Extending mechanochemical porphyrin synthesis to bulkier aromatics: tetramesitylporphyrin

• Qiwen Su and
• Tamara D. Hamilton

Beilstein J. Org. Chem. 2019, 15, 1149–1153, doi:10.3762/bjoc.15.111

• -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 tetra-meso-substituted porphyrins. In the present study, mesitaldehyde undergoes acid-catalyzed

• , simple, room-temperature method for producing tetra-meso-substituted porphyrins with bulky substituents. Keywords: condensation; grinding; mechanochemistry; milling; porphyrin; sterically-hindered; Introduction Porphyrins and related macrocycles such as chlorins, corroles, and bacteriochlorins carry

• out important functions in nature including light harvesting (i.e., chlorophyll), oxygen transport (i.e., heme), biocatalysis, and electron transfer. The ability to synthesize porphyrins bearing a variety of chemical and steric functionalities on the periphery is important in fields as diverse as

Design, synthesis and spectroscopic properties of crown ether-capped dibenzotetraaza[14]annulenes

• Krzysztof M. Zwoliński and
• Julita Eilmes

Beilstein J. Org. Chem. 2019, 15, 617–622, doi:10.3762/bjoc.15.57

• techniques and apparatuses [11]. Particularly, the crown ether-capped (or ‘crown-capped’) porphyrins are synthesized conventionally under high-dilution conditions starting from two porphyrin building blocks bearing complementary functionalities, such as amine and either acyl chloride [12] or halomethyl [13

• emerged as non-pyrrolic surrogates of porphyrins, and have become a versatile platform for supramolecular [15], biomimetic [16][17], biological [18][19] and material chemistry [20][21]. Although much effort has been directed towards the study of crown ether-capped porphyrins [22] and sapphyrines [23

• no diamagnetic ring current characteristic for porphyrins, the remarkable chemical shift differentiation observed for the crown strap shall be rationalized by its close spatial proximity to anisotropy cones spanning from aromatic substituent’s. Moreover, vicinal coupling constants 3JH-H found for the

Learning from B₁₂ enzymes: biomimetic and bioinspired catalysts for eco-friendly organic synthesis

• Keishiro Tahara,
• Ling Pan,
• Toshikazu Ono and
• Yoshio Hisaeda

Beilstein J. Org. Chem. 2018, 14, 2553–2567, doi:10.3762/bjoc.14.232

• ligand. B12 is reduced to Co(I) species in the active center by reductases in sustainable processes. The partially π-conjugated system of the corrin ring is less easy to be adducted by free radicals than those of porphyrins. B12 is bound to a number of proteins and acts as a module. Different chemical

Synthesis and characterization of π–extended “earring” subporphyrins

• Haiyan Guan,
• Mingbo Zhou,
• Bangshao Yin,
• Ling Xu and
• Jianxin Song

Beilstein J. Org. Chem. 2018, 14, 1956–1960, doi:10.3762/bjoc.14.170

• 3Pd is further red-shifted and more intense. Keywords: aromaticity; earring subporphyrin; π-extended; supramolecular chemistry; Findings Since its first synthesis in 2006 [1][2], subporphyrin, the lowest homolog of porphyrins, has received considerable attention [3][4][5][6][7][8] due to its 14π

• cavities π-extended “earring” porphyrins through the aforementioned Suzuki–Miyaura coupling reaction and subsequent oxidation [38]. In this case β,β′-dibromo/tetrabromoporphyrins and diboryltripyrrane were applied as reactants. We discovered that both the π-extended “earring” porphyrins and the

• . Furthermore, we speculate that this strain should be the origin of the much lower yield of 3 comparing to the corresponding “earring” porphyrins. Concerning the diameter of the cavity and the strain of the skeleton, we assumed that some metal ions may insert into the hole surrounded by the tripyrrin moiety

Synthesis and spectroscopic properties of β-meso directly linked porphyrin–corrole hybrid compounds

