Enabling artificial photosynthesis systems with molecular recycling: A review of photo- and electrochemical methods for regenerating organic sacrificial electron donors

• Grace A. Lowe

Beilstein J. Org. Chem. 2023, 19, 1198–1215, doi:10.3762/bjoc.19.88

• predominantly earth-abundant materials. The recycling of NADH analogues has been carried out using precious metal complexes, such as [CpRh(bpy)(H2O)]2+ [47]. This rhodium complex was adhered to a photoelectrode in a photoelectrochemical cell which also contained a second photoelectrode functionalized with a set

Synthesis of aliphatic nitriles from cyclobutanone oxime mediated by sulfuryl fluoride (SO₂F₂)

• Xian-Lin Chen and
• Hua-Li Qin

Beilstein J. Org. Chem. 2023, 19, 901–908, doi:10.3762/bjoc.19.68

• of novel synthetic methods and strategies toward nitrile group construction continues to be a focus for synthetic chemists. The cross-coupling reactions of C–C bonds catalyzed by transition-metal complexes play a crucial role in modern organic synthesis, as they make it feasible to synthesize complex

Pyridine C(sp²)–H bond functionalization under transition-metal and rare earth metal catalysis

• Haritha Sindhe,
• Malladi Mounika Reddy,
• Karthikeyan Rajkumar,
• Akshay Kamble,
• Amardeep Singh,
• Anand Kumar and
• Satyasheel Sharma

Beilstein J. Org. Chem. 2023, 19, 820–863, doi:10.3762/bjoc.19.62

• . In the same year, Tsurugi and Mashima reported the use of rare earth metal complexes for the insertion of nonpolar unsaturated substrates (C=N) into the ortho-C–H bond of pyridine derivatives [54]. They carried out the C–H aminoalkylation of pyridines 1 using yttrium complex 26 with nonactivated

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

• ). Carbamoylation of 151 gives the intermediate oxcarbazepine 152, whereafter hydrolysis of the methyl enol ether affords oxcarbazepine (153) [32][56]. 6.2.2 Ring functionalisation: Weng et al. [80] reported the synthesis of dihydrodibenzo[b,f]azepine (2a)-based pincer ligands for Rh and Ir metal complexes. The

Direct C2–H alkylation of indoles driven by the photochemical activity of halogen-bonded complexes

• Martina Mamone,
• Giuseppe Gentile,
• Jacopo Dosso,
• Maurizio Prato and
• Giacomo Filippini

Beilstein J. Org. Chem. 2023, 19, 575–581, doi:10.3762/bjoc.19.42

• on noble metal complexes has been constantly declined over recent years due to cost, availability, and toxicity, therefore discouraged by the modern guidelines towards implementation of sustainable chemical production schemes [6]. In the last decades, organic photochemistry has become a prominent

A new oxidatively stable ligand for the chiral functionalization of amino acids in Ni(II)–Schiff base complexes

• Alena V. Dmitrieva,
• Oleg A. Levitskiy,
• Yuri K. Grishin and
• Tatiana V. Magdesieva

Beilstein J. Org. Chem. 2023, 19, 566–574, doi:10.3762/bjoc.19.41

• employing chiral auxiliaries [4][5] and asymmetric phase-transfer catalysis [6][7]. The former approach is commonly based on the application of chiral derivatives of glycine containing structurally diverse chiral auxiliaries, both cyclic [8][9][10][11] and acyclic [12][13]. Transition-metal complexes

Mechanochemical solid state synthesis of copper(I)/NHC complexes with K₃PO₄

• Ina Remy-Speckmann,
• Birte M. Zimmermann,
• Mahadeb Gorai,
• Martin Lerch and
• Johannes F. Teichert

Beilstein J. Org. Chem. 2023, 19, 440–447, doi:10.3762/bjoc.19.34

• to the wide area of applications of mechanochemical synthesis but also showcase that transition metal complexes bearing additional functional groups can be prepared with a ball milling synthesis. We think that our protocol could be useful for the atom economic preparation of other complex catalysts

Cyclometalated iridium complexes-catalyzed acceptorless dehydrogenative coupling reaction: construction of quinoline derivatives and evaluation of their antimicrobial activities

• Hongling Shui,
• Yuhong Zhong,
• Renshi Luo,
• Zhanyi Zhang,
• Jiuzhong Huang,
• Ping Yang and
• Nianhua Luo

