Melifoliox B, a novel phloroglucin derivative isolated from Melicope barbigera (Rutaceae) and synthesis of new oxidation products from melifoliones A and B

• Horst Weber,
• Kim-Thao Tran-Cong,
• Bernhard Mayer,
• Guido J. Reiss,
• Iryna S. Konovalova,
• Marc S. Appelhans,
• Kenneth R. Wood and
• Claus M. Passreiter

Beilstein J. Org. Chem. 2026, 22, 535–546, doi:10.3762/bjoc.22.39

• and 14 seems also to be possible [19] (Scheme 5). Compounds 11 and 12 are the first representatives of two new heterocyclic ring systems consisting of two pyran rings, one cyclohexane and one furan ring. Conclusion Finally, it remains to be noted that it was not possible to prepare the quinols 3 and 4

• ), 2.26 (dt, 1H, H-10), 2.35 (s, 3H, CH3CO), 2.88 (“s”, 1H, H-10a), 6.75 (d, 2H, H-2’/H-6’), 6.97 (t, 1H, H-4’), 7.23 (t, 2H, H-3’/H-5’). Octahydro-1,1,6-trimethyl-3’,6-epoxy-spiro[1H-2-benzopyran-4,2’(5’H)-furan]-3,5’-dione (11): A mixture of 1 and 2 (300 mg, 1 mmol, ratio ca. 10:1) was dissolved in 30

Modern synthetic pathways towards eribulin and its subunits

• Sebastian Dominik Graf

Beilstein J. Org. Chem. 2026, 22, 495–526, doi:10.3762/bjoc.22.37

• : Reaction conditions: (a) i. K2CO3, MeOH, 60 °C; ii. 2,2-dimethoxypropane, H2SO4 (aq), acetone, rt; (b) i. PMBCl, t-BuOK, TBAI, DMF, THF, rt; ii. OsO4, NaIO4, 2,6-lutidine, 1,4-dioxane, H2O, −20 °C; iii. N-BuLi, furan, THF, 0 °C; (c) i. (PhO)3PMeI, dimethylacetamide, rt; ii. AD-mix-α, t-BuOH, H2O, rt; (d) i

Ring contraction and ring expansion reactions in terpenoid biosynthesis and their application to total synthesis

• Nicolas Kratena,
• Nicolas Heinzig and
• Peter Gärtner

Beilstein J. Org. Chem. 2026, 22, 289–343, doi:10.3762/bjoc.22.21

Recent advancements in the synthesis of Veratrum alkaloids

• Morwenna Mögel,
• David Berger and
• Philipp Heretsch

Beilstein J. Org. Chem. 2025, 21, 2657–2693, doi:10.3762/bjoc.21.206

• veratramine in 13 steps LLS (19 steps total, overall yield of 3.7%). Similar Diels–Alder strategies to construct the D-ring, e.g., a Diels–Alder reaction in the synthesis of 4-methylenegermine (Stork, 2017) [22] and an intramolecular Diels–Alder reaction with furan for several congeners (Luo, 2023 and 2024

Visible-light-driven NHC and organophotoredox dual catalysis for the synthesis of carbonyl compounds

• Vasudevan Dhayalan

Beilstein J. Org. Chem. 2025, 21, 2584–2603, doi:10.3762/bjoc.21.200

• regioselective acylation products, but heteroarene substrates produced a mixture of products, for example, furan, thiophene, and benzothiophene. Compared to the traditional LAs-mediated Friedel–Crafts acylation, the described radical method offers a regiodivergent result with good functional group tolerance. The

Ni-promoted reductive cyclization cascade enables a total synthesis of (+)-aglacin B

• Si-Chen Yao,
• Jing-Si Cao,
• Jian Xiao,
• Ya-Wen Wang and
• Yu Peng

Beilstein J. Org. Chem. 2025, 21, 2548–2552, doi:10.3762/bjoc.21.197

• aryltetralin[2,3-c]furan skeleton embedded in this natural product. Keywords: aryltetralin; conjugate addition; cyclolignan; nickel; reductive coupling; Introduction Proksch and co-workers isolated aglacins A, B, C, and E (1–4, Figure 1) from the methanolic extract of stem bark of Aglaia cordata Hiern from

