Synthetic approach to borrelidin fragments: focus on key intermediates

• Yudhi Dwi Kurniawan,
• Zetryana Puteri Tachrim,
• Teni Ernawati,
• Faris Hermawan,
• Ima Nurasiyah and
• Muhammad Alfin Sulmantara

Beilstein J. Org. Chem. 2025, 21, 1135–1160, doi:10.3762/bjoc.21.91

• stereoselectivity. The authors emphasized that, as the alkene moiety in 54 was in a terminal position, the stereoselectivity of the products was determined solely by the chiral environment of the catalysts. The application of this method to construct the C3–C11 fragment 60 of borrelidin is summarized in Scheme 8

• compound 84 through a series of sequential steps, including chemoenzymatic (ω-1)-hydroxylation, regioselective dehydration of the resulting alcohol to form a terminal alkene, ozonolysis of the alkene to yield an aldehyde, reduction of the aldehyde product to a primary alcohol, and protection of the alcohol

• subsequently dehydrated using Martin’s sulfurane to produce terminal alkene 90 in 97% yield. A sequence of ozonolysis, reduction with sodium borohydride, and PMB protection using camphorsulfonic acid and PMB-trichloroacetimidate reagents followed, yielding compound 87 in 62% yield. Next, the ester

Recent advances in synthetic approaches for bioactive cinnamic acid derivatives

• Betty A. Kustiana,
• Galuh Widiyarti and
• Teni Ernawati

Beilstein J. Org. Chem. 2025, 21, 1031–1086, doi:10.3762/bjoc.21.85

Recent total synthesis of natural products leveraging a strategy of enamide cyclization

• Chun-Yu Mi,
• Jia-Yuan Zhai and
• Xiao-Ming Zhang

Beilstein J. Org. Chem. 2025, 21, 999–1009, doi:10.3762/bjoc.21.81

• , the terminal alkene remains intact during this process, and the initial protonation proceeds with full stereocontrol, rendering this transformation both highly chemo- and diastereoselective. From the cyclization result, it is presumed that the higher nucleophilicity of the alkyne functionality over

• the terminal alkene and the conformational strain of forming a bridge[3.2.1]bicycle might be responsible for a selective 6-exo-trig cyclization. From tricyclic compound 4, anti-Markovnikov oxidation catalyzed by palladium led to the formation of aldehyde 5. When treated with p-TsOH, the intramolecular

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

• diastereoselectivity (Table 4, entry 1). A urea substrate also furnished the expected product in a good yield and with high diastereoselectivity (Table 4, entry 3). With tri-substituted allylic carbamate 35, some amount of expected mesyloxylated product 36 did form, but there was also an isolable amount of a terminal

• unpurified reaction residues showed a complex mixture of products. There were some signals suggestive of terminal alkenes, implying that olefin transposition was a competing pathway. With alkyne substrate 59, decomposition occurred, and the 1H NMR of the unpurified reaction mixture was illegible. With

• terminal alkene substrate 60, unproductive decomposition of starting material was again observed. Given the highly predictable diastereoselectivity of this transformation and by analogy to prior art [4][6], we hypothesize that the reaction proceeds through the formation of a transient nitrenium species

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

• ) [46]. In 2019, Li, Yang, Van der Eycken and co-workers reported a modification of this strategy relying on thermal activation instead of cationic gold catalysis [47]. The approach worked particularly well with substrates featuring terminal alkynes. Inspired by these developments and taking into

• . Another set of pyrazolodiazepines 16p–v was readily obtained from the substrates 15p–v stemming from various 3-substituted propiolic acids and aliphatic or aromatic isocyanides. Finally, the annulation of substrates 15w and 15x, featuring a terminal alkyne, also proceeded in a 7-endo-dig fashion, yielding

• pyrazolodiazepines 16w and 16x, respectively. Such an outcome is notable, as related carbocyclizations often switch to an exo mode when shifting from internal to terminal alkynes [61][62][63]. To demonstrate the robustness of our methodology, we tested a telescope procedure in which, after the Ugi step, the product

