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

• Daniel Straub Markus Gross Mona E. Arnold Julia Zolg Alexander J. C. Kuehne OC III - Institute of Organic and Macromolecular Chemistry, Ulm University, Albert-Einstein-Allee 11, 89081 Ulm, Germany Center for Integrated Quantum Science and Technology, Ulm University, Albert-Einstein-Allee 11, 89081

• –LUMO energy gaps are identical and their respective transitions exhibit identical transition dipole moments [19][32][33]. For the |D1⟩ transition these two degenerate transitions mix in an out-of-phase fashion leading to the observed weak absorption at 544 nm (see Figure 1b and c). When looking at the

• Mulliken symmetry labels, one realizes that the |D1⟩ transition is in fact symmetry forbidden. By contrast, in-phase mixing of the transitions for the |D2⟩ transition leads to strong absorption at 374 nm, a transition that is symmetry allowed (see Figure 1b and c). In TTM, the ϕ is independent of the

Studies on the syntheses of β-carboline alkaloids brevicarine and brevicolline

• Benedek Batizi,
• Patrik Pollák,
• András Dancsó,
• Péter Keglevich,
• Gyula Simig,
• Balázs Volk and
• Mátyás Milen

Beilstein J. Org. Chem. 2025, 21, 955–963, doi:10.3762/bjoc.21.79

• , versatile key triflate intermediate 3, which allowed the introduction of substituents attached by a C–C bond to position 4 of the β-carboline scaffold by cross-coupling reactions. Sonogashira reaction of compound 3 with N-(3-butynyl)phthalimide (4) led to coupled compound 5. Cleavage of the phthalimide

• hydrogenation of the C=C double bond in the side chain gave brevicarine (2). The first total synthesis of brevicarine is shown in Scheme 3 [2][20][21]. Condensation of indole (11) with 1-methylpiperidone (12) gave compound 13 [22]. N-Alkylation of 13 with benzyl bromide, followed by treatment of the quaternary

• 21 under extremely harsh conditions (100 °C, 130 bar), followed by N-acetylation gave a mixture of diastereomeric racemates 22, which was cyclized to a diastereomeric mixture of β-carboline derivatives 23. Heating of 23 in pivalic acid in the presence of a catalytic amount of trifluoroacetic acid

Harnessing tethered nitreniums for diastereoselective amino-sulfonoxylation of alkenes

• Shyam Sathyamoorthi,
• Appasaheb K. Nirpal,
• Dnyaneshwar A. Gorve and
• Steven P. Kelley

Beilstein J. Org. Chem. 2025, 21, 947–954, doi:10.3762/bjoc.21.78

• equivalent of commercial iodomesitylene diacetate (CAS [33035-41-5]) and 1 equivalent of MsOH (Table 1, entry 4). Here, it was necessary to maintain a temperature of 0 °C, as vigorous bubbling and rapid decomposition occurred when the reaction was initiated at room temperature. In all cases (Table 1), only a

• steric bulk of the isopropyl group unfavorably affected the reaction outcome. However, we found that when 3 was subjected to the more active combination of iodomesitylene diacetate and p-TsOH·H2O at 0 °C in CH2Cl2, the desired product 4 formed in a much-improved yield of 57%. Not all tethers were

Study of tribenzo[b,d,f]azepine as donor in D–A photocatalysts

• Katy Medrano-Uribe,
• Jorge Humbrías-Martín and
• Luca Dell’Amico

Beilstein J. Org. Chem. 2025, 21, 935–944, doi:10.3762/bjoc.21.76

• offers unique features, including twisted structures, reduced π–π stacking, and enhanced reverse intersystem crossing rates, becoming a better donor compared to fully planar compounds as carbazole (c). Similarly, 5H-dibenz[b,f]azepine (IMD, b) has been incorporated into D–A–D structures, showing

• interesting photophysical properties compared to common substrates like c, diphenylamine (d), and phenoxazine (e) [28][29][30]. However, their potential as D-unit in organic PCs remains unexplored. For this reason, studying this avenue could unlock new opportunities for the synthesis and design of more