Beilstein J. Org. Chem. 2022, 18, 1507–1517, doi:10.3762/bjoc.18.159

• as raw material. In order to solve such problems, chemists have developed ADC reactions catalyzed by metal complexes (such as Ir [18][19], Ru [20][21][22][23][24], Re [25], Mn [26][27], Pd [28], Ni [29], Cu [30], etc.) to synthesize quinolines using o-aminobenzyl alcohol as starting material. ADC

1,4,6,10-Tetraazaadamantanes (TAADs) with N-amino groups: synthesis and formation of boron chelates and host–guest complexes

• Artem N. Semakin,
• Ivan S. Golovanov,
• Yulia V. Nelyubina and
• Alexey Yu. Sukhorukov

Beilstein J. Org. Chem. 2022, 18, 1424–1434, doi:10.3762/bjoc.18.148

• as synthetic receptors to form host–guest complexes based on H-bond interactions with amide/carbamoyl groups [31][32]. In addition, N-TAADs can be viewed as analogs of hexahydrazide ligands, which were reported to stabilize high-valent metal complexes [33][34]. Since N-amino groups can be easily

Ionic multiresonant thermally activated delayed fluorescence emitters for light emitting electrochemical cells

• Merve Karaman,
• Abhishek Kumar Gupta,
• Subeesh Madayanad Suresh,
• Tomas Matulaitis,
• Lorenzo Mardegan,
• Daniel Tordera,
• Henk J. Bolink,
• Sen Wu,
• Stuart Warriner,
• Ifor D. Samuel and
• Eli Zysman-Colman

Beilstein J. Org. Chem. 2022, 18, 1311–1321, doi:10.3762/bjoc.18.136

• and emission takes place within the intrinsic region [2][3][4][5][6]. Two families of widely investigated emitters for LEECs are ionic transition metal complexes (iTMCs) [7][8][9][10] and conjugated polymers (CPs) [4]. From the early use of ruthenium(II) complexes, a significant amount of research has

• focussed on developing high-performance iTMC-based LEECs [11][12], with iridium(III) complexes typically showing the greatest potential. A detracting feature of many iTMC LEECs is the use of scarce noble metal complexes. Despite the enormous number of low molecular weight organic emitters designed for use

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

• investigated and the denitrogenative annulation towards imidazoloquinoxalines could be observed as a competing reaction depending on the alkyne concentration and the substitutions at the quinoxaline. Keywords: click reaction; CuAAC; denitrogenative annulation; imidazole; metal complexes; quinoxaline

• diversity of metal complexes incorporating 1,2,3-triazoles as ligands have been reported [16][17][18]. Triazole ligands with N-heterocycles such as Pyta (4-(2-pyridyl)-1,2,3-triazole) and related structures were employed to obtain novel metal complexes as catalysts [19][20] and imaging probes [21], as well

• -diisopropylethylamine; OLED, organic-light emitting diode; SCE, saturated calomel electrode; TADF, thermally activated delayed fluorescence; TEMPO, 2,2,6,6-tetramethylpiperidinyloxyl; TIQ, triazoloimidazoquinoxaline. UV–vis absorption spectra of the obtained metal complexes (18 µM solutions) in acetonitrile at 20 °C

Post-synthesis from Lewis acid–base interaction: an alternative way to generate light and harvest triplet excitons

• Hengjia Liu and
• Guohua Xie

Beilstein J. Org. Chem. 2022, 18, 825–836, doi:10.3762/bjoc.18.83

• are fluorescent compounds. Based on the spin statistics, the fluorescent emitters can only use singlet excitons for light generation [5]. In contrast, phosphorescent materials based on metal complexes could achieve a high internal quantum efficiency (IQE) up to 100% through intersystem crossing (ISC

Inductive heating and flow chemistry – a perfect synergy of emerging enabling technologies

• Conrad Kuhwald,
• Sibel Türkhan and
• Andreas Kirschning

Beilstein J. Org. Chem. 2022, 18, 688–706, doi:10.3762/bjoc.18.70

• reaction. Reactions with soluble metal complexes or metal nanoparticles, utilized in transition-metal catalysis, are often avoided, especially if the metal contamination in the product exceeds certain limits. This is particularly true for the pharmaceutical industry. A continuous flow protocol for

