- Investigation of cocatalysis conditions using an automated microscale multireactor workstation: Synthesis of meso-tetramesitylporphyrin
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Prior manual work has shown that the condensation of mesitaldehyde and pyrrole leading to tetramesitylporphyrin depends sensitively on concentration and requires cocatalysis involving BF3·O(Et)2 and ethanol or other protic species. W
- Wagner, Richard W.,Li, Feirong,Du, Hai,Lindsey, Jonathan S.
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Read Online
- AN IMPROVED SYNTHESIS OF TETRAMESITYLPORPHYRIN
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We report a simple two-step one-flask procedure for the synthesis of tetramesitylporphyrin in 29 percent yield.Pyrrole and mesitaldehyde react at room temperature to form tetramesitylporphyrinogen.The addition of an oxidant yields the porphyrin.Macrocycle formation and oxidative aromatization are thus performed separately.The reaction at higher temperature results in a lower yield of porphyrin.
- Wagner, Richard W.,Lawrence, David S.,Lindsey, Jonathan S.
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Read Online
- Extending mechanochemical porphyrin synthesis to bulkier aromatics: Tetramesitylporphyrin
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Aldehydes with bulky substituents in the ortho-positions have been historically difficult in porphyrin synthesis, presumably owing to steric hindrance around the reactive site. We have used mechanochemistry for the simple, room-temperature synthesis of te
- Su, Qiwen,Hamilton, Tamara D.
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Read Online
- Significant Solvent Effect on Reactivity of Oxoiron(IV) Porphyrin π-Cation Radical Complex: Activation in n-Alkane Solvent
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The solvent effect on the reactivity of high-valent metal oxo complexes has not been studied well, because of their solubility and stability. We synthesize oxoiron(IV) porphyrin π-cation radical complexes (1-CompI and 2-CompI) having the n-hexyl side chains. 1-CompI and 2-CompI are soluble in various solvents, even in hexane, at -80 °C, allowing for the study of their reactivity in various organic solvents. We show that pentane, hexane, heptane, and tert-butyl methyl ether significantly increase the reactivity of 1-CompI and 2-CompI, but dichloromethane, the most frequently used solvent in previous studies, is the worst for increasing the reactivity among the solvents. 1H NMR and EPR spectroscopies show no significant change in hexane, but the Eyring plots for the epoxidation reactions indicate that the entropies of activation in n-alkane solvents are larger than those in dichloromethane. The observed solvent effect can be rationalized with reorganization energy of the solvent in the reaction.
- Ueno, Kanako,Ishimizu, Yuri,Fujii, Hiroshi
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supporting information
p. 9243 - 9247
(2021/06/30)
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- Oxidative Cyclodehydrogenation Reactions with Tetraarylporphyrins
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The extension of the aromatic π-system of porphyrins is a powerful method to alter their optoelectronic properties. Herein, aryl substituents were fused to porphyrin cores by Scholl oxidation reactions that selectively produced mono- and doubly-fused porphyrins in yields of up to 69 %. Several different aryl substituents attached to the porphyrin were investigated with respect to their reactivity under Scholl conditions. The fused products were fully characterized, i.e., by UV/Vis absorption spectroscopy, which showed drastic changes in the electronic features. Insight into the solid-state behavior was obtained by X-ray crystallography. Our approach represents a novel option for the late-stage functionalization of porphyrin-based compounds.
