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

Effect of substitution position of aryl groups on the thermal back reactivity of aza-diarylethene photoswitches and prediction by density functional theory

• Misato Suganuma,
• Daichi Kitagawa,
• Shota Hamatani and
• Seiya Kobatake

Beilstein J. Org. Chem. 2025, 21, 242–252, doi:10.3762/bjoc.21.16

• benzothiophene (N3 and I3) or benzofuran (N4 and I4), the ΔH‡ values were almost the same, but the ΔS‡ values became larger and took positive values by the change of the substitution position of the aryl group from N to I. Furthermore, comparing the ΔG‡(exp) and the t1/2 values, when the aryl group is

• phenylthiophene (N1 and I1) or benzothiophene (N3 and I3), the ΔG‡(exp) value decreased and the t1/2 became shorter by the change of the substitution position of the aryl group from N to I. On the other hand, when the aryl group is phenylthiazole (N2 and I2) or benzofuran (N4 and I4), the ΔG‡(exp) and the t1/2

• )benzofuran (I4(a)). Compound I4(a) was synthesized in a manner similar to a procedure from [56]. 3-Methylbenzofuran (2.0 g, 15 mmol) was dissolved in anhydrous THF (200 mL) under argon atmosphere. A 1.6 M n-BuLi hexane solution (10 mL, 17 mmol) was slowly added dropwise to the solution at −78 °C, and the

Streamlined modular synthesis of saframycin substructure via copper-catalyzed three-component assembly and gold-promoted 6-endo cyclization

• Asahi Kanno,
• Ryo Tanifuji,
• Satoshi Yoshida,
• Sota Sato,
• Saori Maki-Yonekura,
• Kiyofumi Takaba,
• Jungmin Kang,
• Kensuke Tono,
• Koji Yonekura and
• Hiroki Oguri

Beilstein J. Org. Chem. 2025, 21, 226–233, doi:10.3762/bjoc.21.14

• pathway leading to 13, we strategically designed 2,3-diaminobenzofuran 11 as a suitably functionalized cyclization precursor for the gold(I)-promoted hydroamination, considering the following three factors. Firstly, the appropriate trajectory of the secondary amino group in the benzofuran moiety is

• a phenol moiety. The final step is assumed to be facilitated by the release of the ring distortion of the benzofuran system. Overall, triggered by the gold(I)-promoted 6-endo hydroamination between the 2,3-diaminobenzofuran and the alkyne in 11, dehydrogenative oxidation of the resulting 12 to form

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

• motifs such as a benzofuran, indazole, and quinoline were also shown to undergo the desired Markovnikov amidation with high efficiency (23j–l). Several mechanistic experiments were performed to rationalize the reaction pathways. As shown in Figure 7, copper hydride, generated from a copper precatalyst

Nickel-catalyzed cross-coupling of 2-fluorobenzofurans with arylboronic acids via aromatic C–F bond activation

• Takeshi Fujita,
• Haruna Yabuki,
• Ryutaro Morioka,
• Kohei Fuchibe and
• Junji Ichikawa

Beilstein J. Org. Chem. 2025, 21, 146–154, doi:10.3762/bjoc.21.8

• coupling reactions of aromatic C–F and C–Br bonds with arylboronic acids. Keywords: arylboronic acid; benzofuran; C–F bond activation; cross-coupling; nickel; Introduction The metal-catalyzed activation of aromatic carbon–fluorine (C–F) bonds is widely recognized as a challenging task in synthetic

• distinct aryl groups onto a benzofuran ring through orthogonal coupling reactions, exploiting the reactivity difference between C–F and C–Br bonds (Scheme 4). Using a palladium catalyst, 5-bromo-2-fluorobenzofuran (1e) was coupled with [4-(trifluoromethyl)phenyl]boronic acid (2g). In this reaction, only

