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

• , HOAt, N,N-dimethylformamide 0 °C for 2 h and at rt for 20 min, 11%; f) Grubbs II catalyst, CH2Cl2, reflux, 3 h, 84%; g) TFA, H2O, CH2Cl2, 0 °C to rt, 5 h, 91%. EDC·HCl = 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride; DMAP = 4-(dimethylamino)pyridine; TFA = trifluoroacetic acid; HOAt = 1

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

• (9) in ortho- and para-positions. The increase is even stronger if electron-withdrawing pyridine- (14), cyano- (23) or the strong +M amino substituents (21) are attached to the N-acetyl diazocine in meta-position. In contrast to the extended half-life of the unsubstituted amine 21 the Boc-protected

The effect of neighbouring group participation and possible long range remote group participation in O-glycosylation

• Rituparna Das and
• Balaram Mukhopadhyay

Beilstein J. Org. Chem. 2025, 21, 369–406, doi:10.3762/bjoc.21.27

• -assisted departure of the leaving group, the lone pair of electrons of the nitrogen atom of the pyridine fragment of the Pic group participates to form a stable oxocarbenium intermediate 91 through the formation of a six-membered ring. The glycosylation mechanism proceeds via an SN2-like pathway through

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

• photocatalyst has shown superior yields compared to free-base and other phthalocyanin first-row transition-metal complexes, such as nickel. The choice of solvent was also critical for optimizing the reaction efficiency: a mixture of pyridine and methanol not only improved the yield but also has helped to

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

• , reacts with an enol species activated by the copper catalyst, affording the final product. The same research group reported an extension of this study by starting from arylacetylenes instead of arylketones [42]. Imidazo[1,2-a]pyridine derivatives 33 can be achieved by Cu(OTf)2-catalyzed multicomponent

• reactions starting from different reagents. In a first approach proposed by Meshram and co-workers, pyridin-2-one, O-tosylhydroxylamine and acetophenone treated in an ionic liquid assembled through the cascade formation of three C–N bonds to give the imidazo[1,2-a]pyridine scaffold 33 (Scheme 25) [43]. The

Emerging trends in the optimization of organic synthesis through high-throughput tools and machine learning

• Pablo Quijano Velasco,
• Kedar Hippalgaonkar and
• Balamurugan Ramalingam

Beilstein J. Org. Chem. 2025, 21, 10–38, doi:10.3762/bjoc.21.3

• with feedback DOE facilitated the rapid identification of appropriate solvents. Notably, the use of DMSO, DMF, and pyridine led to an enhanced yield of the monoalkylated product. An experimental setup was developed for single-droplet studies of visible-light photoredox catalysis using an oscillatory

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

• the regioselectivity of the reaction when 3-pyridylboronic acid is used as substrate as there are two different positions (C2 and C4) on the pyridine ring available for the C–H arylation step. Interestingly, azafluoranthene 15h was obtained as the only product in this reaction, albeit in a lower yield

• analogues via a Pd-catalyzed reaction cascade that consists of a Suzuki–Miyaura cross-coupling reaction followed by an intramolecular C–H arylation. These heterocyclic fluoranthene analogues include a variety of acenaphthylene-fused heteroarenes such as thiophene, furan, benzofuran, pyrazole, pyridine and

Reactivity of hypervalent iodine(III) reagents bearing a benzylamine with sulfenate salts

• Beatriz Dedeiras,
• Catarina S. Caldeira,
• José C. Cunha,
• Clara S. B. Gomes and
• M. Manuel B. Marques

Beilstein J. Org. Chem. 2024, 20, 3281–3289, doi:10.3762/bjoc.20.272

• functionalized thiols (aromatic, aliphatic, and heterocyclic) were chosen to produce the β-sulfinyl esters 4 (Scheme 3). We next investigated the electrophilic amination reaction (Scheme 4). First, different functionalized β-sulfinyl esters were reacted with BBX 2a. For the aromatic and pyridine moieties, the

Intramolecular C–H arylation of pyridine derivatives with a palladium catalyst for the synthesis of multiply fused heteroaromatic compounds

• Yuki Nakanishi,
• Shoichi Sugita,
• Kentaro Okano and
• Atsunori Mori

Beilstein J. Org. Chem. 2024, 20, 3256–3262, doi:10.3762/bjoc.20.269

• Abstract The C–H arylation of 2-quinolinecarboxyamide bearing a C–Br bond at the N-aryl moiety is carried out with a palladium catalyst. The reaction proceeds at the C–H bond on the pyridine ring adjacent to the amide group in the presence of 10 mol % Pd(OAc)2 at 110 °C to afford the cyclized product in 42