- Hampel, Frank,Jux, Norbert,Martin, Max M.,Oleszak, Christoph
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supporting information
p. 6758 - 6762
(2020/11/23)
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- Effects of porphyrin deformation on the 13 C and 1H NMR chemical shifts in high-spin five-and six-coordinate manganese(III) porphyrin complexes
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As an extension of our study to reveal the effect of porphyrin deformation on the 13C and 1H NMR chemical shifts, both five-and six-coordinate high-spin (S = 2) Mn(III) complexes such as Mn(Por)Cl and [Mn(Por)(CD3OD)2]Cl h
- Ikezaki, Akira,Nakamura, Mikio
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p. 318 - 330
(2016/07/07)
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- Click reaction synthesis and photophysical studies of dendritic metalloporphyrins
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Several dendritic zinc(II)-porphyrins bearing carbazole units at the terminals have been prepared through click reaction of azide-substituted Zn-porphyrin precursors and carbazole-based alkynes under [Cu(NCCH 3)4][PF6] cat
- Nguyen, Nguyen Tran,Hofkens, Johan,Scheblykin, Ivan G.,Kruk, Mikalai,Dehaen, Wim
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p. 1766 - 1777
(2014/03/21)
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- Sulfonated graphenes catalyzed synthesis of expanded porphyrins and their supramolecular interactions with pristine graphene
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A newer synthesis of sulfonic acid functionalized graphenes have been developed, which have been characterized, examined as heterogeneous solid acid carbocatalyst in the synthesis of selected expanded porphyrins in different reaction conditions. This envi
- Mishra, Sweta,Arora, Smriti,Nagpal, Ritika,Chauhan, Shive Murat Singh
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p. 1729 - 1736
(2015/02/05)
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- Palladium porphyrin catalyzed hydrogenation of alkynes: Stereoselective synthesis of cis -alkenes
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(Tetraphenylporphyrin)palladium was developed as a catalyst for the chemoselective and stereoselective hydrogenation of alkynes to cis-alkenes by the syn-addition of hydrogen. Alkynes containing various functional groups were tolerated in the reaction, which gave the corresponding cis-alkenes in good to excellent yields. Georg Thieme Verlag Stuttgart New York.
- Nishibayashi, Ryo,Kurahashi, Takuya,Matsubara, Seijiro
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supporting information
p. 1287 - 1290
(2014/06/10)
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- Highly efficient conversion of aldehydes to carboxylic acid in the presence of platinum porphyrin sensitizers, air and sunlight
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A variety of aromatic and aliphatic aldehydes were oxidized to the corresponding carboxylic acids in the presence of platinum porphyrin, sunlight and air in acetonitrile solvent under mild conditions. Nitrobenzaldehydes were found to be very efficient 1O2 scavengers that quench the formation of acids from any aldehyde in the presence of free-base porphyrin sensitizers. However, nitrobenzaldehydes were converted to the corresponding acids in the presence of platinum porphyrins. The platinum porphyrins are very good and efficient catalysts for a wide range of applications in the aerobic conversion of aldehydes to acids.
- Hajimohammadi, Mahdi,Mofakham, Hamid,Safari, Nasser,Manesh, Anahita Mortazavi
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experimental part
p. 93 - 100
(2012/07/17)
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- Naphthalene-fused metallo-porphyrins-synthesis and spectroscopy
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Oxidative aromatic coupling of meso-substituted porphyrins bearing one electron-rich naphthalene unit has been studied in detail. After thorough optimization of oxidant, naphthalene-fused porphyrins were prepared in high yield without contamination from c
- Lewtak, Jan P.,Gryko, Dorota,Bao, Duoduo,Sebai, Ernest,Vakuliuk, Olena,Scigaj, Mateusz,Gryko, Daniel T.
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supporting information; experimental part
p. 8178 - 8181
(2012/01/04)
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- METHODS AND COMPOSITIONS COMPRISING MACROCYCLES
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The present invention relates generally to methods and compositions comprising macrocycles. In some embodiments, the present invention provides methods for modifying macrocycles comprising a pendant group. In some cases, the pendent group comprises a hydrolyzable group. The present invention also provides methods for metallating a macrocycle using microwave energy, in some embodiments.