Menadione: a platform and a target to valuable compounds synthesis

• Acácio S. de Souza,
• Ruan Carlos B. Ribeiro,
• Dora C. S. Costa,
• Fernanda P. Pauli,
• David R. Pinho,
• Matheus G. de Moraes,
• Fernando de C. da Silva,
• Luana da S. M. Forezi and
• Vitor F. Ferreira

Beilstein J. Org. Chem. 2022, 18, 381–419, doi:10.3762/bjoc.18.43

• (Scheme 24). Tang and co-workers described the synthesis of thiosemicarbazone 80 from menadione (10) through a condensation reaction with thiosemicarbazide (79), which was used as a ligand in the synthesis of metal complexes using different transition metals, in refluxing ethanol (Scheme 25) [125

Synthesis of piperidine and pyrrolidine derivatives by electroreductive cyclization of imine with terminal dihaloalkanes in a flow microreactor

• Yuki Naito,
• Naoki Shida and
• Mahito Atobe

Beilstein J. Org. Chem. 2022, 18, 350–359, doi:10.3762/bjoc.18.39

• which realizes for the construction of medium-sized saturated nitrogen heterocycles [21]. Although the process enables the rapid construction of saturated nitrogen heterocycles from acyclic precursors, it requires homogeneous precious transition metal complexes as photocatalysts. On the other hand

New advances in asymmetric organocatalysis

• Radovan Šebesta

Beilstein J. Org. Chem. 2022, 18, 240–242, doi:10.3762/bjoc.18.28

• undoubtedly the most efficient way to prepare chiral compounds that our society requires as medicines, materials, or crop protecting agents. Traditionally, enzymes and metal complexes with chiral ligands served as the main type of enantioselective catalysts. Even though small chiral organic compounds have

Earth-abundant 3d transition metals on the rise in catalysis

• Nikolaos Kaplaneris and
• Lutz Ackermann

Beilstein J. Org. Chem. 2022, 18, 86–88, doi:10.3762/bjoc.18.8

• industries as one of the most powerful methods for molecular assembly. With regard to the cost of goods and the allowance of trace metal impurities in medicinally relevant compounds, 3d transition metal complexes, such as those of iron, copper, cobalt or nickel, represent exciting, more sustainable

Biological properties and conformational studies of amphiphilic Pd(II) and Ni(II) complexes bearing functionalized aroylaminocarbo-N-thioylpyrrolinate units

• Samet Poyraz,
• Samet Belveren,
• Sabriye Aydınoğlu,
• Mahmut Ulger,
• Abel de Cózar,
• Maria de Gracia Retamosa,
• Jose M. Sansano and
• H. Ali Döndaş

Beilstein J. Org. Chem. 2021, 17, 2812–2821, doi:10.3762/bjoc.17.192

• ; Introduction In recent years, metal complexes with biological activity are of paramount relevance in medicine as valuable alternatives for the classical pharmaceuticals based on organic compound scaffolds. In this line, metal complexes incorporating an amphiphilic character (also called metallosurfactants

• ligands that could coordinate several metal centers with the aid of sulfur, nitrogen or oxygen donor atoms that allow multiple bindings [13]. Moreover, compounds bearing a –C(O)NHC(S)– moiety and their metal complexes have assorted biological and pharmacological properties such as anti(myco)bacterial

Photophysical, photostability, and ROS generation properties of new trifluoromethylated quinoline-phenol Schiff bases

• Inaiá O. Rocha,
• Yuri G. Kappenberg,
• Wilian C. Rosa,
• Clarissa P. Frizzo,
• Nilo Zanatta,
• Marcos A. P. Martins,
• Isadora Tisoco,
• Bernardo A. Iglesias and
• Helio G. Bonacorso

Beilstein J. Org. Chem. 2021, 17, 2799–2811, doi:10.3762/bjoc.17.191

• electron-withdrawing group that enhances the effects of many bioactive molecules due to a significant improvement in stability, lipophilicity, and resistance to enzymatic degradation [17][18]. Also, it has been widely applied as a special alkyl substituent for ligands of phosphorescent heavy metal

• complexes in OLEDs. Due to the ability to increase the electron transport and decrease molecule stacking, trifluoromethyl-substituted molecules have been employed to the development of phosphorescent materials [19][20][21]. On the other hand, antioxidants are known for protecting organisms against cell

