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

• tetrahedral value which results in a large ring strain of 25.5 kcal/mol, comparable to oxirane (27.3 kcal/mol) and much greater than tetrahydrofuran (5.6 kcal/mol) [4]. Moreover, the strained C–O–C bond angle effectively exposes the oxygen lone pairs, making oxetane a strong hydrogen-bond acceptor and Lewis

• loadings were necessary for ortho-substituted phenyls. Control experiments and DFT calculations revealed that the oxetane ring is formed before the tetrahydrofuran in the domino process. In 2023, Shigehisa and co-workers published a new cycloisomerisation strategy for the construction of oxetane rings from

• electrophilicity of the carbonyl [74]. The oxetane products were obtained in good to high yields and further transformed into useful sulphone, butenolide and tetrahydrofuran derivatives. Besides laboratory-scale reactions, this ring expansion has also found applications in industry, specifically for a multi

On the photoluminescence in triarylmethyl-centered mono-, di-, and multiradicals

• Daniel Straub,
• Markus Gross,
• Mona E. Arnold,
• Julia Zolg and
• Alexander J. C. Kuehne

Beilstein J. Org. Chem. 2025, 21, 964–998, doi:10.3762/bjoc.21.80

• compared to PTM, peaking at 625 nm in tetrahydrofuran (THF) (see Figure 1a). Unfortunately, the photostability of para-iodinated radicals is too low to record ϕ in solution [43]. However, when the 3I-PTM radical is incorporated into a crystalline matrix of the closed-shell 3I-PTM-H compound, the radical is

Copper-catalyzed domino cyclization of anilines and cyclobutanone oxime: a scalable and versatile route to spirotetrahydroquinoline derivatives

• Qingqing Jiang,
• Xinyi Lei,
• Pan Gao and
• Yu Yuan

Beilstein J. Org. Chem. 2025, 21, 749–754, doi:10.3762/bjoc.21.58

• ) trifluoroacetate (Cu(TFA)2) as the catalyst (20 mol %) under ambient air at 80 °C for 12 hours; the product 3aa was isolated by chromatographic purification (Table 1, entry 1). The use of other solvents, including acetonitrile (MeCN), tetrahydrofuran (THF), toluene, acetone and methanol (MeOH), resulted in

Entry to 2-aminoprolines via electrochemical decarboxylative amidation of N‑acetylamino malonic acid monoesters

• Olesja Koleda,
• Janis Sadauskis,
• Darja Antonenko,
• Edvards Janis Treijs,
• Raivis Davis Steberis and
• Edgars Suna

Beilstein J. Org. Chem. 2025, 21, 630–638, doi:10.3762/bjoc.21.50

• and the development of efficient synthetic methods to access these medicinally relevant structural motifs. Herein, we report an electrochemical synthesis of 2-aminoproline and 2-aminopipecolic acid derivatives 6 (Figure 1). Recently, we disclosed an electrochemical approach to tetrahydrofuran and

Cryptophycin unit B analogues

• Thomas Schachtsiek,
• Jona Voss,
• Maren Hamsen,
• Beate Neumann,
• Hans-Georg Stammler and
• Norbert Sewald

Beilstein J. Org. Chem. 2025, 21, 526–532, doi:10.3762/bjoc.21.40

• : formalin, (NH4)HCO2, Pd/C, MeOH, rt, 20 min, 35%; f) N-chlorosuccinimide, MeCN, reflux, 16 h, 77%; g) AllocCl, NaHCO3, CHCl3, H2O, rt, 5 h, 89%; h) LiOH·H2O, MeOH, tetrahydrofuran, H2O, 0 °C to rt, 3 h, 99%; i) formalin, NaBH3CN, MeCN, rt, 55 min, 61%; j) 1. TFA, CH2Cl2, 0 °C, 1.5 h; 2. acryloyl chloride

• , NEt3, CH2Cl2, 0 °C to rt, 19 h, 63% over two steps; k) LiOH·H2O, MeOH, tetrahydrofuran, H2O, 0 °C, 3.5 h, 82% with unconverted 12 (18 mol %). Synthesis of cryptophycin diols 24 and 25. a) EDC·HCl, DMAP, NEt3, CH2Cl2, 0 °C to rt, 22 h, 60%; b) TFA, CH2Cl2, 0 °C, 4 h, 100%; c) 2,4,6-trichlorobenzoyl

• chloride, DMAP, NEt3, THF, 0 °C or 0 °C to rt, 3h, tetrahydrofuran, 77% (for 20)/88% (for 21); d) 1. piperidine, N,N-dimethylformamide, rt, 1.5 h; 2. unit B (11 for 20 and 13 for 21), HOAt, NEt3, EDC·HCl, CH2Cl2, 0 °C to rt, 18 h, 49% (for 22)/38% (for 23); e) 1. TFA, CH2Cl2, 0 °C to rt, 2.5 h; 2. HATU

