Synthesis of the hemin of β-tetrakis(trifluoromethyl)-meso-tetraphenylporphyrin and its evaluation as a P-450 mimic

Terazono, Yuichi; Dolphin, David

doi:10.1016/s0020-1693(02)01389-0

Cited by 9 publications

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“…During our ongoing efforts in synthesis and application of perfluoroalkylated porphyrins, a facile and effective synthesis of the isophlorin 2 was achieved with the accidental discovery of a ready reduction of Cu(II) β-tetrakis(trifluoromethyl)- meso -tetraphenylporphyrin ( Cu1 ) . When adding activated zinc powder into a DMSO solution of Cu1 at room temperature under nitrogen, the color of the contents changed form green to brown after 1 h. TLC indicated almost complete consumption of the starting porphyrin and formation of a main orange product 2 .…”

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confidence: 99%

Synthesis and Reactions of 20 π-Electron β-Tetrakis(trifluoromethyl)-meso-tetraphenylporphyrins

2007

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Porphyrin and their analogues usually have a stable aromatic (4n + 2) π-electron system. Porphyrin itself shows aromatic behavior with an 18 π-electron main conjugation pathway in the molecule and has been intensively investigated. 1 However, porphyrin derivatives with 4n π-electron delocation pathways have been little explored owing to their synthetic difficulty, 2,3 and the majority of them are expanded porphyrins 3 because the difference between resonance stabilization energies of 4n and (4n + 2) π-electron systems decreases for larger values of n. 4 To the best of our knowledge, the synthesis of 20 π-electron N,N′-dihydroporphryin (isophlorin) B, referred to for the first time by Woodward during the synthesis of chlorophyll about half a century ago, 5 has represented a challenge for porphyrin chemistry and remained elusive thus far because of its intensive tendency to undergo a twoelectron oxidation and deprotonation to form its corresponding 18 π-electron aromatic porphyrin A.(Scheme 1) Herein, we report the isolation and structural characterization of the 20 π-electron nonaromatic isophlorin 2 and its N-methylation reactions.During our ongoing efforts in synthesis and application of perfluoroalkylated porphyrins, 6 a facile and effective synthesis of the isophlorin 2 was achieved with the accidental discovery of a ready reduction of Cu(II) -tetrakis(trifluoromethyl)-meso-tetraphenylporphyrin (Cu1). 7 When adding activated zinc powder into a DMSO solution of Cu1 at room temperature under nitrogen, the color of the contents changed form green to brown after 1 h. TLC indicated almost complete consumption of the starting porphyrin and formation of a main orange product 2. (Scheme 2) It was relatively air stable 8 to be successfully isolated and thoroughly characterized, although being easily reoxidated to free-base -tetrakis(trifluoromethyl)-meso-tetraphenylporphyrin (H 2 1) with 2,6-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ).X-ray crystal diffraction analysis of 2 ( Figure 1) elucidated that it was a 20 π-electron isophlorin with a highly distorted skeleton that displays a nonplanar saddle conformation. 9 The average displacement for the -carbons from the least-squares plane of the meso-carbon atoms, which can be used to evaluate the magnitude of distortion in the macrocycle, was 1.36 Å for 2 in contrast with 0.89 Å for Cu1. 8 It is also a manifestation of serious distortion of the macrocycle that the pyrrole rings with trifluoromethyl groups and pyrroline rings without trifluoromethyl groups are titled on average by 69.7°and 33.5°, respectively, out of the least-squares plane. The remarkably strong twisting of the pyrrole units might be attributed to considerable steric congestion present between meso and substituents, as well as NH-hydrogen atoms. In addition, an expected feature exhibited in the structure of 2 is that clear C-C bond-length alternation is observed around the macrocycle periphery, which dramatically contrasts with its corresponding 18 π-electron aromatic porphyrin Cu1. 8 Spectroscopic data ...

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Synthesis and Reactions of 20 π-Electron β-Tetrakis(trifluoromethyl)-meso-tetraphenylporphyrins

2007

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“…The Fe III /Fe II redox potential of the hemin [ 58(FeCl) ] (0.05 V vs. SCE in PhCN) is similar to that of the complex [(β‐Cl 8 TDCPP)FeCl] (0.10 V) and positively shifted from the value of –0.32 V for [(TPP)FeCl]. Nevertheless, this positive shift alone appeared to be insufficient to improve the catalytic ability of the hemin 64c…”

Section: β‐(Perfluoroalkyl)porphyrinsmentioning

confidence: 92%

“…The yield of 58 was improved by up to about 40 % by increasing the reaction temperature. The zinc(II) complex [ 58(Zn) ] was obtained from the free‐base by a standard procedure64a while preparation of the hemin [ 58(FeCl) ] required a special procedure (see below) 64c. The electronic structure of the antipodal, partially β‐trifluoromethylated TPPs was shown to display intriguing features.…”

Section: β‐(Perfluoroalkyl)porphyrinsmentioning

confidence: 99%

“…Moreover, the selectivity of norbornene oxidations with the same oxidant was not seriously affected by the electron‐deficiency of the central metal of the trifluoromethylated porphyrin 67. More recently, an evaluation of the related hemin [ 58(FeCl) ] as an oxidation catalyst was made 64c. Insertion of iron into the macrocycle of the free‐base 58 to give the hemin [{β‐(CF 3 ) 4 TPP}FeCl] [ 58(FeCl) ] required the formation of the lithium complex, from lithium bis(trimethylsilyl)amide, followed by treatment with ferrous chloride.…”

