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

• accessible for the cell [2][3]. In addition to the siderophores forming the stable Fe(III) complexes described above, certain siderophores create Fe(III) complexes with the ability to release Fe(II) ions in a light-responsive manner within the extracellular environment. The released Fe(II) ions in the ocean

• C45H79O17N11, as suggested by the HRESIMS data (m/z 1044.5603 for the [M − H]− ion), indicating the loss of two methylene groups (C2H4) from 1. In addition, the MS/MS fragmentation profile of 3 was consistent with those of 1 and 2, except for the loss of 28 mass units in the N-terminal Nγ-acyl-γ-amino acid

• )-ʟ-alaninamide) derivatives [5]. In addition, a combination of NOESY and bioinformatics analyses proposed all three stereocenters of 4-amino-7-guanidino-3-hydroxy-2-methylheptanoic acid as S configured [5]. The stereochemistry of these moieties in 3–5 are discussed in the next section, regarding the

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

• the C=O bond. In this manner, the asymmetric induction results in the restricted addition of nitromethane influenced by imidazolidin-4-one moieties. The higher enantioselectivity of complexes of the ligands with cis-cis configuration could be explained by the fact that the larger (RL) alkyl group is

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

• terazosin and prazosin [20]. Herein, we report the use of the sulfonyl group dance to synthesize novel 4-azido-2-sulfonylquinazolines and their C2-selective modification in SNAr reactions. In addition, we offer an approach for the synthesis of terazosin and prazosin, known medications against hypertension

• hydrolysis product 5a. In MeCN the conversion to derivative 2a was stopped at 50% and was not facilitated by an extra addition of sulfinate. To our delight, in MeOH we observed the formation of intermediate 2a over 5 hours, and after the subsequent addition of sodium azide product 4a was isolated in 31

• % 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

Organic electron transport materials

• Joseph Cameron and
• Peter J. Skabara

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

• soluble in ethyl acetate, a green solvent, and solution-processed for PM6:Y6 bulk-heterojunction solar cells with power conversion efficiency > 13% [6]. In addition to orthogonal processing, it has been shown that treatment with base [7] or photo-crosslinking [8] can insolubilise solution-processed layers

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

• a challenge. In addition, many studies show that unsaturated AAs exhibit a variety of unique biological activities [21][22][23][24]. Accordingly, the development of efficient methods to synthesize unsaturated γ- and ε-AA derivatives is a highly sought-after target to enrich non-natural AA chemistry

• diverse alkenes followed by a diradical coupling or radical addition process to achieve the difunctionalization (Scheme 1b, middle) [32][33][34][35][36][37]. However, to the best of our knowledge, the methodology involving the addition of a carbon radical from a diazo compound onto the double bond of an

• alkene followed by a nucleophilic addition, is unknown (Scheme 1b, bottom). The radical-polar crossover strategy has been steadily emerging in synthetic organic chemistry during the last few years [43][44][45][46]. This strategy allows complex chemicals to be assembled with high step economy that would

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

• member of the emerging ion-endohedral fullerene family, have attracted significant attention owing to the distinctive ionic properties originating from the ion pair structure consisting of a cationic endohedral fullerene core and an external counter anion. Despite being a relatively recent addition, Li

• , resulting in much better yields of the target monoadducts. Electrochemical measurements revealed that the functionalization raised the LUMO level of Li+@C60, leading to lower reactivity for the second addition. With this facile, selective, and high-yield approach for the derivatization of ion-endohedral

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

• geometry of the remaining double bond at C-18 was established to be trans by comparing the 13C NMR chemical shifts at C-16 and C-21 between 1 and polycavernoside D (5) (Table S1 in Supporting Information File 1) [5]. In addition, a 4J long-range coupling between δH 1.95 (H-26) and δH 2.18 (H-24) and three

• chain structure from C-2 to C-8. In addition, eight HMBC, δH 5.17 (H-15)/δC 171.9 (C-1), δH 2.29 (H-2)/δC 171.9 (C-1), δH 0.85 (H-28)/δC 83.5 (C-13), δH 0.85 (H-28)/δC 39.8 (C-14), δH 0.85 (H-28)/δC 78.4 (C-15), δH 0.86 (H-29)/δC 83.5 (C-13), δH 0.86 (H-29)/δC 39.8 (C-14), and δH 0.86 (H-29)/δC 78.4 (C