Synthesis and characterizations of highly luminescent 5-isopropoxybenzo[rst]pentaphene

• Islam S. Marae,
• Jingyun Tan,
• Rengo Yoshioka,
• Zakaria Ziadi,
• Eugene Khaskin,
• Serhii Vasylevskyi,
• Ryota Kabe,
• Xiushang Xu and
• Akimitsu Narita

Beilstein J. Org. Chem. 2025, 21, 270–276, doi:10.3762/bjoc.21.19

• toluene, and BPP-t-Bu (excitation at 360 nm) [22], c) normalized PL spectra of BPP-OiPr 3 measured in hexane, toluene, tetrahydrofuran (THF), dichloromethane (CH2Cl2), and DMF, and d) normalized PL spectra of BPP-dione 4 measured in toluene, THF, CH2Cl2, and DMF. SEM images of BPP-OiPr showing: a) the

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

Transition-metal-free decarbonylation–oxidation of 3-arylbenzofuran-2(3H)-ones: access to 2-hydroxybenzophenones

• Bhaskar B. Dhotare,
• Seema V. Kanojia,
• Chahna K. Sakhiya,
• Amey Wadawale and
• Dibakar Goswami

Beilstein J. Org. Chem. 2024, 20, 2655–2667, doi:10.3762/bjoc.20.223

• protocol using a hydroperoxide (Figure 2d) gave us an idea that the use of an in-situ-generated hydroperoxide may trigger the reaction, and may avoid the use of transition metal in the reaction. Many solvents, e.g., tetrahydrofuran (THF), dioxanes etc. are known for producing hydroperoxides in situ on long

• NMR spectrum was consistent with the generation of tetrahydrofuran-2-hydroperoxide in THF, and was similar to the NMR reported earlier [25]. Further, the reaction of 3ba was scaled up to demonstrate the synthetic utility of our protocol. The reactions involving hydroperoxides are known to be difficult

• to afford substituted 2-hydroxybenzophenones in good to excellent yields. The method utilizes hydroperoxide-generated in situ autoxidation of tetrahydrofuran. The mechanism of the transformation of benzofuranone to benzophenone are proposed based on control experiments. Further, the UV-protection

Regioselective alkylation of a versatile indazole: Electrophile scope and mechanistic insights from density functional theory calculations

• Pengcheng Lu,
• Luis Juarez,
• Paul A. Wiget,
• Weihe Zhang,
• Krishnan Raman and
• Pravin L. Kotian

Beilstein J. Org. Chem. 2024, 20, 1940–1954, doi:10.3762/bjoc.20.170

• Cs2CO3, 90 °C, 2 h). Compounds containing linear or branched alkyl substitutions (15a–g), varied sizes of cycloalkane or saturated heterocycles (15h–p), including S- and R-tetrahydrofuran substitutions (15j, 15k) were isolated in excellent yields (>90%). Azetane 14m was unreactive towards alkylation in

Synthesis of polycyclic aromatic quinones by continuous flow electrochemical oxidation: anodic methoxylation of polycyclic aromatic phenols (PAPs)

• Hiwot M. Tiruye,
• Solon Economopoulos and
• Kåre B. Jørgensen

Beilstein J. Org. Chem. 2024, 20, 1746–1757, doi:10.3762/bjoc.20.153

• the four-electron oxidation product 1,1-dimethoxynaphthalen-2(1H)-one (2). Best results were obtained with a carbon/platinum electrode pair, although stainless steel (SS) could also be used as cathode. The experiments were conducted with a 3:1 mixture of methanol/tetrahydrofuran (optimization not

Rapid construction of tricyclic tetrahydrocyclopenta[4,5]pyrrolo[2,3-b]pyridine via isocyanide-based multicomponent reaction

• Xiu-Yu Chen,
• Ying Han,
• Jing Sun and
• Chao-Guo Yan

Beilstein J. Org. Chem. 2024, 20, 1436–1443, doi:10.3762/bjoc.20.126

• ), dimethyl but-2-ynedioate (2a) and 5,6-unsubstituted dihydropyridine 3a as standard reaction. The main results are summarized in Table 1. The expected product was not observed when the three-component reaction was carried out in methanol, ethanol or tetrahydrofuran at room temperature (Table 1, entries 1–3

A comparison of structure, bonding and non-covalent interactions of aryl halide and diarylhalonium halogen-bond donors

• Nicole Javaly,
• Theresa M. McCormick and
• David R. Stuart

Beilstein J. Org. Chem. 2024, 20, 1428–1435, doi:10.3762/bjoc.20.125

• engage in halogen-bonding interactions [29][30]. In this work, a series of halogen-bond donor molecules and their halogen bond complexes with chloride anion were optimized at the M062x/6-311+G(d) level of theory [31] with def2-tzvpp used for iodine and astatine, and with SMD solvation in tetrahydrofuran