• % yield, respectively. The related reaction is also carried out with amides of non-pyridine derivatives terephthal- and benzamides to afford multiply fused heterocyclic compounds in 81% and 89% yields, respectively. Keywords: intramolecular C–H arylation; multiply fused heterocycles; palladium acetate

• ; phosphine ligand; pyridine amides; Introduction Transition-metal-catalyzed synthetic reactions have recently attracted much attention in synthetic organic chemistry [1][2]. C–H Arylation reactions catalyzed by a transition metal are of particular interest because these reactions involve rather superior

Discovery of ianthelliformisamines D–G from the sponge Suberea ianthelliformis and the total synthesis of ianthelliformisamine D

• Sasha Hayes,
• Yaoying Lu,
• Bernd H. A. Rehm and
• Rohan A. Davis

Beilstein J. Org. Chem. 2024, 20, 3205–3214, doi:10.3762/bjoc.20.266

• /CH2Cl2 at room temperature (17% yield). Subjecting the methoxylated benzaldehyde intermediate 9 to a Doebner–Knoevenagel condensation with malonic acid and pyridine afforded the brominated cinnamic acid analogue 10 in 54% yield [19]. Amidation chemistry using carbonyldiimidazole (CDI) [18] and the

• (4-OCH3); LRESIMS (m/z): 293/295/297 [M + H]+. Doebner–Knoevenagel condensation of 3,5-dibromo-4-methoxybenzaldehyde with malonic acid 3,5-Dibromo-4-methoxybenzaldehyde (9, 80.0 mg, 0.27 mmol), malonic acid (56.0 mg, 0.54 mmol) and dry pyridine (1 mL) were refluxed at 100 °C for 5 h. The reaction

Germanyl triazoles as a platform for CuAAC diversification and chemoselective orthogonal cross-coupling

• John M. Halford-McGuff,
• Thomas M. Richardson,
• Aidan P. McKay,
• Frederik Peschke,
• Glenn A. Burley and
• Allan J. B. Watson

Beilstein J. Org. Chem. 2024, 20, 3198–3204, doi:10.3762/bjoc.20.265

• reactivity compared to other alkynes, which typically require much shorter reaction times. Extending the reaction time provided a higher conversion to the product 14. Yields were observed to be greater for aryl azides (e.g., 4 vs 6). Heterocycles such as pyridine (1), pyrimidine (10), phenothiazine (11), and

Synthesis of extended fluorinated tripeptides based on the tetrahydropyridazine scaffold

• Thierry Milcent,
• Pascal Retailleau,
• Benoit Crousse and
• Sandrine Ongeri

Beilstein J. Org. Chem. 2024, 20, 3174–3181, doi:10.3762/bjoc.20.262

• , Tomilov et al. described the formation of tetrahydropyridazine 3,4,5,6-tetracarboxylic esters in 42% yield upon the decomposition in chloroform at 60 °C of methyl diazoacetate in the presence of pyridine and catalyzed by rhodium(II) acetate (Scheme 1b) [24][25]. More recently, an unusual [4 + 2

Hypervalent iodine-mediated intramolecular alkene halocyclisation

• Charu Bansal,
• Oliver Ruggles,
• Albert C. Rowett and
• Alastair J. J. Lennox

Beilstein J. Org. Chem. 2024, 20, 3113–3133, doi:10.3762/bjoc.20.258

• instead proceeded with addition of dichloro(pyridine-2-carboxylato)gold(III) complex in combination with silver triflimide, AgNTf2. A range of β-fluoroazepanes 7 were successfully synthesised with high enantiomeric purity in good yields. A mechanism for the synthesis of β-fluorinated piperidines was

• nucleophiles In 2000, Hara and co-workers reported the fluorocyclisation of unsaturated alcohols and carboxylic acids promoted by HVI reagents (Scheme 11) [36]. Using 4-tolyl difluoroiodane 10 as the reaction promoter, and pyridine·6HF as a source of fluoride, a range of unsaturated alcohols 23 to fluorinated

Tunable full-color dual-state (solution and solid) emission of push–pull molecules containing the 1-pyrindane moiety

• Anastasia I. Ershova,
• Sergey V. Fedoseev,
• Konstantin V. Lipin,
• Mikhail Yu. Ievlev,
• Oleg E. Nasakin and
• Oleg V. Ershov

Beilstein J. Org. Chem. 2024, 20, 3016–3025, doi:10.3762/bjoc.20.251

• pyrindane – (E)-7-arylmethylene-2-chloro-6,7-dihydro-5H-cyclopenta[b]pyridine-3,4-dicarbonitriles – was developed. Tunable full-color emission was achieved for the synthesized push–pull molecules, solely by changing donor groups while keeping both the conjugated system and acceptor part of the molecule

