Synthesis of new representatives of A₃B-type carboranylporphyrins based on meso-tetra(pentafluorophenyl)porphyrin transformations

• Victoria M. Alpatova,
• Evgeny G. Rys,
• Elena G. Kononova and
• Valentina A. Ol'shevskaya

Beilstein J. Org. Chem. 2024, 20, 767–776, doi:10.3762/bjoc.20.70

• single pentafluorophenyl ring was prepared through the regioselective nucleophilic aromatic substitution reaction of the p-fluorine atoms in 5,10,15,20-tetrakis(pentafluorophenyl)porphyrin with 9-mercapto-m-carborane. The reaction of this porphyrin with sodium azide led to the selective substitution of

• the p-fluorine atom in the pentafluorophenyl substituent with an azide functionality which upon reduction with SnCl2 resulted in the formation of the corresponding porphyrin with an amino group. Pentafluorophenyl-substituted A3B-porphyrins were studied and transformed to thiol and amino-substituted

• carborane A3B-porphyrin were also synthesized based on the amino-substituted A3B-porphyrin. The structures of the prepared carboranylporphyrins were determined by UV–vis, IR, 1H, 19F, 11B NMR spectroscopic data and MALDI mass spectrometry. Keywords: bioconjugation; carboranes; fluorine; porphyrin; SNAr

Switchable molecular tweezers: design and applications

• Pablo Msellem,
• Maksym Dekthiarenko,
• Nihal Hadj Seyd and
• Guillaume Vives

Beilstein J. Org. Chem. 2024, 20, 504–539, doi:10.3762/bjoc.20.45

• homometallic (Zn/Zn) and heterometallic (Zn/Au) compounds. In the open state, the porphyrins do not interact and the closing process allows the system to acquire distinct properties depending on the porphyrin. For the Zn/Zn system, guest binding abilities have been observed with diamines that can coordinate

• units composed of two pyridine units linked with a propyldiamine spacer (tweezers 25, see Figure 14c) have been reported by Fuzukumi and co-workers [57]. This unit has four coordination sites and can bind copper in a square planar geometry. The authors functionalized this spacer with two zinc–porphyrin

• arms. In the uncoordinated state, the conformation is not fixed so the porphyrins do not interact but when the tweezers are closed the porphyrins are facing each other and can interact. The closed and open states exhibit different electrochemical and photochemical properties. The porphyrin interaction

Synthesis of π-conjugated polycyclic compounds by late-stage extrusion of chalcogen fragments

• Aissam Okba,
• Pablo Simón Marqués,
• Kyohei Matsuo,
• Naoki Aratani,
• Hiroko Yamada,
• Gwénaël Rapenne and
• Claire Kammerer

Beilstein J. Org. Chem. 2024, 20, 287–305, doi:10.3762/bjoc.20.30

• retrocycloadditions were further exploited from bridged bicyclo[2.2.2]octadiene solubilizing fragments to generate (hetero)acenes and larger bidimensional π-CPCs such as extended porphyrin derivatives with the concomitant release of ethylene (Scheme 1, bottom left) [9][11][15]. It is important to note here that in

Catalytic multi-step domino and one-pot reactions

• Svetlana B. Tsogoeva

Beilstein J. Org. Chem. 2024, 20, 254–256, doi:10.3762/bjoc.20.25

• in the Full Research Paper by Nath and co-workers. The newly synthesized porphyrin derivatives displayed significant red-shifted absorption and emission compared to simple meso-tetraarylporphyrins [14]. The Carlone group reports an Enders-type triple cascade reaction toward cyclohexenals, using

Perspectives on push–pull chromophores derived from click-type [2 + 2] cycloaddition–retroelectrocyclization reactions of electron-rich alkynes and electron-deficient alkenes

• Michio Yamada

Beilstein J. Org. Chem. 2024, 20, 125–154, doi:10.3762/bjoc.20.13

• ’-dicyanoquinone diimides [82], and 6,6-dicyanopentafulvenes (DCFs) [83][84] have been employed. Notably, the [2 + 2] CA–RE reaction of DMA-ethynyl-appended porphyrin with TCNQ is observed to occur on a metal surface (specifically Au(111)) under high-vacuum conditions, with successful visualization achieved