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Page/Page column 13
(2011/06/26)
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- Towards the synthesis of substituted porphyrins by a pyridyl group bearing a reactive functionality
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Pyridyl-substituted porphyrins bearing a reactive functionality were prepared via Suzuki cross-coupling reactions and resulted in very good yields. These compounds are precursors of new porphyrin architectures able to coordinate two metals: one in the porphyrin core and the second around the pyridyl moiety. During the coupling reactions, a higher reactivity of a chloro picolyl group was evidenced compared to a bromo function on the same reacting molecule.
- Ojaimi, Maya El,Habermeyer, Benoit,Gros, Claude P.,Barbe, Jean-Michel
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experimental part
p. 469 - 480
(2011/03/20)
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- Controlled porphyrinogen oxidation for the selective synthesis of meso-tetraarylchlorins
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Chlorins have been synthesized through the reduction of the corresponding porphyrins although theoretically they can be obtained from reduced macrocycle forms as porphyrinogens. A new method for the oxidation of meso- tetraarylporphyrinogens was developed generating a substantial amount of chlorin relatively to porphyrin. The structure of the porphyrinogen, particularly the presence of substituents on the meso-phenyl groups, is decisive for the final yield of chlorin. In the case of meso-tetrakis(2,6-dichlorophenyl)porphyrinogen, 92% of the corresponding chlorin is obtained.
- Serra, Arménio C.,Rocha Gonsalves, António M.D'A.
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supporting information; experimental part
p. 4192 - 4194
(2010/09/12)
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- Efficient synthesis of hangman porphyrins
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Chemical equation presented A two-step synthetic method has been designed to furnish hangman porphyrins In good yields from easily available starting materials. The use of the microwave Irradiation technique has been found to be valuable for delivering the car boxy lie acid hanging group in a much simplified and less time-consuming basic ester hydrolysis (4 h vs 7 days under harsh acidic conditions). The new route facilitates the synthesis of various hangman porphyrins that previously had limited or no access.
- Dogutan, Dilek K.,Kwabena Bediako,Teets, Thomas S.,Schwalbe, Matthias,Nocera, Daniel G.
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supporting information; experimental part
p. 1036 - 1039
(2010/06/15)
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- PROCESSES FOR THE PREPARATION OF ARTEMISININ AN ITS PRECURSORS
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The present invention provides processes for the preparation of artemisinin and its precursors including amorphadiene, amorphadiene epoxide, dihydroartemisinic alcohol and dihydroartemisinic acid. Specifically, artemisinin is prepared by multi-step synthetic processes from amorphadiene, amorphadiene epoxide, dihydroartemisinic alcohol or dihydroartemisinic acid. Processes for the preparation of amorphadiene, amorphadiene epoxide, dihydroartemisinic alcohol and dihydroartemisinic acid are also disclosed.
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Page/Page column 37
(2009/09/04)
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- Meso-13C-labeled porphyrins for studies of ground-state hole transfer in multiporphyrin arrays
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(Chemical Equation Presented) Understanding electronic communication among interacting chromophores provides the foundation for a variety of applications. The ground-state electronic communication in diphenylethyne-linked zinc-porphyrin dyads has been investigated by a novel molecular design strategy that entails introduction of a 13C-atom (*) at specific sites of the porphyrins where there is substantial electron density in the relevant frontier (highest occupied) molecular orbital. The site of 13C substitution is at a meso-position, either the site of attachment of the linker (proximal, "P") or the site trans to the linker (distal, "D"). The substituents (R) at the non-linking meso-positions are mesityl, tridec-7-yl ("swallowtail"), or p-tolyl groups. Altogether five isotopically labeled porphyrin dyads have been prepared. The hole/electron-transfer properties of one-electron oxidized dyads have been examined by electron paramagnetic resonance (EPR) spectroscopy. The introduction of the meso-13C label provides a "clock" (via the hyperfine interactions) that allows investigation of a time scale for hole transfer that is 3-4 times shorter than that provided by the natural abundance 14N nuclei of the pyrrole nitrogen atoms. The EPR studies indicate that the hole transfer, which has been previously shown to be fast on the time scale of the 14N hyperfine clock (~220 ns), remains fast on the time scale of the 13C hyperfine clock (~50 ns).