• pyridine as an acceptor. The introduction of additional substituents to stilbazole makes it possible to change the optical properties of this molecular framework within a wide range [16][17][18][19]. This approach has found many applications in the synthesis of compounds that are used in various optical

• the facile preparation of molecular libraries with an emphasis on skeletal diversity for the development of new push–pull molecules. Results and Discussion Synthesis and structure determination A two-step procedure was used to obtain the target compounds (Scheme 1). Cyclopenta[b]pyridine derivative 2

Synthesis of fluorinated acid-functionalized, electron-rich nickel porphyrins

• Mike Brockmann,
• Jonas Lobbel,
• Lara Unterriker and
• Rainer Herges

Beilstein J. Org. Chem. 2024, 20, 2954–2958, doi:10.3762/bjoc.20.248

• ether synthesis with 2-hydroxy-3,4,5-trimethoxybenzaldehyde (21). Conditions: a) K2CO3, benzyl bromide, abs. MeCN, N2, reflux, 18 h; b) TEMPO, KBr, NaOCl, NaHCO3, MeCN, rt, 76 h; c) MeOH, H2SO4, reflux, 18 h; d) Pd/C, H2, EtOH, rt, 24 h; e) Tf2O, pyridine, DCM, rt, 18 h. Synthesis of perfluoroalkyl

The charge transport properties of dicyanomethylene-functionalised violanthrone derivatives

• Sondos A. J. Almahmoud,
• Joseph Cameron,
• Dylan Wilkinson,
• Michele Cariello,
• Claire Wilson,
• Alan A. Wiles,
• Peter J. Skabara and
• Graeme Cooke

Beilstein J. Org. Chem. 2024, 20, 2921–2930, doi:10.3762/bjoc.20.244

• anhydrous chlorobenzene (6 mL). To the dark blue mixture titanium tetrachloride (100 μL, 0.840 mmol) and pyridine (130 μL, 1.68 mmol) were added and the mixture was stirred under reflux overnight. After cooling the reaction mixture to room temperature, it was poured into ice-water (50 mL) and extracted with

• in anhydrous chlorobenzene (6 mL). To the dark blue mixture, titanium tetrachloride (50.0 μL, 0.420 mmol) and pyridine (70.0 μL, 0.84 mmol) were added and the mixture was stirred under reflux overnight. After cooling the reaction mixture to room temperature, it was poured into ice-water (50 mL) and

• mL). To the dark blue mixture titanium tetrachloride (120 μL, 1.08 mmol) and pyridine (170 μL, 2.16 mmol) were added and the mixture was stirred under reflux overnight. After cooling the reaction mixture to room temperature, it was poured into ice-water (50 mL) and extracted with dichloromethane (3

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

• olefins, showcasing an efficient utilization of aryliodonium salts in the process. Later in the same year, Song and colleagues reported a protocol for the efficient synthesis of 2-aryl-substituted quinolines 27 and pyridine N-oxides 29 [63]. This reaction involved the selective arylation at the C2

• position of quinoline N-oxides and pyridine N-oxides, utilizing hypervalent iodine salts as the arylation reagents. The reaction was facilitated by visible light in conjunction with a photocatalyst. The absence of either the photocatalyst or light resulted in only trace amounts of the product, underscoring

• -donating groups. The reaction exhibited high selectivity, with substitution at the C3 position not impeding the reaction. Different substituted diaryliodonium tetrafluoroborates were also investigated, yielding good product yields. The above protocol for the arylation of pyridine N-oxides 28, resulted in

C–H Trifluoromethylthiolation of aldehyde hydrazones

• Victor Levet,
• Balu Ramesh,
• Congyang Wang and
• Tatiana Besset

Beilstein J. Org. Chem. 2024, 20, 2883–2890, doi:10.3762/bjoc.20.242

• -substituted derivatives (1l–o) were converted into the corresponding fluorinated analogs. The functionalization of the 2,4-difluorophenyl derivative (1p) and the heteroaromatic compounds such as furan (1q) as well as pyridine (1r) derivatives went smoothly, with the lower yield obtained in the case of 2r

N-Glycosides of indigo, indirubin, and isoindigo: blue, red, and yellow sugars and their cancerostatic activity

• Peter Langer

Beilstein J. Org. Chem. 2024, 20, 2840–2869, doi:10.3762/bjoc.20.240

• steps from indigo (1a). The reaction of 1a with potassium permanganate afforded product 12 which was transformed to dehydroindigo (13) by pyridine-mediated elimination of acetic acid. The reaction of 13 with tetra-O-trimethylsilyl-ʟ-rhamnopyranose (4b) in the presence of trimethylsilyl iodide, addition