• . Additionally, we aim to evaluate the unique effect of the TBA donor unit (a) compared to other donors. We next synthesized diverse D–A structures employing common nitrogen-based compounds widely used in materials chemistry like carbazole (c), diphenylamine (d), and phenoxazine (e). Furthermore, we wanted to

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

• involving limonoids. Krishnolides A and C (7 and 8, respectively; Scheme 1A) were identified by Wu and co-workers from the seeds of a Krishna mangrove Xylocarpus moluccensis [26]. These two molecules belong to khayanolides, a class of rearranged phragmalin limonoids characterized by a structurally intricate

• tricyclo[4.2.110,30.11,4]decane ring system. Additionally, krishnolides A and C contain 9–11 stereogenic centers and exhibit diverse oxidation patterns. Their relative and absolute configurations were determined through NMR, HRESIMS and ECD experiments, as well as single crystal X-ray diffraction analysis

• convergent approach leveraging an AcOH-interrupted Nazarov cyclization to establish the [5,5,6,6]-tetracyclic scaffold with precise stereochemical fidelity. Results and Discussion Our retrosynthetic analysis toward krishnolides A (7) and C (8) is delineated in Scheme 1B. We hypothesized that these two

Silver(I) triflate-catalyzed post-Ugi synthesis of pyrazolodiazepines

• Muhammad Hasan,
• Anatoly A. Peshkov,
• Syed Anis Ali Shah,
• Andrey Belyaev,
• Chang-Keun Lim,
• Shunyi Wang and
• Vsevolod A. Peshkov

Beilstein J. Org. Chem. 2025, 21, 915–925, doi:10.3762/bjoc.21.74

• , propiolic acids 8a–d, and isocyanides 4a–e. By conducting the reactions in methanol at 70 °C, we obtained the desired Ugi adducts 15a–x in fair to good yields of 26–72% allowing for the variation of substituents across all components of the U4CR (Scheme 2). Notably, the Ugi reaction toward substrate 15a

• , when performed at room temperature, proceeded with lower efficiency compared to the reaction at 70 °C, leaving some of the starting 1H-pyrazole-3-carbaldehyde (14a) unreacted. Propargylamide 15a was selected as a model substrate to optimize the reaction conditions for the intramolecular

• by nitrogen nucleophiles [59][60]. When the reaction was conducted with 5 mol % of AgOTf in toluene at 80 °C for 20 hours, pyrazolo[1,5-a][1,4]diazepine 16a was obtained in 46% yield, while complete conversion of the starting material 15a was not achieved (Table 1, entry 1). Increasing the

Recent advances in controllable/divergent synthesis

• Jilei Cao,
• Leiyang Bai and
• Xuefeng Jiang

Beilstein J. Org. Chem. 2025, 21, 890–914, doi:10.3762/bjoc.21.73

• , oxidative addition of the C–I bond to palladium formed the four-membered aryl–palladium complex Int-5. Steric hindrance from the bulky dppm ligand, combined with slower aryne release (using KF as the fluoride source), attenuated aryne coordination. Under these electron-deficient conditions, CO

• ensuring high regioselectivity. In 2018, the Jiang group developed a regiodivergent synthetic method for indolo[3,2-c]coumarins 10 and benzofuro[3,2-c]quinolinones 9 via controllable palladium(II)-catalyzed carbonylative cyclization (Scheme 3) [21]. When ligand L3 coordinates with the palladium center, the

• elimination yields the benzofuro[3,2-c]quinolinone product 9 along with a Pd(0) species, which is reoxidized to Pd(II) by BQ (benzoquinone). When the ligand is switched to the sterically bulky and electron-rich dppm, the chemoselectivity is reversed: the palladium center now preferentially coordinates with

Dicarboxylate recognition based on ultracycle hosts through cooperative hydrogen bonding and anion–π interactions

• Wen-Hui Mi,
• Teng-Yu Huang,
• Xu-Dong Wang,
• Yu-Fei Ao,
• Qi-Qiang Wang and
• De-Xian Wang

Beilstein J. Org. Chem. 2025, 21, 884–889, doi:10.3762/bjoc.21.72

• reorganization likely involves the cleavage and re-formation of the dynamic Ctriazine–OAr bonds, and the presence of an excess of base could facilitate the formation of the thermodynamic-favored reorganized products [29][31]. The benzyl groups were subsequently removed under Pd/C and H2 conditions to afford the

