Formaldehyde surrogates in multicomponent reactions

• Cecilia I. Attorresi,
• Javier A. Ramírez and
• Bernhard Westermann

Beilstein J. Org. Chem. 2025, 21, 564–595, doi:10.3762/bjoc.21.45

• this context, quinoline and its derivatives are privileged structures in several natural products and biologically active compounds, rendering this scaffold an important synthetic target. An attractive strategy to afford tetrahydroquinolines and quinolines is the Povarov reaction, a type of aza-Diels

• –Alder reaction between an imine and an alkene (Scheme 6). Very successfully, the multicomponent version of the Povarov reaction using aldehydes, anilines, and alkenes has been explored in a three-component cascade reaction to quinolines [28][29][30][31] (Scheme 6). Furthermore, protocols have been

• separation processes are required [32][35][36]. In this context, DMSO has been used as an alternative to formaldehyde for the MCR synthesis of a wide variety of quinolines and related compounds. For example, Zhang et al. showed that starting from anilines and substituted styrenes while using K2S2O8 for the

Photomechanochemistry: harnessing mechanical forces to enhance photochemical reactions

• Francesco Mele,
• Ana M. Constantin,
• Andrea Porcheddu,
• Raimondo Maggi,
• Giovanni Maestri,
• Nicola Della Ca’ and
• Luca Capaldo

Beilstein J. Org. Chem. 2025, 21, 458–472, doi:10.3762/bjoc.21.33

• -workers in 2022. They reported the photo-thermo-mechanochemical approach for the synthesis of quinolines from sulfoxonium ylides and 2-vinylanilines promoted by an iron(II) phthalocyanine (FeIIPc) photocatalyst (Scheme 3) [65]. First, a mixture of 2-(1-phenylvinyl)aniline (3.1), sulfoxonium ylide 3.2, and

• ]. Photo-thermo-mechanosynthesis of quinolines [65]. Study of the mechanically assisted [2 + 2] photodimerization of chalcone [66]. Liquid-assisted vortex grinding (LAVG) for the synthesis of [2.2]paracyclophane [68]. Photomechanochemical approach for the riboflavin tetraacetate-catalyzed photocatalytic

Heteroannulations of cyanoacetamide-based MCR scaffolds utilizing formamide

• Marios Zingiridis,
• Danae Papachristodoulou,
• Despoina Menegaki,
• Konstantinos G. Froudas and
• Constantinos G. Neochoritis

Beilstein J. Org. Chem. 2025, 21, 217–225, doi:10.3762/bjoc.21.13

• utilized numerous times in medicinal chemistry campaigns as hits, leads and eventually even drugs, such as 2-aminothiophenes, -quinolines and -indoles [42][43][44][45]. Synthetic exploitation The synthesis of the key cyanoacetamide building blocks was our primary objective. In a parallel setup, a variety

Cu(OTf)₂-catalyzed multicomponent reactions

• Sara Colombo,
• Camilla Loro,
• Egle M. Beccalli,
• Gianluigi Broggini and
• Marta Papis

Beilstein J. Org. Chem. 2025, 21, 122–145, doi:10.3762/bjoc.21.7

• the triple bond furnishes the furo-ring and the final oxidation affords the tricyclic product 22. Substituted quinolines 23 were obtained in a convenient solvent-free multicomponent reaction starting from electron-rich or electron-poor anilines, alkyl or arylaldehydes and terminal alkynes, performing

• the C=S bond. The subsequent elimination of H2S afforded the final product (Scheme 30) [48]. Analogously, piperazinylthiazoloquinolines 40 and thiazolocoumarins 41 were obtained using piperazine or piperidine, CS2 and substituted quinolines or coumarins [49]. The synthesis of furo[3,4-b]pyrazolo[4,3-f