• (Scheme 3). By slightly modifying the reaction conditions of our previous studies [11][12], the expected bicyclization of 5 occurred smoothly, resulting in an efficient construction of the trans-tetrahydronaphtho[2,3-c]furan skeleton embedded in 13, which could be separated from the other diastereomer [14

• of (+)-aglacin B, a typical aryltetralin natural product [23][24], was completed from 2,6-dimethoxyphenol. The key Ni-promoted reductive cyclization cascade of a β-bromo acetal with an allyl tether, smoothly established the tetrahydronaphtho[2,3-c]furan core of this molecule in a new fashion. The

Recent advances in Norrish–Yang cyclization and dicarbonyl photoredox reactions for natural product synthesis

• Peng-Xi Luo,
• Jin-Xuan Yang,
• Shao-Min Fu and
• Bo Liu

Beilstein J. Org. Chem. 2025, 21, 2315–2333, doi:10.3762/bjoc.21.177

• delivered 68. A one-pot desilylation/oxidation of 67 produced an aldehyde, which was subject to selective nucleophilic addition in the presence of a ketone, allowing for access to the furan precursor 68 [37]. Oxidation–cyclization–aromatization of 68 with Dess–Martin periodinane (DMP) constructed the

• southern furan moiety of 69. Finally, hydrolysis of the carbonate followed by oxidation of the resulting diol completed the Norrish–Yang cyclization precursor gracilisoid A (49). Irradiation of 49 under anaerobic conditions with a CFL, followed by treatment with silica gel, successfully generated a pair of

• 56a (Scheme 9) – formed via [4 + 2] cycloaddition of singlet oxygen with the southern furan moiety in gracilisoid F (54) and gracilisoid H (56), respectively – served as branching points in the downstream divergent synthesis. Kornblum–DeLaMare-type rearrangement of 54a and 56a assembled gracilisoids B

Pathway economy in cyclization of 1,n-enynes

• Hezhen Han,
• Wenjie Mao,
• Bin Lin,
• Maosheng Cheng,
• Lu Yang and
• Yongxiang Liu

Beilstein J. Org. Chem. 2025, 21, 2260–2282, doi:10.3762/bjoc.21.173

• terminal alkyne proceeded via a gold(I)-catalyzed propargyl-Claisen rearrangement, generating a β-allenic intermediate 35. This intermediate underwent a Markovnikov-type nucleophilic addition followed by a 5-exo-trig cyclization to stereoselectively construct the furo[3,2-b]furan bicyclic framework 36

• allene intermediate 141, which subsequently underwent 5-exo-trig cyclization to construct polysubstituted furan compounds 142. Liu et al. discovered that the regioselectivity of cyclization could be completely altered by introducing a cyclic structure to modify the bond angle of the enol ether

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

• -hydroxypropan-2-one with acylacetonitrile towards furan derivatives using a Sc(OTf)3 catalyst. C2-based bifunctional acetals, such as glycolaldehyde diethyl acetal, α-bromoacetaldehyde acetal, and 1,4-dithiane-2,5-diol also take part in the reaction as counterpart reagents. The well-known fungicide fenfuram was

• prepared using this process. Antifungal activity assays against four general plant fungi demonstrated that several of the synthesized new furan products exhibited also broad and strong biological activities (Scheme 21) [95]. A metal-free efficient strategy was developed by the Gu group for the synthesis of

• Griesbeck reported the tetraphenylporphin-photosensitized oxygenations of furan and derivatives in non-polar aprotic solvents, yielding the corresponding monomeric unsaturated secondary ozonides through a (4 + 2) cycloaddition of singlet oxygen onto the diene linkage of the furan ring. The attack of a

Chiral phosphoric acid-catalyzed asymmetric synthesis of helically chiral, planarly chiral and inherently chiral molecules

• Wei Liu and
• Xiaoyu Yang

Beilstein J. Org. Chem. 2025, 21, 1864–1889, doi:10.3762/bjoc.21.145

• various aldehydes and 3-vinylindoles but also conducted extensive structural modifications on the polycyclic arylamine components, which enabled the asymmetric synthesis of azahelicenes with diverse frameworks, including the chromene- and furan-containing quinohelicenes 12d,e, respectively. They also