• ) solution of the compound at 4 °C, enabling structural analysis of the ultracycle. As illustrated in Figure 1, the backbone of B4aH adopts a Z-like shape with a flexible conformation. The two oxacalix[2]arene[2]triazine subcavities are positioned along the short axis in a staggered face-to-face arrangement

• , while the glycol chains are oriented along the long axis in the opposite orientations. In packing mode, the submacrocycle units form close contacts through intermolecular hydrogen bonding, C–H···π, and lone pair–π interactions, resulting in a 1D linear assembly. Anion recognition With the functional

Cu–Bpin-mediated dimerization of 4,4-dichloro-2-butenoic acid derivatives enables the synthesis of densely functionalized cyclopropanes

• Patricia Gómez-Roibás,
• Andrea Chaves-Pouso and
• Martín Fañanás-Mastral

Beilstein J. Org. Chem. 2025, 21, 877–883, doi:10.3762/bjoc.21.71

• species A which is in equilibrium with the Cu–O enolate B [11]. In the presence of excess of LiOt-Bu, a salt metathesis reaction between this base and intermediate B generates lithium enolate C and LCuOt-Bu to close the copper catalytic cycle. The formation of a lithium enolate is consistent with the

• different diastereoselectivity observed when other bases featuring different metal cations were used (Table 1, entry 2 vs entry 5), and the absence of any significant stereochemical influence from the copper complex (Table 1, entries 9–14). Lithium enolate C would then undergo a diastereoselective conjugate

• details). In contrast, the use of CsF in dioxane at 70 °C proved to be efficient and selectively provided cyclopropane 9 in good yield, albeit with no diastereoselectivity (Table 2, entry 1). Cs2CO3 was also selective for this cyclization and provided a slight increase in diastereoselectivity, although

Light-enabled intramolecular [2 + 2] cycloaddition via photoactivation of simple alkenylboronic esters

• Lewis McGhie,
• Hannah M. Kortman,
• Jenna Rumpf,
• Peter H. Seeberger and
• John J. Molloy

Beilstein J. Org. Chem. 2025, 21, 854–863, doi:10.3762/bjoc.21.69

• considering recent advances enabling subsequent intramolecular H-atom abstraction [51] and efficient rearrangements [73][74]. A) Energy transfer catalysis of alkenes in organic synthesis. B) Energy transfer catalysis of conjugated borylated alkenes. C) Energy transfer catalysis of simple alkenylboronic esters

• cyclobutyldiol. A) Product derivatization and B) transition-metal EnT catalysis. Reaction conditions A): 4d (1 equiv), H2O2 (30 wt % in H2O), aq NaH2PO4, THF, 0 °C; B) 4 (1 equiv), KF (4 equiv), ʟ-tartaric acid (2.1 equiv), MeOH, MeCN, H2O, rt. Probing EnT catalysis of alkenylboronic ester 1a via alkene

Unraveling cooperative interactions between complexed ions in dual-host strategy for cesium salt separation

• Zhihua Liu,
• Ya-Zhi Chen,
• Ji Wang,
• Qingling Nie,
• Wei Zhao and
• Biao Wu

Beilstein J. Org. Chem. 2025, 21, 845–853, doi:10.3762/bjoc.21.68

• carbonyl (C=O) groups, as well as direct ion-pairing interactions between 18-crown-6-complexed Cs+ and hexaurea-bound PO43−. Single-crystal structural analysis corroborates these interactions, shedding light on the underlying mechanisms and providing valuable guidance for the rational design of advanced

• , only two examples provide clear evidence of cooperative interactions based on single crystal structures [28][29], where the 18-crown-6 complexed K+ cation forms ion-dipole interactions with the carbonyl (C=O) or nitro (NO2) groups of the anion-bound receptors (KF and K2CO3). Recently, we demonstrated

• interactions between K+ and C=O moieties [31], similar to these seen in the single crystal structures of KF and K2CO3 complexes. These provide a promising opportunity that can be used to identify the cooperative interaction underpinning complexed ions in dual-host strategy-based extraction. To do this, the

