Organic electron transport materials

• Joseph Cameron and
• Peter J. Skabara

Beilstein J. Org. Chem. 2024, 20, 672–674, doi:10.3762/bjoc.20.60

• materials. One of the potential benefits of organic semiconductors is the ability to use solution-processing techniques, which are more sustainable than thermal evaporation which is wasteful and requires high vacuum and temperature. Moreover, organic electron transport layers do not typically need treatment

Palladium-catalyzed three-component radical-polar crossover carboamination of 1,3-dienes or allenes with diazo esters and amines

• Geng-Xin Liu,
• Xiao-Ting Jie,
• Ge-Jun Niu,
• Li-Sheng Yang,
• Xing-Lin Li,
• Jian Luo and
• Wen-Hao Hu

Beilstein J. Org. Chem. 2024, 20, 661–671, doi:10.3762/bjoc.20.59

• temperature (rt), the desired unsaturated ε-AA derivative 4a was obtained in 75% isolated yield (Table 1, entry 1). Isolation and NMR analysis demonstrated that this model reaction provided amino acid 4a with good E-selectivity and excellent regioselectivity (E/Z = 91:9, 1,4-/1,2-addition >20:1). Control

Enhanced reactivity of Li⁺@C₆₀ toward thermal [2 + 2] cycloaddition by encapsulated Li⁺ Lewis acid

• Hiroshi Ueno,
• Yu Yamazaki,
• Hiroshi Okada,
• Fuminori Misaizu,
• Ken Kokubo and
• Hidehiro Sakurai

Beilstein J. Org. Chem. 2024, 20, 653–660, doi:10.3762/bjoc.20.58

• technique [25]. As expected, both substrates 1 and 2 reacted with Li+@C60 at room temperature and exhibited HPLC signals assignable to the desirable monoadducts 5a and 5b (Figure 2). It is noteworthy that the reaction of 2 proceeded faster than that of 1, although 2 has a lower HOMO level than 1. This is

• ] cycloaddition was significantly prevented, even under conditions with an excess amount of reactant, resulting in much better yields of the target products compared to other reported reactions of Li+@C60. It should also be mentioned that while these products were stable at ambient temperature in the dark

• , photoirradiation triggered the elimination of the addends, reforming the starting Li+@C60 (Figure 3). No other insoluble or undetectable products by HPLC were identified during the study. On the other hand, the reactions of 3 and 4 with Li+@C60 did not proceed significantly even under higher temperature reaction

Isolation and structure determination of a new analog of polycavernosides from marine Okeania sp. cyanobacterium

• Kairi Umeda,
• Naoaki Kurisawa,
• Ghulam Jeelani,
• Tomoyoshi Nozaki,
• Kiyotake Suenaga and
• Arihiro Iwasaki

Beilstein J. Org. Chem. 2024, 20, 645–652, doi:10.3762/bjoc.20.57

• ) [7]. Isolation of polycavernoside E (1) In a manner analogous to [7], the collected cyanobacterium (340 g) was extracted with EtOH (0.5 L) for 10 days at room temperature (rt). The extract was filtered, and the residue was homogenized with a blender and re-extracted with EtOH (0.5 L) at room

• temperature for one day. The extract was filtered, and the combined filtrates were concentrated. The residue was partitioned between EtOAc (3 × 300 mL) and H2O (300 mL). The combined organic layers were concentrated, and the residue was partitioned between 90% aqueous MeOH (300 mL) and hexane (3 × 300 mL

HPW-Catalyzed environmentally benign approach to imidazo[1,2-a]pyridines

• Luan A. Martinho and
• Carlos Kleber Z. Andrade

Beilstein J. Org. Chem. 2024, 20, 628–637, doi:10.3762/bjoc.20.55

• single report on the use of a heteropolyacid (phosphomolybdic acid) in the GBB reaction but for a limited number of examples (Scheme 1a) [50]. That caught our attention for being the only example so far of a room temperature GBB reaction carried out in less than an 18-hour period. However, at least in

• attractive intrinsic properties, HPW was used in our initial studies to find the best reaction conditions. Additionally, knowing that a higher temperature is crucial for faster GBB reactions, μw heating was used, taking into account our experience over the years on the μw-mediated MCRs [51][52][53]. 2