- Thamyongkit, Patchanita,Muresan, Ana Z.,Diers, James R.,Holten, Dewey,Bocian, David F.,Lindsey, Jonathan S.
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p. 5207 - 5217
(2008/02/08)
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- Novel synthesis of meso-tetraarylporphyrins using CF3SO 2Cl under aerobic oxidation
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meso-Tetraarylporphyrins are synthesized from pyrrole and aryl aldehydes cleanly and efficiently in one pot at room temperature using equimolar amount of CF3SO2Cl in the presence of air as oxidant. By this novel method 5,10,15,20-tetraarylporphyrins can be prepared in excellent yields.
- Sharghi, Hashem,Nejad, Alireza Hassani
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p. 1863 - 1868
(2007/10/03)
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- Effects of aldehyde or dipyrromethane substituents on the reaction course leading to meso-substituted porphyrins
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To better understand the effects of diverse substituents on reactions leading to porphyrins, pyrrole+aldehyde condensations and related reactions of dipyrromethanes were examined. The course of pyrrole+aldehyde condensations was investigated by monitoring the yield of porphyrin (by UV-Vis spectroscopy), reaction of aldehyde (by TLC), and changes in the composition of oligomers (by laser desorption mass spectrometry). Reaction reversibility was examined via exchange experiments. Reversibility of reactions leading to porphyrin was further probed with studies of dipyrromethanes. The reaction course was found to depend on the nature of the substituent and the acid catalyst. Alkyl or electron-donating substituents displayed levels of reversibility (exchange/scrambling) on par or greater than that of the phenyl substituent, whereas electron-withdrawing or sterically bulky substituents exhibited little to no reversibility. The results obtained provide insight into the electronic and steric effects of different substituents and should facilitate the design of synthetic plans for preparing porphyrinic macrocycles. Graphical abstract.
- Geier III, G. Richard,Lindsey, Jonathan S.
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p. 11435 - 11444
(2007/10/03)
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- Phosphorus pentachloride (PCl5) mediated synthesis of tetraarylporphyrins
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A new synthesis of porphyrins from pyrrole and substituted benzaldehydes is described, with PCl5 as catalyst. Aromatic aldehydes condense irreversibly with pyrrole in the presence of this catalyst, and aerobic oxidation of porphyrinogen provides functionalized porphyrins in yields of 20-65%.
- Sharghi, Hashem,Nejad, Alireza Hassani
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p. 408 - 414
(2007/10/03)
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- Porphyrin architectures bearing functionalized xanthene spacers
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A modular synthetic strategy for the construction of cofacial porphyrin architectures bearing hydrogen-bond synthons on a xanthene platform is presented. The convergent approach is based on a xanthene aldehyde-ester building block that is easily obtainable on a multigram scale with minimal purification. Treatment of this xanthene derivative with a variety of aryl aldehydes and pyrrole under standard Lindsey conditions affords a family of meso-substituted porphyrins bearing a single functionalized xanthene spacer. Direct modification of the hydrogen-bond synthon after macrocyclization proceeds smoothly to furnish porphyrin systems with a variety of cofacial functionalities (e.g., carboxylic acid, ester, amide). Porphyrins bearing two trans-functionalized xanthene spacers are prepared by the MacDonald [2 + 2] condensation of the xanthene aldehyde-ester with readily available 5-aryl-substituted dipyrromethanes such as 5-mesityldipyrromethane to afford the pure α,α- and α,β-porphyrin atropisomers after chromatographic separation. The versatility of this synthetic method offers intriguing opportunities for the use of these and related templates for the study of proton-coupled activation of small molecules.
- Chang, Christopher J.,Yeh, Chen-Yu,Nocera, Daniel G.
