Red light excitation: illuminating photocatalysis in a new spectrum

• Lucas Fortier,
• Corentin Lefebvre and
• Norbert Hoffmann

Beilstein J. Org. Chem. 2025, 21, 296–326, doi:10.3762/bjoc.21.22

• bacteriochlorin for photoinduced electron transfer-reversible addition-fragmentation chain transfer (PET-RAFT) polymerization under far-red light (Figure 4) [43]. This synthetic bacteriochlorin, structurally modified from tetraphenylporphyrin with two reduced pyrrole rings, exhibits strong absorption in the far

Hydrogen-bonded macrocycle-mediated dimerization for orthogonal supramolecular polymerization

• Wentao Yu,
• Zhiyao Yang,
• Chengkan Yu,
• Xiaowei Li and
• Lihua Yuan

Beilstein J. Org. Chem. 2025, 21, 179–188, doi:10.3762/bjoc.21.10

• cucurbituril [18], cyclodextrin [19], and calix[4]pyrrole [20], as well as flexible crown ethers [10][21]. Few two-dimensional (2D) shape-persistent macrocyclic compounds are used for this purpose. One difficulty in realizing 2D macrocycle-based orthogonal assembly is that the construction motif must be

Recent advances in organocatalytic atroposelective reactions

• Henrich Szabados and
• Radovan Šebesta

Beilstein J. Org. Chem. 2025, 21, 55–121, doi:10.3762/bjoc.21.6

• -naphthols, new atroposelective reactions of quinones and iminoquinones were developed [63]. The reaction of quinones with an ester group 109 and indoles with alkyl substituents 110 catalyzed by CPA C29 provided products 112 with regioselectivity on the pyrrole ring of indole (Scheme 35). On the contrary

• and, by extension, atom economy. Through the thermal racemization experiment, the rotational barrier of the product 206 was calculated to be 31.1 kcal/mol at 100 °C, corresponding to a half-life of 107 years at 25 °C. Han et al. developed a protocol to construct pyrrole rings from 1-naphthyl

• between the ketomalonate and organocatalyst Int-68 were shown as the pivotal interaction that formed the chiral pocket for the induction of chirality. Nucleophilic addition followed by rearomatization of the pyrrole ring and protonation of the oxygen forms the axially chiral arylpyrrole 237. The

Surprising acidity for the methylene of 1,3-indenocorannulenes?

• Shi Liu,
• Märt Lõkov,
• Sofja Tshepelevitsh,
• Ivo Leito,
• Kim K. Baldridge and
• Jay S. Siegel

Beilstein J. Org. Chem. 2024, 20, 3144–3150, doi:10.3762/bjoc.20.260

• conformationally planar-locked 2,3-diphenylindene (pKa 17.7 in DMSO [17]. The CL perspective also allows one to create graphs with points representing the aromatic elements, such as, benzene, Cp anion, pyrrole, etc. (Scheme 2, top). Triphenylene is a simple cyclic graph of three benzene elements and their direct

• DMSO. This high acidity is well seen if one recognizes that, when seen through the CL model, pentabenzocorannulene is more of a well-overlapping pentaphenyl-CpH derivative than a pentabenzocorannulene. Swap out Cp− by the isolelectronic pyrrole and it becomes clear that pentabenzoazacorannulene is also

Advances in the use of metal-free tetrapyrrolic macrocycles as catalysts

• Mandeep K. Chahal

Beilstein J. Org. Chem. 2024, 20, 3085–3112, doi:10.3762/bjoc.20.257

• these are porphyrins, chlorins, porphyrazines, bacteriochlorins, corroles, calix[4]pyrroles, and phthalocyanines. One of the major differences between these pyrrolic macrocycles is how the adjacent pyrrole rings are connected. The most widely studied tetrapyrrolic macrocycles are typically π‐conjugated

• with porphyrins, the direct linkage between their pyrrole units leads to a more contracted cavity compared to that of porphyrins. Similar to calix[4]pyrroles, synthetic metallo- and free-base (metal-free) porphyrins find various applications in the fields of medicine, energy, catalysis, molecular