• Baris Temelli and
• Hilal Kalkan

Beilstein J. Org. Chem. 2018, 14, 187–193, doi:10.3762/bjoc.14.13

• -5,10,15,20-tetraphenylporphyrins with meso-substituted dipyrromethanes. Hybrid compounds have been characterized by 1H NMR, 13C NMR, 2D NMR, UV–vis absorption and fluorescence spectroscopy. Keywords: corrole; hybrid compounds; indium(III) chloride; porphyrin; porphyrinoids; Introduction Porphyrins and

• ], subporphyrin [27] and expanded porphyrins [28][29][30] were prepared and their photophysical and electrochemical properties were characterized. Among these compounds, corroles, contracted porphyrin analogues [31][32][33], assumed an important place in porphyrin chemistry due to their small cavities, trianionic

• aldehydes, which have been used frequently for the synthesis of meso-substituted corroles, were carried out [31][39][40]. The key bilane-substituted porphyrin intermediates 3 were obtained by the addition of an excess amount of meso-substituted dipyrromethanes 2 to β-formylated porphyrins 1 and these

Polarization spectroscopy methods in the determination of interactions of small molecules with nucleic acids – tutorial

• Tamara Šmidlehner,
• Ivo Piantanida and
• Gennaro Pescitelli

Beilstein J. Org. Chem. 2018, 14, 84–105, doi:10.3762/bjoc.14.5

• flattening artifacts [26]. The same cuvette should be used for all the measurements of one system (titration). A good cleaning of the cuvettes is essential (see producer manual or [9]), particularly for ligands that adhere to glass (e.g., porphyrins). For particularly adhering ligands, whose ICD spectra are

Structure–property relationships and third-order nonlinearities in diketopyrrolopyrrole based D–π–A–π–D molecules

• Jan Podlesný,
• Lenka Dokládalová,
• Oldřich Pytela,
• Adam Urbanec,
• Milan Klikar,
• Numan Almonasy,
• Tomáš Mikysek,
• Jaroslav Jedryka,
• Iwan V. Kityk and
• Filip Bureš

Beilstein J. Org. Chem. 2017, 13, 2374–2384, doi:10.3762/bjoc.13.235

• utilized in two-photon excited fluorescence microscopy and bioimaging [13][14], most often upon their further structural tuning towards higher polar character and solubility in water [20][21][22]. Their linking to porphyrins proved to be a useful strategy for two-photon photodynamic therapy [23][24][25

Direct catalytic arylation of heteroarenes with meso-bromophenyl-substituted porphyrins

• Alexei N. Kiselev,
• Olga K. Grigorova,
• Alexei D. Averin,
• Sergei A. Syrbu,
• Oskar I. Koifman and
• Irina P. Beletskaya

Beilstein J. Org. Chem. 2017, 13, 1524–1532, doi:10.3762/bjoc.13.152

• , Russia Ivanovo State University of Chemistry and Technology, 7 Sheremetyevskii prosp., Ivanovo, 153000, Russia 10.3762/bjoc.13.152 Abstract The arylation of mono-, di- and tetra-meso-bromophenyl-substituted porphyrins with the heteroarenes containing “acidic” C–H bonds, such as benzoxazole

• our purpose, while the third system proved to be most versatile and afforded corresponding mono-, di-, tri- and even tetraarylated derivatives of porphyrins. Keywords: arylation; copper catalysis; heteroarenes; palladium catalysis; porphyrins; Introduction Porphyrins play an outstanding role in many

• date certain tetrapyrrole derivatives of such type were described in the literature, for example, porphyrins with imidazole and benzimidazole substitutents at meso-positions [6][7], meso-pyridinyl and meso-quinolinyl-substituted porphyrins [8], an imidazolyl group was attached to the meso-position also

Mechanochemical borylation of aryldiazonium salts; merging light and ball milling