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p. 1403 - 1406
(2007/10/03)
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- Microwave-assisted synthesis of 5,10,15,20-tetraaryl porphyrins
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Clean and eco-friendly microwave-assisted cyclocondensation of different aryl aldehydes with pyrrole forms 5,10,15,20 tetraaryl porphyrins in 20 to 43% yields in very low amount of propionic acid in one step is presented.
- Chauhan,Sahoo,Srinivas
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- N-confused tetraphenylporphyrin and tetraphenylsapphyrin formation in one-flask syntheses of tetraphenylporphyrin
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The yields of tetraphenylporphyrin (TPP), N-confused tetraphenylporphyrin (NC-TPP), and tetraphenylsapphyrin (TPS) were examined under diverse conditions in the one-flask room-temperature reaction of pyrrole and benzaldehyde. The conditions examined included TFA and BF3- etherate catalysis, acid concentrations, pyrrole and benzaldehyde concentrations, pyrrole: benzaldehyde ratios, the addition of salt, and reaction times. The quantities of TPP, NC-TPP, and TPS were determined by HPLC. The yield of NC-TPP mirrored that of TPP during systematic variation of reaction parameters but was consistently lower (≤ 7.5%). The rate of NC-TPP formation also resembled that of TPP. Excess pyrrole was not required to form NC-TPP. About 2-fold more NC-TPP was obtained with BF3-etherate compared with TFA catalysis. TPS was observed in only a few of the reactions examined. The yield of TPS peaked early and declined well before the maximum yields of TPP and NC-TPP were reached. The highest yield of TPS observed was 1.2%. TPS was produced in higher yields by TFA compared with BF3-etherate catalysis. Additional pigments with chromatographic properties spanning the range of TPP and NC-TPP were observed in very low yield but were not characterized. N- confused tetramesitylporphyrin was isolated from the reaction of mesitaldehyde and pyrrole under BF3-ethanol cocatalysis. Examination of the Adler reaction of benzaldehyde and pyrrole revealed the presence of NC-TPP and TPS in the filtrate but not in the crystalline TPP material. The substantial chromatographic differences between the porphyrins and N-confused porphyrins make for straightforward isolation of the purified porphyrin devoid of contaminating N-confused porphyrin. These studies indicate that the scope of conditions yielding NC-TPP is extremely broad.
- Geier III, G. Richard,Lindsey, Jonathan S.
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p. 1596 - 1603
(2007/10/03)
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- Beneficial effects of salts on an acid-catalyzed condensation leading to porphyrin formation
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Addition of one of a variety of salts to the room temperature, two-step, one flask reaction at 0.1 M forming tetraphenylporphyrin (TPP) gave yield increases of up to 2-fold. Among 21 insoluble salts, 12 gave increased yields, 6 had no effect, and 3 gave diminished yields. The salts that gave increases encompassed diverse cations but were restricted to the anions Cl-, Br-, I-, and Ph4B- while SO42-, F-, or BF4- did not give improved yields. All 7 soluble tetraalkylammonium or tetraphenylphosphonium salts (F-, Cl-, Ph4B-, PF6-, or HSO4- counterions) that were surveyed gave yield increases of > 1.5 fold. Thus a 10-1 M pyrrole-benzaldehyde condensation catalyzed with 10-2 M BF3·O(Et)2 in CH2Cl2 containing 0.1 equiv of NaCl (5.85 mg/10 mL CH2Cl2) or 0.0031 equiv of benzyltributylammonium chloride (Bu3BzlNCl) (based on [benzaldehyde]) gave ~50% yield compared with ~25% in the reaction without salt. The pyrrole-aldehyde condensation is much faster in the presence of salt, as measured by the rate of disappearance of benzaldehyde and the rate of formation of the porphyrin. Yield increases in the presence of salt were observed with catalysis by BF3·O(Et)2, BF3·2H2O, and CF3CO2H. Significant salt effects also were observed with BF3·O(Et)2 or CF3CO2H in the solvent diethyl ether, but the maximum yield was 15%. A survey of nine aldehydes showed yield improvements of up to 2-fold in