• investigated by Diederich et al. [145]. The representative molecules among these are shown in Figure 10. In 86, wherein ZnP and anilino-PCBD are linked using a spacer, the excitation of the porphyrin chromophore (at 560 nm, corresponding to the Q-band) generated an excited singlet state of ZnP (1ZnP*) with a

• , the emergence of the weak absorption band of the ZnP radical cation at 640 nm was hindered by the overwhelming absorption intensity of the residual porphyrin. The transient absorption spectra of 87 were obtained in benzonitrile solvent, which was expected to stabilize the CS state. Absorption

Substituent-controlled construction of A₄B₂-hexaphyrins and A₃B-porphyrins: a mechanistic evaluation

• Seda Cinar,
• Dilek Isik Tasgin and
• Canan Unaleroglu

Beilstein J. Org. Chem. 2023, 19, 1832–1840, doi:10.3762/bjoc.19.135

• of porphyrinogen and hexaphyrinogen forms. Keywords: A4B2-hexaphyrin; A3B-porphyrin; N-tosylimine; Cu(OTf)2 catalysis; HRESI–TOF analysis; Introduction Porphyrins and expanded porphyrins have found widespread applications in supramolecular chemistry [1][2][3][4]. Expanded porphyrins are utilized as

• -substituted N-tosylimine and 5,10-bis(pentafluorophenyl)tripyrromethane formed A6-hexaphyrin as the main product along with the inevitable formation of side products, A4-porphyrin and higher expanded porphyrins [28]. meso-Phenyloligopyrroles having electron-rich substituents at the 2-, 4-, or 6-positions were

• screened in the literature. To the best of our knowledge, hexaphyrin synthesis from the least substituted aryls appears to be not much studied. In the following study, we focused on the use of less hindered variety of precursors in hexaphyrin and porphyrin synthesis via the Cu(OTf)2-catalyzed reaction of

Tying a knot between crown ethers and porphyrins

• Maksym Matviyishyn and
• Bartosz Szyszko

Beilstein J. Org. Chem. 2023, 19, 1630–1650, doi:10.3762/bjoc.19.120

• metals. In this perspective article, the overview of both the early designs of porphyrin-crown ether hybrids, as well as the most recent advances in the synthesis and characterisation of this remarkable group of macrocyclic systems, are addressed. The discussion covers the strategies employed in

• synthesising these systems, including cyclisation reactions, self-assembly, and their remarkable reactivity. The potential applications of porphyrin-crown ether hybrids are also highlighted. Moreover, the discussion identifies the challenges associated with synthesising and characterising hybrids, outlining

• opposites, and as opposites attract, several studies were devoted to investigating the systems combining such contradictory structural elements [22][23][24][25]. In this perspective article, the subjective selection of literature demonstrating developments in the area of hybrid porphyrin-crown ether

Radical ligand transfer: a general strategy for radical functionalization

• David T. Nemoto Jr,
• Kang-Jie Bian,
• Shih-Chieh Kao and
• Julian G. West

Beilstein J. Org. Chem. 2023, 19, 1225–1233, doi:10.3762/bjoc.19.90

• found to be capable of functionalizing specific C–H bonds to numerous functionalities, including C–F [21][22], C–N3 [23], and C–Cl bonds [24][25]. Upon these remarkable observations, methodologies involving manganese–porphyrin catalysts have been developed over the years. These methods take advantage of

• functionalization via the canonical organometallic steps of oxidative addition/reductive elimination was ruled out via catalytic reaction of the macrocyclic Groves-type porphyrin catalyst V, a species that is unable to accommodate the mutual cis-orientation of ligands for metal-centered reductive elimination. The

• much more efficiently in decarboxylative RLT reactions than aliphatic acids [42]. Outside of decarboxylation, X. Peter Zhang recently reported the enantioselective synthesis of allylic amines through coupled HAT and RLT on allylic C–H bonds [45], using a bulky cobalt porphyrin complex developed and