• dihydropyrimidines 18. Regioselective synthesis of 1,4-dihydropyridines 20. Synthesis of tetrahydropyridines 21. Synthesis of furoquinoxalines 22. Synthesis of 2,4-substituted quinolines 23. Synthesis of cyclic ether-fused tetrahydroquinolines 24. Practical route for 1,2-dihydroisoquinolines 25. Synthesis of 2,3

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

• products 89 and their subsequent oxidation with DDQ provided axially chiral quinolines 90 (Scheme 29) [53]. Good retention of the stereoinformation acquired in the first transformation, moderate to excellent yields and consistently high degrees of enantiomeric purity were achieved. The reaction could also

Recent advances in transition-metal-free arylation reactions involving hypervalent iodine salts

• Ritu Mamgain,
• Kokila Sakthivel and
• Fateh V. Singh

Beilstein J. Org. Chem. 2024, 20, 2891–2920, doi:10.3762/bjoc.20.243

• olefins, showcasing an efficient utilization of aryliodonium salts in the process. Later in the same year, Song and colleagues reported a protocol for the efficient synthesis of 2-aryl-substituted quinolines 27 and pyridine N-oxides 29 [63]. This reaction involved the selective arylation at the C2

Efficient modification of peroxydisulfate oxidation reactions of nitrogen-containing heterocycles 6-methyluracil and pyridine

• Alfiya R. Gimadieva,
• Yuliya Z. Khazimullina,
• Aigiza A. Gilimkhanova and
• Akhat G. Mustafin

Beilstein J. Org. Chem. 2024, 20, 2599–2607, doi:10.3762/bjoc.20.219

• compounds such as phenols, coumarins, pyridines, pyrimidines, quinolines, and others. This has resulted in the production of numerous valuable products. The reaction's appeal lies in its simplicity and the fact that there is no requirement to protect sensitive functional groups, thus making the introduction

Asymmetric organocatalytic synthesis of chiral homoallylic amines

• Nikolay S. Kondratyev and
• Andrei V. Malkov

Beilstein J. Org. Chem. 2024, 20, 2349–2377, doi:10.3762/bjoc.20.201

• the H-bond-donor association of catalysts 111 to the Cl− ion of the N-acylquinolinium intermediate 108, though a detailed investigation into the mechanism of the enantiodifferentiation has not been carried out (Scheme 22). In total 15 different quinolines were tested. The yields varied in the range of

Catalysing (organo-)catalysis: Trends in the application of machine learning to enantioselective organocatalysis

• Stefan P. Schmid,
• Leon Schlosser,
• Frank Glorius and
• Kjell Jorner

Beilstein J. Org. Chem. 2024, 20, 2280–2304, doi:10.3762/bjoc.20.196

• three different reactions (Figure 11A). Mechanistic model transferability for CPA-catalysed Minisci reactions [125] was utilised for the derivatization of quinolines and pyridines. Models trained on these compound classes show good generalisation towards other nitrogen-containing heteroaromatics

Efficacy of radical reactions of isocyanides with heteroatom radicals in organic synthesis

• Akiya Ogawa and
• Yuki Yamamoto

Beilstein J. Org. Chem. 2024, 20, 2114–2128, doi:10.3762/bjoc.20.182

• aliphatic thiols, hydrogen abstraction reaction by quinoline-2,4-biradical intermediates occurred to give 2,4-hydrogenated quinolines [69]. In the case of aromatic thiols, the ionic cycloaddition reaction proceeds to give 2-thiolated quinoline derivatives. In addition, the aza-Bergman cyclization can be

Harnessing the versatility of hydrazones through electrosynthetic oxidative transformations

• Aurélie Claraz

Beilstein J. Org. Chem. 2024, 20, 1988–2004, doi:10.3762/bjoc.20.175

• engaged aromatic aldehyde-derived NH-tosylhydrazones 83 in an iodide-catalyzed electrochemical formal (3 + 2)-cycloaddition with quinolines 84 to build [1,2,4]triazolo[4,3-a]quinoline derivatives 85. Better yields were obtained with hydrazones bearing an electron-rich substituent on the aromatic ring. The