six cases in the presence of salt. During the pyrrole-aldehyde reaction in CH2Cl2 either in the presence or absence of soluble salts, the medium becomes heterogeneous (measured by nephelometry). The addition of water to BF3·O(Et)2 in CH2Cl2 also yields a heterogeneous medium; in the presence of salt this medium affords twice the yield of porphyrin as that formed in the absence of salt. 11B NMR and 19F NMR experiments failed to unveil any new species formed by interaction of chloride-containing salts with BF3·O(Et)2. The complexity of the reaction medium, as well as insufficient information about the nature of the pyrrole-aldehyde condensation, preclude an assignment of mechanisms underlying the salt effects. However, a rank ordering of salts in the porphyrin reaction does not correlate with their desiccative power, and the generality of the salt effects is at odds with the selective anion templating of tetrapyrrolic macrocycles. Irreversible features of the pyrrole-aldehyde condensation have been identified via exchange experiments during the course of the reaction and 13C NMR labeling experiments. The improved reaction conditions can be used for preparative-scale syntheses, as 720 mg tetra(nphenylporphyrin (47% yield) was obtained from a 100 mL-scale reaction with 0.1 M reactants at room temperature.
- Li, Feirong,Yang, Kexin,Tyhonas, John S.,MacCrum, Kristy A.,Lindsey, Jonathan S.
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p. 12339 - 12360
(2007/10/03)
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- Soluble synthetic multiporphyrin arrays. 1. Modular design and synthesis
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A set of porphyrin building blocks has been developed for the construction of light-harvesting model compounds and related molecular photonic devices. The porphyrins are facially encumbered to enhance solubility in organic solvents, are employed in a defi
- Wagner, Richard W.,Johnson, Thomas E.,Lindsey, Jonathan S.
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p. 11166 - 11180
(2007/10/03)
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- Porphyrin synthesis in surfactant solution: Multicomponent assembly in micelles
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A synthesis of meso-substituted porphyrins in anionic sodium dodecyl sulfate micelles has been developed. Polar, functionalized aromatic aldehydes condense reversibly with pyrrole in the micellar phase. Oxidation of the porphyrinogen then provides functionalized porphyrins in yields of 10-48%. Hydrophobic aldehydes condense irreversibly to give low yields at practical substrate concentrations. Synthesis in D2O solution results in per-β-deuterated porphyrins. A two-phase model is used to rationalize the dependence of porphyrin yield on reactant and surfactant concentration. Micelles are viewed as potential wells which promote porphyrinogen assembly by binding products more tightly than reactants.
- Bonar-Law, Richard P.
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p. 3623 - 3634
(2007/10/03)
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- Porphyrins bearing halogens at the meso-phenyl and β-pyrrolic positions: Synthesis and spectral propertiest
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The synthesis of symmetrical porphyrins chlorinated at both ortho positions of the meso-aryl substituents, and the chlorination and bromination of the β-pyrrole positions is reported. The β-chlorination of meso-tetraphenylporphyrin via its nickel(II) comp
- Wijesekera, Tilak,Dupre, Daniel,Cader, Mohamed S.R.,Dolphin, David
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p. 765 - 775
(2007/10/03)
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- Novel synthesis of 5,10,15,20-tetraarylporphyrins using high-valent transition metal salts
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A new synthesis of porphyrins from pyrrole and substituted benzaldehydes, is described, using high-valent transition metal salts i)Cl2, TiCl4 and Mn(OAc)3> as aromatizing agents.This process allows higher working concentrations and larger amounts of reagent to be used, than those previously described.
- Gradillas, Ana,Campo, Carmen del,Sinisterra, Jose V.,Llama, Emilio F.