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

• dicarboxylates interact with each subcavity of B4aH through their terminal anionic groups, utilizing cooperative hydrogen bonding and anion–π interactions. The optimal size matching between dicarboxylate and the host cavity, as seen with C72−, enhances the synergistic effect between the two subcavities

• dicarboxylate C72− is included within the cavity of B4aH. The two subcavities interact synergistically with the included dicarboxylate; the two terminal carboxylate groups are respectively positioned within electron-deficient cavities of the submacrocycles, forming hydrogen bonds (2.49–2.59 Å) with the two

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

• stabilized by the binding with 18-crown-6 and three ion-dipole interactions with O=C (urea unit) and O–N (terminal nitro group). Distances of Cs–O are measured at 3.0 Å and 3.4 Å. Regarding type-(II) cesium binding, four cesium cations are observed to interact with two urea units and two nitro groups through

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

• centers (Scheme 1b). Although both methodologies achieved high regioselectivity, their substrate scopes were limited, and most studies focused on the hydrocyanation of terminal allenes. Given the synthetic importance of nitriles that bear all-carbon quaternary centers and the distinctive reactivity of

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

• proton of the terminal sugar units in the 1H NMR spectrum (Table 1 and Supporting Information File 1, Figures S8, S10, and S12). Irradiation with 365 nm light excites the π–π* band of the ortho-fluorinated S-azobenzene units (ABF4) of both 3 and 4 and the π–π* band of the O-azobenzene (AB) unit of 5

• modeling illustrates the different FimH binding modes of the various isomers of 1 and 2 (Figure 4C and D). Inspection of these ligand–protein complexes reveals that in all isomers, a terminal α-ᴅ-mannoside ligand is complexed within the FimH carbohydrate binding pocket where it forms the classical network

• following conclusions can be drawn. (i) In all inspected azobenzene glycoconjugates (1, 2, 4, and 5), a terminal α-ᴅ-mannopyranoside unit is complexed within the FimH CRD, as expected. (ii) The isomeric state of the azo group in the monovalent azobenzene glycosides 4 and 5 alters the orientation of the non

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

• (I, Figure 2). This has several implications. For example, if the C–C(F) bond rotates, the orientation of the terminal C–F bond dipole changes, and this can alter the overall dipole moment of the molecule. Indoles 1–3 illustrate this point (Figure 2) [9]. The non-fluorinated indole 1 has an unvarying

• polar C–F bonds at the end of an alkyl chain, is that the terminal C–H bond also becomes polarised. In the case of the difluoromethyl group, the terminal hydrogen bears a partial positive charge and is able to act as a H-bond donor (II, Figure 2). This can influence the conformation of the molecule if

• molecular properties. The fluorine–oxygen gauche effect has been exploited to influence the properties of liquid crystals [86][87]. For example, the vicinal fluoroether 50 (Figure 7) can adopt a low-energy conformation in which the terminal C–F bond aligns gauche to the vicinal C–O bond. This orientation of

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

• , Okayama University, Okayama 700-8530, Japan 10.3762/bjoc.21.53 Abstract [n]Phenacenes ([n] = 5–7), octafluorinated at the terminal benzene rings (F8-phenacenes: F8PIC, F8FUL, and F87PHEN), were photochemically synthesized, and their electronic spectra were investigated to reveal the effects of the

• serves as a p-channel organic semiconductor [37], whereas perfluoropentacene can be used as an n-channel material [38]. It has been demonstrated that the molecular structure of [7]helicenes was modified by fluorination, thus, the helicenes’ pitch was manipulated by terminal fluorination modes [39][40

• the corresponding parent phenacenes PIC, FUL, and 7PHEN to reveal the effects of the fluorination at the terminal rings. Results and Discussion Synthesis of F8-phenacenes The synthetic routes to building blocks 10, 13, and 15 and those to the desired F8PIC, F8FUL, and F87PHEN are respectively shown in