Unravelling a trichloroacetic acid-catalyzed cascade access to benzo[f]chromeno[2,3-h]quinoxalinoporphyrins

• Chandra Sekhar Tekuri,
• Pargat Singh and
• Mahendra Nath

Beilstein J. Org. Chem. 2023, 19, 1216–1224, doi:10.3762/bjoc.19.89

• ; multicomponent synthesis; one-pot reaction; trichloroacetic acid; Introduction π-Conjugated porphyrin macrocycles are known for their applications in numerous areas ranging from oxygen transport, photosynthesis, catalysis and medicine [1][2][3]. In the past several years, diverse organic scaffolds have been

• incorporated at the porphyrin periphery and different metal ions in the porphyrin core to modulate ground-state and excited-state characteristics of easily accessible meso-tetraarylporphyrins. Some of these π-extended tetrapyrrolic macrocycles have emerged as potential candidates in photodynamic therapy and

• contruction of periphery-modified porphyrinoids [30][31][32][33][34][35][36][37][38][39][40][41], we thought to assemble benzo[f]chromeno[2,3-h]quinoxalinoporphyrins by incorporating porphyrin, quinoxaline and xanthene scaffolds in a single molecular framework using a multicomponent synthetic strategy. The

Clauson–Kaas pyrrole synthesis using diverse catalysts: a transition from conventional to greener approach

• Dileep Kumar Singh and
• Rajesh Kumar

Beilstein J. Org. Chem. 2023, 19, 928–955, doi:10.3762/bjoc.19.71

• . This methodology has been applied to diverse areas of chemistry, including natural product synthesis [45][46], medicinal chemistry [47][48], polymer chemistry [49][50] and porphyrin chemistry [51][52][53]. In recent years, green chemistry has become a widely used method for organic synthesis in order

• pharmaceutically active molecules, polymer synthesis, total synthesis of natural products, porphyrin functionalization, and the synthesis of various pyrrole-containing heterocyclic molecules. We believe that this review will be useful and will encourage researchers to apply the modified Clauson–Kaas reaction to

Light-responsive rotaxane-based materials: inducing motion in the solid state

• Adrian Saura-Sanmartin

Beilstein J. Org. Chem. 2023, 19, 873–880, doi:10.3762/bjoc.19.64

• direction, one potential strategy is the approach followed by Feringa and co-workers [72], in which palladium-porphyrin photosensitizer-based struts were employed within a metal-organic material, allowing the use of green light as irradiation source because of the effective energy transfer between these

Strategies in the synthesis of dibenzo[b,f]heteropines

• David I. H. Maier,
• Barend C. B. Bezuidenhoudt and
• Charlene Marais

Beilstein J. Org. Chem. 2023, 19, 700–718, doi:10.3762/bjoc.19.51

• transition metal (Ni, Fe, V) porphyrin catalysts and oxygen. Catalytic reduction (H2, Pd/C) affords 2,2'-diaminobibenzyl (20) in the subsequent step [28]. 1.2 Ring-closing via amine condensation The initial synthesis of 10,11-dihydro-5H-dibenzo[b,f]azepine (2a) was reported in 1899 by Thiele and Holzinger

Synthesis, structure, and properties of switchable cross-conjugated 1,4-diaryl-1,3-butadiynes based on 1,8-bis(dimethylamino)naphthalene

• Semyon V. Tsybulin,
• Ekaterina A. Filatova,
• Alexander F. Pozharskii,
• Valery A. Ozeryanskii and
• Anna V. Gulevskaya

Beilstein J. Org. Chem. 2023, 19, 674–686, doi:10.3762/bjoc.19.49

• singlet oxygen production have been identified in porphyrin-based butadiynes [7][8][9], 1,3-butadiyne-linked oligoporphycenes [10], and 1,3-butadiyne-linked amines [13]. A wide variety of applications was proposed for graphdiynes (2D allotropes of graphene), including electrocatalysts and energy devices