• of n-propyl mercaptane with subsequent addition of acetic anhydride, pyridine and KHF2 afforded indigo-N-rhamnoside 5c as a 2:1 mixture of α/β-anomers. The relatively low yield is a result of side reactions and decomposition, due to the rather unstable nature of the product. The reaction of 5c with

• intermediate C which underwent extrusion of iodine and dipropyl disulfide to give intermediate D. Subsequent reaction with acetic anhydride, pyridine and KHF2 resulted in the replacement of the TMS by acetyl groups which was important for practical reasons (stability during chromatography). The reaction of 13

Access to optically active tetrafluoroethylenated amines based on [1,3]-proton shift reaction

• Yuta Kabumoto,
• Eiichiro Yoshimoto,
• Bing Xiaohuan,
• Masato Morita,
• Motohiro Yasui,
• Shigeyuki Yamada and
• Tsutomu Konno

Beilstein J. Org. Chem. 2024, 20, 2776–2783, doi:10.3762/bjoc.20.233

• 22b could not be completely suppressed. The thus obtained [1,3]-proton shift product (S)-20b was subjected to 2 N HCl aq in Et2O for 2 h, and subsequently 2 N NaOH aq, affording the corresponding free amine (S)-17b. Then, treatment of the amine with CbzCl and pyridine in CH2Cl2 gave the corresponding

5th International Symposium on Synthesis and Catalysis (ISySyCat2023)

• Anthony J. Burke and
• Elisabete P. Carreiro

Beilstein J. Org. Chem. 2024, 20, 2704–2707, doi:10.3762/bjoc.20.227

• -dihydro[1,3]thiazolo[4,5-b]pyridine derivatives that exhibited strong herbicidal activity against commercially significant grass weeds in preemergence greenhouse tests. The synthetic route for this new family of compounds was developed and optimized, involving several reaction steps, included Pd-catalyzed

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

• , entry 10). Other bases like NaOMe, triethylamine, DBU, DMAP, sodium acetate, or DABCO also produced the product in moderate to good yields (42–87%) when used in excess (Table 1, entries 11–16). Interestingly, the reaction did not proceed in the presence of pyridine as a base (Table 1, entry 17). Finally

The scent gland composition of the Mangshan pit viper, Protobothrops mangshanensis

• Jonas Holste,
• Paul Weldon,
• Donald Boyer and
• Stefan Schulz

Beilstein J. Org. Chem. 2024, 20, 2644–2654, doi:10.3762/bjoc.20.222

• , catalytic amounts of 4-(dimethylamino)pyridine (DMAP) and freshly distilled 3-pyridinemethanol (1 drop) were added. The reaction mixture was heated to 60 °C for 1 h and filtered. The filtrate was washed three times with H2O, the organic phases were dried over sodium sulfate and filtered before GC–MS

Efficient modification of peroxydisulfate oxidation reactions of nitrogen-containing heterocycles 6-methyluracil and pyridine

• Alfiya R. Gimadieva,
• Yuliya Z. Khazimullina,
• Aigiza A. Gilimkhanova and
• Akhat G. Mustafin

Beilstein J. Org. Chem. 2024, 20, 2599–2607, doi:10.3762/bjoc.20.219

• are widely used in pharmacology due to their pronounced biological activities and low toxicities. The introduction of a hydroxy function into uracil and pyridine molecules has led to compounds with antioxidant, anti-inflammatory, and immunomodulatory activity (3-hydroxy-6-methyl-2-ethylpyridine, 5

• : oxidation; 6-methyluracil; peroxydisulfate; phthalocyanine catalysts; pyridine; Introduction The Elbs and Boyland–Sims peroxydisulfate oxidation reactions offer a convenient means of introducing the hydroxy function into phenols and aromatic amines [1]. The oxidation of phenol using peroxydisulfate was

• as 6-methyluracil (MU), 1,3,6-trimethyluracil (TMU), and pyridine (Py), and the results of the experiments are presented in this article. The hydroxy derivatives of MU and Py, obtained through oxidation followed by acid hydrolysis, possess compelling biological properties, rendering them practically

A review of recent advances in electrochemical and photoelectrochemical late-stage functionalization classified by anodic oxidation, cathodic reduction, and paired electrolysis

• Nian Li,
• Ruzal Sitdikov,
• Ajit Prabhakar Kale,
• Joost Steverlynck,
• Bo Li and
• Magnus Rueping

Beilstein J. Org. Chem. 2024, 20, 2500–2566, doi:10.3762/bjoc.20.214

• mechanism is as follows: pyridine deprotonates tetrachloro-N-hydroxyphthalimide (R2N–OH), which is subsequently anodically oxidized. The resulting N-oxyl radical abstracts a hydrogen atom from the position adjacent to the olefin, forming an allylic radical. This allylic radical then reacts with cathodically