• José G. Hernández

Beilstein J. Org. Chem. 2017, 13, 1463–1469, doi:10.3762/bjoc.13.144

• and catalysts of very different solubility, into close proximity for achieving chemical reactivity. This last aspect is foreseen as highly valuable in transformations using low-soluble PCs (e.g., porphyrins) [16] or during the photochemical synthesis or modification of polymers [17]. The

Efficient access to β-vinylporphyrin derivatives via palladium cross coupling of β-bromoporphyrins with N-tosylhydrazones

• Vinicius R. Campos,
• Ana T. P. C. Gomes,
• Anna C. Cunha,
• Maria da Graça P. M. S. Neves,
• Vitor F. Ferreira and
• José A. S. Cavaleiro

Beilstein J. Org. Chem. 2017, 13, 195–202, doi:10.3762/bjoc.13.22

• such synthetic methodology in porphyrin chemistry allowing the synthesis of new derivatives, containing β-arylvinyl substituents. Keywords: N-tosylhydrazones; Pd-catalyzed cross coupling; porphyrins; Introduction Porphyrin-type heterocycles are well known for their special role in several scientific

• , confirming the molecular formula of these derivatives. All the new porphyrins 3a–c were also characterized by UV–vis spectroscopy, showing the typical profile of the Zn(II) complex of meso-tetraarylporphyrins, with a Soret band at ca. 420 nm and two Q bands between 549 and 586 nm (See Supporting Information

A self-assembled cyclodextrin nanocarrier for photoreactive squaraine

• Ulrike Kauscher and
• Bart Jan Ravoo

Beilstein J. Org. Chem. 2016, 12, 2535–2542, doi:10.3762/bjoc.12.248

• interference of the PS with the triplet ground state of oxygen, leading to the production of singlet oxygen. In both mechanisms, the PS harvests the energy of incident light to form reactive oxygen species or singlet oxygen, which are highly cytotoxic [6][7]. Most clinically used PSs are based on porphyrins

Recent advances in C(sp³)–H bond functionalization via metal–carbene insertions

• Bo Wang,
• Di Qiu,
• Yan Zhang and
• Jianbo Wang

Beilstein J. Org. Chem. 2016, 12, 796–804, doi:10.3762/bjoc.12.78

• development of intermolecular C–H insertion in the application of C(sp3)–H bond functionalizations, especially for light alkanes, is reviewed. The challenging problem of regioselectivity in C–H bond insertions has been tackled by the use of sterically bulky metal catalysts, such as metal porphyrins and silver

• through judicious combination of metal and ligands. In 1982, Callot and Metz reported Rh(III) porphyrins catalyzed intermolecular C–H insertion, which showed an extraordinary selectivity for 1° C–H bonds [28]. Other metal porphyrin complexes, such as Os [29], Fe, Cu, Ag [30], can also serve as catalysts

• chiral porphyrins D4-por*, the enantioselective intermolecular carbene insertion into C(sp3)–H bonds was achieved with moderate to high selectivities (Scheme 7). Besides, the reaction of diazo compounds with benzylic, allylic and alkane C(sp3)–H bonds afforded the insertion products in up to 80% yield

Life lessons

• Jonathan R. Nitschke

Beilstein J. Org. Chem. 2015, 11, 2350–2354, doi:10.3762/bjoc.11.256

• materials. Three of these containers are shown below: Figure 2a depicts an FeII8L6 cubic cage with walls constructed from porphyrins that binds guests such as fullerenes and coronene [26]; Figure 2b shows a CoII10L15 pentagonal prism that embeds five anions, such as PF6− (shown) or ClO4− in its walls, and a

Easy access to heterobimetallic complexes for medical imaging applications via microwave-enhanced cycloaddition

• Nicolas Desbois,
• Sandrine Pacquelet,
• Adrien Dubois,
• Clément Michelin and
• Claude P. Gros