• free-base) macrocycles have not been explored as much in terms of catalysis, even though they are starting compounds for the preparation of their metallated analogues that are commonly used as catalysts. In contrast with a calix[4]pyrrole macrocycle with four NHs (from four pyrrole units), a metal-free

Synthesis of fluorinated acid-functionalized, electron-rich nickel porphyrins

• Mike Brockmann,
• Jonas Lobbel,
• Lara Unterriker and
• Rainer Herges

Beilstein J. Org. Chem. 2024, 20, 2954–2958, doi:10.3762/bjoc.20.248

• –CH2–(CF2)n–COOCH3 (n = 2,4,6, Tf = triflate) were synthesized. The triflates were reacted with 2-hydroxy-3,4,5-trimethoxybenzaldehyde via Williamson ether syntheses. The resulting electron-rich compounds were used as aldehydes in the Rothemund reaction with pyrrole to form ester-substituted porphyrins

• porphyrins with Ni(acac)2; c) ester hydrolysis to generate the free acids 32, 33, and 34. Conditions: a) 1) 22/23/24, TFA, abs. DCM, N2, reflux, 30 min, 2) pyrrole, reflux, 2.5 h, 3) DDQ, reflux, 2 h; b) Ni(acac)2, toluene, reflux, 20 h; c) 1) LiOH, MeOH, rt, 1 h, 2) HCl. Supporting Information Supporting

Synthesis of pyrrole-fused dibenzoxazepine/dibenzothiazepine/triazolobenzodiazepine derivatives via isocyanide-based multicomponent reactions

• Marzieh Norouzi,
• Mohammad Taghi Nazeri,
• Ahmad Shaabani and
• Behrouz Notash

Beilstein J. Org. Chem. 2024, 20, 2870–2882, doi:10.3762/bjoc.20.241

• .20.241 Abstract An efficient and facile synthesis of pyrrole-fused dibenzoxazepine/dibenzothiazepine/triazolobenzodiazepine derivatives was developed through the isocyanide-based multicomponent reaction of isocyanides, gem-diactivated olefins, and cyclic imines such as dibenzoxazepine, dibenzothiazepine

• great attention in biomedical applications, clinical diagnostics, and conjugate materials. Keywords: cyclic imines; dibenzothiazepine; dibenzoxazepine; isocyanides; multicomponent reactions; pyrrole; triazolobenzodiazepine; Introduction Pyrroles and their derivatives are important N-heterocyclic

• , benzoxazepine, and benzothiazepine derivatives are especially important. These consitute the central core of many natural and biological compounds and commercial drugs, including diazepam, clonazepam, lorazepam, telenzepine, chlordiazepoxide, loxapine, and amoxapine [13][14][15][16][17][18][19][20][21]. Pyrrole

C–C Coupling in sterically demanding porphyrin environments

• Liam Cribbin,
• Brendan Twamley,
• Nicolae Buga,
• John E. O’ Brien,
• Raphael Bühler,
• Roland A. Fischer and
• Mathias O. Senge

Beilstein J. Org. Chem. 2024, 20, 2784–2798, doi:10.3762/bjoc.20.234

• alternatively by core protonation, whereby all four-core nitrogen atoms are protonated to produce the diacid [12][13]; these diacids can tilt the pyrrole rings 20–40° [14] from the mean-porphyrin plane. Norvaiša et al. showed that a saddle-shaped porphyrin as a dodecasubstituted diacid can bind anions via two

• , 12, and 13 had to be synthesized (Scheme 1). The synthetic route to achieve OET-xBrPPs (2,3,7,8,12,13,17,18-octaethyl-5,10,15,20-tetra(x-bromo)phenylporphyrin, where x = ortho/meta/para) pyrrole 7 was synthesized through literature procedures [40][41]. Pyrrole 7 was then subjected to condensation

• Figure 3. Furthermore, the mean pyrrole ring tilt increases by 3–5° in the case of compounds 28 and 29 compared to that of compound 26. Saddle-shape distortion is reduced compared to that of biphenyl 26; this may be due to the proximity of the anthracene moiety to the β-ethyl positions, with C23–C14B