Recent advances in allylation of chiral secondary alkylcopper species

• Minjae Kim,
• Gwanggyun Kim,
• Doyoon Kim,
• Jun Hee Lee and
• Seung Hwan Cho

Beilstein J. Org. Chem. 2025, 21, 639–658, doi:10.3762/bjoc.21.51

• bearing various functionalities. Notably, no erosion of enantiomeric excess was observed during any of the transformations. Double CuH insertion into alkynes for regiodivergent allylic substitution Generating chiral secondary alkylcopper species in situ through sequential hydrocupration of terminal

• readily available starting materials: terminal alkynes, HBdan, polymethylhydrosiloxane (PMHS), and allylic phosphates, through a complex cascade hydroboration and hydroallylation sequence [56]. Shortly after this work, Xiong, Zhu, and co-workers reported a ligand-controlled copper-catalyzed regiodivergent

• asymmetric difunctionalization of terminal alkynes through a cascade process involving initial hydroboration followed by a hydroallylation (Scheme 15) [57]. Employing a catalytic system consisting of (R)-DTBM-Segphos (L4) and CuBr resulted in the exclusive 1,1-difunctionalization of aryl- and alkyl

Photocatalyzed elaboration of antibody-based bioconjugates

• Marine Le Stum,
• Eugénie Romero and
• Gary A. Molander

Beilstein J. Org. Chem. 2025, 21, 616–629, doi:10.3762/bjoc.21.49

• acts as a microtubule destabilizer. To ensure the stability and homogeneity of the final product, the design of the FcBP included a norbornene motif at the N-terminal end of the peptide sequence. The norbornene motif selectively reacts with a tetrazine located on the spacer-payload. This study

Formaldehyde surrogates in multicomponent reactions

• Cecilia I. Attorresi,
• Javier A. Ramírez and
• Bernhard Westermann

Beilstein J. Org. Chem. 2025, 21, 564–595, doi:10.3762/bjoc.21.45

• (CuCl2, NaNO2, TEMPO) using molecular oxygen as a terminal oxidant have also been used [12]. Nevertheless, neither of these conditions was successful when they were applied to methanol to generate formaldehyde, because overoxidation is an important side reaction in these cases [12][13][14][15]. However

• (DMF), dimethyl sulfoxide (DMSO), or dioxane to achieve high yields. The assumed mechanism is initiated by activation of the C–H bond of the terminal alkyne by a metal catalyst. The resulting metal acetylide reacts with the imine/enamine through a nucleophilic addition. Because imines/enamines are

• the same amine component) deprotonates the terminal alkyne, generating the metal acetylide derivative A, which is the active nucleophilic species in the reaction. Intermediate A undergoes an oxidative addition by the dihaloalkane, generating intermediate B. This undergoes reductive elimination to

Binding of tryptophan and tryptophan-containing peptides in water by a glucose naphtho crown ether

• Gianpaolo Gallo and
• Bartosz Lewandowski

Beilstein J. Org. Chem. 2025, 21, 541–546, doi:10.3762/bjoc.21.42

• tripeptides 2–7 consisting of one tryptophan and two alanine residues. We varied the position of the tryptophan in the peptide sequence, N-terminus in 2, middle of the chain in 3, and C-terminus in 4 to check if this affects their binding by 1. To probe the importance of the N-terminal amino group in the

• fluorescence measurements where a strong quenching of the naphthalene fluorescence upon addition of each of the Trp-containing tripeptides 2–7 was observed. For peptides 2 and 3 interactions of the receptor with the N-terminal ammonium cation are likely also involved in the binding process (Figure 5). This is

• as well indicated by the lower binding affinity of 1 to the acetylated analogues of peptides 2 and 3. In the case of peptide 4, acetylation of its N-terminus did not affect the stability of the complex with receptor 1. This suggests that 1 interacts with the N-terminal ammonium in 4 to a much lesser

Synthesis of the aggregation pheromone of Tribolium castaneum

• Biyu An,
• Xueyang Wang,
• Ao Jiao,
• Qinghua Bian and
• Jiangchun Zhong

Beilstein J. Org. Chem. 2025, 21, 510–514, doi:10.3762/bjoc.21.38

• coupling, and finally leads to the target pheromones by olefin oxidation with RuCl3/NaIO4. Results and Discussion The retrosynthetic analysis of the aggregation pheromone (4R,8R)-1 is shown in Scheme 1. Obviously, the target pheromone (4R,8R)-1 could be synthesized via an oxidation of chiral terminal