Section: β‐(Perfluoroalkyl)porphyrinsmentioning

confidence: 99%

“…A comparison of its performances with that of the complexes [(β‐Br 4 TPP)FeCl] [ 57(FeCl) ] and [(β‐Cl 8 TDCPP)FeCl] showed a comparable activity in the oxidation of cyclohexene but the catalysts [ 57(FeCl) ] and [ 58(FeCl) ] were destroyed during the oxidation of cyclohexane giving low yields of cyclohexanol and low turnovers. Thus, the hemin [ 58(FeCl) ], in spite of its electron‐deficient nature, was found to be ineffective as an oxidation catalyst 64c…”

Section: β‐(Perfluoroalkyl)porphyrinsmentioning

confidence: 99%

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β‐Fluorinated Porphyrins and Related Compounds: An Overview

Leroy

Bondon

2008

Eur J Org Chem

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Apart from a few examples, β‐(poly)fluorinated and β‐(poly)perfluoroalkylated porphyrins were practically unknownuntil recently. In particular, β‐octafluoro‐meso‐tetraarylporphyrins remained elusive ligands owing to the lack of any convenient access. The aim of this microreview is to highlight recent progress in the synthesis and characterization of β‐fluoroporphyrins and β‐(perfluoroalkyl)porphyrins, two new classes of so‐called electron‐deficient porphyrins. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)

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Iron Porphyrin Chemistry

Walker¹,

Simonis²

2005

Encyclopedia of Inorganic Chemistry

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This article reviews most aspects of the chemistry of iron porphyrins, from Fe(0) to Fe(V), including occurrence and roles of natural iron porphyrins (hemes) and their synthetic analogs, structures and electron configurations of iron porphyrins of all oxidation and spin states, π electron configuration of the porphyrin ring, synthesis of metal‐free porphyrins and other related macrocycles, insertion of iron into free‐base porphyrins and related macrocycles, the properties, reactions, uses and biological relevance of iron(0), ‐(I), ‐(II) porphyrins (the latter with S = 0, 1, and 2 spin state possibilities), of iron(II) porphyrin π‐cation radicals, of iron(III) porphyrins (with S = 1/2, 3/2, and 5/2 spin state possibilities), of iron(III) porphyrin and corrole π‐cation radicals, of iron(IV) porphyrins (including five‐ and six‐coordinate ferryl (FeO) 2+ , iron(IV) phenyl, carbene and hydrazine complexes, and the bis‐methoxide complex) and a comparison of iron(IV) porphyrins to iron(III) porphyrin π‐cation radicals, of iron(IV) porphyrin π‐cation radicals, and of the possible existence of iron(V) porphyrins. Included in the Fe(II) part are sections on addition of ligands to four‐coordinate iron(II) porphyrins, including equilibrium binding constants, photodissociation of ligands from PFeL 2 complexes, binding of small molecules (O 2 , CO, NO, HNO) to 5‐coordinate iron(II) porphyrins and design of porphyrin ligands that will mimic the active sites of heme proteins such as myoglobin and hemoglobin, the cytochromes P450 and nitric oxide synthases, and the nitrophorins and guanylyl cyclases. Included in the iron(III) part are sections on both 5‐ and 6‐coordinate high‐spin complexes and their similarities and differences, bridged or through‐space magnetically coupled complexes of high‐spin iron(III) porphyrins with other metal complexes as possible models for cytochrome oxidase and the assimilatory sulfite reductases, coupled oxidation of hemes by hydrogen peroxide or its equivalent, and the relationship of this reactivity to the reactions of heme oxygenase, iron(III) porphyrins as reduction catalysts, and photochemistry of iron(III) porphyrins, possible electron configurations of low‐spin iron(III) porphyrins, the phenomenon and possible electronic consequences of ruffling of the porphinato core in iron(III) porphyrins, the preferred orientation of planar axial ligands bound to low‐spin iron(III) porphyrins, NO complexes of iron(III) porphyrins, reduction potentials, equilibrium constants and rates of axial‐ligand addition and exchange, kinetics of axial‐ligand rotation and porphyrin ring inversion, kinetics of reduction and autoreduction of iron(III) porphyrins, electron self‐exchange between low‐spin iron(III) and iron(II) porphyrins, synthetic ferriheme proteins, and synthesis of five‐coordinate low‐spin iron(III) porphyrins having σ‐alkyl or σ‐aryl groups as axial ligands. The iron(IV) and iron(IV) cation radical sections discuss the high‐valent states of cytochromes P450 and related enzymes.

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Synthesis of the hemin of β-tetrakis(trifluoromethyl)-meso-tetraphenylporphyrin and its evaluation as a P-450 mimic

Cited by 9 publications

References 13 publications

Synthesis and Reactions of 20 π-Electron β-Tetrakis(trifluoromethyl)-meso-tetraphenylporphyrins

Synthesis and Reactions of 20 π-Electron β-Tetrakis(trifluoromethyl)-meso-tetraphenylporphyrins

β‐Fluorinated Porphyrins and Related Compounds: An Overview

Iron Porphyrin Chemistry

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