• -triazoles [49]. Synthesis of 1,3,5-trisubstituted 1,2,4-triazoles [50]. Alternative synthesis of 1,3,5-trisubstituted 1,2,4-triazoles [51]. Synthesis of 5-amino 1,2,4-triazoles [55]. Synthesis of 1-arylpyrazolines [58]. Synthesis of 3‑aminopyrazoles [60]. Synthesis of [1,2,4]triazolo[4,3-a]quinolines [61

Electrocatalytic hydrogenation of cyanoarenes, nitroarenes, quinolines, and pyridines under mild conditions with a proton-exchange membrane reactor

• Koichi Mitsudo,
• Atsushi Osaki,
• Haruka Inoue,
• Eisuke Sato,
• Naoki Shida,
• Mahito Atobe and
• Seiji Suga

Beilstein J. Org. Chem. 2024, 20, 1560–1571, doi:10.3762/bjoc.20.139

• cyanoarenes, nitroarenes, quinolines, and pyridines using a proton-exchange membrane (PEM) reactor was developed. Cyanoarenes were then reduced to the corresponding benzylamines at room temperature in the presence of ethyl phosphate. The reduction of nitroarenes proceeded at room temperature, and a variety of

• pharmaceuticals, and the reductive syntheses of these heterocycles from pyridines and quinolines have been well studied [12]. Although these transformations have been studied intensively, such reductive reactions usually require harsh reaction conditions such as high reaction temperatures and high pressure of

• ]. As mentioned above, there have been several reports on reductive reactions using PEM reactors; however, the application of PEM reactors for precise chemical transformations remains limited. To the best of our knowledge, no reports are available on the efficient reduction of cyanoarenes, quinolines

Synthesis and optical properties of bis- and tris-alkynyl-2-trifluoromethylquinolines

• Stefan Jopp,
• Franziska Spruner von Mertz,
• Peter Ehlers,
• Alexander Villinger and
• Peter Langer

Beilstein J. Org. Chem. 2024, 20, 1246–1255, doi:10.3762/bjoc.20.107

• /bjoc.20.107 Abstract Three bis- or tris-brominated 2-trifluoromethylquinolines have been successfully applied in palladium-catalysed Sonogashira reactions, leading to several examples of alkynylated quinolines in good to excellent yields. Optical properties of selected products have been studied by

• ). Fluorine-containing quinolines and quinolinones are of particular interest, since fluorine atoms are known to enhance the pharmacological properties of organic molecules [7][8][9][10][11][12][13][14][15]. Fluorine atoms act as bioisosteres of hydrogen atoms, while CF3 groups are bioisosteres of hydroxy and

• properties of selected products, bis- and tris-alkynylated quinolines, were studied to gain insights into how the substitution pattern at different positions may alter the optical properties. Results and Discussion The starting material, 4,8-dibromo-2-(trifluoromethyl)quinoline (4), was synthesized from 2

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

• -Alkylation of heterocyclic compounds with alcohols Functionalized heterocyclic compounds are omnipresent structural skeletons in bioactive compounds [82]. Remarkably, the alkylation of indoles and quinolines received significant interest since they are common compounds in pharmaceutical and agrochemical

• industries [83][84][85]. Various manganese catalysts have been reported (Figure 4) for the C-alkylation of heterocyclic compounds with several alcohols, including indoles and quinolines. In 2017, Kirchner’s group established a new method for the aminomethylation of aromatic compounds with secondary amines

Synthesis and biological profile of 2,3-dihydro[1,3]thiazolo[4,5-b]pyridines, a novel class of acyl-ACP thioesterase inhibitors

• Jens Frackenpohl,
• David M. Barber,
• Guido Bojack,
• Birgit Bollenbach-Wahl,
• Ralf Braun,
• Rahel Getachew,
• Sabine Hohmann,
• Kwang-Yoon Ko,
• Karoline Kurowski,
• Bernd Laber,
• Rebecca L. Mattison,
• Thomas Müller,
• Anna M. Reingruber,
• Dirk Schmutzler and
• Andrea Svejda