• temperature or in the reaction time were checked, however, with no benefit in the yields (Table 1, entries 9–12). Accordingly, with the established optimal conditions of 2 mol % of HPW, 120 °C, and 30 min, other solvents were tested, and ethanol was found to give similar results (Table 1, entry 13). For being

A myo-inositol dehydrogenase involved in aminocyclitol biosynthesis of hygromycin A

• Michael O. Akintubosun and
• Melanie A. Higgins

Beilstein J. Org. Chem. 2024, 20, 589–596, doi:10.3762/bjoc.20.51

• , the pellet was resuspended in 40 mL of sucrose solution (25% sucrose, 50 mM Tris pH 8) using continuous stirring. Then, 10 mg of lysozyme (Bio Basic) was added and stirred at room temperature for 10 min, followed by the addition of 80 mL deoxycholate solution (1% deoxycholate, 1% Triton X-100, 100 mM

Possible bi-stable structures of pyrenebutanoic acid-linked protein molecules adsorbed on graphene: theoretical study

• Yasuhiro Oishi,
• Motoharu Kitatani and
• Koichi Kusakabe

Beilstein J. Org. Chem. 2024, 20, 570–577, doi:10.3762/bjoc.20.49

• II. Thus, as the polarity of the solvent increases, the probability of the appearance of conformation II is expected to increase. Then, conditions of the temperature and the external pressure of gases have to be chosen properly, too. We need to keep the pyrene part stable in the whole procedures

• increase in the probability that the active center of the antigen/antibody reaction reacts with the antigen. To realize a good temperature condition, the barrier height should be close to or even less than 0.3 eV. Reducing the barrier height may be achieved by optimizing the solution to achieve nearly

• equal stability in between two conformations. Selection of a solute with a solvent, e.g., those considered in reference [9] can be a solution. Therefore, it is desirable to select the solvent and temperature conditions so that the probability of appearance of conformation II increases as well as

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

• the reaction in the presence of DIPEA proceeded selectively, albeit more slowly. By increasing the DIPEA loading to 50 mol %, the product 2a was isolated in 75% yield after incubation for 7 days at room temperature. The structure of the obtained spirobutenolide was confirmed by single crystal X-ray

• data. Further syntheses of spirobutenolides 2 were performed under the one-pot conditions: after completion of the first O–H insertion step, a base was added to the reaction mixture and kept at room temperature until completion of the cyclization step, controlled by TLC. The results of the syntheses

• cyclization step was more selective and the total yield of the desired product was higher. The 6-exo-tet cyclization of intermediate compounds 16 under the action of DBU in acetone at room temperature proceeded within a few minutes, which is much faster than in the case of compounds 14. This can be explained

Synthesis and biological profile of 2,3-dihydro[1,3]thiazolo[4,5-b]pyridines, a novel class of acyl-ACP thioesterase inhibitors

• Jens Frackenpohl,
• David M. Barber,
• Guido Bojack,
• Birgit Bollenbach-Wahl,
• Ralf Braun,
• Rahel Getachew,
• Sabine Hohmann,
• Kwang-Yoon Ko,
• Karoline Kurowski,
• Bernd Laber,
• Rebecca L. Mattison,
• Thomas Müller,
• Anna M. Reingruber,
• Dirk Schmutzler and
• Andrea Svejda

Beilstein J. Org. Chem. 2024, 20, 540–551, doi:10.3762/bjoc.20.46

• ). Correspondingly, [1,3]thiazolo[4,5-b]pyridine 5 remained unchanged upon application of methods that had been successfully utilized in the hydrogenation of 1,3-benzothiazoles, involving diboronic acid or hydrazine hydrate as key reagents [21] in protic solvents at an elevated temperature (Table 1, entries 3 and 4

• ). Whilst tetrabutylammonium borohydride [22] at room temperature did not lead to a conversion of the starting material 5 either, a trace amount of desired 2,3-dihydro[1,3]thiazolo[4,5-b]pyridine 7b was formed at elevated temperature, accompanied by disulfide 18b as the main product (Table 1, entries 5 and

