Electrochemical cyclization of alkynes to construct five-membered nitrogen-heterocyclic rings

• Lifen Peng,
• Ting Wang,
• Zhiwen Yuan,
• Bin Li,
• Zilong Tang,
• Xirong Liu,
• Hui Li,
• Guofang Jiang,
• Chunling Zeng,
• Henry N. C. Wong and
• Xiao-Shui Peng

Beilstein J. Org. Chem. 2025, 21, 2173–2201, doi:10.3762/bjoc.21.166

• [61], [3 + 2] reductive cycloadditions of enal-alkyne [62], [2 + 2 + 1] cycloaddition of acetylenes [63] and cyclization of 1,6-enyne [64] were efficient approaches towards five-membered rings. Since Faraday synthesized hydrocarbons by employing electric current to an acetate solution [65], the use of

C2 to C6 biobased carbonyl platforms for fine chemistry

• Jingjing Jiang,
• Muhammad Noman Haider Tariq,
• Florence Popowycz,
• Yanlong Gu and
• Yves Queneau

Beilstein J. Org. Chem. 2025, 21, 2103–2172, doi:10.3762/bjoc.21.165

Azide–alkyne cycloaddition (click) reaction in biomass-derived solvent Cyrene^TM under one-pot conditions

• Zoltán Medgyesi and
• László T. Mika

Beilstein J. Org. Chem. 2025, 21, 1544–1551, doi:10.3762/bjoc.21.117

• involving benzyl azide (1a) and various acetylenes 2b–h in CyreneTM at 30 °C for 12 h (Figure 3). It should be noted that all components readily dissolved in CyreneTM, resulting in clear, homogeneous reaction mixtures. With the exception of 3-(1-benzyl-1H-1,2,3-triazol-4-yl)pentan-3-ol (3g), the isolated

• results reported by Citarella et al. [39], excellent functional group tolerance was verified and the isolated yields are in the same range as reported by Citarella et al. (for 3a, 90% [39] and 87% [39]). It should be noted that no Cu-catalyzed Glaser-coupling of acetylenes [45] was observed, indicating

• in the formation of 1-allyl-4-substituted-1H-1,2,3-triazoles bearing a terminal C–C double bond moiety. Thus, we attempted to prepare a series of 1-allyl-4-substituted-1H-1,2,3-triazoles (Figure 5, 6a–f) from allyl bromide (4g) and selected acetylenes 2a–f. Similar to the formation of N-substituted-4

Dioxazolones as electrophilic amide sources in copper-catalyzed and -mediated transformations

• Seungmin Lee,
• Minsuk Kim,
• Hyewon Han and
• Jongwoo Son

Beilstein J. Org. Chem. 2025, 21, 200–216, doi:10.3762/bjoc.21.12

• afforded the product 10g in good yield. Acetylenes containing tolyl and trifluorophenyl substituents also exhibited improved reactivity (10h and 10i). Heteroaromatic acetylenes were effective in this transformation, forming N-acyl amidines 10j and 10k, respectively. On the other hand, the use of linear

• terminal alkynes did not result in the desired N-acyl amidine 10l. Based on the substrate scope of acetylenes, the authors noted that the lower acidity of terminal acetylenes led to a diminished formation of the copper acetylide intermediate. Based on several mechanistic experiments and density functional

• mixture (E/Z = 1.4:1) of dioxazolones was used. Copper(II)-catalyzed synthesis of 1,2,4-triazole derivatives. Copper(I)-catalyzed synthesis of N-acyl amidines from dioxazolones, acetylenes, and amines. aPerformed under N2 atmosphere. b10 mol % of CuI was used instead of [Cu(OAc)(Xantphos)], with a

Extension of the π-system of monoaryl-substituted norbornadienes with acetylene bridges: influence on the photochemical conversion and storage of light energy

• Robin Schulte,
• Dustin Schade,
• Thomas Paululat,
• Till J. B. Zähringer,
• Christoph Kerzig and
• Heiko Ihmels

Beilstein J. Org. Chem. 2024, 20, 3061–3068, doi:10.3762/bjoc.20.254

• acetylenes at ca. 85 ppm and 95 ppm were observed. The norbornadienes 1h–l,n exhibit very good solubility in organic solvents, like ethyl acetate, chloroform, or benzene, whereas they have poor solubility in cyclohexane, acetonitrile, or ethanol. In polar protic solvents, like methanol or water, they are

4,6-Diaryl-5,5-difluoro-1,3-dioxanes as chiral dopants for liquid crystal compositions