Copper-catalyzed yne-allylic substitutions: concept and recent developments

• Shuang Yang and
• Xinqiang Fang

Beilstein J. Org. Chem. 2024, 20, 2739–2775, doi:10.3762/bjoc.20.232

• substituted pybox ligand (Scheme 28, 26a–m). The thiophene unit of the carbonate could also be replaced by benzothiophene (Scheme 28, 26h) or furan (Scheme 28, 26m), and pyrrole (Scheme 28, 26j), phenol (Scheme 28, 26k); coumarin derivative (Scheme 28, 26n), and dibenzylamine (Scheme 28, 24a) could also

• ethynylethylene carbonates and copper catalysts (Scheme 37). He et al. [77] completed formal [4 + 1] and [4 + 2] annulations and obtained two types of seldomly studied heterocycles of thieno[2,3-c]pyrrole (Scheme 38, 36a–j) and thieno[2,3-d]pyridazine (Scheme 39, 38a–h) in high yields. It is worth noting that the

• yne-allylic sulfonylation. Proposed mechanism of yne-allylic sulfonylation. Aymmetric yne-allylic substitutions using indoles and indolizines. Double yne-allylic substitutions using pyrrole. Proposed mechanism of yne-allylic substitution using electron-rich arenes. Aymmetric yne-allylic

Interaction of a pyrene derivative with cationic [60]fullerene in phospholipid membranes and its effects on photodynamic actions

• Hayato Takagi,
• Çetin Çelik,
• Ryosuke Fukuda,
• Qi Guo,
• Tomohiro Higashino,
• Hiroshi Imahori,
• Yoko Yamakoshi and
• Tatsuya Murakami

Beilstein J. Org. Chem. 2024, 20, 2732–2738, doi:10.3762/bjoc.20.231

• generation of ROS by catC60 in the absence or presence of PyBA. As spin trapping reagents for the singlet oxygen (1O2), hydroxyl radical (•OH) and superoxide radical anion (O2•–); 2,2,6,6,-tetramethyl-4-piperidone (4-oxo-TEMP), 3,4-dihydro-2,3-dimethyl-2H-pyrrole 1-oxide (DMPO), and 5-(diethoxyphosphoryl)-5

• µM, PyBA 67 µM, and 4-oxo-TEMP 100 μM, in PBS(–) under irradiation for 30 min by blue LED lamp. (b) X-band ESR spectra of 3,4-dihydro-2,3-dimethyl-2H-pyrrole 1-oxide (DMPO) adduct with •OH generated by catC60 under irradiation by a blue LED. Experimental conditions: (i) catC60 5 µM, β-nicotinamide

Deuterated reagents in multicomponent reactions to afford deuterium-labeled products

• Kevin Schofield,
• Shayna Maddern,
• Yueteng Zhang,
• Grace E. Mastin,
• Rachel Knight,
• Wei Wang,
• James Galligan and
• Christopher Hulme

Beilstein J. Org. Chem. 2024, 20, 2270–2279, doi:10.3762/bjoc.20.195

• aldehyde [10]. Latterly, Yamamoto utilized a 90% deuterated [D2]-isocyanide in a copper catalyzed [3 + 2] cycloaddition to afford a 60% deuterated [D2]-pyrrole [11]. The utility of the Leuckart–Wallach reaction towards the generation of isocyanides was first explored by Dömling [12], yet the use of such

Novel truxene-based dipyrromethanes (DPMs): synthesis, spectroscopic characterization and photophysical properties

• Shakeel Alvi and
• Rashid Ali

Beilstein J. Org. Chem. 2024, 20, 2163–2170, doi:10.3762/bjoc.20.186

• for diverse applications in future studies. Keywords: condensation; co-timerization; dipyrromethane; Friedel–Crafts acylation; heterocycles; pyrrole; truxene; Introduction The scaffold of truxene (10,15‐dihydro‐5H‐diindeno[1,2‐a;1′,2′‐c]fluorene) and its congeners comprises three fluorene subunits

