Demetalation of Metal Porphyrins via Magnesium Porphyrins by Reaction with Grignard Reagents

Murakami, Kei; Yamamoto, Yoshimi; Yorimitsu, Hideki; Osuka, Atsuhiro

doi:10.1002/chem.201301146

Cited by 34 publications

(35 citation statements)

References 59 publications

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“…Free bases of TADAP derivatives (H 2 TADAPs) were not afforded by the acidolysis of zinc(II) complexes 2Zn and 3Zn,w hich remained intact after prolonged treatment with CF 3 CO 2 H. Therefore, we used the Yorimitsu-Osuka procedure fort he two-step transformation of metalloporphyrins into free bases via magnesium(II) porphyrins: [22] step one was exchange of the central metal from Ni/Zn/Cu/Ag to Mg by treatment with a Grignardr eagent, and step two was acidolysis. Under our optimized reaction conditions, we obtained H 2 TADAP from ZnTA-DAP 2Zn-a in am oderate yield (Scheme 4).…”

Section: Synthesismentioning

confidence: 99%

Syntheses, Properties, and Catalytic Activities of Metal(II) Complexes and Free Bases of Redox‐Switchable 20π, 19π, and 18π 5,10,15,20‐Tetraaryl‐5,15‐diazaporphyrinoids

Sudoh

Satoh

Amaya

et al. 2017

Chemistry A European J

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In spite of significant advances in redox-active porphyrin-based materials and catalysts, little attention has been paid to 20π and 19π porphyrins because of their instability in air. Here we report the meso-modification of 5,10,15,20-tetraarylporphyrin with two nitrogen atoms, which led to redox-switchable 20π, 19π, and 18π 5,10,15,20-tetraaryl-5,15-diazaporphyrinoids (TADAPs). Three kinds of metal(II) complexes and free bases of TADAP were prepared by the metal-templated annulation of the corresponding metal-bis(dipyrrin) complexes. The inductive and resonance effects of the meso-nitrogen atoms on the aromatic, optical, electrochemical, and magnetic properties of the entire TADAP π-systems were assessed by using various spectroscopic measurements and density functional theory calculations. The aromaticity and π-π* electronic transition energies of the TADAPs varied considerably, and were shown to be dependent on the oxidation states of the π-systems. In contrast to the isoelectronic 5,10,15,20-tetraarylporphyrin derivatives, the 20π and 19π TADAPs were chemically stable under air. In particular, the 19π TADAP radical cations were extremely stable towards dioxygen, moisture, and silica gel. This reflected the low-lying singly occupied molecular orbitals of their π-systems and the efficient delocalization of their unshared electron spin. The capability of MgTADAP to catalyze aerobic biaryl formation from aryl Grignard reagents was demonstrated, which presumably involved a 19π/20π redox cycle.

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Section: Synthesismentioning

confidence: 99%

Syntheses, Properties, and Catalytic Activities of Metal(II) Complexes and Free Bases of Redox‐Switchable 20π, 19π, and 18π 5,10,15,20‐Tetraaryl‐5,15‐diazaporphyrinoids

Sudoh

Satoh

Amaya

et al. 2017

Chemistry A European J

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“…Treatment of 1Ni and 2Ni with p-tolylmagnesium bromide in toluene afforded the corresponding free-base diporphyrins 1H 2 and 2H 2 in 87 %a nd 81 %y ields, respectively (Scheme1). [10] Subsequentm etallation of these free-base diporphyrins with Zn(OAc) 2 ·2 H 2 Of urnished Zn II diporphyrins 1Zn and 2Zn.O n the other hand, treatment of 3Ni (Ar = 4-tolyl) with H 2 SO 4 in TFAp rovided free-base 3H 2 in good yield. Because of its low solubility, 3H 2 was converted to 3Zn withoutf urtherp urification.…”

Section: Resultsmentioning

confidence: 99%

“…The CD spectra were measured in a1cm quartz cell on aJ ASCO J-820 spectropolarimeter.M ass spectra were recorded on aB ruker micro-TOF mass spectrometer using the positive mode ESI-TOF or APCI-TOF method for acetonitrile solutions. To the solution, 4-methylphenylmagnesium bromide [10] (1.0 mL, 1.36 mmol, 1.36 m THF solution) was added. Synthesis of 1H 2 :Atwo-necked flask containing nickel diporphyrin 1Ni [4] (170.8 mg, 0.100 mmol) was evacuated and then refilled with N 2 .T ot he flask, 20 mL of dry and degassed toluene was added.…”