• Maurice Médebielle,
• Peer Kirsch,
• Jérémy Merad,
• Carolina von Essen,
• Clemens Kühn and
• Andreas Ruhl

Beilstein J. Org. Chem. 2024, 20, 2940–2945, doi:10.3762/bjoc.20.246

• 4,5-diaryl-1,3-dioxolanes [15], TADDOLs [16][17], axially chiral alleno-acetylenes [18] and strained axially chiral 1,1’-binaphthyl derivatives [19][20][21][22] to cite a few (Figure 1 for selected examples). As a general observation, the more elongated the liquid crystal-like shape of a molecule

Synthesis of fluoroalkenes and fluoroenynes via cross-coupling reactions using novel multihalogenated vinyl ethers

• Yukiko Karuo,
• Keita Hirata,
• Atsushi Tarui,
• Kazuyuki Sato,
• Kentaro Kawai and
• Masaaki Omote

Beilstein J. Org. Chem. 2024, 20, 2691–2703, doi:10.3762/bjoc.20.226

• 5l) could be introduced into 1a in 76% or 52% yields, respectively (Table 4, entries 10 and 11). Reactions using acetylenes possessing a hydroxy group, amino group and thiophene proceeded well (3m–o) (Table 4, entries 12–14). Hexa-1-yne 5p and cyclopropylacetylene (5q) afforded 3p and 3q

A review of recent advances in electrochemical and photoelectrochemical late-stage functionalization classified by anodic oxidation, cathodic reduction, and paired electrolysis

• Nian Li,
• Ruzal Sitdikov,
• Ajit Prabhakar Kale,
• Joost Steverlynck,
• Bo Li and
• Magnus Rueping

Beilstein J. Org. Chem. 2024, 20, 2500–2566, doi:10.3762/bjoc.20.214

• complex compounds (Scheme 35). In addition, Niu and coworkers reported a similar work on a cobalt-electrocatalyzed atroposelective C–H annulation of benzamides with acetylenes [48]. 1.3.3 Ni-assisted anodic oxidation: Apart from cobalt, nickel complexes have also been applied in anionic oxidations and

Generation of alkyl and acyl radicals by visible-light photoredox catalysis: direct activation of C–O bonds in organic transformations

• Mithu Roy,
• Bitan Sardar,
• Itu Mallick and
• Dipankar Srimani

Beilstein J. Org. Chem. 2024, 20, 1348–1375, doi:10.3762/bjoc.20.119

• salicylic acid derivatives and aryl acetylenes. Due to irradiation with blue light, Mes–Acr–Me+ gets excited to Mes–Acr–Me+* and takes up a single electron from Ph2S. The reaction of the diphenyl sulfide radical cation with carboxylate and successive acyloxy C–O bond cleavage forms diphenyl sulfoxide and an

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

• cross-coupling reactions of various acetylenes containing electron-rich and electron-withdrawing functional groups, like methoxy or cyano, as well as thienyl and cyclopropyl groups. In general, all products were achieved in very good yields, ranging from 71 to 99%. Only product 6h, containing a TMS

Trifluoromethylated hydrazones and acylhydrazones as potent nitrogen-containing fluorinated building blocks

• Zhang Dongxu

Beilstein J. Org. Chem. 2023, 19, 1741–1754, doi:10.3762/bjoc.19.127

• trifluoroacetonitrile imine, are highly versatile in that they react with olefins, acetylenes, dimethyl fumarate, dimethyl maleate, β-diketones, β-keto esters, bicyclic olefins, and potassium isothiocyanate and isocyanate affording the corresponding trifluoromethyl-containing compounds, generally with good yields [51

Application of N-heterocyclic carbene–Cu(I) complexes as catalysts in organic synthesis: a review

• Nosheen Beig,
• Varsha Goyal and
• Raj K. Bansal

Beilstein J. Org. Chem. 2023, 19, 1408–1442, doi:10.3762/bjoc.19.102

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

Synthesis of tetrahydrofuro[3,2-c]pyridines via Pictet–Spengler reaction

• Elena Y. Mendogralo and
• Maxim G. Uchuskin

Beilstein J. Org. Chem. 2023, 19, 991–997, doi:10.3762/bjoc.19.74

• the use of 3-substituted furans. For example, the intramolecular Friedel–Crafts alkylation reaction (Scheme 1a) of alcohols [9][10][11], alkenes [12] or acetylenes [13] affords the desired tetrahydrofuro[3,2-c]pyridines. A related method is based on a Au(I)-catalyzed domino sequence dearomatization

1,4-Dithianes: attractive C2-building blocks for the synthesis of complex molecular architectures