Beilstein J. Org. Chem. 2015, 11, 2202–2208, doi:10.3762/bjoc.11.239

• chosen two porphyrinoid derivatives that are easy to prepare in only a few steps: an azidocorrole 1 [9] and an azidoporphyrin 2 [10] (Figure 1). Porphyrins and corroles display interesting properties in terms of metal complexation of, e.g., transition metals. We have selected two commercial available

• chloride, chloroform or methanol [12] thus MRI applications of Gd-porphyrins are difficult to envisage. Manganese. The design of gadolinium complex did not fully eliminate the risk of in vivo release and accumulation which is a common problem implicated in nephrogenic systemic fibrosis. A possible solution

• agents for MRI. Indeed, manganese complexes of DOTA/NOTA macrocycles are thermodynamically less stable than other transition metal ions or Gd3+ analogues [13]. Over the years and to overcome this problem, a variety of Mn(III) porphyrins have been prepared and investigated for their potential use as MRI

Deproto-metallation of N-arylated pyrroles and indoles using a mixed lithium–zinc base and regioselectivity-computed CH acidity relationship

• Mohamed Yacine Ameur Messaoud,
• Ghenia Bentabed-Ababsa,
• Madani Hedidi,
• Aïcha Derdour,
• Floris Chevallier,
• Yury S. Halauko,
• Oleg A. Ivashkevich,
• Vadim E. Matulis,
• Laurent Picot,
• Valérie Thiéry,
• Thierry Roisnel,
• Vincent Dorcet and
• Florence Mongin

Beilstein J. Org. Chem. 2015, 11, 1475–1485, doi:10.3762/bjoc.11.160

• using the DFT B3LYP method in order to rationalize the experimental results. Keywords: CH acidity; indoles; iodolysis; mixed lithium–zinc bases; pyrroles; Introduction Pyrrole occurs in very important natural products such as tetrapyrrolic (linear) bilirubinoids, and (cyclic) porphyrins and corrins

Synthesis and spectroscopic properties of β-triazoloporphyrin–xanthone dyads

• Dileep Kumar Singh and
• Mahendra Nath

Beilstein J. Org. Chem. 2015, 11, 1434–1440, doi:10.3762/bjoc.11.155

• demetalation under acidic conditions to afford the corresponding free-base porphyrins in good to excellent yields. After successful spectroscopic characterization, these porphyrins have been evaluated for their photophysical properties. The preliminary results revealed a bathochromic shift in the UV–vis and

• porphyrins can be modulated by introducing diverse functionalities on their periphery or changing the metal ions in the porphyrin core [3][4]. Due to the high thermal stability and extended π-electron system, porphyrins are very useful for the construction of molecular switches [5][6] and other organic

• photoelectric materials [7][8]. In addition, porphyrins are potentially used as photosensitizers in photodynamic therapy to treat various types of tumors [9][10]. In recent years, many hybrid molecules including porphyrin–C60 [11], porphyrin–quinones [12] and porphyrin–cyclodextrin [13] conjugates were

Advances in the synthesis of functionalised pyrrolotetrathiafulvalenes

• Luke J. O’Driscoll,
• Sissel S. Andersen,
• Marta V. Solano,
• Dan Bendixen,
• Morten Jensen,
• Troels Duedal,
• Jess Lycoops,
• Cornelia van der Pol,
• Rebecca E. Sørensen,
• Karina R. Larsen,
• Kenneth Myntman,
• Christian Henriksen,
• Stinne W. Hansen and
• Jan O. Jeppesen

Beilstein J. Org. Chem. 2015, 11, 1112–1122, doi:10.3762/bjoc.11.125

• systems [11][27], to the incorporation of MPTTFs and BPTTFs into more complex molecular architectures such as macrocycles [8][9][14], calix-pyrroles [1][10][11], calixarenes [29] and porphyrins [30]. Note that for MPTTFs, R1 and R2 can be either the same or different. Here, we present recent developments

Discrete multiporphyrin pseudorotaxane assemblies from di- and tetravalent porphyrin building blocks