Section: Methodsmentioning

confidence: 99%

Control of Conformation and Chirality of Nonplanar π‐Conjugated Diporphyrins Using Substituents and Axial Ligands

Ito

Hiroto

Ousaka

et al. 2016

Chemistry An Asian Journal

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Nonplanar conformations of pyrazine-fused Zn(II) diporphyrins could be controlled by the choice of the meso-aryl substituents and an axial ligand on the central metals. Zn(II) diporphyrins bearing sterically demanding meso-aryl groups with ortho-substituents led to a twisted chiral D2 conformation, while an achiral C2h form was preferred in the case of aryl groups without ortho-substituents. Helical chirality induction on Zn(II) diporphyrins in the twisted conformation was achieved by controlling their handedness of the molecular twist through coordination of optically active 1-phenethylamine.

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“…Synthesis of third-generation porphyrins, which contain halogen atoms at the b-pyrrolic positions have been previously reported [10]. Electron withdrawing groups such as cyano or bromo groups at the b-pyrrolic positions cause an anodic shift in the ring oxidation and reduction potentials of the porphyrins [11][12][13][14].…”

Section: Introductionmentioning

confidence: 99%

Synthesis of Ag(II) 2,3,7,8,12,13,17,18-octabromo-5,10,15,20-tetraphenylporphyrin and its facile demetalation to 2,3,7,8,12,13,17,18-octabromo-5,10,15,20-tetraphenylporphyrin

Ravindran

Pennathur

Devi

et al. 2016

J. Porphyrins Phthalocyanines

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Synthesis of Ag(II) 2,3,7,8,12,13,17,18-octabromo-5,10,15,20tetraphenylporphyrin and its facile demetalation to 2,ABSTRACT: A novel one-step strategy for the synthesis of 2, 3,7,8,12,13,17,18-octabromo-5,10,15,20tetraphenylporphyrin using Ag II OBP is described. Ag II OBP was synthesized and was. Bromination of Ag II TPP was carried out in a one-step reaction by varying the subsequently demetalated using H 2 S time interval and stoichiometric addition of Br 2 . The molecular weight of the halogenated porphyrin was confirmed by MALDI-TOF mass spectrometry. The synthesis of Ag(II) 2, 3,7,8,12,13,17,18-octabromo-5,10,15,20-tetraphenylporphyrin was followed by demetalation of Ag(II) ion from the halogenated porphyrin. The demetalation of was carried out under mild conditions using sodium sulphide in trifluoroacetic acid. The time taken for the demetalation was considerably lesser than previously reported and which facilitated a simple way for the isolation of the final product in good yield. The yield of the free base was 98%. The formation of the product and purity was confirmed by 1 H NMR, Mass spectrometry. UV-visible spectrophotometer clearly showed the appearance of a characteristic Q-band of the octa-brominated porphyrin.

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Demetalation of Metal Porphyrins via Magnesium Porphyrins by Reaction with Grignard Reagents

Cited by 34 publications

References 59 publications

Syntheses, Properties, and Catalytic Activities of Metal(II) Complexes and Free Bases of Redox‐Switchable 20π, 19π, and 18π 5,10,15,20‐Tetraaryl‐5,15‐diazaporphyrinoids

Syntheses, Properties, and Catalytic Activities of Metal(II) Complexes and Free Bases of Redox‐Switchable 20π, 19π, and 18π 5,10,15,20‐Tetraaryl‐5,15‐diazaporphyrinoids

Control of Conformation and Chirality of Nonplanar π‐Conjugated Diporphyrins Using Substituents and Axial Ligands

Synthesis of Ag(II) 2,3,7,8,12,13,17,18-octabromo-5,10,15,20-tetraphenylporphyrin and its facile demetalation to 2,3,7,8,12,13,17,18-octabromo-5,10,15,20-tetraphenylporphyrin

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