• truxenes with freshly distilled pyrrole using trifluoroacetic acid (TFA) as an acidic catalyst afforded the anticipated DPM-appended truxene derivatives (14, 16 and 18) in good yields (60–80%). All the newly prepared DPM-linked truxene-hybrid molecules as well as the intermediate acetylated truxene

• General: All the reagents/solvents were purchased from commercial suppliers (Sigma-Aldrich, Alfa Aesar, TCI, GLR innovation, Avera, Spectrochem and Across), and used without further purification. Solvents were dried according to standard reported procedures. Pyrrole was used after a fresh distillation

Allostreptopyrroles A–E, β-alkylpyrrole derivatives from an actinomycete Allostreptomyces sp. RD068384

• Marwa Elsbaey,
• Naoya Oku,
• Mohamed S. A. Abdel-Mottaleb and
• Yasuhiro Igarashi

Beilstein J. Org. Chem. 2024, 20, 1981–1987, doi:10.3762/bjoc.20.174

• , copolymerized β-alkylpyrroles are among the most investigated organic materials for their enhanced physical and electrochemical properties [4][5]. Accordingly, chemists have focused on developing selective synthetic strategies for the construction of β-alkylpyrroles [1]. While the pyrrole nucleus is featured in

• many marine natural products [6][7], pyrroles substituted with long hydrocarbon chains (pyrrole lipids) are seldomly isolated, and their presence is limited to certain marine organisms [8]. A series of 3-alkylpyrrole-2-carbaldehydes/carboxylic acid/methylcarboxylate was reported from the marine sponge

• metabolites, and most of them are pyrroloterpenes from Streptomyces (Figure 1 and Figure S54 in Supporting Information File 1). Examples include pyrrolostatin [12] and its congener geranylpyrrol A [13], bearing a carboxylic group at the C2 and a geranyl group at the C4 position of the pyrrole ring, and their

Radical reactivity of antiaromatic Ni(II) norcorroles with azo radical initiators

• Siham Asyiqin Shafie,
• Ryo Nozawa,
• Hideaki Takano and
• Hiroshi Shinokubo

Beilstein J. Org. Chem. 2024, 20, 1967–1972, doi:10.3762/bjoc.20.172

• through denitrogenation of AIBN, is closer to the HOMO level of Ni(II) norcorrole 1 (−4.68 eV) rather than its LUMO (−3.16 eV). This result explains the selective addition of the electrophilic isobutyronitrile radical to the distal α-position of the pyrrole unit. The calculated molecular orbital

• coefficient of the HOMO indicates that two α-carbon atoms of the pyrrole subunits are the most reactive positions for electrophilic species. In addition, the distal α-carbon atom relative to the meso-position could be more reactive than the proximal α-carbon atom due to the steric hindrance of bulky mesityl

• groups. Consequently, the isobutyronitrile radical predominantly attacks the distal α-carbon atom relative to the meso-position to afford the corresponding radical intermediate I. The calculated spin density of radical I revealed a substantial radical character at the α-position of the pyrrole skeleton

A new platform for the synthesis of diketopyrrolopyrrole derivatives via nucleophilic aromatic substitution reactions

• Vitor A. S. Almodovar and
• Augusto C. Tomé

Beilstein J. Org. Chem. 2024, 20, 1933–1939, doi:10.3762/bjoc.20.169

• Micromass Q-TOF-2TM mass spectrometer and CHCl3 as the solvent. The NMR, absorption and emission spectra of the new compounds are shown in Supporting Information File 1. Synthesis 3,6-Bis(4-chlorophenyl)-2,5-bis(pentafluorobenzyl)-2,5-dihydropyrrolo[3,4-c]pyrrole-1,4-dione (2) A suspension of DPP 1 (1 g

2-Heteroarylethylamines in medicinal chemistry: a review of 2-phenethylamine satellite chemical space

• Carlos Nieto,
• Alejandro Manchado,
• Ángel García-González,
• David Díez and
• Narciso M. Garrido

Beilstein J. Org. Chem. 2024, 20, 1880–1893, doi:10.3762/bjoc.20.163

• 2-aminoethylpyrrole (Scheme 7) hits were elaborated and tested in a stopped-flow CO2 hydrase assay. Comparing this pyrrole family with original histamine inferred a decrease in selectivity towards the hCA VII isoform, while activity was not affected significantly. Tryptamine derivatives, i.e