• reaction produced the imine 16a which, upon treatment with Pd(PPh3)2Cl2 and KHMDS, led to furan ring formation and the generation of hetero[7]helicene 17a while maintaining the stereochemical configuration. Through this methodology, a range of elongated [7]- and [8]heterohelicenes 17b–d incorporating both

• furan and pyridine moieties were successfully synthesized with high enantioselectivity. These compounds would be challenging to access using alternative asymmetric methods. In 2025, our group disclosed a highly efficient catalytic enantioselective double annulation approach for the asymmetric synthesis

Photoswitches beyond azobenzene: a beginner’s guide

• Michela Marcon,
• Christoph Haag and
• Burkhard König

Beilstein J. Org. Chem. 2025, 21, 1808–1853, doi:10.3762/bjoc.21.143

Preparation of a furfural-derived enantioenriched vinyloxazoline building block and exploring its reactivity

• Madara Darzina,
• Anna Lielpetere and
• Aigars Jirgensons

Beilstein J. Org. Chem. 2025, 21, 1737–1741, doi:10.3762/bjoc.21.136

• an alternative to fossil feedstock is central to circular economy for the production of value-added products [1][2][3][4][5][6][7]. Furfural [furan-2-carbaldehyde (1)], a platform compound derived from lignocellulosic biomass, has been utilized to obtain a range of versatile chemicals with

• involves an electrooxidative dialkoxylation of the furan ring providing spirocycles 4a–c which undergo a further electrooxidative fragmentation to products 3a–c. However, the further transformation of products 3a–c was hampered by the problematic removal of the protecting groups (Ts, Boc, Ac) under the

Catalytic asymmetric reactions of isocyanides for constructing non-central chirality

• Jia-Yu Liao

Beilstein J. Org. Chem. 2025, 21, 1648–1660, doi:10.3762/bjoc.21.129

• double C(sp2)–H imidoylative cyclization with aryl iodides, furnishing symmetrical pyrido[6]helicenes 23 or furan-incorporating pyrido[7]helicenes 24 with stable helical chirality, respectively. Furthermore, pre-cyclized monoisocyanides, such as 25a and 25b, were identified as another class of suitable

Advances in nitrogen-containing helicenes: synthesis, chiroptical properties, and optoelectronic applications

• Meng Qiu,
• Jing Du,
• Nai-Te Yao,
• Xin-Yue Wang and
• Han-Yuan Gong

Beilstein J. Org. Chem. 2025, 21, 1422–1453, doi:10.3762/bjoc.21.106

• extended π-conjugation and distinct photophysical characteristics. Furthermore, they established a mild electrochemical protocol for synthesizing oxaza[7]helicenes incorporating pyrrole and furan units [87]. This method afforded products in 50–86% yield with Faradaic efficiencies up to 77%. Among them

Oxetanes: formation, reactivity and total syntheses of natural products

• Peter Gabko,
• Martin Kalník and
• Maroš Bella

Beilstein J. Org. Chem. 2025, 21, 1324–1373, doi:10.3762/bjoc.21.101

• 2020, Bull et al. published a short synthesis of 3-aryloxetan-3-carboxylic acids 152 employing a Friedel–Crafts alkylation (which builds on their previous alkylation of phenols [87]) and a selective furan oxidative cleavage (Scheme 37) [88]. The oxidation protocol uses a catalytic amount of a high

• access to a large library of functionalised oxetanes in moderate to excellent yields and under very simple reaction conditions, which are compatible with a wide range of nucleophiles including alcohols (primary, secondary and tertiary), phenols, aliphatic and aromatic amines or heteroaryls (e.g., furan

• prepared by a Wittig olefination of commercially available 3-oxetanone (Scheme 46) [97]. As for the furan formation, the methodology employs ambient reaction conditions, super-short reaction times and very low catalyst loadings. During the reaction, the oxetane is activated by BF3, opened by the carbonyl

Synthesis of β-ketophosphonates through aerobic copper(II)-mediated phosphorylation of enol acetates