Challenge N- versus O-six-membered annulation: FeCl₃-catalyzed synthesis of heterocyclic N,O-aminals

• Giacomo Mari,
• Lucia De Crescentini,
• Gianfranco Favi,
• Fabio Mantellini,
• Diego Olivieri and
• Stefania Santeusanio

Beilstein J. Org. Chem. 2024, 20, 1412–1420, doi:10.3762/bjoc.20.123

• was incremented with respect to 6a (entry 4, Table 1). Rising the amount of FeCl3 to 30 mol %, the reaction was complete in 2 hours, enhancing the yield of 5a (73%) and minimizing the yield of 6a (8%) (entry 5, Table 1). In reactions carried out in acetonitrile (ACN) or tetrahydrofuran (THF) the yield

Diameter-selective extraction of single-walled carbon nanotubes by interlocking with Cu-tethered square nanobrackets

• Guoqing Cheng and
• Naoki Komatsu

Beilstein J. Org. Chem. 2024, 20, 1298–1307, doi:10.3762/bjoc.20.113

• @(12,2)-SWNT complexes. Chemical structures of Cu-tethered tetragonal nanobrackets 1a and 1b. Synthesis of nanobracket 4. Reaction conditions: i) XPhos Pd G2, XPhos, B2(OH)4, KOAc, EtOH, 80 °C, 2 h; ii) Br-Ar-Br, K2CO3, tetrahydrofuran (THF)/toluene, 80 °C, 16 h; iii) trifluoroacetic acid (TFA), pyrrole

Synthesis of indano[60]fullerene thioketone and its application in organic solar cells

• Yong-Chang Zhai,
• Shimon Oiwa,
• Shinobu Aoyagi,
• Shohei Ohno,
• Tsubasa Mikie,
• Jun-Zhuo Wang,
• Hirofumi Amada,
• Koki Yamanaka,
• Kazuhira Miwa,
• Naoyuki Imai,
• Takeshi Igarashi,
• Itaru Osaka and
• Yutaka Matsuo

Beilstein J. Org. Chem. 2024, 20, 1270–1277, doi:10.3762/bjoc.20.109

• fullerene at the α position facilitated the successful transformation of ketone to thioketone. Initially, we adopted the widely reported reaction conditions with 1.5 equiv of Lawesson's reagent and tetrahydrofuran (THF) as solvent. t-Bu-FIDO was dissolved in THF by sonication for 30 min. Unfortunately, the

Bismuth(III) triflate: an economical and environmentally friendly catalyst for the Nazarov reaction

• Manoel T. Rodrigues Jr.,
• Aline S. B. de Oliveira,
• Ralph C. Gomes,
• Amanda Soares Hirata,
• Lucas A. Zeoly,
• Hugo Santos,
• João Arantes,
• Catarina Sofia Mateus Reis-Silva,
• João Agostinho Machado-Neto,
• Leticia Veras Costa-Lotufo and
• Fernando Coelho

Beilstein J. Org. Chem. 2024, 20, 1167–1178, doi:10.3762/bjoc.20.99

• ). Once the catalyst was chosen, we investigated the influence of the solvent. For this purpose, we evaluated dichloroethane (DCE), dichloromethane (DCM), toluene, and tetrahydrofuran (THF) as solvents for the transformation (Table 1, entries 16–19), but acetonitrile remained the best solvent. Finally, we

Structure–property relationships in dicyanopyrazinoquinoxalines and their hydrogen-bonding-capable dihydropyrazinoquinoxalinedione derivatives

• Tural N. Akhmedov,
• Ajeet Kumar,
• Daken J. Starkenburg,
• Kyle J. Chesney,
• Khalil A. Abboud,
• Novruz G. Akhmedov,
• Jiangeng Xue and
• Ronald K. Castellano

Beilstein J. Org. Chem. 2024, 20, 1037–1052, doi:10.3762/bjoc.20.92

• ; HRESIMS: [M + H]+ calcd for C18H10N4O2, 315.0881; found, 315.0877. 10,13-Dihydropyrazino[2',3':5,6]pyrazino[2,3-f][1,10]phenanthroline-11,12-dione (7b) In a 100 mL three-neck round-bottom flask, compounds 12 (100 mg, 0.624 mmol) and 7e (150 mg, 0.713 mmol) were added to 15 mL of tetrahydrofuran (THF

Confirmation of the stereochemistry of spiroviolene

• Yao Kong,
• Yuanning Liu,
• Kaibiao Wang,
• Tao Wang,
• Chen Wang,
• Ben Ai,
• Hongli Jia,
• Guohui Pan,
• Min Yin and
• Zhengren Xu