CuAAC-inspired synthesis of 1,2,3-triazole-bridged porphyrin conjugates: an overview

• Dileep Kumar Singh

Beilstein J. Org. Chem. 2023, 19, 349–379, doi:10.3762/bjoc.19.29

• connect two diverse moieties in a single framework. Therefore, this review focuses on the synthesis and photophysical studies of β- and meso-substituted and 1,2,3-triazole-fused porphyrin conjugates. All of the porphyrin conjugates discussed here are synthesized via a copper(I)-catalyzed Huisgen 1,3

• -dipolar cycloaddition reaction between an azide and a terminal alkyne, also popular as "click reaction" or CuAAC reaction. Moreover, the 1,2,3-triazole ring also serves as a spacer and an electron transfer bridge between the porphyrin and the attached chromophores. In order to provide a critical overview

• of the synthesis and properties of various porphyrin-triazole hybrids, this review will discuss some of the key reactions involved in the preparation of triazole-linked porphyrin conjugates. Keywords: azide–alkyne; click chemistry; CuAAC; 1,3-dipolar cycloaddition; porphyrin; 1,2,3-triazole

Synthesis of meso-pyrrole-substituted corroles by condensation of 1,9-diformyldipyrromethanes with pyrrole

• Baris Temelli and
• Pinar Kapci

Beilstein J. Org. Chem. 2022, 18, 1403–1409, doi:10.3762/bjoc.18.145

• studies on porphyrins, which have many application areas such as photodynamic therapy and photovoltaic systems, have focused on oligomeric and polymeric structures in the last two decades [5][6][7][8][9]. Although such porphyrin structures have been used successfully in the development of molecular

• our knowledge, there is no generally accepted method for the synthesis of pyrrole-substituted corroles. Very recently, we reported the synthesis of porphyrin–corrole [24][25][26] and porphyrin–porphyrin dyads and triads [27] using formylated porphyrin compounds. In a continuation of research activity

• . Figure 2 shows the absorption spectrum of 2a with a strong Soret band at 412 nm and weak Q-bands at 542 and 611 nm. After the synthesis of corrole compounds, we tried to extent our studies to obtain meso-pyrrole-substituted porphyrin compounds. For this purpose, the MacDonald [2 + 2] porphyrin

Cytochrome P450 monooxygenase-mediated tailoring of triterpenoids and steroids in plants

• Karan Malhotra and
• Jakob Franke

Beilstein J. Org. Chem. 2022, 18, 1289–1310, doi:10.3762/bjoc.18.135

• system as well as a cysteine thiolate ligand from the protein backbone (Figure 1B). The generally accepted catalytic cycle for hydroxylations is shown in Figure 1C. In the resting state A, the central ferric ion is coordinated by six ligands, four from the porphyrin ring system, one cysteine thiolate

• group and an aqua ligand (water), resulting in an octahedral complex [17]. The oxidative reaction is initiated by displacement of the axial water molecule by the substrate (step 1), which pushes the Fe(III) ion out of the porphyrin plane in intermediate B [17]. This geometrical distortion promotes

• compound I (intermediate G), it is now generally accepted as a ferryl (Fe(IV)) oxo species with a radical cation in the porphyrin system [18][23]. In the case of hydroxylations, the oxygen from compound I (intermediate G) can then be transferred by an oxygen rebound mechanism (steps 7 and 8) via the ferryl

Scope of tetrazolo[1,5-a]quinoxalines in CuAAC reactions for the synthesis of triazoloquinoxalines, imidazoloquinoxalines, and rhenium complexes thereof

• Laura Holzhauer,
• Chloé Liagre,
• Olaf Fuhr,
• Nicole Jung and
• Stefan Bräse

Beilstein J. Org. Chem. 2022, 18, 1088–1099, doi:10.3762/bjoc.18.111

• 1,2,3-triazoloquinoxalines 3 and imidazo[1,2-a]quinoxalines 2 under conditions known for copper-catalyzed azide–alkyne cycloaddition (CuAAC) [10]. The currently published porphyrin-catalyzed process requires glovebox conditions and the use of an expensive catalyst [11]. We intend to elucidate the