• ]. (4R,8R)-4,8-Dimethyldecanal ((4R,8R)-1) was obtained from chiral terminal olefine (5R,9R)-12 through the oxidation with RuCl3 and NaIO4 [36], and its specific rotation and NMR spectrum matched with the reference [20]. Moreover, using the similar procedure for (4R,8R)-1, the other three constituents of

Unprecedented visible light-initiated topochemical [2 + 2] cycloaddition in a functionalized bimane dye

• Metodej Dvoracek,
• Brendan Twamley,
• Mathias O. Senge and
• Mikhail A. Filatov

Beilstein J. Org. Chem. 2025, 21, 500–509, doi:10.3762/bjoc.21.37

• refined isotropic on calculated positions using a riding model with their Uiso values constrained to 1.5 times the Ueq of their pivot atoms for terminal sp3 carbon atoms and 1.2 times for all other carbon atoms. Disordered moieties were refined using bond length restraints and displacement parameter

Antibiofilm and cytotoxic metabolites from the entomopathogenic fungus Samsoniella aurantia

• Rita Toshe,
• Syeda J. Khalid,
• Blondelle Matio Kemkuignou,
• Esteban Charria-Girón,
• Paul Eckhardt,
• Birthe Sandargo,
• Kunlapat Nuchthien,
• J. Jennifer Luangsa-ard,
• Till Opatz,
• Hedda Schrey,
• Sherif S. Ebada and
• Marc Stadler

Beilstein J. Org. Chem. 2025, 21, 327–339, doi:10.3762/bjoc.21.23

• one doublet methyl group at δH 0.94 (d, J = 6.6 Hz, H3-15) indicating its presence in the middle between both methyl groups. The latter together with a terminal triplet methyl group at δH 0.80 (t, J = 7.4 Hz, H3-14) further revealed key correlation to one tertiary and one secondary sp3 carbon atoms at

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

• . These groups are distinguished by their terminal structures, which can range from heterocyclic to non-heterocyclic rings or even amino and carbonyl groups. Furthermore, cyanins can also be classified by the number of methine units in their polymethine chains, including monomethin, trimethin, pentamethin

Visible-light-promoted radical cyclisation of unactivated alkenes in benzimidazoles: synthesis of difluoromethyl- and aryldifluoromethyl-substituted polycyclic imidazoles

• Yujun Pang,
• Jinglan Yan,
• Nawaf Al-Maharik,
• Qian Zhang,
• Zeguo Fang and
• Dong Li

Beilstein J. Org. Chem. 2025, 21, 234–241, doi:10.3762/bjoc.21.15

• . Furthermore, terminal olefins with varying chain lengths also reacted successfully, resulting in 5-membered and 7-membered cyclized products (3l–p) with yields between 44% and 66%. The lower yields in these cases might be due to the low reactivity of the intermediate C (Scheme 3), which may have made it less

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

• ) nitrenoid intermediate INT-7. Subsequent nitrene insertion, protodemetalation, and intramolecular cyclization furnish the desired 1,2,4-triazole. 1.3 Three-component formation of N-acyl amidines In 2019, N-acyl amidines were prepared from dioxazolones using a copper catalyst with terminal alkynes and

• bearing linear alkyl groups were transformed into N-acyl amidines 10a–c by copper catalysis. Moreover, good functional group tolerance was observed with a terminal alkene motif (10d). The cyclohexyl-substituted dioxazolone successfully provided the corresponding N-acyl amidine 10e. However, the

• 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

Recent advances in electrochemical copper catalysis for modern organic synthesis

• Yemin Kim and
• Won Jun Jang

Beilstein J. Org. Chem. 2025, 21, 155–178, doi:10.3762/bjoc.21.9

• Cu-catalyzed electrochemical C–H activation strategy through C–H alkynylation of arylamides followed by electrooxidative cascade annulation (Figure 4) [48]. This reaction enables sustainable C–H functionalization by utilizing electricity as the terminal oxidant instead of stoichiometric amounts of