Visible-light-mediated copper photocatalysis for organic syntheses

• Yajing Zhang,
• Qian Wang,
• Zongsheng Yan,
• Donglai Ma and
• Yuguang Zheng

Beilstein J. Org. Chem. 2021, 17, 2520–2542, doi:10.3762/bjoc.17.169

• organic dyes and metal complexes have been investigated [10][11][12]. Photoredox catalysts have been initially applied to organic reactions, but they are now used for complicated organic processes [13]. As photocatalysts, organic dyes have the advantages of having a low price and not containing metals

In-depth characterization of self-healing polymers based on π–π interactions

• Josefine Meurer,
• Julian Hniopek,
• Johannes Ahner,
• Michael Schmitt,
• Jürgen Popp,
• Stefan Zechel,
• Kalina Peneva and
• Martin D. Hager

Beilstein J. Org. Chem. 2021, 17, 2496–2504, doi:10.3762/bjoc.17.166

• ]. This specific process is based on reversible interactions, which are integrated in the chemical structure of the proteins of the thread [5]. Zinc–histidine metal complexes which are part of the protein’s structure enable the material to regenerate its mechanical performance after a damage event [1][6

A visible-light-induced, metal-free bis-arylation of 2,5-dichlorobenzoquinone

• Pieterjan Winant and
• Wim Dehaen

Beilstein J. Org. Chem. 2021, 17, 2315–2320, doi:10.3762/bjoc.17.149

• multistep procedures requiring large amounts of toxic metal complexes [12][33][34]. Later improvements still demand prefunctionalization of the quinone substrate [35][36][37]. While effectively eliminating this requirement, CH bis-arylation using palladium complexes still suffers from regioselectivity

Cerium-photocatalyzed aerobic oxidation of benzylic alcohols to aldehydes and ketones

• Girish Suresh Yedase,
• Sumit Kumar,
• Jessica Stahl,
• Burkhard König and
• Veera Reddy Yatham

Beilstein J. Org. Chem. 2021, 17, 1727–1732, doi:10.3762/bjoc.17.121

• acting as the terminal oxidant [13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33]. Most aerobic oxidation reactions utilize either metal complexes and nanoparticles or persistent radical reagents as catalysts [21]. In the past ten years, visible light-induced

Methodologies for the synthesis of quaternary carbon centers via hydroalkylation of unactivated olefins: twenty years of advances

• Thiago S. Silva and
• Fernando Coelho

Beilstein J. Org. Chem. 2021, 17, 1565–1590, doi:10.3762/bjoc.17.112

• , numerous hydroalkylation methodologies have emerged that have explored the diverse reactivity patterns of the olefin double bond. This review presents examples of olefins acting as electrophilic partners when coordinated with electrophilic transition-metal complexes or, in more recent approaches, when used

• . The efficiency of the solvent radical cage in maintaining the geminate radical pair could be modulated by stereoelectronic changes in the ligands of the transition-metal complexes to favor a desired pathway. One reaction particularity that was sensible to the solvent cage efficiency was the

Free-radical cyclization approach to polyheterocycles containing pyrrole and pyridine rings

• Ivan P. Mosiagin,
• Olesya A. Tomashenko,
• Dar’ya V. Spiridonova,
• Mikhail S. Novikov,
• Sergey P. Tunik and
• Alexander F. Khlebnikov

Beilstein J. Org. Chem. 2021, 17, 1490–1498, doi:10.3762/bjoc.17.105

• ). It is important that the reaction of iodide 1m with 2-pyridyl substituent gave a good yield of the product 3m, which could be used for the preparation of bidentate ligand for metal complexes. Reaction of salts 1 with electron-donating para-substituents (Me, MeO, Me2N) in the pyridine ring (1n–p,s

• metal-catalyzed arylation [17][18][19]. We have recently successfully applied this approach to synthesize the new luminescent heterocyclic system pyrido[2,1-a]pyrrolo[3,2-c]isoquinoline A [17], which turned out to be useful for bioimaging [13] and as a ligand for the preparation of luminescent metal

• complexes, Au(I) [20], Ir(III) [21] and Eu(III) [22] (Scheme 1). According to the calculations, the isomeric pyrido[2,1-a]pyrrolo[3,4-c]isoquinoline system B (Scheme 1) should have no less interesting photophysical properties [17], than skeleton A but its synthesis is still a challenge. In particular