• the C–Br bond was transformed while the C–F bond remained intact, yielding 2-fluoro-5-[4-(trifluoromethyl)phenyl]benzofuran (1f) in 95% yield. Subsequently, nickel-catalyzed defluorinative arylation of 1f with phenylboronic acid (2a) efficiently produced 2-phenyl-5-[4-(trifluoromethyl)phenyl

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

• benzofuran-3-carbaldehydes 50 (Scheme 16). Another demonstration of the atroposelective formation of compounds with a C–N stereogenic axis was developed by Jindal, Mukherjee, Biju, and co-workers [36]. The authors developed an NHC-catalyzed desymmetrization of N-aryl maleimides 53, which afforded a range of

Synthesis of acenaphthylene-fused heteroarenes and polyoxygenated benzo[j]fluoranthenes via a Pd-catalyzed Suzuki–Miyaura/C–H arylation cascade

• Merve Yence,
• Dilgam Ahmadli,
• Damla Surmeli,
• Umut Mert Karacaoğlu,
• Sujit Pal and
• Yunus Emre Türkmen

Beilstein J. Org. Chem. 2024, 20, 3290–3298, doi:10.3762/bjoc.20.273

• , Ankara 06800, Türkiye 10.3762/bjoc.20.273 Abstract Acenaphthylene-fused heteroarenes with a variety of five- and six-membered heterocycles such as thiophene, furan, benzofuran, pyrazole, pyridine and pyrimidine were synthesized via an efficient Pd-catalyzed reaction cascade in good to high yields (45–90

• heterocyclic frameworks (Table 2). The acenaphthylene-fused furan and benzofuran products 15b and 15c were obtained in 54% and 86% yield, respectively, via the reactions of 1,8-diiodonaphthalene (12) with 3-furanylboronic acid and 2-benzofuranylboronic acid (Table 2, entries 1 and 2). It is important to note

• that benzofuran adduct 15c was previously reported by Dyker to be obtained in only 10% yield when 12 was reacted with 10 equivalents of unsubstituted benzofuran, in the presence of 5 mol % of Pd(OAc)2 at 100 °C for 3 days [52]. The compatibility of five-membered nitrogen heterocycles with our

Non-covalent organocatalyzed enantioselective cyclization reactions of α,β-unsaturated imines

• Sergio Torres-Oya and
• Mercedes Zurro

Beilstein J. Org. Chem. 2024, 20, 3221–3255, doi:10.3762/bjoc.20.268

• , respectively. Additionally, the most common cyclic α,β-unsaturated imines involve benzofuran or saccharin-derived azadienes (Figure 1). Cycloaddition reactions, especially Diels–Alder reactions, have attracted a lot of attention since their discovery as one of the most powerful methodologies for the

• ) and good to excellent enantioselectivities (60–97% ee) when using organocatalyst III. Later, in 2018, Zhou and co-workers developed a bifunctional squaramide-catalyzed enantioselective formal [4 + 2] cycloaddition of benzofuran-derived azadienes 11 with malononitrile (12) [26]. This work provides an

• efficient methodology for synthesizing chiral benzofuran-fused 1,4-dihydropyridines 13 in excellent yields (90–99%) and excellent enantioselectivities (92–99% ee) (Scheme 4). The authors also attempted to perform the reaction using 2-tosylacetonitrile instead of malononitrile. However, in this case, the

Multicomponent reactions driving the discovery and optimization of agents targeting central nervous system pathologies

• Lucía Campos-Prieto,
• Aitor García-Rey,
• Eddy Sotelo and
• Ana Mallo-Abreu

Beilstein J. Org. Chem. 2024, 20, 3151–3173, doi:10.3762/bjoc.20.261

• improved biological activities. Employing this approach, Kushwaha et al. [34] synthesized a series of compounds containing benzofuran, tetrazole, and pyrazole within a single structure (Scheme 2). Benzofurans and tetrazole pharmacophores have demonstrated potential anti-Alzheimer activity by inhibiting