• ). Improving this route provides an alternative to the literature-known method [11] that requires both a special porphyrin complex and glovebox conditions. Using neither silver(I) triflate nor copper(I) iodide yielded the imidazole product, indicating that the use of copper(I) triflate is crucial for the

• ]). Reactions of tetrazoloquinoxalines 1 to 1,2,3-triazoloquinoxalines 3 via CuAAC and denitrogenative annulation to imidazo[1,2-a]quinoxalines 2 catalyzed by an iron porphyrin catalyst 5 in combination with Zn. The scheme includes all quinoxaline-based derivatives that were obtained by these procedures so far

Heteroleptic metallosupramolecular aggregates/complexation for supramolecular catalysis

• Prodip Howlader and
• Michael Schmittel

Beilstein J. Org. Chem. 2022, 18, 597–630, doi:10.3762/bjoc.18.62

• demonstrated by Reek and co-workers by using a previously reported heteroleptic bisporphyrin cage [76]. The tetragonal prismatic nanocage 47 consisted of two zinc-porphyrin units along the two tetragonal faces (Figure 11), which allowed encapsulation of the chiral phosphoramidite 48 as a precursor for the

• + was developed on the basis of two complexation events, i.e., the zinc(II) HETTAP (log β = 14, log K1 ≥ 6) and Npy → ZnPor (log K = 4.45) binding motifs (Figure 12) [89]. Due to the design of 52, the pyridine terminal oscillates between the two degenerate zinc porphyrin (ZnPor) stations of 53 at k298

• able to build a new catalytic machinery [100]. Hereunto, the two concepts RPI and ILC were combined in a synergistic manner, starting with rotor [Cu2(83)(91)]2+ (k298 = 46.0 kHz) that catalyzed the click reaction between the zinc porphyrin ligand 92 and the azide 93 furnishing triazole 94 (Figure 20

Site-selective reactions mediated by molecular containers

• Rui Wang and
• Yang Yu

Beilstein J. Org. Chem. 2022, 18, 309–324, doi:10.3762/bjoc.18.35

• substrate 26 was first modified at the hydroxy groups through esterification with a designed acid moiety possessing a p-tert-butylphenyl group and transformed to the corresponding model substrate 27. The catalyst H used here was a manganese(III)-bounded porphyrin module carrying four β-cyclodextrin units at

Constrained thermoresponsive polymers – new insights into fundamentals and applications

• Patricia Flemming,
• Alexander S. Münch,
• Andreas Fery and
• Petra Uhlmann

Beilstein J. Org. Chem. 2021, 17, 2123–2163, doi:10.3762/bjoc.17.138

On the application of 3d metals for C–H activation toward bioactive compounds: The key step for the synthesis of silver bullets

• Renato L. Carvalho,
• Amanda S. de Miranda,
• Mateus P. Nunes,
• Roberto S. Gomes,
• Guilherme A. M. Jardim and
• Eufrânio N. da Silva Júnior

Beilstein J. Org. Chem. 2021, 17, 1849–1938, doi:10.3762/bjoc.17.126

• inspired by the biocatalytic action of the cytochrome P-450 cycle, which is driven by a reductase or bioreductant, and presented high versatility in incorporating both aldehyde and ketone functionalities into unprotected arylboronic acids. The reaction consists of using a porphyrin-based iron catalyst, and

• muscarinic acetylcholine receptor agonists (97, 98, and 99, Scheme 33A) [168]. Asymmetric variations of the porphyrin-based iron catalysts also provided the desired product with 100% conversion and enantiomeric ratios up to 73:27 in some cases. The straightforward Fe catalysis was used as a key step in the

Sustainable manganese catalysis for late-stage C–H functionalization of bioactive structural motifs