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p. 2611 - 2614
(2007/10/02)
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- Investigation of a Synthesis of meso-Porphyrins Employing High Concentration Conditions and an Electron Transport Chain for Aerobic Oxidation
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The room-temperature synthesis of meso-porphyrins has been investigated at aldehyde and pyrrole concentrations >/= 0.1 M using tetraphenylporphyrin (TPP) and tetramesitylporphyrin (TMP) as models.The decline in yield that occurs at higher reactant concent
- Lindsey, Jonathan S.,MacCrum, Kristy A.,Tyhonas, John S.,Chuang, Yao-Yuan
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p. 579 - 587
(2007/10/02)
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- Preparation and catalytic activities of the manganese and iron derivatives of Br8TMP and Cl12TMP, two robust porphyrin ligands obtained by halogenation of tetramesitylporphyrin
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Tetramesitylporphyrin is one of the most accessible sterically hindered tetraphenylporphyrin ligands which has been widely used in metalloporphyrin catalyzed oxygenation reactions.The ionic halogenation of this porphyrin by N-bromosuccinimide or N-chloros
- Hoffmann, P.,Robert, A.,Meunier, B.
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- An improved synthesis of tetraarylporphirins
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An improved synthesis for 5,10,15,20-tetrakis(pentafluorophenyl)porphyrin, 5,10,15,20-tetrakis(2,4,6-trimethylphenyl)porphyrin and 5,10,15,20-tetrakis(2,6-dichlorophenyl)porphyrin by an acid-catalysed condensation of pyrrole and properly substituted aldeh
- Made, A. W. van der,Hoppenbrouwer, E. J. H.,Nolte, R. J. M.,Drenth, W.
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- meso-Substituted Porphyrins, 4
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2-Pyrryl-(3,5-dimethylphenyl)-carbinol, 2-pyrryl-(3,5-di-t-butyl-phenyl)-carbinol and 2-pyrryl-mesityl-carbinol are cyclised in acidic medium to the corresponding meso-tetraarylporphyrins.The meso-tetraarylporphyrins are transfered to the iron complexes.The reactions of the iron-porphyrins with OH(-) and H3CO(-) are studied and the products of these reactions are characterised. - Keywords: meso-Tetraarylporphyrins, meso-Tetraarylporphinatoiron(III) Complexes, meso-Tetramesitylporphinatoiron(III)methoxide, meso-Tetraarylporphinatoiron(III)hydroxides, μ-Oxo-bis(meso-tetraarylporphinatoiron(III))
- Volz, Heinrich,Hassler, Michael,Schaeffer, Hermann
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p. 1265 - 1272
(2007/10/02)
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- Aliphatic Hydroxylation Catalyzed by Iron Porphyrin Complexes
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The hydroxylation of unactivated alkanes has been observed in a catalytic system containing iodosylbenzene and various iron porphyrins.The yields and distributions of products have been found to be sensitive to the peripheral substitution pattern of the porphyrin.The oxidation of cyclohexane with chloro(5,10,15,20-tetra-o-tolylporphyrinato)iron(III) gave a 31percent yield of cyclohexanol and 6percent cyclohexanone based on iodosylbenzene.Two samples of Fe(TTP)ClCl with differing atropisomeric composition gave different product ratios.The hydroxylation of cycloheptane under these conditions and in the presence of bromotrichloromethane gave 24percent cycloheptanol and 18percent bromocycloheptane.Steric selectivity was observed by comparing the hydroxylation of cis-decalin with Fe(TPP)Cl, Fe(TTP)Cl, Fe(TNP)Cl, and Fe(TMP)Cl.The hydrogen-isotope effect for cyclohexane hydroxylation by Fe(TTP)Cl was found to be 12.9+/- 1.A mechanism for hydroxylation is proposed on the basis of these results that involves initial oxidation of the iron porphyrin, hydrogen atom abstraction from the alkane, and rapid collapse of this radical to give the product alcohol and to regenerate the iron(III) catalyst.
- Groves, John T.,Nemo, Thomas E.
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p. 6243 - 6248
(2007/10/02)
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