• Bram Ryckaert,
• Ellen Demeyere,
• Frederick Degroote,
• Hilde Janssens and
• Johan M. Winne

Beilstein J. Org. Chem. 2023, 19, 115–132, doi:10.3762/bjoc.19.12

• acetylenes in Diels–Alder reactions [49], since desulfonylation of the cyclohexene-disulfones with sodium amalgam or samarium(II) iodide affords 1,4-cyclohexadienes (Scheme 8). In a comparative study by Nakayama [50], the dithiin-type cyclic disulfone 7 emerged as a much stronger dienophile than any other

Organophosphorus chemistry: from model to application

• György Keglevich

Beilstein J. Org. Chem. 2023, 19, 89–90, doi:10.3762/bjoc.19.8

• derivatives. In another study, the synthesis of bis(chlorophenyl)acetylenes that were useful for the preparation of 1,2,3-tris(chlorophenyl)cyclopropenylium bromides was accomplished [3]. The latter species were converted to tributyl(1,2,3-tris(chlorophenyl)cyclopropenyl)phosphonium bromides, affording 3,4,5

Synthesis and electrochemical properties of 3,4,5-tris(chlorophenyl)-1,2-diphosphaferrocenes

• Almaz A. Zagidullin,
• Farida F. Akhmatkhanova,
• Mikhail N. Khrizanforov,
• Robert R. Fayzullin,
• Tatiana P. Gerasimova,
• Ilya A. Bezkishko and
• Vasili A. Miluykov

Beilstein J. Org. Chem. 2022, 18, 1338–1345, doi:10.3762/bjoc.18.139

• transition metal-catalyzed cross-coupling reactions broadly used for the preparation of different diarylacetylenes and, rarely, bis(chlorophenyl)acetylenes. Next, starting substituted benzaldehydes were treated with an excess of SOCl2 for 24 h at 25 °C. Corresponding substituted benzal chlorides 4 were

• was shown for pentaphosphaferrocene Cp*Fe(η5-P5) [49] and the corresponding Sm complexes [50]. Conclusion In summary, a series of bis(сhlorophenyl)acetylenes 3, substituted benzal chlorides 4, and tris(chlorophenyl)cyclopropenylium bromides 5 were synthesized starting from corresponding chloro

• . Front., vol. 9, Issue 11, © 2022); permission conveyed through Copyright Clearance Center, Inc. This content is not subject to CC BY 4.0. Synthesis of bis(chlorophenyl)acetylenes 3. Synthesis of 1,2,3-tris(chlorophenyl)cyclopropenylium bromides 5 and tributyl(1,2,3-tris(chlorophenyl)cyclopropenyl

Cathodic generation of reactive (phenylthio)difluoromethyl species and its reactions: mechanistic aspects and synthetic applications

• Sadanobu Iwase,
• Shinsuke Inagi and
• Toshio Fuchigami

Beilstein J. Org. Chem. 2022, 18, 872–880, doi:10.3762/bjoc.18.88

• . The generated radicals undergo addition to olefins and acetylenes [5][33]. Pohmakotr et al. and Yoshida et al. reported that the reaction of PhSCF2Br and PhCF2Cl with SmI2 generated PhSCF2 and PhCF2 radicals, which were trapped with styrene [5][34][35]. Therefore, we carried out the reaction of

Recent developments and trends in the iron- and cobalt-catalyzed Sonogashira reactions

• Surendran Amrutha,
• Sankaran Radhika and
• Gopinathan Anilkumar

Beilstein J. Org. Chem. 2022, 18, 262–285, doi:10.3762/bjoc.18.31

• 30 mol % of dmeda as ligand in toluene at 135 °C for 72 h (Scheme 7). On the other hand, acetylenes with alkyl substitution showed lower reactivity. In addition, to increase the importance of iron catalysts as a versatile tool in organic synthesis, a novel iron-catalyzed domino Sonogashira coupling

• various acetylenes. With regard to alkynes, 1-chloro-4-ethynylbenzene and 1-bromo-4-ethynylbenzene were found suitable substrates, which provided good to excellent yields of the products, and no homocoupling was observed in any reaction. Shim and co-workers demonstrated an efficient iron powder/CuI

• . This synthetic protocol offers increased functional group tolerance and moderate to good yields of the products by the coupling of various functional group-substituted acetylenes with o-iodophenol. The proposed mechanistic study involves a Sonogashira coupling followed by a 5-endo-dig cyclization

(Phenylamino)pyrimidine-1,2,3-triazole derivatives as analogs of imatinib: searching for novel compounds against chronic myeloid leukemia