Chitosan-supported CuI-catalyzed cascade reaction of 2-halobenzoic acids and amidines for the synthesis of quinazolinones

• Xuhong Zhao,
• Weishuang Li,
• Mengli Yang,
• Bojie Li,
• Yaoyao Zhang,
• Lizhen Huang and
• Lei Zhu

Beilstein J. Org. Chem. 2025, 21, 839–844, doi:10.3762/bjoc.21.67

• (acac)2) and chitosan-supported on CuSO4 (CS@CuSO4) were explored, and the results showed that CS@CuI was the most effective catalyst (Table 1, entries 7−11, 65−89% yields). To further enhance the reaction yield, the reaction temperature was increased to 90 °C, and the target product 3a was obtained in

• -halobenzoic acids and amidines for the synthesis of quinazolinones. Substrate scope. Reaction conditions: 1 (0.5 mmol, 1.0 equiv), amidines hydrochloride 2 (0.75 mmol, 1.5 equiv), CS@CuI (10.0 mg, ICP: 14.6%, 5.0 mol %), Na2CO3 (1.25 mmol, 2.5 equiv), iPrOH/H2O 9:1 (2.0 mL), 90 °C, 12 h, argon atmosphere; a1

• (0.2 mmol), amidine hydrochloride 2 (0.3 mmol, 1.5 equiv), CS@CuI (5.0 mol %), Na2CO3 (1.25 mmol, 2.5 equiv), iPrOH/H2O 9:1 (2.0 mL), 90 °C, 12 h, argon atmosphere. Proposed mechanism for the CS@CuI-catalyzed synthesis of quinazolinones. Scaling-up experiment (a) and recyclability of CS@CuI (b

Substituent effects in N-acetylated phenylazopyrazole photoswitches

• Radek Tovtik,
• Dennis Marzin,
• Pia Weigel,
• Stefano Crespi and
• Nadja A. Simeth

Beilstein J. Org. Chem. 2025, 21, 830–838, doi:10.3762/bjoc.21.66

• . Acylation of the pyrazole moiety led to an enhanced metastable half-life compared to the NH-PAPs. For NAc-PAP-H, we observed increased half-lifes (21.5 days, 30 °C), compared to the reported NH-PAP-H (0.066 days; 25 °C [51]) or NMe-PAP-H (10 days; 25 °C [31], all in CH3CN). In the presence of OH as

• -PAP-CN upon 365 nm irradiation (12.5 µM in CH3CN, at 25 °C). B) Absorbance of the same sample at 365 nm (Ar, 365nm) after reaching PSS365 or PSS455, respectively, to show the recyclability. Hammett plot of NAc-PAP derivatives. Eyring plots for NAc-PAP-CN and NAc-PAP-OMe. Reaction pathway for

• synthesizing NH-substituted, methylated-, and acetylated arylazopyrazoles. Conditions: A) NaNO2, AcOH + HCl at 0 °C, then, 2,4-pentanedione, NaOAc in EtOH + H2O, reflux; B) MeNHNH2, EtOH, reflux; C) NH2NH2, EtOH, reflux; D) AcCl, NaOAc in DCM, 0 °C to rt. Photophysical properties of synthesized PAP derivatives

4-(1-Methylamino)ethylidene-1,5-disubstituted pyrrolidine-2,3-diones: synthesis, anti-inflammatory effect and in silico approaches

• Nguyen Tran Nguyen,
• Vo Viet Dai,
• Luc Van Meervelt,
• Do Thi Thao and
• Nguyen Minh Thong

Beilstein J. Org. Chem. 2025, 21, 817–829, doi:10.3762/bjoc.21.65

• , we report the synthesis of 4-(1-methylamino)ethylidene-1,5-disubstituted pyrrolidine-2,3-diones via a reversible transimination reaction between Schiff’ base (C=N) linkage-containing pyrrolidine-2,3-dione derivatives and methylamine with yields of 80 to 92%. In addition to nuclear magnetic resonance