• trypanosomiasis) (Table 3). As a result, 1 showed moderate growth-inhibitory activities against Trypanosoma brucei rhodesiense (IC50: 9.9 μM). In addition, we examined the growth-inhibitory activity of 1 on normal human fibroblasts WI-38 (Table 3). In summary, 1 showed a moderate activity against Trypanosoma

Production of non-natural 5-methylorsellinate-derived meroterpenoids in Aspergillus oryzae

• Jia Tang,
• Yixiang Zhang and
• Yudai Matsuda

Beilstein J. Org. Chem. 2024, 20, 638–644, doi:10.3762/bjoc.20.56

• polyketide portion [11][12][13][14]. One exception has been found in funiculolide biosynthesis, in which a 5-MOA-derived phthalide undergoes dearomatizing prenylation catalyzed by the UbiA-like prenyltransferase FncB (Figure 1B) [15]. In addition to prenyltransferases, transmembrane terpene cyclases play a

• into distinct cyclized products (Figure 1C) [17][18][19]. In addition, a recent study has demonstrated that some of these transmembrane terpene cyclases can accept synthetic substrate analogues to yield several unnatural meroterpenoid molecules [20]. By mimicking nature’s strategy to synthesize diverse

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

• /heteroaromatic and aliphatic aldehydes. Furthermore, the isolation process is simple and there is no need for liquid–liquid extraction. In addition, our methodology showed superior Green Chemistry metrics as compared to some already reported methodologies. Selected examples of commercial drugs containing the

Introduction of a human- and keyboard-friendly N-glycan nomenclature

• Friedrich Altmann,
• Johannes Helm,
• Martin Pabst and
• Johannes Stadlmann

Beilstein J. Org. Chem. 2024, 20, 607–620, doi:10.3762/bjoc.20.53

• signifying additional branching. As no other branching point is given, the root residue is GlcNAc. LacNAc repeats The primary LacNAc disaccharide Galβ1-4GlcNAcβ1- that is linked to a mannose can be further elongated by the addition of GlcNAc (in β1-3 linkage to Gal), which usually is followed by the quick

• addition of Gal to arrive at another Galβ1-4GlcNAcβ1- (= LacNAc) unit. The following annotation scheme is a suggestion that may be substituted by a better option. Such LacNAc repeats occur in recombinant erythropoietin [46] where the root galactose was found in 4-linkage. To allow for the occurrence of 3

• “HNK-1” (from human natural killer cells) with sulfated glucuronic acid [47]. Annotating a structure like this requires some form of linear code and the addition of abbreviations for non-sugar substituents, in this case sulfate. Note that the hyphen binds the “su” to “Ga”, which in turn is hyphenated

Chemical and biosynthetic potential of Penicillium shentong XL-F41

• Ran Zou,
• Xin Li,
• Xiaochen Chen,
• Yue-Wei Guo and
• Baofu Xu

Beilstein J. Org. Chem. 2024, 20, 597–606, doi:10.3762/bjoc.20.52

• 175.94, δC 194.36). Its NMR data closely resemble those of brocaeloid D [23], with the notable addition of a methoxy group (δH 3.20/δC 53.92). HMBC correlations confirmed the presence of a reversed prenyl group and differentiated compound 1 from brocaeloid D by the substitution of a succinimide

• pathway (Figure 5). Briefly, the prenyl group is attached to tryptophan through a prenylation reaction catalyzed by ShnA, followed by the decarboxylation of the carboxy group by ShnC. Subsequently, compound 2 is formed by the addition of succinimide to N15 in 1 via a reaction catalyzed by ShnB. The

• from the known brocaeloid D by the addition of a methyl group, and there is a change in the relative stereochemistry at C2 and C3. In addition, the conversion of the five-membered pyrrole ring in compound 2 to the six-membered piperidine ring in compound 1 is intriguing. Although there have been many