• Mirko Lohse,
• Larissa K. S. von Krbek,
• Sebastian Radunz,
• Suresh Moorthy,
• Christoph A. Schalley and
• Stefan Hecht

Beilstein J. Org. Chem. 2015, 11, 748–762, doi:10.3762/bjoc.11.85

• stoichiometry, while the amount of alternative structures can be neglected. Our results illustrate the power of multivalency to program the multicomponent self-assembly of specific entities into discrete functional nanostructures. Keywords: crown ethers; multicomponent assembly; multivalency; porphyrins

• structures, functional supramolecular architectures such as molecular switches and motors [43][44][45] as well as artificial muscles [46][47][48][49][50], have been synthesized. Due to their four-fold symmetry, porphyrins are excellent candidates to extend these concepts to tetravalent supramolecules. Beyond

• being a mere spacer and scaffold connecting the binding sites, porphyrins also offer interesting physical and optical properties [51][52]. Therefore, they have played a pivotal role in supramolecular chemistry [53][54][55][56][57][58][59][60][61][62][63][64][65][66], for example as potential candidates

A versatile δ-aminolevulinic acid (ΑLA)-cyclodextrin bimodal conjugate-prodrug for PDT applications with the help of intracellular chemistry

• Chrysie Aggelidou,
• Theodossis A. Theodossiou,
• Antonio Ricardo Gonçalves,
• Mariza Lampropoulou and
• Konstantina Yannakopoulou

Beilstein J. Org. Chem. 2014, 10, 2414–2420, doi:10.3762/bjoc.10.251

• in terms of water solubility and lack of aggregation. Keywords: cyclodextrins; PDT; protoporphyrin IX; prodrug; δ-aminolevulinic acid; Introduction Porphyrins have long been used as agents for tumor photodiagnosis (PDD) and photodynamic therapy (PDT) because of their preferential accumulation in

• tethering β-CD to PpIX, was the reduced aggregation of the conjugate in aqueous solutions. Formation of aggregates is an adverse yet typical characteristic of porphyrins that reduces their photodynamic efficiency, quenches their fluorescence and complicates their delivery [8][9][10]. In the system presented

Synthesis of chiral N-phosphoryl aziridines through enantioselective aziridination of alkenes with phosphoryl azide via Co(II)-based metalloradical catalysis

• Jingran Tao,
• Li-Mei Jin and
• X. Peter Zhang

Beilstein J. Org. Chem. 2014, 10, 1282–1289, doi:10.3762/bjoc.10.129

• the porphyrin ring are also omitted in (B). Structures of D2-symmetric chiral cobalt(II) porphyrins. [Co(TPP)]-catalyzed olefin aziridination with DPPA. [Co(P1)]-catalyzed asymmetric olefin aziridination with DPPA. Optimization of catalytic aziridination of styrene with phosphoryl azides by Co(II

First synthesis of meso-substituted pyrrolo[1,2-a]quinoxalinoporphyrins

• Dileep Kumar Singh and
• Mahendra Nath

Beilstein J. Org. Chem. 2014, 10, 808–813, doi:10.3762/bjoc.10.76

• ]quinoxalinoporphyrins; Pictet–Spengler reaction; synthesis; Introduction Many natural porphyrins are known to play essential roles in a number of biological processes including oxygen transport [1], solar energy conservation [2][3][4] and photosynthesis [5]. Owing to the expanded π-conjugation system as well as good

• thermal stabilities, various artificial porphyrins have been prepared as promising materials for organic photonic and electronic applications [6][7][8][9]. In addition, porphyrins fused with external aromatic systems exhibit a broad range of applications in diverse areas such as molecular devices [10][11

• of biologically important functional groups were also introduced on the periphery of meso-substituted porphyrins to develop efficient photosensitizers for photodynamic therapy applications [41][42][43]. However, the porphyrins with a pyrrolo[1,2-a]quinoxaline moiety at the meso-positions have not