• AChE, while pyrazole scaffolds possess the ability to reduce the tau and β-amyloid dual aggregation. Benzofuran-pyrazole aldehydes were employed in the Ugi azide reaction to give the desired hybrids. From the screened compounds, 2a, 2b, 2c, 2d, 2e, and 2f demonstrated notable efficacy in regulating the

• of best derivatives obtained by Hasaninejad et al. [49]. Best DRD2 compounds synthesized using a multicomponent strategy. Oxoindole-β-lactam core produced in a U4C-3CR. Ugi-azide synthesis of benzofuran, pyrazole and tetrazole hybrids. Four-component Ugi reaction for the synthesis of novel

Synthesis of the 1,5-disubstituted tetrazole-methanesulfonylindole hybrid system via high-order multicomponent reaction

• Cesia M. Aguilar-Morales,
• América A. Frías-López,
• Nadia V. Emilio-Velázquez,
• Alejandro Islas-Jácome,
• Angelica Judith Granados-López,
• Jorge Gustavo Araujo-Huitrado,
• Yamilé López-Hernández,
• Hiram Hernández-López,
• Luis Chacón-García,
• Jesús Adrián López and
• Carlos J. Cortés-García

Beilstein J. Org. Chem. 2024, 20, 3077–3084, doi:10.3762/bjoc.20.256

• study commenced with synthesizing a series of 1,5-disubstituted tetrazole-methanesulfonylindoles 18a–n, achieved through a high-order multicomponent approach. This strategy, similar to that previously reported by our research group for synthesizing the 1,5-disubstituted tetrazole-benzofuran bis

• the application of this reagent as a central building block in the synthesis of hybrid systems via Ugi-azide reactions, including structures based on triazoles-tetrazoles [24][26][27], benzofuran-tetrazoles [23] and indolizines-tetrazoles [25], all of which have significant relevance in medicinal

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

• -carboxaldehyde-derived acetal 100 (82% yield, 90% ee). 2-Methallylsilane showed universally high enantioselectivity across a range of acetal components (95–99% ee), except for a slight drop in the case of 5-bromo-2-furan (102, 86% ee) and 2-benzofuran-substituted (103, 86% ee) substrates. Regarding the silane

Multicomponent syntheses of pyrazoles via (3 + 2)-cyclocondensation and (3 + 2)-cycloaddition key steps

• Ignaz Betcke,
• Alissa C. Götzinger,
• Maryna M. Kornet and
• Thomas J. J. Müller

Beilstein J. Org. Chem. 2024, 20, 2024–2077, doi:10.3762/bjoc.20.178

• preparation of these pyrazoles involves the cycloaddition of diazo compounds generated in situ with (Z)-2-arylidene-2H-benzofuran-3-ones. This reaction yields intermediate spiropyrazolines, which react undergo 1,3-prototropic rearrangement to form the corresponding pyrazoles [175]. Aggarwal's method was also

Solvent-dependent chemoselective synthesis of different isoquinolinones mediated by the hypervalent iodine(III) reagent PISA

• Ze-Nan Hu,
• Yan-Hui Wang,
• Jia-Bing Wu,
• Ze Chen,
• Dou Hong and
• Chi Zhang

Beilstein J. Org. Chem. 2024, 20, 1914–1921, doi:10.3762/bjoc.20.167

• postulated for the synthesis of benzofuran derivatives from styrene derivatives by iodane reagents [29][30]. Subsequently, intermediate D is attacked by H2O at the benzylic carbon atom to afford intermediate E. Intramolecular proton shift occurs, generating the intermediate F, which undergoes phenyl

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

• replacements leading to novel MAO-A bioactive entities [16][17]. The brominated analogue 8 showed moderate MAO-A activity compared to the parent 2-furyl compound 7, as a result of increased polarizability. The condensed benzofuran 9 revealed submicromolar MAO-A potency, a resemblance to the indole system of 5