• temperature [23] led to the cleavage of the thiazole ring, furnishing disulfides 18b and 18c exclusively (Table 1, entries 7–10). Interestingly, the reaction of 5 with ammonia borane at elevated temperature in toluene [20] furnished three reaction products with a low yield since 2,3-dihydro[1,3]thiazolo[4,5-b

Switchable molecular tweezers: design and applications

• Pablo Msellem,
• Maksym Dekthiarenko,
• Nihal Hadj Seyd and
• Guillaume Vives

Beilstein J. Org. Chem. 2024, 20, 504–539, doi:10.3762/bjoc.20.45

• coordination-switchable tweezers for switching between two magnetic states that are stable at room temperature [44]. To increase the magnetic coupling between the metal center the group investigated the Mn(III)–salphen tweezers 14 that can coordinate in apical position to cyanide ions. The complexation of CN

• , conformational analysis performed by variable temperature NMR led to the conclusion that the open and closed conformations have similar energies and are in fast exchange at ambient temperature. This fluxionality resulted in a relatively low affinity for the electron-poor aromatic guest 2,4,7-trinitro-9

• electrostatic repulsion between the doubly charged redox-active units. Thus, it can be concluded that, although the tweezers exhibit different conformations in neutral and oxidized states, at room temperature

A new analog of dihydroxybenzoic acid from Saccharopolyspora sp. KR21-0001

• Rattiya Janthanom,
• Yuta Kikuchi,
• Hiroki Kanto,
• Tomoyasu Hirose,
• Arisu Tahara,
• Takahiro Ishii,
• Arinthip Thamchaipenet and
• Yuki Inahashi

Beilstein J. Org. Chem. 2024, 20, 497–503, doi:10.3762/bjoc.20.44

• wavelengths of 200 to 800 nm. Optical rotation was measured using a P-2200 polarimeter (JASCO). De-sulfurization and hydrolyzation KR21-0001A (1) (1 mg) was dissolved in EtOH (0.5 mL) and treated with skeletal Ni (1 mg). The reaction mixture was stirred for 13 h at room temperature under H2 (Figure S6

Ligand effects, solvent cooperation, and large kinetic solvent deuterium isotope effects in gold(I)-catalyzed intramolecular alkene hydroamination

• Ruichen Lan,
• Brock Yager,
• Yoonsun Jee,
• Cynthia S. Day and
• Amanda C. Jones

Beilstein J. Org. Chem. 2024, 20, 479–496, doi:10.3762/bjoc.20.43

• % conversion after 24 h, estimated t1/2 = 96 h, kobs = 1.4 × 10−6 s−1). With 55 μL MeOH in DCM, the relative rates for each substrate are 3,850:50:1 with urea 1a > carbamate 1b > benzamide 1c. The analogous toluene sulfonamide substrate 1d did not react on measurable timescales at room temperature (no product

• have been masked by the high temperatures and long reaction times of early reports. For example, Widenhoefer engaged carbamates and amides in dioxane at temperatures >80 °C [12][13]. Later work showed that ureas could be engaged at room temperature when a NHC–gold catalyst system was used, outpacing

Pseudallenes A and B, new sulfur-containing ovalicin sesquiterpenoid derivatives with antimicrobial activity from the deep-sea cold seep sediment-derived fungus Pseudallescheria boydii CS-793

• Zhen Ying,
• Xiao-Ming Li,
• Sui-Qun Yang,
• Hong-Lei Li,
• Xin Li,
• Bin-Gui Wang and
• Ling-Hong Meng

Beilstein J. Org. Chem. 2024, 20, 470–478, doi:10.3762/bjoc.20.42

• medium at 28 °C for five days, which were then inoculated into the noted rice solid medium in 1 L Erlenmeyer flasks and static cultivation for 30 days at room temperature. After fermentation, it was fragmented mechanically and extracted thoroughly with EtOAc. The combined extracts were filtered and

• , the bacteria were cultivated in the LB broth medium at 37 °C for the human pathogenic bacteria, while the temperature was 28 °C for the aquatic pathogens, and they were prepared at a concentration of 1.5 × 108 CFU/mL. Tested compounds and positive control (chloramphenicol) were dissolved in DMSO to