• Jongwoo Son

Beilstein J. Org. Chem. 2021, 17, 1733–1751, doi:10.3762/bjoc.17.122

• late-stage fluorination (Csp3–F) is relatively challenging due to the omnipresent unactivated C–H bonds of the substrate molecules. In 2012, Groves et al. revealed a manganese porphyrin-catalyzed late-stage Csp3–H fluorination method (Scheme 1) [22]. In the authors’ approach, a direct late-stage

• [24]. This manganese porphyrin catalytic system was also effective in the direct site-selective fluorination of complex steroid scaffold 3, containing 28 unactivated C–H bonds. Based on the authors’ analysis of steric and electronic factors, it was suggested that the methylene units at C2 and C3 of

• future, such as protecting-group-free methodologies, peptide biosensors, and facile functionalizations within unexplored realms of complex peptides. Proposed reaction mechanism of C–H fluorination by a manganese porphyrin catalyst. Proposed mechanism of C–H radiofluorination. Proposed reaction mechanism

Structural effects of meso-halogenation on porphyrins

• Keith J. Flanagan,
• Maximilian Paradiz Dominguez,
• Zoi Melissari,
• Hans-Georg Eckhardt,
• René M. Williams,
• Dáire Gibbons,
• Caroline Prior,
• Gemma M. Locke,
• Alina Meindl,
• Aoife A. Ryan and
• Mathias O. Senge

Beilstein J. Org. Chem. 2021, 17, 1149–1170, doi:10.3762/bjoc.17.88

• , Trinity College Dublin, The University of Dublin, Dublin 2, Ireland Van ‘t Hoff Institute for Molecular Sciences, University of Amsterdam, P.O. Box 94157, 1090 GD Amsterdam, The Netherlands 10.3762/bjoc.17.88 Abstract The use of halogens in the crystal engineering of supramolecular porphyrin assemblies

• we were able to deduce the impact a meso halogen has on a porphyrin, for example, meso-halogenation is dependent on the type of alternate substituents present when forming supramolecular assemblies. Furthermore, we have designed a method to predict the conformation of halogenated porphyrins, without

• few decades. Byrn et al. were the first to observe that porphyrins have a high propensity to form “porous” clathrates and suggested that they can be used as a “porphyrin sponge” [1]. They reported that 5,10,15,20-tetraphenylporphyrin could act like a ‘host’ which could trap a variety of solvent

Manganese/bipyridine-catalyzed non-directed C(sp³)–H bromination using NBS and TMSN₃

• Kumar Sneh,
• Takeru Torigoe and
• Yoichiro Kuninobu

Beilstein J. Org. Chem. 2021, 17, 885–890, doi:10.3762/bjoc.17.74

• reported the manganese-porphyrin-catalyzed chlorination and bromination of C(sp3)−H bonds, respectively (Scheme 1d). Groves et al. also reported the manganese-salen-catalyzed fluorination of benzylic C(sp3)−H bonds [49]. Although these methods are efficient, they have a limited substrate scope

Insight into functionalized-macrocycles-guided supramolecular photocatalysis

• Minzan Zuo,
• Krishnasamy Velmurugan,
• Kaiya Wang,
• Xueqi Tian and
• Xiao-Yu Hu

Beilstein J. Org. Chem. 2021, 17, 139–155, doi:10.3762/bjoc.17.15

• + and crown ether, leading to the formation of cyclobutane in a high yield. D’Souza et al. constructed a photosynthetic triad 4 to mimic the photosynthetic reaction center [19]. A BODIPY, an ammonium-functionalized fullerene, and a zinc porphyrin functioned as the energy donor, electron acceptor, and

• electron donor, respectively (Figure 3). A benzo-18-crown-6 derivative was connected to the porphyrin ring, which could form a supramolecular complex with fullerene through dipole interactions. The formed supramolecular self-assembly resulted in a high energy-transmission efficiency (over 97%) between the

• BODIPY and the zinc porphyrin. The excited zinc porphyrin further transferred the electron to the fullerene, yielding a charge-separated state, with a long lifetime of 23 µs, indicating the charge stabilization of the supramolecular assembly. Thus, an artificial photocatalytic system that can mimic the