• Alexander S. Budnikov,
• Igor B. Krylov,
• Fedor K. Monin,
• Valentina M. Merkulova,
• Alexey I. Ilovaisky,
• Liu Yan,
• Bing Yu and
• Alexander O. Terent’ev

Beilstein J. Org. Chem. 2025, 21, 1192–1200, doi:10.3762/bjoc.21.96

• , 80% and 79% yield). A furan moiety was also tolerated, giving the corresponding phosphorylated product 3n in 19% yield. Next, we evaluated the scope of the phosphorous component (products 3p–r). The best result was obtained with di-n-butyl H-phosphonate (product 3q). To our delight, diphenylphosphine

A multicomponent reaction-initiated synthesis of imidazopyridine-fused isoquinolinones

• Ashutosh Nath,
• John Mark Awad and
• Wei Zhang

Beilstein J. Org. Chem. 2025, 21, 1161–1169, doi:10.3762/bjoc.21.92

• R1 residue on the furan ring was found to have the most significant impact on the IMDA reaction. A bromine atom at the 3- or the 4-position resulted in products 8a–i in 66–86% yields, while a bromine atom or a methyl group at the 5-position inhibited the IMDA reaction in the preparation of 8j and 8k

• . Conclusion In summary, we developed a reaction sequence involving GBB, N-acylation, IMDA and dehydrative re-aromatization reactions for the synthesis of imidazopyridine-fused isoquinolinones. Computational studies of the IMDA reaction indicated that the position of the R1 group on the furan ring and the R2

Salen–scandium(III) complex-catalyzed asymmetric (3 + 2) annulation of aziridines and aldehydes

• Linqiang Wang and
• Jiaxi Xu

Beilstein J. Org. Chem. 2025, 21, 1087–1094, doi:10.3762/bjoc.21.86

• 3ah in lower yields and enantioselectivities than 4-chlorobenzaldehyde (2e). Multisubstituted 3,4,6-trimethoxybenzaldehyde (2i) also delivered the corresponding product 3ai in good yield (74%) and enantioselectivity (80% ee). However, heteroaromatic furan-2-carbaldehyde (2j) yielded the expected

Biobased carbon dots as photoreductants – an investigation by using triarylsulfonium salts

• Valentina Benazzi,
• Arianna Bini,
• Ilaria Bertuol,
• Mariangela Novello,
• Federica Baldi,
• Matteo Hoch,
• Alvise Perosa and
• Stefano Protti

Beilstein J. Org. Chem. 2025, 21, 1024–1030, doi:10.3762/bjoc.21.84

• material was observed, thus pointing out the key role of CDs in the process. Some additional irradiation was carried out to identify the aryl radical released during the irradiation. Unfortunately, when the reaction was conducted in the presence of both furan and allyl phenyl sulfone [27] no arylation

A convergent synthetic approach to the tetracyclic core framework of khayanolide-type limonoids

• Zhiyang Zhang,
• Jialei Hu,
• Hanfeng Ding,
• Li Zhang and
• Peirong Rao

Beilstein J. Org. Chem. 2025, 21, 926–934, doi:10.3762/bjoc.21.75

• oxidative truncation of apotirucallane or apoeuphane precursors coupled with subsequent β-furan annulation [1][2][3][4][5][6], constitute an architecturally sophisticated family of natural products. Based on their specific skeletal rearrangements, limonoids can be systematically categorized into four

Synthesis and photoinduced switching properties of C₇-heteroatom containing push–pull norbornadiene derivatives

• Daniel Krappmann and
• Andreas Hirsch

Beilstein J. Org. Chem. 2025, 21, 807–816, doi:10.3762/bjoc.21.64

• . Starting with 1-((bromoethynyl)sulfonyl)-4-methylbenzene, which was previously prepared and characterized [40][41], Diels–Alder reaction with either cyclopentadiene, furan or Boc-protected pyrrol, resulted in the NBD precursors C-NBD1, O-NBD1 and N-NBD1, respectively [31][42]. With these precursors in hand

• were observed. However, purification was not possible. Furthermore, an alternative commonly used synthetic strategy involving the Diels–Alder reaction of a pre-functionalized push–pull acetylene with furan or pyrrol derivatives proved unsuccessful [4][43]. All synthesized NBD derivatives were