(E,Z)-1,1,1,4,4,4-Hexafluorobut-2-enes: hydrofluoroolefins halogenation/dehydrohalogenation cascade to reach new fluorinated allene

• Nataliia V. Kirij,
• Andrey A. Filatov,
• Yurii L. Yagupolskii,
• Sheng Peng and
• Lee Sprague

Beilstein J. Org. Chem. 2024, 20, 452–459, doi:10.3762/bjoc.20.40

• was complex, we focused our attention on carrying out the reaction with KOH. The best result was obtained by treatment of 1 equivalent of butane 2 with 1.3 equivalents of KOH in the presence of 5 mol % of Bu4NBr as an interfacial carrier in water at room temperature for 2 h (Table 1, entry 7). After

• ) and butyllithium (BuLi), as well as the reactions of the resulting organometallic compounds. 1.2 Equivalents of a solution of iPrMgCl in THF were added to bromoolefin 3a in Et2O or THF at −78 °C and then after 1 h at the same temperature 1 equivalent of 4-fluorobenzaldehyde (9) was added. After

• room temperature MgBrF was produced together with allene 11 (Scheme 8). In addition to the allene, the formation of olefin 1b was also recorded in the 19F NMR spectrum. Unfortunately, due to difficulties in separating from olefin 1b and diethyl ether, allene 11 was not isolated in a pure state

Enhanced host–guest interaction between [10]cycloparaphenylene ([10]CPP) and [5]CPP by cationic charges

• Eiichi Kayahara,
• Yoshiyuki Mizuhata and
• Shigeru Yamago

Beilstein J. Org. Chem. 2024, 20, 436–444, doi:10.3762/bjoc.20.38

• that the complex formation occurs between neutral [10]CPP and [5]CPP2+ forming [10]CPP⊃[5]CPP2+ (Figure 1c, path A) [21]. The absence of signals in the ESR measurements at room temperature also suggests the formation of complexes with a closed-shell electronic structure. The same complex was formed

Mono or double Pd-catalyzed C–H bond functionalization for the annulative π-extension of 1,8-dibromonaphthalene: a one pot access to fluoranthene derivatives

• Nahed Ketata,
• Linhao Liu,
• Ridha Ben Salem and
• Henri Doucet

Beilstein J. Org. Chem. 2024, 20, 427–435, doi:10.3762/bjoc.20.37

• gave 1 in slightly lower yields than those obtained using DMA as solvent, while xylene was inefficient (Table 1, entries 11–13). Using a lower reaction temperature or lower catalyst loadings (1% and 2% instead of 5%) led to lower yields of 1 due to the partial conversion of 1,8-dibromonaphthalene

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

• the synthesis of BIMs, using a catalytic amount of I2 under solvent-free conditions at room temperature (Scheme 8) [91]. The differentiating factor of this technique is the employment of solid grind, which avoids the need for a reaction medium, while also utilizing the same amount of I2 (20 mol

• -free and room temperature conditions. In these optimized conditions, several aromatic aldehydes and indoles formed the respective BIMs in excellent yields (84–95%), without any noteworthy differences between the various carbonyl substrates. Indoles, substituted at the 2’ position, were much more

• show any further enhancement, in reflux temperature (65 °C) conditions, with methanol emerging as the superior medium over other polar solvents. A wide range of aromatic aldehydes containing both electron-withdrawing and electron-donating substituents were employed with the former, improving the

Facile approach to N,O,S-heteropentacycles via condensation of sterically crowded 3H-phenoxazin-3-one with ortho-substituted anilines

• Eugeny Ivakhnenko,
• Vasily Malay,
• Pavel Knyazev,
• Nikita Merezhko,
• Nadezhda Makarova,
• Oleg Demidov,
• Gennady Borodkin,
• Andrey Starikov and
• Vladimir Minkin

Beilstein J. Org. Chem. 2024, 20, 336–345, doi:10.3762/bjoc.20.34

• -phenoxazin-3-ones 4, compounds 5 and 6 display intense fluorescence in solution at room temperature (Figure 5). The excitation spectra of the compounds (Figures S7–S11, Supporting Information File 1) correspond to the longest-wavelength absorption bands. The absorption and emission spectra of benzo[5,6][1,4

