Ortho-ester-substituted diaryliodonium salts enabled regioselective arylocyclization of naphthols toward 3,4-benzocoumarins

• Ke Jiang,
• Cheng Pan,
• Limin Wang,
• Hao-Yang Wang and
• Jianwei Han

Beilstein J. Org. Chem. 2024, 20, 841–851, doi:10.3762/bjoc.20.76

• reaction was performed in the presence of 10 mol % Cu(OTf)2 and 1.0 equivalent of K2CO3 in DCE at a temperature of 80 °C. To our delight, the reaction afforded 3,4-benzocoumarin 3aa in a 27% yield (Table 1, entry 1). The structure of 3aa was confirmed through NMR spectroscopy and mass spectra analysis

• (Table 1, entries 15–18). Finally, the reaction temperature and time were optimized, 3aa was produced in 61% yield at a temperature of 80 °C after 3 hours (Table 1, entry 15). With the optimized reaction conditions in hand, we started to explore the substrate scope of the cyclization to construct a

Advancements in hydrochlorination of alkenes

• Daniel S. Müller

Beilstein J. Org. Chem. 2024, 20, 787–814, doi:10.3762/bjoc.20.72

• significantly accelerate the reaction with aliphatic alkenes (Figure 3B) [38]. A detailed mechanistic analysis for the hydrochlorination with (Z)-2-butene (9) was carried out by Dalton and co-workers [39]. The reaction between (Z)-2-butene (9) and hydrogen chloride gas possesses an expected temperature

• dependence (higher temperature results in higher rates). In 1966, Brown and co-worker reported a specialized apparatus enabling the monitoring and control of HCl gas consumption during the reaction [40]. They observed full conversion of α-methylstyrene (11) within minutes and suggested that the

• hydrochlorination is operating within the rate of diffusion control (Figure 4). They also noted that the reaction was significantly slower at room temperature when compared to reactions carried out at 0 °C. However, reaction rates were exclusively reported at 0 and −45 °C, indicating an inverse temperature

Synthesis and characterization of water-soluble C₆₀–peptide conjugates

• Yue Ma,
• Lorenzo Persi and
• Yoko Yamakoshi

Beilstein J. Org. Chem. 2024, 20, 777–786, doi:10.3762/bjoc.20.71

• LED lamp (527 nm) for 1 min or 10 min. PS: 40 μM, 4-oxo-TEMP: 80 mM, in 60 mM phosphate buffer (pH 7.0). Measurement conditions: temperature 296 K, microwave frequency 10.03 GHz, microwave power 10 mW, receiver gain 5.0 × 104, modulation amplitude 1.00 G, modulation frequency 100 KHz, sweep time 83.89

Synthesis of new representatives of A₃B-type carboranylporphyrins based on meso-tetra(pentafluorophenyl)porphyrin transformations

• Victoria M. Alpatova,
• Evgeny G. Rys,
• Elena G. Kononova and
• Valentina A. Ol'shevskaya

Beilstein J. Org. Chem. 2024, 20, 767–776, doi:10.3762/bjoc.20.70

• temperature for 4 h. Under these reaction conditions, monoazide derivative 2 was obtained in 40% yield along with a mixture of porphyrin 1, di- and triazido-substituted derivatives. The reaction mixture was separated by column chromatography on SiO2 using CH2Cl2/hexane 2:8 as an eluent. The reduction of the

• temperature under argon. Under these reaction conditions, the tris(carboranyl)-substituted porphyrin 6 was obtained in 39% yield after purification by column chromatography on SiO2 using CHCl3/hexane 1:1 as eluent (Scheme 3). It should be noted that the reaction of porphyrin 6 with NaN3 in DMSO at 20 °C for

• DMSO at room temperature for 10 min using anhydrous NaOAc as a base to afford the corresponding boronated porphyrin conjugates 18–20 in 80–87% yields. Exploring the reactivity of the p-fluorine atom similar nucleophilic substitution reactions of porphyrin 6 were carried out with 1,8-diamino-3,6

Methodology for awakening the potential secondary metabolic capacity in actinomycetes

• Shun Saito and
• Midori A. Arai

Beilstein J. Org. Chem. 2024, 20, 753–766, doi:10.3762/bjoc.20.69

• Zeeck and co-workers in the early 2000s, is a method in which the target bacteria are cultured under various conditions (medium composition, temperature, pH, oxygen supply, light quality and quantity, addition of precursors and enzyme inhibitors, etc.) and all metabolites obtained from them are analyzed

• of silent genes. The authors’ group has been working on methods to activate these genes by increasing the culture temperature above the normal level. Temperature – heat-shock metabolites (HSMs) – metabolites for which production is activated by high-temperature culture Several examples of high

• -temperature culture of actinomycetes have been reported prior to the authors’ examples as studies attempting to increase the production of the targeted metabolites (Figure 4a). For example, Doull et al. achieved an increase in the production of jadomycin B (30) produced by Streptomyces venezuelae ISP5230 by