• toxic chemical oxidants and releasing hydrogen gas as the sole byproduct. Various benzamides 1 and terminal arylalkynes 2 bearing electron-rich or electron-withdrawing groups provided the desired products 3 with high chemoselectivities. However, terminal alkynes with alkyl substituents did not yield the

• desired annulation products. Moreover, the same products were generated using alkynyl carboxylic acids instead of terminal alkynes via decarboxylative C–H alkynylation and annulation. Cyclic voltammetry (CV) studies exhibited an oxidative current at 0.95 V vs SCE in the presence of the Cu(II) salt, base

Cu(OTf)₂-catalyzed multicomponent reactions

• Sara Colombo,
• Camilla Loro,
• Egle M. Beccalli,
• Gianluigi Broggini and
• Marta Papis

Beilstein J. Org. Chem. 2025, 21, 122–145, doi:10.3762/bjoc.21.7

• ]. Three-component coupling of amines, aldehydes or ketones, and terminal alkynes catalyzed by Cu(OTf)2 is a fruitful tool for the production of α-substituted propargylamines 10 (Scheme 7) [20]. The reaction involves the alkynylation of the corresponding imines formed in situ and provides higher yields

• as a catalyst in three-component processes was also demonstrated in three-component reactions involving alkynes, amines and α,β-unsaturated aldehydes to obtain 1,4-dihydropyridines 20 (Scheme 14) [31]. By using terminal alkynes, 2,6-unsubstituted products were achieved. Concerning the mechanism, it

• the initial formation of imine XII and enamine XIII, reacting each other in a mechanism that involved two Mannich-type reactions (Scheme 15) [32]. Activation of terminal alkynes with Cu(OTf)2 is the key step for the preparation of furoquinoxalines 22 from o-phenylenediamine and ethyl glyoxylate

Synthesis, structure and π-expansion of tris(4,5-dehydro-2,3:6,7-dibenzotropone)

• Yongming Xiong,
• Xue Lin Ma,
• Shilong Su and
• Qian Miao

Beilstein J. Org. Chem. 2025, 21, 1–7, doi:10.3762/bjoc.21.1

• symmetry in the polycyclic skeleton of 3. This indicates that the polycyclic skeleton of 3 is flexible, similar to that of 1. In the crystal, the neighbouring enantiomers of 3 show minimal π-overlap with each other and a large π to π distance of 3.68 Å between terminal benzene rings. Compound 3 forms

Efficient synthesis of fluorinated triphenylenes with enhanced arene–perfluoroarene interactions in columnar mesophases

• Yang Chen,
• Jiao He,
• Hang Lin,
• Hai-Feng Wang,
• Ping Hu,
• Bi-Qin Wang,
• Ke-Qing Zhao and
• Bertrand Donnio

Beilstein J. Org. Chem. 2024, 20, 3263–3273, doi:10.3762/bjoc.20.270

• substitution of the terminal phenyl ring with a pentafluorophenyl ring. Thus, as expected, they display a Colhex mesophase over large temperature ranges, with only small differences in the mesophase stability and transition temperatures. Furthermore, the presence of the terminal fluorophenyl group enables a

• new, structurally-related series of π-conjugated aromatic compounds (Figure 1) based on a simple triphenylene core and evaluating the mesomorphic and optical properties. Specifically 1,2,4-trifluoro-6,7,10,11-tetraalkoxy-3-(perfluorophenyl)triphenylenes (Fn, Figure 1), bearing a terminal fluoroarene

• ring was obtained using the same reaction as previously reported for PHn (Figure 1) [45], between 2,2’-dilithiobiphenyl derivatives but this time with the electrophile decafluorobiphenyl C6F5–C6F5 instead of C6H5–C6F5 (Fn, n = 3–12, Scheme 1). The presence of the terminal fluoroarene group in Fn