• 6a,b) and c = 2⋅10−6 M (compound 10c) in toluene solutions with a Varian Cary Eclipse fluorescence spectrophotometer. UV–vis and fluorescence spectra were recorded using standard 1 cm quartz cells at room temperature. Toluene of spectroscopic grade (Aldrich) was used to prepare the solutions. The

• compounds 5a–c in toluene before irradiation (no emission) and c) during irradiation (photoluminescence, λex = 365 nm) at room temperature. UV–vis (solid lines) and fluorescence emission (dashed, λex = 365 nm) spectra of compounds 6a,b in toluene (c = 2 10−5 M, l = 1 cm) at room temperature. UV–vis

Discovery of unguisin J, a new cyclic peptide from Aspergillus heteromorphus CBS 117.55, and phylogeny-based bioinformatic analysis of UngA NRPS domains

• Sharmila Neupane,
• Marcelo Rodrigues de Amorim and
• Elizabeth Skellam

Beilstein J. Org. Chem. 2024, 20, 321–330, doi:10.3762/bjoc.20.32

• and 700 nm. The MS was optimized using the following conditions: interface voltage 4.5 kV; interface temperature 350 °C; DL temperature 250 °C; heat block 200 °C; ESI mode, acquisition range 100 to 1000 Da; nebulizing gas 1.5 L min−1; drying gas flow 15 L min−1. The fractionation of the sample was

• 100 ms. The mass ranges for MS and MS2 scan surveys were 500–800 amu and 30–800 amu, respectively. The curtain gas (nitrogen), nebulizing and heating gas were fixed at 25 psi, 20 psi and 15 psi, respectively. The temperature of the source was 25 °C. MS spectra were acquired and processed using Analyst

Elucidating the glycan-binding specificity and structure of Cucumis melo agglutinin, a new R-type lectin

• Jon Lundstrøm,
• Emilie Gillon,
• Valérie Chazalet,
• Nicole Kerekes,
• Antonio Di Maio,
• Ten Feizi,
• Yan Liu,
• Annabelle Varrot and
• Daniel Bojar

Beilstein J. Org. Chem. 2024, 20, 306–320, doi:10.3762/bjoc.20.31

• supplier instructions (New England Biolabs, #T1020S) and ligation using the DNA ligation kit, Mighty Mix (Ozyme, Takara, #TAK6023Z), at room temperature to form the pET40b-TEV-CMA11 plasmid. The N-terminal domain of CMA1 (6–132 in mature protein) was amplified by PCR using the following primers: forward

• overnight. Then, 1 L LB medium supplemented with 25 µg/mL kanamycin was inoculated with 25 mL of the pre-culture and incubated at 37 °C, 180 rpm. When OD600nm reached 0.4, the temperature was lowered to 16 °C, and when OD600nm reached 0.8, protein expression was induced by the addition of 0.1 mM isopropyl β

• 1 μL of Denarase® (C-LEcta GmbH, #20804) and moderate agitation on a rotating wheel for a period of 30 min at room temperature, cells were lysed using a cell disruptor (Constant Systems Ltd, UK) under a pressure of 2.5 kbar. The lysate was cleared by centrifugation at 24,000g for 30 min at 4 °C and

Synthesis of π-conjugated polycyclic compounds by late-stage extrusion of chalcogen fragments

• Aissam Okba,
• Pablo Simón Marqués,
• Kyohei Matsuo,
• Naoki Aratani,
• Hiroko Yamada,
• Gwénaël Rapenne and
• Claire Kammerer

Beilstein J. Org. Chem. 2024, 20, 287–305, doi:10.3762/bjoc.20.30

• room temperature, other group-16 heteropines suffer from thermal instability. Indeed, the low activation barrier for S, Se or Te cheletropic extrusion from the norcaradiene valence isomer, combined with the irreversibility of this process, shifts the tautomerization equilibrium and delivers benzene as