• -hybridized carbon atom directly bonded to the nitrogen atom of the secondary amino group of compound 5a. In the structure of each pyrrolidine-2,3-dione derivative 3a–e, there is an α,β-unsaturated ketone moiety in which the π systems of the C=C and C=O bonds could overlap each other to yield an extended

• and charge separation. In the resonance forms 3a’–e’, the 4-methoxybenzylamino group is covalently attached to the 4-position of the 1,5-disubstituted pyrrolidine-2,3-dione core via a Schiff’ base (C=N) linkage in which the positive charge could be delocalized on both carbon and nitrogen atoms. In

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

• a subsequent Suzuki cross-coupling reaction with (4-(diphenylamino)phenyl)boronic acid was performed. The reaction conditions were adapted from prior experiments with C-NBD1 [40] and further refined for the heterocyclic analogues. Optimal results were achieved using K2CO3, Pd(OAc)2 and RuPhos with

• the corresponding boronic acid in a degassed toluene/H2O mixture (4:1, v/v) which was heated to 80 °C for 18 h (for detailed information see Supporting Information File 1). Using the described procedure, the oxygen containing derivatives O-NBD2 and nitrogen substituted N-NBD2 were successfully

Regioselective formal hydrocyanation of allenes: synthesis of β,γ-unsaturated nitriles with α-all-carbon quaternary centers

• Seeun Lim,
• Teresa Kim and
• Yunmi Lee

Beilstein J. Org. Chem. 2025, 21, 800–806, doi:10.3762/bjoc.21.63

• bonds is one of the most efficient and atom-economical approaches for synthesizing alkyl nitriles [15][16]. Among the potential substrates, allenes have attracted significant attention because of their unique structural features, which consist of two orthogonal and contiguous C=C bonds. This dual π

• efficiently constructed α-all-carbon quaternary centers on β,γ-unsaturated nitriles with excellent >98% regioselectivity and >98% (E)-selectivity. 1,1-Disubstituted allenes bearing silyl ether- and benzyl ether-tethered propyl groups were successfully converted into the desired nitriles 3a–c in yields ranging

• quaternary and tertiary carbon centers. The scope of monosubstituted allenes is illustrated in Scheme 4. Allenes 4a–c substituted with alkyl groups, including phenethyl, decyl, and cyclohexyl groups, smoothly underwent hydrocyanation, yielding the corresponding nitriles 5a–c in 79–90% yield with excellent

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

• electrosynthesis as a green, precise, and low-cost method to prepare phosphorous structures. Keywords: electrosynthesis; green synthesis; organophosphorus compounds; P–C bond formation; P–heteroatom bond formation; Introduction The electrochemical synthesis is a valuable and beneficial method for the preparation

• electrode with the reaction solution. The oxidation–reduction process complements each other, and the surface of the electrode in the reaction is critical. The material of the electrode is essential [44]. Various electrodes, including carbon (C), platinum (Pt), nickel (Ni), and reticulated vitreous carbon

• (RVC), are extensively used in the electrosynthesis of organophosphorus compounds (Table 1). Carbon (C) electrode: The carbon electrode is one of the most widely used electrodes in electrochemical synthesis. This electrode is a porous material that allows chemicals to penetrate it. On the other hand

Development and mechanistic studies of calcium–BINOL phosphate-catalyzed hydrocyanation of hydrazones

• Carola Tortora,
• Christian A. Fischer,
• Sascha Kohlbauer,
• Alexandru Zamfir,
• Gerd M. Ballmann,
• Jürgen Pahl,
• Sjoerd Harder and
• Svetlana B. Tsogoeva

Beilstein J. Org. Chem. 2025, 21, 755–765, doi:10.3762/bjoc.21.59

• our previous work [45], we carried out the enantioselective hydrocyanation of hydrazones using Ca–BINOL phosphate complex 6 at −10 °C in DCM for 72 h. In addition to those reaction conditions, we initially used t-BuOH as an additive [45]. The Ca–BINOL phosphate complex 6 was prepared in situ by

• moiety are non-linear with a Ca–N–C angle of 100°. Due to the stereospecificity of the reaction, racemization would have to occur already in 9 through a topomerization (e.g., similar to a Berry pseudorotation) of the metal complex, considering that species with a quaternary carbon, as they appear in