Beilstein J. Org. Chem. 2024, 20, 540–551, doi:10.3762/bjoc.20.46

• quinolines and indoles [24], pyridines [25], and imines [26], the reactions of 5 and 15c with ammonia borane (3 equiv) in the presence of a catalytic amount of B(C6F5)3 in toluene as an aprotic solvent at a temperature of 80 °C afforded aminoboranes 17b (R1 = F) and 17c (R1 = CH3) as main products along with

Substitution reactions in the acenaphthene analog of quino[7,8-h]quinoline and an unusual synthesis of the corresponding acenaphthylenes by tele-elimination

• Ekaterina V. Kolupaeva,
• Narek A. Dzhangiryan,
• Alexander F. Pozharskii,
• Oleg P. Demidov and
• Valery A. Ozeryanskii

Beilstein J. Org. Chem. 2024, 20, 243–253, doi:10.3762/bjoc.20.24

• quinolines, at the benzene ring, and the resulting nitro compounds could potentially be subjected to further transformations, including nucleophilic substitution of nitro groups. Indeed, under the action of a small excess of the nitrating mixture, dipyridoacenaphthene 5 undergoes double nitration at

Lewis acid-promoted direct synthesis of isoxazole derivatives

• Dengxu Qiu,
• Chenhui Jiang,
• Pan Gao and
• Yu Yuan

Beilstein J. Org. Chem. 2023, 19, 1562–1567, doi:10.3762/bjoc.19.113

• atmosphere, 90 °C, 24 h. Reaction substrate scope of quinolines. Conditions: 1a (0.1 mmol, 1 equiv), 2 (0.2 mmol, 2 equiv), AlCl3 (0.3 mmol, 3 equiv), NaNO2 (1 mmol, 10.0 equiv), DMAc (1.0 mL), N2 atmosphere, 90 °C, 24 h. Gram scale reaction. Control experiments and possible reaction mechanism. Optimization

Non-noble metal-catalyzed cross-dehydrogenation coupling (CDC) involving ether α-C(sp³)–H to construct C–C bonds

• Hui Yu and
• Feng Xu

Beilstein J. Org. Chem. 2023, 19, 1259–1288, doi:10.3762/bjoc.19.94

• source played a key role, with lower yields or no product obtained when the reaction was performed without water or under other light source conditions such as 19 W CFL or irradiation with blue or green LEDs. This method is applicable to various heteroatom-containing compounds such as quinolines

• , pyrazines, pyridines, quinolines, isoquinolines, benzothiazoles, benzoquinones, etc. Under the reaction conditions, various ethers such as 1,4-dioxane, tetrahydropyran, tetrahydrofuran, diethyl ether, etc. are suitable substrates. Immediately thereafter, various photocatalytic catalysts were developed for

Photoredox catalysis harvesting multiple photon or electrochemical energies

• Mattia Lepori,
• Simon Schmid and
• Joshua P. Barham

Beilstein J. Org. Chem. 2023, 19, 1055–1145, doi:10.3762/bjoc.19.81

• and co-workers also demonstrated the synthesis of pyrrolo[1,2-a]quinolines (12) and ullazines (13) from N-arylpyrroles (10) with arylalkynes (11) using Rh-6G (Figure 6) [46]. Additionally, the König group also used Rh-6G as a catalyst for a photo-Arbuzov reaction to generate arylphosphonates (15) from

Aromatic C–H bond functionalization through organocatalyzed asymmetric intermolecular aza-Friedel–Crafts reaction: a recent update

• Anup Biswas

Beilstein J. Org. Chem. 2023, 19, 956–981, doi:10.3762/bjoc.19.72

• -derived ketimines 49 was reported by Vila, Pedro and co-workers. Regioisomeric hydroxyquinolines were tested in this reaction to facilitate the electrophilic aromatic substitution on the ortho-carbon atom with respect to the hydroxy group in quinolines 15. The reaction affords oxindole scaffolds 116 with