• -hydroxytryptamine (a MAO-A substrate), in a molecular docking experiment tested against serotonin (Scheme 3). A similar class of benzofuran systems with attractive binding properties are those represented by 4-amino-3-(benzo[b]furan-2-yl)butanoic acids, baclofen analogs, elaborated to elucidate the structural

Chemo-enzymatic total synthesis: current approaches toward the integration of chemical and enzymatic transformations

• Ryo Tanifuji and
• Hiroki Oguri

Beilstein J. Org. Chem. 2024, 20, 1693–1712, doi:10.3762/bjoc.20.151

• aromatization provides chalcone 43. Prenylation of the resultant aromatic ring of 43, catalyzed by MaIDT (Morus alba isoliquiritigenin 3-dimethylallyltransferase), leads to morachalcone A (44) [50][51]. In parallel, benzofuran 46 was biosynthesized from 4-coumaroyl-CoA via thioester 45. Further prenylation of

Primary amine-catalyzed enantioselective 1,4-Michael addition reaction of pyrazolin-5-ones to α,β-unsaturated ketones

• Pooja Goyal,
• Akhil K. Dubey,
• Raghunath Chowdhury and
• Amey Wadawale

Beilstein J. Org. Chem. 2024, 20, 1518–1526, doi:10.3762/bjoc.20.136

• fascinating but at the same time challenging. Pyrazoles [4][5][6][7], benzofurans [34], and indoles [35][36] are popular scaffolds as they are prevalent in many bioactive molecules. Compounds bearing both pyrazole and indole moieties or pyrazole and benzofuran moieties (Figure 1) are highly attractive since

• ). On the other hand, the reaction of pyrazolin-5-one (2a) with benzofuran-derived α,β-unsaturated ketone 1n delivered the product 3na in 85.5% yield and 95.5% ee (Scheme 3). Moreover, by employing the catalytic composite II (15 mol %) and A5 (30 mol %) under otherwise identical optimized reaction

• chiral column. cValues in parentheses represent % ee after single recrystallization. dReaction time for the first step was 4 h. Synthesis of pyrazole-benzofuran and pyrazole–indole hybrid molecules. Reaction conditions: 1m or 1n (0.3 mmol), 2a (0.2 mmol), 15 mol % of catalyst I, 30 mol % A5 (for 3) or 15

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

• -opioid receptor agonist and exhibits excellent antinociceptive activity [2]. Lactam C possesses potent antituberculosis activity and excellent selectivity to Mycobacterium tuberculosis strain H37Rv [3]. Araliopsine (D) was isolated from the fruits of Zanthoxylum simulans [4]. Benzofuran E is a potent and

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

• -naphthofuran or benzofuran analogues. The achiral phosphoric acid (PhO)2P(O)OH was the catalytic reagent to execute the process delivering the products with low to moderate chemical yields. Attempts to make the process stereoselective, a series of chiral phosphoric acid catalysts were screened in the model

• benzofuran-2(3H)-one derivative 144 having an aza-quaternary stereocenter. The achiral Lewis acid tris(pentafluorophenyl)borane was required as additive in the reaction system to enhance the chemical yield and enantioselectivity. After two additional steps, i.e., demethylation of the phenolic ether and ester

Transition-metal-catalyzed domino reactions of strained bicyclic alkenes

• Austin Pounder,
• Eric Neufeld,
• Peter Myler and
• William Tam

Beilstein J. Org. Chem. 2023, 19, 487–540, doi:10.3762/bjoc.19.38

• this shift as these systems lack the hydrogen to participate in this shift. This reaction proceeded smoothly with a variety of bicyclic alkenes although diazabicyclic alkenes had little to no reactivity. Moreover, benzofuran and benzopyrrole boronate esters resulted in low yields. In 2011, the Lautens

A novel spirocyclic scaffold accessed via tandem Claisen rearrangement/intramolecular oxa-Michael addition

• Anastasia Vepreva,
• Alexander Yanovich,
• Dmitry Dar’in,
• Grigory Kantin,
• Alexander Bunev and
• Mikhail Krasavin