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

• peptidyl transferase activity while the furanose group does not appear to be important for target inhibition [6][7]. In addition, hygromycin A contains a unique methylenedioxy group found on the aminocyclitol that is not required for ribosome interaction and in vitro inhibition [8]. Instead, it is

• annotations and in vivo studies [8]. However, validation by in vitro approaches or biochemical analysis of the individual enzymes is lacking. Here, we verify that Hyg17 is a myo-inositol dehydrogenase and show that it has a distinct substrate scope. In addition, we use sequence similarity networks to compare

• 584 sequences were near an acyl synthase domain, 340 sequences by an acyl carrier protein domain, and 1,193 sequences by a thioesterase domain. In addition, Hyg17 works together with the aminotransferase Hyg8 to replace a hydroxy group with an amine generating an aminocyclitol from myo-inositol. We

Recent developments in the engineered biosynthesis of fungal meroterpenoids

• Zhiyang Quan and
• Takayoshi Awakawa

Beilstein J. Org. Chem. 2024, 20, 578–588, doi:10.3762/bjoc.20.50

• Aspergillus nidulans, within the same phylogenetic clade. Expression of this enzyme in place of Trt1 resulted in the formation of the 6-6-6-6-membered ring protoaustinoid A (8) (Figure 2) [9]. In addition, the expression of the cyclase AdrI (38% identity with Trt1) from Penicillium chrysogenum produced the 6

• compounds (40, 43, 44, 47, 48, 50, 51, and 53–55) (Figure 7A). In addition, a structure-based mutagenesis study of SptF was performed to further amplify its catalytic potential. Firstly, the hydrophobic residues Ile63, Phe133, and Ile231, which compose the substrate binding site of SptF, were mutated. As a

• the filamentous fungus Stachbotrys bisbyi were produced in A. oryzae to synthesize grifolic acid (60) (Figure 9) [39]. In addition, the gene encoding DCAS, a prenyl group oxidase from the plant Rhododendron dauricum, was additionally expressed in A. oryzae expressing stbAC after codon-optimization to

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

• synthesis of spiro-annulated pyrrolidine-2,5-diones by catalyzed spirocyclizations involving aldehydes [11], tetrahydrofuran [12][13], and in the O–H insertion/Claisen rearrangement/intramolecular oxa-Michael addition cascade [14] (Scheme 1). Herein, we report our findings obtained, while investigating the

• the addition of base (DIPEA). The target α,β-disubstituted spirobutenolides 3a–d were isolated in high yields irrespective of the change in the type of substitution in the initial DAS. However, in the case of 3d, the cyclization stage proceeded slower (8 days instead of 3) and under an elevated amount

• monitor the progress of the reaction and the formation of the OH-insertion product 14. An attempt to carry out the second step in a one-pot format with the addition of 1.2 equiv of base (DIPEA or DBU) was unsuccessful and the formation of the spirocyclic product was not observed. Replacing DCM with a more

Synthesis of photo- and ionochromic N-acylated 2-(aminomethylene)benzo[b]thiophene-3(2Н)-ones with a terminal phenanthroline group

• Vladimir P. Rybalkin,
• Sofiya Yu. Zmeeva,
• Lidiya L. Popova,
• Irina V. Dubonosova,
• Olga Yu. Karlutova,
• Oleg P. Demidov,
• Alexander D. Dubonosov and
• Vladimir A. Bren

Beilstein J. Org. Chem. 2024, 20, 552–560, doi:10.3762/bjoc.20.47

• light and H+ or sequential addition of Fe2+ and AcO− ions. Keywords: fluorescence; molecular switches; N→O acyl rearrangement; naked eye effect; photochromism; Introduction Photochromism is defined as the reversible transformation of a molecular entity between different forms, having different

• sequential addition of Fe2+ and AcO−, we synthesized N-acylated 2-(aminomethylene)benzo[b]thiophene-3(2Н)-ones with a terminal phenanthroline substituent and studied the spectral-luminescent, photochromic and ionochromic properties. The phenanthroline moiety was incorporated into the molecule due to the

• catalysis and bioimaging [24][25][26]. In addition, such systems provide a convenient platform for creating chemo- and biosensors for rapid analysis of the ionic composition of the environment [27][28]. Results and Discussion The starting compound for the synthesis of N-acylated 2-(aminomethylene)benzo[b