The Groebke–Blackburn–Bienaymé reaction in its maturity: innovation and improvements since its 21st birthday (2019–2023)

• Cristina Martini,
• Muhammad Idham Darussalam Mardjan and
• Andrea Basso

Beilstein J. Org. Chem. 2024, 20, 1839–1879, doi:10.3762/bjoc.20.162

• intramolecular nucleophilic addition of the secondary amines to the internal alkyne was expected to occur, forming a new pyrrole ring in 93 through a 5-endo-dig cyclization. Unexpectedly, they observed the generation of 95 with a new pyridine ring. The authors proposed that the benzylamine unit of 92 was

Hetero-polycyclic aromatic systems: A data-driven investigation of structure–property relationships

• Sabyasachi Chakraborty,
• Eduardo Mayo Yanes and
• Renana Gershoni-Poranne

Beilstein J. Org. Chem. 2024, 20, 1817–1830, doi:10.3762/bjoc.20.160

• in size, composition, and aromatic character: benzene, pyridine, pyrazine, borinine, 1,4-diborinine, 1,4-dihydro-1,4-diborinine, borole, pyrrole, furan, thiophene, and cyclobutadiene (Figure 1A). These building blocks encompass 6-, 5-, and 4-membered rings with aromatic and antiaromatic character

• pronounced for pyrazine than pyridine). Conversely, the five-membered ring (pyrrole) shifts it to the right and upwards, maintaining a similar HOMO range to COMPAS-1, but extending into much higher LUMO values. The behavior of the various N-containing rings is well documented in the literature [17][44][45

• findings, however they also reveal additional information. Primarily, these plots demonstrate the cumulative effect of incorporating multiple rings. Furthermore, the slopes of the lines indicate the strength of the effects – e.g., it can be seen clearly that pyrrole has a much stronger effect on the HOMO

Ugi bisamides based on pyrrolyl-β-chlorovinylaldehyde and their unusual transformations

• Alexander V. Tsygankov,
• Vladyslav O. Vereshchak,
• Tetiana O. Savluk,
• Serhiy M. Desenko,
• Valeriia V. Ananieva,
• Oleksandr V. Buravov,
• Yana I. Sakhno,
• Svitlana V. Shishkina and
• Valentyn A. Chebanov

Beilstein J. Org. Chem. 2024, 20, 1773–1784, doi:10.3762/bjoc.20.156

• University, Svobody sq., 4, 61022, Kharkiv, Ukraine 10.3762/bjoc.20.156 Abstract By one-pot four- and three-component Ugi reactions involving convertible isocyanides and unexplored pyrrole-containing β-chlorovinylaldehyde, a small library of 20 bisamides with unusual behavior in post-Ugi transformations was

• ; post-Ugi transformation; pyrrole derivative; Ugi reaction; Introduction One of the keys to the development of mankind is the constant search for new substances and advanced materials. Today, we have powerful tools at our disposal that allow us to create entire libraries of structurally complex organic

• , azomethines based on aromatic amines and substituted pyrrolecarbaldehyde [40] or pyrrolyl-β-chlorovinylaldehyde [39], contain several frequently encountered motifs in drugs and drug candidates – a pyrrole heterocycle and an azomethine C=N fragment (Figure 1) – and exhibit some biological activity. Thus, Ugi

Harnessing unprotected deactivated amines and arylglyoxals in the Ugi reaction for the synthesis of fused complex nitrogen heterocycles

• Javier Gómez-Ayuso,
• Pablo Pertejo,
• Tomás Hermosilla,
• Israel Carreira-Barral,
• Roberto Quesada and
• María García-Valverde

Beilstein J. Org. Chem. 2024, 20, 1758–1766, doi:10.3762/bjoc.20.154

• acid, indole-2-carboxylic acid, pyrrole-2-carboxylic acid or N-phenylglycine has allowed the use of these compounds in the Ugi reaction without triggering competitive reactions. The additional functional group present in the resulting Ugi adduct can be leveraged in different post-condensation