• %; furan, 45 °C, 24 h, 84%; N-Boc-pyrrol, 90 °C, 68 h, 53%; ii) (4-(diphenylamino)phenyl)boronic acid (1.2 equiv), K2CO3, Pd(OAc)2, RuPhos, 4:1 toluene/H2O, 80 °C , 18 h. Overview of the new NBD derivatives and the isomerization products (QCs) expected upon isomerization. Formation of N-QC1 and N-QC2 could

Recent advances in the electrochemical synthesis of organophosphorus compounds

• Babak Kaboudin,
• Milad Behroozi,
• Sepideh Sadighi and
• Fatemeh Asgharzadeh

Beilstein J. Org. Chem. 2025, 21, 770–797, doi:10.3762/bjoc.21.61

• compounds such as furan and thiophene can be critical materials if attached to the phosphorus group. Wang et al. [53] reported an electrochemical process for the coupling of five-membered heteroaromatic rings with the P–H bond of diarylphosphine oxide in the presence of Mn(OAc)2. This report found that

Study of the interaction of 2H-furo[3,2-b]pyran-2-ones with nitrogen-containing nucleophiles

• Constantine V. Milyutin,
• Andrey N. Komogortsev and
• Boris V. Lichitsky

Beilstein J. Org. Chem. 2025, 21, 556–563, doi:10.3762/bjoc.21.44

• , interaction with dinucleophiles results in recyclization accompanied by opening of the furan ring. Relied on the aforementioned process a general method for the synthesis of substituted pyrazol-3-ones with allomaltol fragment was designed. Structures of representatives of all obtained products were

• unambiguously confirmed by X-ray diffraction. Keywords: allomaltol; enamines; 2H-furo[3,2-b]pyran-2-ones; pyrazol-3-ones; recyclization; Introduction Substituted furan-2(5H)-ones (butenolides) are widely used as precursors for the preparation of diverse types of heterocyclic compounds possessing various

Synthesis of N-acetyl diazocine derivatives via cross-coupling reaction

• Thomas Brandt,
• Pascal Lentes,
• Jeremy Rudtke,
• Michael Hösgen,
• Christian Näther and
• Rainer Herges

Beilstein J. Org. Chem. 2025, 21, 490–499, doi:10.3762/bjoc.21.36

• observed. The synthesis of N-acetyl diazocines connected to heteroaromatic aromatic systems 14–16 was less successful. The pyridine-substituted N-acetyl diazocine 14 was formed in yields of 7% or 19% while furan- 15 and thiophene-substituted N-acetyl diazocine 16 could not be obtained. The reaction with

New tandem Ugi/intramolecular Diels–Alder reaction based on vinylfuran and 1,3-butadienylfuran derivatives

• Yuriy I. Horak,
• Roman Z. Lytvyn,
• Andrii R. Vakhula,
• Yuriy V. Homza,
• Nazariy T. Pokhodylo and
• Mykola D. Obushak

Beilstein J. Org. Chem. 2025, 21, 444–450, doi:10.3762/bjoc.21.31

• reaction and Diels–Alder [4 + 2] cycloaddition based on vinylfuran and 1,3-butadienylfuran derivatives was designed and studied. It was found that in the case of 3-(furan-2-yl)acrylaldehyde, a one-pot Ugi reaction and intramolecular Diels–Alder vinylarene (IMDAV) reaction leads to the formation of the

• insufficiently studied furo[2,3-f]isoindole derivatives. Ugi adducts formed from (E)-3-(furan-2-yl)acrylaldehyde, maleic acid monoanilide, isonitrile, and an amine spontaneously underwent the IMDAV reaction with a high level of stereoselectivity, leading to single pairs of enantiomers of 4,4a,5,6,7,7a-hexahydro

• -3aH-furo[2,3-f]isoindole core in excellent yields. Under the same conditions, the (2E,4E)-5-(furan-2-yl)penta-2,4-dienal gives an Ugi adduct that undergoes the IMDA reaction without involving the furan core. The cycloaddition leads to the formation of 2,3,3a,4,5,7a-hexahydro-1H-isoindoles in high