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

• the use of pyridines for the formation of quinolines and isoquinolines, an oxidant-dependent rhodium-catalyzed C–H annulation of pyridines with alkynes was reported by Li and co-workers [105] in 2011 for the direct synthesis of quinolines 180 and isoquinolines 181 involving a two-fold C–H activation

Facile access to 3-sulfonylquinolines via Knoevenagel condensation/aza-Wittig reaction cascade involving ortho-azidobenzaldehydes and β-ketosulfonamides and sulfones

• Ksenia Malkova,
• Andrey Bubyrev,
• Stanislav Kalinin and
• Dmitry Dar’in

Beilstein J. Org. Chem. 2023, 19, 800–807, doi:10.3762/bjoc.19.60

• have developed a new convenient protocol for the synthesis of 3-sulfonyl-substituted quinolines (sulfonamides and sulfones). The approach is based on a Knoevenagel condensation/aza-Wittig reaction cascade involving o-azidobenzaldehydes and ketosulfonamides or ketosulfones as key building blocks. The

• , the method for the synthesis of 3-acyl-substituted quinolines from o-azidobenzaldehydes and 1,3-dicarbonyl compounds was reported [70][71] (Figure 2a). A combination of Knoevenagel condensation and aza-Wittig reaction allowed to build up target products in high yields. In case of [70], the procedure

• quinolines (sulfonamides and sulfones) (Figure 2b). Herein, we report the successful implementation of this approach. Results and Discussion The Knoevenagel condensation/aza-Wittig reaction cascade was used for the preparation of 3-sulfonyl-substituted quinolines. The process proceeds in a domino fashion

One-pot double annulations to confer diastereoselective spirooxindolepyrrolothiazoles

• Juan Lu,
• Bin Yao,
• Desheng Zhan,
• Zhuo Sun,
• Yun Ji and
• Xiaofeng Zhang

Beilstein J. Org. Chem. 2022, 18, 1607–1616, doi:10.3762/bjoc.18.171

• UMB32 and UMB136 [33][34]. Zhang developed 4-aminoquinolines for the synthesis of fluorinated analogues of acetylcholinesterase (AChE) inhibitors [35] in cascade reactions, such as one-step syntheses of quinolines. Quinolin-4-ols involving histone acetyltransferases (HAT) inhibitors [36][37], as well as

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

• Abstract The acceptorless dehydrogenative coupling (ADC) reaction is an efficient method for synthesizing quinoline and its derivatives. In this paper, various substituted quinolines were synthesized from 2-aminobenzyl alcohols and aryl/heteroaryl/alkyl secondary alcohols in one pot via a cyclometalated

• loading offers the potential to access the aryl/heteroaryl quinolones in suitable amounts. In addition, the antibacterial and antifungal activities of the synthesized quinolines were evaluated in vitro, and the experimental results showed that the antibacterial activities of compounds 3ab, 3ad, and 3ah

• against Gram-positive bacteria and compound 3ck against C. albicans were better than the reference drug norfloxacin. Keywords: acceptorless dehydrogenative coupling reaction; antibacterial; cyclometalated iridium complexes; quinolines; Introduction As an important class of heterocyclic compounds

Design, synthesis, and evaluation of chiral thiophosphorus acids as organocatalysts

• Karen R. Winters and
• Jean-Luc Montchamp

Beilstein J. Org. Chem. 2022, 18, 1471–1478, doi:10.3762/bjoc.18.154

• thiophosphorus acid 2. Synthesis of N-biphenyl-DOPO CPA 4. Transfer hydrogenation of 2-phenylquinoline and transition-state proposed by Guinchard and coworkers [28]. P-stereogenic CPAs in the transfer hydrogenation of quinolines. Supporting Information Supporting Information File 332: Experimental procedures