• isomer, with a more acute Ca–N–C angle of 92°, has greater resemblance to a (here absent) side-on form (found to dominate computationally for Ca(CN)2 in the gas phase) [54]. Fortunately, that isomer in which the isonitrile carbon is closer to the imine carbon (i.e., the hydrocyanation reaction center

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

• moderate yield (Table 1, entry 6). Conducting the reaction at room temperature (rt) instead of the optimal elevated temperature resulted in a lower yield (Table 1, entry 7). Increasing the reaction temperature to 100 °C did not improve the yield (Table 1, entry 8). Having established the optimal reaction

• spirotetrahydroquinoline (STHQ) scaffolds. Substrate scope. General reaction conditions: aniline 1 (0.2 mmol), 2 (0.4 mmol), and Cu(TFA)2 (0.04 mmol) in hexane (2.0 mmol) under air atmosphere, 12 h, 80 °C. Yields refer to isolated yields. Scale-up reaction.a Proposed mechanism. Optimization of reaction conditions.a

Orthogonal photoswitching of heterobivalent azobenzene glycoclusters: the effect of glycoligand orientation in bacterial adhesion

• Leon M. Friedrich and
• Thisbe K. Lindhorst

Beilstein J. Org. Chem. 2025, 21, 736–748, doi:10.3762/bjoc.21.57

• azobenzene derivative 9 [34] to furnish 10. This reaction had to be carried out at −78 °C in order to suppress nucleophilic substitution of the ortho-fluorine substituents in 9 by the thiol 8, a reaction that competes with the desired cross-coupling. For the second Buchwald–Hartwig–Migita cross-coupling, the

• thermodynamically stable EE isomer was followed over time starting from the PSS@365 nm. The kinetic traces of the relaxation process were recorded by 1H NMR spectroscopy at 37 °C (Supporting Information File 1, Figure S2) and the population of the EE, ZE, EZ, and ZZ isomers were plotted against time. Using a

• published tailor-made fitting program [24], the rate constants k1–k4 were extracted from the kinetic traces and are summarized in Table 2. The thermal relaxation of the glycoazobenzene antennas 3, 4, and 5, on the other hand, was monitored by UV–vis spectroscopy at 37 °C and the rate constants k5, k6, and

Synthesis of HBC fluorophores with an electrophilic handle for covalent attachment to Pepper RNA

• Raphael Bereiter and
• Ronald Micura

Beilstein J. Org. Chem. 2025, 21, 727–735, doi:10.3762/bjoc.21.56

• Exactive Orbitrap. General procedure A. 4-Fluorobenzaldehyde, the corresponding N-methylated amino alcohol and potassium carbonate were suspended in dimethyl sulfoxide and stirred for 30 hours at 120 °C. The resulting suspension was poured on crushed ice and extracted four times with chloroform, dried over

• piperidine and stirred at 100 °C for 20 hours. A strongly yellow-colored solution was obtained and cooled on ice, whereby a precipitate was formed and filtered off. The filter cake was washed with ice-cold ethanol and dried under high vacuum. General procedure C. In a manner similar to [11], the product

• obtained in general procedure B was dissolved in dichloromethane and cooled to 0 °C under argon atmosphere. Then, triphenylphosphine and carbon tetrabromide were added and stirred at room temperature for two hours. Afterwards, the entire mixture was loaded on a silica gel column and eluted with 100

Acyclic cucurbit[n]uril bearing alkyl sulfate ionic groups

• Christian Akakpo,
• Peter Y. Zavalij and
• Lyle Isaacs

Beilstein J. Org. Chem. 2025, 21, 717–726, doi:10.3762/bjoc.21.55

• acyclic CB[n] are not macrocycles, they are preorganized into a C-shaped geometry by virtue of their polycyclic chemical structure and display binding affinities approaching those of macrocyclic CB[n]. M1 and analogues display outstanding biocompatibility and have been used for a number of in vivo

• closer to the ureidyl C=O portals [68][69]. However, a close examination of the structures of M0 and M1 show that the ionic group for M1 is a sulfonate and for M0 is a sulfate. Accordingly, M1 and M0 differ in two ways: a) different (CH2)n linker length and b) different ionic group (sulfonate versus

