new porphyrin synthesis starting from nitroalkenes or their equivalents is described. For example, octaethylporphyrin, coproporphyrin, porphyrin-1,2,3,4,5,6,7,8 octapropionic acid, and 2,7,12,17 tetraarylporphyrin are prepared in good yield from readily available materials such as 1-nitropropane, nitroethane, nitromethane, and aldehydes.
- Ono, Noboru,Kawamura, Hisayuki,Bougauchi, Masahiro,Maruyama, Kazuhiro
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p. 7483 - 7496
(2007/10/02)
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- An Improved Method for the Preparation of Symmetrically Substituted Porphyrins via 2-Methoxymethyl-3,4-disubstituted Pyrrole Derivatives
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2-Methoxymethylpyrrole derivatives readily available from 2-methylthiomethylpyrroles were found to be readily cyclized to porphyrinogens with formic acid, and subsequent oxidation with O2 affords the corresponding porphyrins in excellent yields.
- Kinoshita, Hideki,Tanaka, Shingo,Inomata, Katsuhiko
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p. 1107 - 1108
(2007/10/02)
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- Synthesis of Octaalkyl- and Octaarylporphyrins from Nitroalkenes
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Symmetrically substituted octaalkyl- and octaarylporphyrins are readily prepared by the reduction of 2-ethoxycarbonyl-3,4-dialkyl (or diaryl)pyrroles with LiAlH4 followed by treatment with acetic acid and oxidizing agents.
- Ono, Noboru,Maruyama, Kazuhiro
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p. 1511 - 1514
(2007/10/02)
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- Molecular Fossils of Chlorophyll c of the 17-nor-DPEP Series. Structure Determination, Synthesis, Geochemical Significance.
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Two porphyrins 1 and 2, having totally (1) or partially (2) lost the C-17 substituent, have been isolated from two Moroccan oil shales of Cretaceous age.An origin from chlorophyll c, which possesses a 17-acrylic side-chain, can explain this transformation.A synthesis of 1 from chlorophyll (a+b) is described.Porphyrin 1 is widely distributed in sediments and its relative abundance with regard to other molecular fossils of chlorophyll c is discussed briefly.
- Verne-Mismer, J.,Ocampo, R.,Callot, H. J.,Albrecht, P.
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p. 371 - 374
(2007/10/02)
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- meso-Reactivity of Porphyrins and Related Compounds. Part 9. Photo-oxygenation of Octaethyloxophlorin
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The photo-oxygenation of octaethyloxophlorin has been investigated under basic and under neutral conditions.In both cases unstable intermediate stages are observed spectroscopically.In methanolic sodium methoxide the solution becomes bleached and tetraethyl(methanol)propentdyopent is a significant product.In neutral solutions (e.g. benzene-methanol) the major products are octaethyl-5,15-dioxo-5,15-dihydroporphyrin (4) and octaethyl-19-formyl-21H,24H-bilin-1,15-dione (7), the formation of octaethyl-21H,24H-bilin-1,19-dione (6) being a minor pathway.A mechanistic rationalisation is proposed.
- Bonnett, Raymond,Chaney, Brian D.
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p. 1063 - 1068
(2007/10/02)
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- The Preparation and Reactions of Porphyrin N-Oxides
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The reaction of octaethylporphyrin with hypofluorous acid and with permaleic acid gives a mono-oxygen adduct formulated as the porphyrin N-oxide, a novel chemical system.Octaethylporphyrin N-oxide is a sensitive molecule: it is gradually converted into octaethylporphyrin when manipulated under ordinary conditions.Examples of deoxygenation, nucleophilic attack at C-5, and metal complexation are described.
- Andrews, Laura E.,Bonnett, Raymond,Ridge, Richard J.,Appelman, Evan H.
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p. 103 - 107
(2007/10/02)
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- Synthesis and cyanation of octaalkylporphyrins using electrochemical methods
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The total synthesis of octaalkylporphyrins (ethyl, buthyl, isopropyl) and the cyanation of the meso (methine bridge) positions have been achieved using electrochemical methods.The coupled products (diketals) from anodic oxidation of aldehydes enol ethers (or enamines) in methanol, on subsequent reaction with benzyl carbamate undergo cyclisation to N-carbobenzyloxypyrroles.Deprotection and reaction with formaldehyde afforded the corresponding porphyrins.Electrolysis of zinc-octaethylporphyrin in dimethylformamide in the presence of cyanide at various concentrations and potentials (+0.45 to 0.9 V/SCE) gave mono- to tetracyano-octaethylporphyrins which were fully caracterized.
- Callot, Henry J.,Louati, Abderrazak,Gross, Maurice
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p. 317 - 320
(2007/10/02)
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- Chemistry of Pyrrolic Compounds. XLVIII. The Chemistry of Porphyrins Carrying Sulfur-Containing Substituents at a meso-Carbon
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The preparation of a meso-thioacetoxyporphyrin by ring synthesis from a dipyrrylthione is described together with the reaction of thiocyanogen with octaethylporphyrin and coproporphyrin II to give meso-thiocyanatoporphyrins.Attempts to produce meso-mercaptoporphyrins by hydrolysis of either meso-thioacetoxy- or meso-thiocyanato-porphyrins failed.Instead the corresponding disulfides were produced and the properties of this latter group are described.
- Clezy, Peter S.,Fookes, Christopher J. R.,Smythe, George A.
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p. 2595 - 2606
(2007/10/02)
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- Der Einbau von Magnesium in Liganden der Chlorophyll-Reihe mit (2,6-Di-t-butyl-4-methylphenoxy)magnesiumjodid
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Experimental details are given for the new method of introducing magnesium into porhpinoid ligands by (2,6-di-t-butyl-4-methylphenoxy)magnesium iodide (1), previously published in preliminary form .Besides magnesium octaethylporphyrinate (14), methyl pyrochlorophyllide a (10), methyl chlorophyllide a (8), and methyl bacteriochlorophyllide a (12), the complexation of pheophytin a (2) to chlorophyll a (3) and of pheophytin b (4) to chlorophyll b (5) are described.
- Zass, Engelbert,Isenring, Hans Peter,Etter, Rolf,Eschenmoser, Albert
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p. 1048 - 1067
(2007/10/02)
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