• thiepine precursor 3a exhibited a mass decrease at 300 °C in agreement with the expected elimination of sulfur to yield almost quantitatively the corresponding PBI 6a. Its sulfoxide analogue 4a exhibited higher thermal reactivity, with the loss of SO identified at lower temperature (225 °C). As a proof of

• lower temperature (140 °C) than previously. These preliminary studies thus validated the suitability of the dinaphthothiepine core and particularly its S-oxide as soluble precursors for perylene, with three different activation modes to generate the target PBI semiconductor. This “precursor approach

Synthesis of spiropyridazine-benzosultams by the [4 + 2] annulation reaction of 3-substituted benzoisothiazole 1,1-dioxides with 1,2-diaza-1,3-dienes

• Wenqing Hao,
• Long Wang,
• Jinlei Zhang,
• Dawei Teng and
• Guorui Cao

Beilstein J. Org. Chem. 2024, 20, 280–286, doi:10.3762/bjoc.20.29

• ketimine and its subsequent [4 + 2] annulation reaction with 1,2-diaza-1,3-diene in the presence of Et3N (2.0 equiv) in diethyl ether at room temperature (Table 1, entry 1). However, no product was detected under these conditions. We then replaced diethyl ether with toluene, which resulted in the desired

• different reaction times revealed that the reaction was complete within 2 hours (Table 1, entry 14). We then explored the effect of the temperature on the reaction and found that 25 °C was the most suitable temperature, resulting in a 91% yield (Table 1, entry 14). Lower temperatures of 0 °C and 10 °C led

• to decreased yields of 24% and 49%, respectively (Table 1, entries 16 and 17). Increasing the temperature beyond 25 °C resulted in the formation of impurities and a decrease in the yield of the target compound (Table 1, entries 18 and 19). Finally, the optimal reaction conditions were determined as

Unveiling the regioselectivity of rhodium(I)-catalyzed [2 + 2 + 2] cycloaddition reactions for open-cage C₇₀ production

• Cristina Castanyer,
• Anna Pla-Quintana,
• Anna Roglans,
• Albert Artigas and
• Miquel Solà

Beilstein J. Org. Chem. 2024, 20, 272–279, doi:10.3762/bjoc.20.28

• was obtained from HRMS, which gave a single peak at m/z 1138.0868 corresponding to [2a + Na]+. Further optimization was then carried out to obtain the bis(fulleroid) derivative alone (Table S1 in Supporting Information File 1). On increasing the reaction temperature to 120 °C and 180 °C the results

Additive-controlled chemoselective inter-/intramolecular hydroamination via electrochemical PCET process

• Kazuhiro Okamoto,
• Naoki Shida and
• Mahito Atobe

Beilstein J. Org. Chem. 2024, 20, 264–271, doi:10.3762/bjoc.20.27

• ][6][7][8]. Recent advances in photoredox and electrochemical PCET reactions have significantly expanded the substrate scope of amidyl-radical-based molecular transformations because the harsh acidic and high-temperature conditions required in the classical Hofmann–Löffler–Freytag reaction can be

Substitution reactions in the acenaphthene analog of quino[7,8-h]quinoline and an unusual synthesis of the corresponding acenaphthylenes by tele-elimination

• Ekaterina V. Kolupaeva,
• Narek A. Dzhangiryan,
• Alexander F. Pozharskii,
• Oleg P. Demidov and
• Valery A. Ozeryanskii

Beilstein J. Org. Chem. 2024, 20, 243–253, doi:10.3762/bjoc.20.24

• ), the basicity of which must obviously be higher than that of the starting heterocycle 5. To this end, we conducted a series of experiments on its oxidative amination by varying the reaction conditions (time, temperature, addition of n-butyllithium to increase the nucleophilicity of amines), and

• 5Н+PicO−, in the cationic part of which a similar intramolecular NHN hydrogen bond is realized [15]. To understand the structure of the resulting complex, we tried to grow its crystals from acetonitrile by co-evaporating solutions of quinoline 5 and chloranil at room temperature. Interestingly, in

• positions 5 and 8 already at room temperature (Scheme 3). The overall yield of the main product 10 turned out to be high, but the substance contained a hard-to-separate impurity in an amount of up to 12%, to which, judged by the high-field position of the signals in the corresponding proton spectrum, was