• sulfate) while maintaining the distance of the ionic group from the ureidyl C=O portal we designed acyclic CB[n]-type receptor C1 (Scheme 1). The only structural difference between M1 and C1 is the swapping of one CH2 group for one O atom in each alkyl chain which effectively changes the sulfonate group

Origami with small molecules: exploiting the C–F bond as a conformational tool

• Patrick Ryan,
• Ramsha Iftikhar and
• Luke Hunter

Beilstein J. Org. Chem. 2025, 21, 680–716, doi:10.3762/bjoc.21.54

• Patrick Ryan Ramsha Iftikhar Luke Hunter School of Chemistry, The University of New South Wales (UNSW), Sydney 2052, Australia 10.3762/bjoc.21.54 Abstract When present within an organic molecule, the C–F bond tends to align in predictable ways with neighbouring functional groups, due to

• fluorine atoms into the structure. The C–F bond has certain fundamental characteristics that enable it to serve as an effective conformational tool (Figure 1) [2][3][4]. First, the C–F bond is quite short at only ≈1.35 Å (cf. ≈1.09 Å for C–H, or ≈1.43 Å for C–O). The short length of the C–F bond, and the

• compact size of the fluorine atom itself, means that fluorine can be incorporated into an organic molecule as a replacement for hydrogen without drastically altering the molecular volume. Second, the C–F bond is highly polarised. This means that any molecular conformation in which the C–F dipole is

Photochemically assisted synthesis of phenacenes fluorinated at the terminal benzene rings and their electronic spectra

• Yuuki Ishii,
• Minoru Yamaji,
• Fumito Tani,
• Kenta Goto,
• Yoshihiro Kubozono and
• Hideki Okamoto

Beilstein J. Org. Chem. 2025, 21, 670–679, doi:10.3762/bjoc.21.53

• the manipulation of the solid-state optoelectronic nature of polycyclic aromatic molecules to develop future functional materials in organic electronics. Chemical structures of phenacenes studied in this work. UV–vis and fluorescence spectra of F8PIC (a), F8FUL (b), and F87PHEN (c) (red lines) and the

• corresponding parent phenacenes (black lines) in CHCl3. The broken lines show long-wavelength absorption bands at 10-times magnification of the intensity for clarity. Photoluminescence spectra of F8PIC (a), F8FUL (b), and F87PHEN (c) in toluene at 77 K. Electronic spectra of F8PIC (a), F8FUL (b), and F87PHEN (c

• state. The orange and blue sites, respectively, indicate negative and positive regions (−0.02 ≈ 0.02 hartree). Synthesis of building blocks 10, 13, and 15. Reagents and conditions: a) NaBH4, MeOH, THF, reflux; b) PBr3, reflux; c) N-methylmorpholine-N-oxide, THF, reflux; d) ethylene glycol, p-TsOH

Asymmetric synthesis of fluorinated derivatives of aromatic and γ-branched amino acids via a chiral Ni(II) complex

• Maurizio Iannuzzi,
• Thomas Hohmann,
• Michael Dyrks,
• Kilian Haoues,
• Katarzyna Salamon-Krokosz and
• Beate Koksch

Beilstein J. Org. Chem. 2025, 21, 659–669, doi:10.3762/bjoc.21.52

• identified as optimal delivering a yield of alkylated complex of 60% (Table 1, entry 4). With DBU as base different solvents differing in polarity have been tested. At room temperature, acetonitrile proved best and increased the yield to 88% (Table 1, entry 11). Lowering the temperature to 0 °C led to a

• final yield of 94%. At these conditions (DBU, MeCN and 0 °C) the base and bromide equivalents were further modified but no further increase in yield could be achieved. Thus, 1.5 equiv DBU with 1.05 equiv alkyl bromide in MeCN at 0 °C have been identified as optimal conditions for the Ni complex

• (II) complex of bisTfMePhe have differed significantly. Here, sodium hydride (NaH) was identified as optimal base leading to a yield of 85% when using DMF as solvent at 0 °C to room temperature (Table 2, entry 4). Testing different base equivalents, solvents, solvent mixtures and temperatures didn’t