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

• , 1.37 mmol, 0.3 equiv) were dissolved in absolute toluene (40 mL) in an oven-dried round-bottom flask under argon. The resulting reaction mixture was stirred at reflux for 3.5 h. After cooling to room temperature, water (80 mL) and toluene (20 mL) were added, followed by addition of ammonium

• aqueous suspension or emulsion, with the addition of 0.5% of an additive at an application rate of 600 L of water/ha (converted). Following treatment, the pots were placed in a greenhouse and kept under optimum growth conditions for the test plants. The test plants were placed in the greenhouse for ca

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

• mainly driven by intramolecular hydrogen bonds. The methoxyphenyl-pyridine-methoxyphenyl moiety, developed by Petitjean et al. [19], demonstrates conformational switching upon the addition of acid in aqueous media (Figure 2). The neutral tweezers adopt a "U"-shaped conformation with both arms pointing in

• evidence was reported. Nevertheless, conformational changes were obtained from two other stimuli: (i) alkylation of phenolic OH groups [25] that leads to the disappearance of the hydrogen bonds and a more stable W-shaped conformation; (ii) addition of F− anion [26] as a competitive hydrogen-bond acceptor

• acridinium is that it can undergo the addition of a nucleophile like HO− or RO− forming an acridane derivative having non-planar geometry and different electronic properties. Triphenylene tweezers 6 are able to intercalate planar electron-rich guest molecules like TTF and pyrene. Upon the addition of a

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

• Since the seminal 1998 report by Teles et al. on the gold(I)-catalyzed addition of alcohols to alkynes [1], a multitude of gold-catalyzed reactions have been reported. Great successes in mechanistic analysis and synthetic methods have been achieved for allene and alkyne activation, while the activation

• intermediates (expected from allene/alkyne addition) are more reactive than the C(sp3)-alkylgold intermediates expected from alkene addition [29]. Another study demonstrated the inefficiency of protodeauration in the presence of (albeit more basic) alkylamines [30]. These studies cast doubt on protodeauration

• slight inhibitory effect that does not change significantly with concentration. Addition of 5 μL hexafluoroisopropanol (HFIP) slows the reaction. Additional HFIP disrupts catalytic reactivity almost completely; none of the expected product 3a was detectable after 1.6 hours in the presence of 55 μL HFIP

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

• of 0.048(7), which suggested all the stereogenic centers in compound 2 as 1R, 2R, 3R, 6R, 7R, 8S. In addition to compounds 1 and 2, three related ovalicin-type sesquiterpenoid derivatives 3 [10], 4 [11], and chlovalicin (5) [12][13] were isolated and identified from the fungus P. boydii CS-793. It

• (pathway b), while nucleophilic attack at C-14 of intermediate IV by a chloride could generate compound 5 (pathway a). In addition, compound 5 might also be derived from intermediate IV by cleavage of the ester bond at C-2 to form the intermediate VI [15], followed by chlorination (pathway c). Compounds 1

Synthesis of 2,2-difluoro-1,3-diketone and 2,2-difluoro-1,3-ketoester derivatives using fluorine gas

• Alexander S. Hampton,
• David R. W. Hodgson,
• Graham McDougald,
• Linhua Wang and
• Graham Sandford

Beilstein J. Org. Chem. 2024, 20, 460–469, doi:10.3762/bjoc.20.41

• -diketones occurs rapidly because the substrates lie predominantly in their enol tautomeric forms. The resulting 2-difluoro-1,3-diketones, on the other hand, are formed in their keto-tautomeric forms. Thus, we found difluorination could only be achieved upon addition of water or a base to accelerate the

• enolization of the monofluoro-diketone intermediates. In addition, imines and α-diboryl ketone derivatives can also be transformed to 2,2-difluoroketones using an N–F electrophilic fluorinating reagent [18]. Alternatively, building blocks containing CF2 units such as ethyl bromodifluoroacetate and

• of diazo compounds using F2 [37] is the only report of a useful synthetic procedure to selectively prepare a difluoromethylene containing product using F2 but, in these cases, CFCs, now banned under the Montreal protocol, were used as the reaction medium. Here, we demonstrate that the addition of