Research progress on the pharmacological activity, biosynthetic pathways, and biosynthesis of crocins

• Zhongwei Hua,
• Nan Liu and
• Xiaohui Yan

Beilstein J. Org. Chem. 2024, 20, 741–752, doi:10.3762/bjoc.20.68

• are highly soluble in hot water but slightly soluble in anhydrous ethanol and ether. The presence of multiple conjugated double bonds in crocins makes them susceptible to degradation when exposed to certain conditions, such as high temperature, the presence of metal ions or light, certain pH values

• , etc. For example, during the harvest of C. sativus, a high drying temperature leads to the cleavage of the glycosidic bonds [20][21][22]. Crocins are stable in alkaline and neutral solutions but are labile under acidic solutions. Crocins can be detected in the flowers, fruits, stigmas, leaves, and

• supply, overexpressing PsBCH-CsCCD2, and optimizing the fermentation medium, the yield of crocetin (1) reached 12.43 ± 0.62 mg/L in a 5 L bioreactor [115]. While CCD has a higher catalytic activity at low temperature, the biosynthesis of zeaxanthin (7) is more suited to a higher temperature. As such, Liu

SOMOphilic alkyne vs radical-polar crossover approaches: The full story of the azido-alkynylation of alkenes

• Julien Borrel and
• Jerome Waser

Beilstein J. Org. Chem. 2024, 20, 701–713, doi:10.3762/bjoc.20.64

• the reasons why no reaction occurred. Next, we turned our attention to the temperature of the reaction, a factor rarely explored in photocatalyzed reaction due to the lack of available set-ups allowing an efficient light irradiation in addition to a proper temperature control. In our case, since the

• ). Decreasing the temperature to −20 °C slightly improved the yield and the mass balance of the reaction (Table 6, entry 3). At −41 °C the reaction time had to be increased to reach full conversion of styrene (1a), and the yield slightly decreased (Table 6, entry 4). As full conversion is still reached rapidly

• reagents as SOMOphilic alkynes but this only afforded a 29% yield of the desired product. After switching to a radical-polar crossover approach the yield could be significantly improved. Key to the reaction optimization was the reduction of the temperature to −20 °C and the addition of BF3·Et2O. A large

New variochelins from soil-isolated Variovorax sp. H002

• Jabal Rahmat Haedar,
• Aya Yoshimura and
• Toshiyuki Wakimoto

Beilstein J. Org. Chem. 2024, 20, 692–700, doi:10.3762/bjoc.20.63

• kept at room temperature for one hour. The reaction mixtures were concentrated in vacuo, dissolved in acetone, and then injected into a GC–MS system, Zebron ZB-WAX (30 m × 0.25 mm ID × 0.25 µm, Phenomenex), using He as the gas source at a flow rate of 1.41 mL/min. The initial temperature (120 °C) was

• for 1 h with 10 mg/mL lysozyme. After 10% SDS was added to the tube, the mixture was incubated at room temperature, 60 °C, and then 0 °C, for 5 min durations. AcOK (5 M) and phenol/CHCl3/isoamyl alcohol (25:24:1) were then added, and the resulting solution was gently mixed by inversion and centrifuged

Evaluation of the enantioselectivity of new chiral ligands based on imidazolidin-4-one derivatives

• Jan Bartáček,
• Karel Chlumský,
• Jan Mrkvička,
• Lucie Paloušová,
• Miloš Sedlák and
• Pavel Drabina

Beilstein J. Org. Chem. 2024, 20, 684–691, doi:10.3762/bjoc.20.62

• (i.e., temperature, reaction time, amount of catalyst, solvent) were adopted from the pilot study [5] for relevant comparison of catalyst characteristics. From Table 1 and Table 2, which summarise results obtained using tridentate ligands Ia–c and IIa–c, it is evident that the catalytic activity their

• . Thus, early attempts at the aldol reaction of 4-nitrobenzaldehyde with cyclohexanone were performed to evaluate the reaction parameters, i.e., solvent, reaction temperature, and amount of acidic additive (Table 5). Hence, using DMF at −25 °C were the most convenient conditions regarding diastereo- and

Regioselective quinazoline C2 modifications through the azide–tetrazole tautomeric equilibrium

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

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

• % yield over 2 steps. The full conversion was achieved by keeping the reaction mixture at a temperature of 0 °C and by the stepwise additions of the sulfinate and NaN3. Any deviation from these conditions facilitated the formation of byproducts. In addition, the sulfonyl group dance reactions were carried

• azide–tetrazole equilibrium of product 12a was initiated, revealing a singular form present in all solvents. Despite attempts to increase the amount of the azide form with the increase of the temperature in NMR experiments [27], no observable alteration in the tautomeric equilibrium was observed. FTIR

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