From porphyrin benzylphosphoramidate conjugates to the catalytic hydrogenation of 5,10,15,20-tetrakis(pentafluorophenyl)porphyrin

• Marcos C. de Souza,
• Leandro F. Pedrosa,
• Géssica S. Cazagrande,
• Vitor F. Ferreira,
• Maria G. P. M. S. Neves and
• José A. S. Cavaleiro

Beilstein J. Org. Chem. 2014, 10, 628–633, doi:10.3762/bjoc.10.54

• reduction of the macrocycle, thereby affording chlorin and other derivatives (Scheme 1). Considering the importance of TPPF20 as a template for further functionalizations [7] and the better suitability of chlorins for PDT compared to porphyrins due to their enhanced red-shifted Q bands [2], we decided to

• with 10% Pd/C and NEt3 the benzyl groups could not be selectively removed without affecting the phosphoramidate moiety and the porphyrin core. Catalytic hydrogenation of TPPF20 with H2/10% Pd/C There are many methods for performing the reduction of porphyrins (or metalloporphyrins) leading to different

• levels of hydrogenation on the β-pyrrolic double bonds [12][13]. Most of these methods employ chemicals other than H2 as hydrogen donors to reduce porphyrins into chlorins [14][15][16][17][18]. In our case, we decided to investigate the extent of the direct catalytic hydrogenation with H2 over TPPF20 in

Simple two-step synthesis of 2,4-disubstituted pyrroles and 3,5-disubstituted pyrrole-2-carbonitriles from enones

• Murat Kucukdisli,
• Dorota Ferenc,
• Marcel Heinz,
• Christine Wiebe and
• Till Opatz

Beilstein J. Org. Chem. 2014, 10, 466–470, doi:10.3762/bjoc.10.44

• connection to the porphyrins, the chlorins, and the corrins. Furthermore, they are regarded as privileged structures by synthetic chemists because of widespread applications in medicinal chemistry [2][3] and materials science [4]. Not surprisingly, numerous synthetic methods [5][6][7][8][9][10][11][12][13

Synthesis of meso-substituted dihydro-1,3-oxazinoporphyrins

• Satyasheel Sharma and
• Mahendra Nath

Beilstein J. Org. Chem. 2013, 9, 496–502, doi:10.3762/bjoc.9.53

• derived from porphyrins [11][12]. Previously, a large number of these molecules have been synthesized by the coupling of diverse pharmaceutically important moieties, such as carbohydrates [13][14][15], amino acid residues [16][17][18][19], steroids [20][21], glycosides [22][23][24], nitroxyl derivatives

• . Further, these free-base porphyrins were successfully converted to their zinc(II) analogues 10–13 by using Zn(OAc)2·2H2O as outlined in Scheme 1. In contrast, the synthesis of new dihydro-1,3-naphthoxazinoporphyrins 14 and 16 was achieved in 75–85% yields in a one-pot three-component Mannich type

• -dihydroxynaphthalenes and formaldehyde in THF under reflux (Scheme 3). Attempts have also been made to prepare the corresponding zinc naphthoxazinoporphyrin dyads, but always impure products were obtained even after repeated column chromatography. The newly synthesized porphyrins were characterized on the basis of 1H

Intramolecular carbenoid ylide forming reactions of 2-diazo-3-keto-4-phthalimidocarboxylic esters derived from methionine and cysteine

• Marc Enßle,
• Stefan Buck,
• Roland Werz and
• Gerhard Maas

Beilstein J. Org. Chem. 2012, 8, 433–440, doi:10.3762/bjoc.8.49

• sulfonium ylide 20 in practically quantitative yield. It has recently been reported that ruthenium(II) porphyrins are suitable catalysts for carbenoid sulfonium ylide formation as well [43]. In continuation of our comparative studies of dirhodium(II,II) tetracarboxylate and tetracarbonyldiruthenium(I,I