(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

• the corresponding =CF2 containing products [10]. In addition to complexes of aluminum and boron, several magnesium and lithium silyl reagents were prepared and proved to be good nucleophiles in reactions with (Z)-1,1,1,4,4,4-hexafluorobut-2-ene, as a result of which the corresponding

• defluorosilylation product was obtained [11]. In a related study of the hydrosilylation reaction of olefins 1a,b, it was shown that, depending on the catalyst used, platinum or rhodium compounds, along with the products of the addition of silane to the double bond, the elimination of the fluorine atom occurs with

• the formation of the corresponding olefin [12]. Another area of application of olefins 1a,b is based on C=C double bond addition reactions. As early as 1968, Atherton and Fields showed that (Z)- and (E)-butenes 1a,b reacted with diazotrifluoroethane to give 3,4,5-tris(trifluoromethyl)pyrazoline [13

Development of a chemical scaffold for inhibiting nonribosomal peptide synthetases in live bacterial cells

• Fumihiro Ishikawa,
• Sho Konno,
• Hideaki Kakeya and
• Genzoh Tanabe

Beilstein J. Org. Chem. 2024, 20, 445–451, doi:10.3762/bjoc.20.39

• activities against the A-domain of MbtA, a component of mycobactin synthetase and antimicrobial activities against M. tuberculosis [7]. In addition, aminoacyl (AA)-AMS has been designed to inhibit the amino acid-activating A-domains in NRPSs and has been found to be a tight-binding inhibitor (Figure 2b) [8

• fluorescence scanning (excitation wavelength, 532 nm; emission wavelength, 580 nm). The labeling of GrsA by probe 3 was completely suppressed by the addition of inhibitors 1, 2, 4, 5, and 7 (Figure 4a). In contrast, inhibitors 6, 8, and 9 moderately inhibited labeling, which was consistent with the decreased

• scaffold on the binding affinities for A-domains and cell permeability. Our experiments demonstrated that inhibitor 7, harboring a cyanomethyl group at the 2′-OH, showed a Kd value comparable to that of the original ʟ-Phe-AMS 1. In addition, intracellular competitive ABPP suggested that the inhibitor 7 can

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

• [23][24][25][26] and CH–π interactions [27][28][29][30], forming the corresponding host–guest complexes. In addition, the concave outer surface of the CPP also interacts with the convex surface of the CPP (Figure 1b) [31][32][33], resulting in the formation of the shortest possible double-layer CNTs

• mixture of [8]–[12]CPPs and [5]CPP2+[B(C6F5)4−]2 before and after the addition of [5]CPP2+[B(C6F5)4−]2, and b) [10]CPP and [5]CPP2+[B(C6F5)4–]2 before and after the addition of [5]CPP2+[B(C6F5)4−]2. Cyclic voltammograms of [10]CPP⊃[5]CPP2+[B(C6F5)4−]2, [10]CPP, and [5]CPP2+[B(C6F5)4−]2 in Bu4N+ B(C6F5)4

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

• cycle involves the oxidative addition of 1,8-dibromonaphthalene. Then, a concerted metalation–deprotonation of the arene, which usually occurs at the ortho-position of an activating group such as a fluorine or a chlorine atom, followed by reductive elimination, gives the corresponding intermediate 1

• -aryl-8-bromonaphthalene A (Scheme 2). This catalytic cycle is followed by a second involving oxidative addition of 1-aryl-8-bromonaphthalene A, followed by intramolecular C–H coupling of the two aryl rings to give the fluoranthene derivative. Consequently, the use of arenes bearing substituents at the

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

• electron-withdrawing substituents. The reaction mechanism is based on the activation of the carbonyl group by molecular I2, through the formation of a halogen bond, which lowers the LUMO of the carbonyl moiety, increasing its electrophilicity, and thus allowing the addition of the indole group (Scheme 7

• reaction mixture for up to 8 cycles before signs of deactivation were observed. The mechanism of action was also identical with the Cu–isatin Schiff base complex activation of the carbonyl group, facilitating the electrophilic addition of indole (Scheme 19). The main drawback of the method, however, is the