• Luiz Claudio Ferreira Pimentel,
• Lucas Villas Boas Hoelz,
• Henayle Fernandes Canzian,
• Frederico Silva Castelo Branco,
• Andressa Paula de Oliveira,
• Vinicius Rangel Campos,
• Floriano Paes Silva Júnior,
• Rafael Ferreira Dantas,
• Jackson Antônio Lamounier Camargos Resende,
• Anna Claudia Cunha,
• Nubia Boechat and
• Mônica Macedo Bastos

Beilstein J. Org. Chem. 2021, 17, 2260–2269, doi:10.3762/bjoc.17.144

• cycloaddition reactions via the copper-catalyzed 1,3-dipolar cycloaddition reaction (CuAAC) of the azides 5 and 9 with suitably functionalized acetylenes 6a–j, using sodium ascorbate and copper sulfate in ACN/H2O 2:1 under microwave irradiation were carried out to obtain the 1,4-regioisomers of the final

• volatility of some acetylenes used, which have been lost at the time of irradiation. All compounds were obtained with satisfactory purity (>95%) determined by liquid chromatography or elemental analysis. Despite their purity, compounds 2b, 2d, 2e, and 2h had an absence of some signals in the 1H NMR and 13C

2,4-Bis(arylethynyl)-9-chloro-5,6,7,8-tetrahydroacridines: synthesis and photophysical properties

• Najeh Tka,
• Mohamed Adnene Hadj Ayed,
• Mourad Ben Braiek,
• Mahjoub Jabli,
• Noureddine Chaaben,
• Kamel Alimi,
• Stefan Jopp and
• Peter Langer

Beilstein J. Org. Chem. 2021, 17, 1629–1640, doi:10.3762/bjoc.17.115

• DIPEA at 80 °C for three hours. With the optimized conditions in hand, we examined the scope of the coupling reaction of 2 with different phenylacetylenes 3b–g. As shown in Table 2, tetrahydroacridine derivatives 4a–g were obtained in moderate to good yields. The yields were better for acetylenes

A recent overview on the synthesis of 1,4,5-trisubstituted 1,2,3-triazoles

• Pezhman Shiri,
• Ali Mohammad Amani and
• Thomas Mayer-Gall

Beilstein J. Org. Chem. 2021, 17, 1600–1628, doi:10.3762/bjoc.17.114

• products, allowing the construction of a number of medium- and large-sized triazole-fused heterocycles 75 and 77. Many aliphatic, aromatic, thiophenyl-, and ferrocenyl-substituted acetylenes were found to give excellent results in the reaction with aliphatic tosylthio azides 74 with different chain length

Copper-mediated oxidative C−H/N−H activations with alkynes by removable hydrazides

• Feng Xiong,
• Bo Li,
• Chenrui Yang,
• Liang Zou,
• Wenbo Ma,
• Linghui Gu,
• Ruhuai Mei and
• Lutz Ackermann

Beilstein J. Org. Chem. 2021, 17, 1591–1599, doi:10.3762/bjoc.17.113

• electrophilic substitutes were well tolerated. Moreover, substrates with a highly reactive unprotected amino group also delivered the corresponding product 3cn with good yield. The robustness of this protocol was further highlighted by the excellent reactivity of heterocyclic acetylenes (see 2p–r). However, a

Synthesis of N-perfluoroalkyl-3,4-disubstituted pyrroles by rhodium-catalyzed transannulation of N-fluoroalkyl-1,2,3-triazoles with terminal alkynes

• Olga Bakhanovich,
• Viktor Khutorianskyi,
• Vladimir Motornov and
• Petr Beier

Beilstein J. Org. Chem. 2021, 17, 504–510, doi:10.3762/bjoc.17.44

• alkynes was described. The reaction led to a mixture of the N-perfluoroalkyl-3,4- and 2,4-disubstituted pyrroles. The reactions with phenylacetylene afforded a mixture of 3,4- and 2,4-disubstituted pyrroles in a ratio from 59:41 to 79:21, while the reactions with aliphatic acetylenes gave higher product

Efficient [(NHC)Au(NTf₂)]-catalyzed hydrohydrazidation of terminal and internal alkynes

• Maximillian Heidrich and
• Herbert Plenio

Beilstein J. Org. Chem. 2020, 16, 2080–2086, doi:10.3762/bjoc.16.175

• reactivity in the present study was as follows: RCCH > alkyl-CC-alkyl > aryl-CC-alkyl ≥ aryl-CC-aryl. Disubstituted acetylenes with different substituents tended to produce isomers in the hydrohydrazidation reaction (Scheme 4, products 7b, c, d, i, and j). No preference for either isomer was observed – not