Beilstein J. Org. Chem. 2024, 20, 852–858, doi:10.3762/bjoc.20.77

• the double bond in a congested environment of spiroviolene (Scheme 2). Low conversion was observed when a tetrahydrofuran (THF) solution of 1 was treated with BH3·THF at ambient temperature. The hydroboration reaction could be driven to synthetically useful yield when 1 was directly dissolved in 1 M

Regioselective quinazoline C2 modifications through the azide–tetrazole tautomeric equilibrium

• Dāgs Dāvis Līpiņš,
• Andris Jeminejs,
• Una Ušacka,
• Anatoly Mishnev,
• Māris Turks and
• Irina Novosjolova

Beilstein J. Org. Chem. 2024, 20, 675–683, doi:10.3762/bjoc.20.61

• pharmaceutically active substances such as terazosin and prazosin, nucleophilic substitution at the C2 position was carried out with the corresponding amines – piperazin-1-yl(tetrahydrofuran-2-yl)methanone and furan-2-yl(piperazin-1-yl)methanone to give products 17e and 17f. Products 17e,f can be obtained through

Recent developments in the engineered biosynthesis of fungal meroterpenoids

• Zhiyang Quan and
• Takayoshi Awakawa

Beilstein J. Org. Chem. 2024, 20, 578–588, doi:10.3762/bjoc.20.50

• hydroxy group terminates the cyclization [20][21]. In ascofuranone biosynthesis, compound 21 is initially hydroxylated at C-8, and then the hydroxylated product is cyclized via epoxidation by AscI to form the tetrahydrofuran ring of 23. The biosynthetic pathways of 22 and 23 were elucidated through

Entry to new spiroheterocycles via tandem Rh(II)-catalyzed O–H insertion/base-promoted cyclization involving diazoarylidene succinimides

• Alexander Yanovich,
• Anastasia Vepreva,
• Ksenia Malkova,
• Grigory Kantin and
• Dmitry Dar’in

Beilstein J. Org. Chem. 2024, 20, 561–569, doi:10.3762/bjoc.20.48

• synthesis of spiro-annulated pyrrolidine-2,5-diones by catalyzed spirocyclizations involving aldehydes [11], tetrahydrofuran [12][13], and in the O–H insertion/Claisen rearrangement/intramolecular oxa-Michael addition cascade [14] (Scheme 1). Herein, we report our findings obtained, while investigating the

• including aldosterone receptor antagonistic [22], anti-inflammatory [23], and anti-HIV [24] activity. Substantial drugs based on spirocyclic tetrahydrofuran and pyran moieties include spironolactone (a multi-target drug that is primarily used to treat high blood pressure and heart failure) [25

Development of a chemical scaffold for inhibiting nonribosomal peptide synthetases in live bacterial cells

• Fumihiro Ishikawa,
• Sho Konno,
• Hideaki Kakeya and
• Genzoh Tanabe

Beilstein J. Org. Chem. 2024, 20, 445–451, doi:10.3762/bjoc.20.39

• deprotection of the 5′-OH group using 25% trifluoroacetic acid in tetrahydrofuran. Subsequently, the 5′-OH group of compounds 12a–e were reacted with sulfamoyl chloride in the presence of NaH. Compounds 13a–e were coupled to pre-activated Boc-ʟ-Phe-OSu in the presence of Cs2CO3. Removal of the Boc and TBS

Green and sustainable approaches for the Friedel–Crafts reaction between aldehydes and indoles

• Periklis X. Kolagkis,
• Eirini M. Galathri and
• Christoforos G. Kokotos

Beilstein J. Org. Chem. 2024, 20, 379–426, doi:10.3762/bjoc.20.36

Perspectives on push–pull chromophores derived from click-type [2 + 2] cycloaddition–retroelectrocyclization reactions of electron-rich alkynes and electron-deficient alkenes

• Michio Yamada

Beilstein J. Org. Chem. 2024, 20, 125–154, doi:10.3762/bjoc.20.13

1-Butyl-3-methylimidazolium tetrafluoroborate as suitable solvent for BF₃: the case of alkyne hydration. Chemistry vs electrochemistry

• Marta David,
• Elisa Galli,
• Richard C. D. Brown,
• Marta Feroci,
• Fabrizio Vetica and
• Martina Bortolami

Beilstein J. Org. Chem. 2023, 19, 1966–1981, doi:10.3762/bjoc.19.147

• classical volatile and, in some cases, toxic organic solvents, such as dioxane, tetrahydrofuran, methanol, dichloromethane or 1,2-dichloroethane. The efficiency of the reported catalysts and of the examined reaction conditions are variable according to the alkynes considered and, nowadays, the