Beilstein J. Org. Chem. 2022, 18, 1649–1655, doi:10.3762/bjoc.18.177

• Center, Togliatti State University, Togliatti 445020, Russian Federation Immanuel Kant Baltic Federal University, Kaliningrad 236016, Russian Federation 10.3762/bjoc.18.177 Abstract A straightforward access to novel spiro[benzofuran-2,3'-pyrrolidine]-2',5'-diones based on the Rh2(esp)2-catalyzed

• [benzofuran-2,3'-pyrrolidine]-2',5'-diones based on Rh2(esp)2-catalyzed insertion of carbenes derived from α-diazosuccinimides (DAS) into the O–H bond of phenols. The initial adducts underwent a thermally promoted Claisen rearrangement followed by a DABCO-catalyzed intramolecular 5-exo-dig Michael addition

Lewis acid-catalyzed Pudovik reaction–phospha-Brook rearrangement sequence to access phosphoric esters

• Jin Yang,
• Dang-Wei Qian and
• Shang-Dong Yang

Beilstein J. Org. Chem. 2022, 18, 1188–1194, doi:10.3762/bjoc.18.123

• heterocycle, such as a benzothiophene (in 1l) or a benzofuran unit (in 1m), could smoothly be transformed into the desired products 3al and 3am, respectively, in moderate yield. Phosphinates 3an and 3ao could both be prepared under this Pudovik reaction–phospha-Brook rearrangement sequence in moderate to good

Electrochemical vicinal oxyazidation of α-arylvinyl acetates

• Yi-Lun Li,
• Zhaojiang Shi,
• Tao Shen and
• Ke-Yin Ye

Beilstein J. Org. Chem. 2022, 18, 1026–1031, doi:10.3762/bjoc.18.103

• ), and benzofuran (23) were all amenable in this transformation. In addition, various linear- (24, 25) and cyclic enol acetates (26, 27) also readily underwent the anticipated oxyazidation. Unfortunately, the current protocol was not applicable to the oxyazidation of enol acetate deriving from aliphatic

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

• heated flow system [65][66][67][68][69][70][71]. This is exemplified for the tandem synthesis of benzofuran 47 and phenylindole 48 (Scheme 10, case B) starting from phenol 44 and aniline derivative 46, respectively. The latter reaction was carried out in a glass reactor filled with MagSilicaTM [53

α-Ketol and α-iminol rearrangements in synthetic organic and biosynthetic reactions

• Scott Benz and
• Andrew S. Murkin

Beilstein J. Org. Chem. 2021, 17, 2570–2584, doi:10.3762/bjoc.17.172

• heteroarenes were much poorer, with pyrroles and thiophenes giving yields of ≈20% or less and benzofuran and benzothiophene failing to produce any product. Interestingly, a cyclopentanone-derived substrate (120) failed to yield the corresponding α-amino cyclohexanone 121 under the standard conditions used for

Advances in mercury(II)-salt-mediated cyclization reactions of unsaturated bonds

• Sumana Mandal,
• Raju D. Chaudhari and
• Goutam Biswas

Beilstein J. Org. Chem. 2021, 17, 2348–2376, doi:10.3762/bjoc.17.153

• with HgCl2 (0.5 equiv) in presence of N-bromosuccinimide (NBS) undergoes cyclization yielding stable bromo alkenes 87 (Scheme 28) [80][81]. Atta et al. reported the specific cyclization of ethynyl phenols 88 in presence of HgCl2 at ambient temperature yielding benzofuran derivatives 89. They had

• . Synthesis of exocyclic and endocyclic enol ether derivatives. Cyclization of trans-acetylenic alcohol by treatment with HgCl2. Synthesis of benzofuran derivatives in presence of HgCl2. a) Hg(II)-salt-mediated cyclization of 4-hydroxy-2-alkyn-1-ones to furan derivatives and b) its mechanistic pathway