• strategy with aromatic amines [24], pyrrole-2-carboxylic acid and N-phenylglycine, and carried out their reactions with arylglyoxals, alkylamines and isocyanides (Scheme 5). As we expected, the cyclization product 9 was observed, although the complete cyclization of the Ugi adduct, found as the enol

• tautomer, needed the addition of hydrochloric acid (1 equiv) in the case of the tert-butylamine derivatives. However, the nature of the cyclization product depended on the carboxylic acid employed in the Ugi reaction. Thus, the indole and pyrrole derivatives yielded the corresponding hemiaminal 9 as a

Polymer degrading marine Microbulbifer bacteria: an un(der)utilized source of chemical and biocatalytic novelty

• Weimao Zhong and
• Vinayak Agarwal

Beilstein J. Org. Chem. 2024, 20, 1635–1651, doi:10.3762/bjoc.20.146

• together with genes encoding the production of polybrominated pyrroles [138][139][140]. The Microbulbifer BGCs lack genes for brominated pyrrole biosynthesis and polybrominated pyrroles have not been reported to be produced by Microbulbifer bacteria. Future studies looking at the evolutionary relationship

Synthetic applications of the Cannizzaro reaction

• Bhaskar Chatterjee,
• Dhananjoy Mondal and
• Smritilekha Bera

Beilstein J. Org. Chem. 2024, 20, 1376–1395, doi:10.3762/bjoc.20.120

• an aldol transformation to the final product. Bruckner and coworkers synthesized pyrrole-modified porphyrin ring systems from secochlorin bisaldehydes, representing an interesting application of the intramolecular Cannizzaro reaction. Subjecting the bisaldehyde 92 to basic conditions using Et4NOH

Diameter-selective extraction of single-walled carbon nanotubes by interlocking with Cu-tethered square nanobrackets

• Guoqing Cheng and
• Naoki Komatsu

Beilstein J. Org. Chem. 2024, 20, 1298–1307, doi:10.3762/bjoc.20.113

• @(12,2)-SWNT complexes. Chemical structures of Cu-tethered tetragonal nanobrackets 1a and 1b. Synthesis of nanobracket 4. Reaction conditions: i) XPhos Pd G2, XPhos, B2(OH)4, KOAc, EtOH, 80 °C, 2 h; ii) Br-Ar-Br, K2CO3, tetrahydrofuran (THF)/toluene, 80 °C, 16 h; iii) trifluoroacetic acid (TFA), pyrrole

The Ugi4CR as effective tool to access promising anticancer isatin-based α-acetamide carboxamide oxindole hybrids

• Carolina S. Marques,
• Aday González-Bakker and
• José M. Padrón

Beilstein J. Org. Chem. 2024, 20, 1213–1220, doi:10.3762/bjoc.20.104

• alkene 2j carboxylic acids were used successfully in this MCR, demonstrating a great reaction scope (Scheme 2 and Figure 2). Remarkably, the best yields were obtained when heterocyclic carboxylic acid components like 1H-pyrrole-3-carboxylic acid (2n), 2-furoic acid (2o) and 5-nitrofuran-2-carboxylic acid

• , 72, 74 and 84% yield, respectively. An exception was noticed for N-heterocycle units (pyridine and 1H-pyrrole) substituted in the same position, since compounds 8g, 8l and 8i were obtained in 56, 51 and 36% yield, respectively. The 1,2,3-triazole hybrid isatin compound 8n was obtained in 56% yield

Manganese-catalyzed C–C and C–N bond formation with alcohols via borrowing hydrogen or hydrogen auto-transfer

• Mohd Farhan Ansari,
• Atul Kumar Maurya,
• Abhishek Kumar and
• Saravanakumar Elangovan

Beilstein J. Org. Chem. 2024, 20, 1111–1166, doi:10.3762/bjoc.20.98

• pyrrole synthesis under the same reaction conditions. In 2019, Rueping, El-Sepelgy and co-workers achieved the sustainable multicomponent synthesis of pyrroles from readily available substrates catalyzed by manganese-pincer complex Mn12 [96]. The use of 2 mol % of Mn12 in combination with a catalytic