Radical reactivity of antiaromatic Ni(II) norcorroles with azo radical initiators

• Siham Asyiqin Shafie,
• Ryo Nozawa,
• Hideaki Takano and
• Hiroshi Shinokubo

Beilstein J. Org. Chem. 2024, 20, 1967–1972, doi:10.3762/bjoc.20.172

• analysis, which revealed that two alkyl substituents were located on the same side of the molecule (Figure 2a). Compared to the planar structure of 1 (Figure 2b) [2], 2a displays a nonplanar structure due to the sp3 carbon atoms adjacent to the nitrogen atoms. The 1H NMR spectrum of 2a confirmed that the

• coefficient of the HOMO indicates that two α-carbon atoms of the pyrrole subunits are the most reactive positions for electrophilic species. In addition, the distal α-carbon atom relative to the meso-position could be more reactive than the proximal α-carbon atom due to the steric hindrance of bulky mesityl

• groups. Consequently, the isobutyronitrile radical predominantly attacks the distal α-carbon atom relative to the meso-position to afford the corresponding radical intermediate I. The calculated spin density of radical I revealed a substantial radical character at the α-position of the pyrrole skeleton

Regioselective alkylation of a versatile indazole: Electrophile scope and mechanistic insights from density functional theory calculations

• Pengcheng Lu,
• Luis Juarez,
• Paul A. Wiget,
• Weihe Zhang,
• Krishnan Raman and
• Pravin L. Kotian

Beilstein J. Org. Chem. 2024, 20, 1940–1954, doi:10.3762/bjoc.20.170

• yields from the same carbon sources through reagent control. Experimental General methods All materials were obtained from commercial suppliers and used without further purification unless otherwise noted. Anhydrous solvents were obtained from Sigma-Aldrich and used directly. Reactions involving air- or

Negishi-coupling-enabled synthesis of α-heteroaryl-α-amino acid building blocks for DNA-encoded chemical library applications

• Matteo Gasparetto,
• Balázs Fődi and
• Gellért Sipos

Beilstein J. Org. Chem. 2024, 20, 1922–1932, doi:10.3762/bjoc.20.168

• subsequent re-esterification was necessary to achieve the desired ketoester. Reduction of the oximes Oximes are commonly reduced to the corresponding amines using either palladium on activated carbon and hydrogen gas [65][66][67][68], or with zinc and a Brønsted acid as source of hydrogen [68][69]. Both

Solvent-dependent chemoselective synthesis of different isoquinolinones mediated by the hypervalent iodine(III) reagent PISA

• Ze-Nan Hu,
• Yan-Hui Wang,
• Jia-Bing Wu,
• Ze Chen,
• Dou Hong and
• Chi Zhang

Beilstein J. Org. Chem. 2024, 20, 1914–1921, doi:10.3762/bjoc.20.167

• postulated for the synthesis of benzofuran derivatives from styrene derivatives by iodane reagents [29][30]. Subsequently, intermediate D is attacked by H2O at the benzylic carbon atom to afford intermediate E. Intramolecular proton shift occurs, generating the intermediate F, which undergoes phenyl

Novel oxidative routes to N-arylpyridoindazolium salts

• Oleg A. Levitskiy,
• Yuri K. Grishin and
• Tatiana V. Magdesieva

Beilstein J. Org. Chem. 2024, 20, 1906–1913, doi:10.3762/bjoc.20.166

• conditions of the potentiostatic electrolysis were the following: a two-compartment cell, a glassy carbon (GC) anode, DMF, the potential increased from 1.0 V to 1.4 V vs Ag/AgCl, KCl(sat.)), 2 F per mol of amine electricity passed, sodium tosylate (0.1 M) as a supporting electrolyte, and 2 equiv of 2.6

Electrochemical radical cation aza-Wacker cyclizations

• Sota Adachi and
• Yohei Okada

Beilstein J. Org. Chem. 2024, 20, 1900–1905, doi:10.3762/bjoc.20.165

• cyclization using the alkene 1 as a model (Table 1). Based on the conditions reported by Yoon and Moeller, the initial screening was carried out using tetrabutylammonium triflate (Bu4NOTf)/1,2-dichloroethane (1,2-DCE) solution. Carbon felt (CF) was used as an anode instead of reticulated vitreous carbon (RVC

2-Heteroarylethylamines in medicinal chemistry: a review of 2-phenethylamine satellite chemical space

• Carlos Nieto,
• Alejandro Manchado,
• Ángel García-González,
• David Díez and
• Narciso M. Garrido

Beilstein J. Org. Chem. 2024, 20, 1880–1893, doi:10.3762/bjoc.20.163

• hydration reaction of carbon dioxide to bicarbonate, cyanates to carbamic acids, aldehydes to gem-diols, etc., and represent a potential therapeutic target for diseases like osteoporosis, edema, obesity or cancer [29]. Alım et al. [30] evaluated a series of thiophene sulfonamides based on the high stability

The Groebke–Blackburn–Bienaymé reaction in its maturity: innovation and improvements since its 21st birthday (2019–2023)

• Cristina Martini,
• Muhammad Idham Darussalam Mardjan and
• Andrea Basso

Beilstein J. Org. Chem. 2024, 20, 1839–1879, doi:10.3762/bjoc.20.162

• adducts. An intriguing study is reported by Porcal et al. [35] in which they evaluate the use of 5-hydroxymethylfurfural (5-HMF, 23). Nowadays, the need to move towards more sustainable protocols is impending and the emphasis on green chemistry and on the use of renewable carbon sources is huge. Indeed

• , the use of 5-HMF (23) [36], a renewable carbon source derived from biomass, responds to these requirements. This aldehyde displays additional functionalities useful for further modifications of the GBB adducts, but some optimization was necessary due to its intolerance to high temperatures and

• proof of concept, one of the GBB adducts was transformed into a N,C-palladacycle and was investigated as a potential catalyst for carbon–carbon bond-forming reactions. Furthermore, the authors studied in detail the fluorescence properties of the GBB adducts, that will be discussed in chapter 5. As

A facile three-component route to powerful 5-aryldeazaalloxazine photocatalysts

• Ivana Weisheitelová,
• Radek Cibulka,
• Marek Sikorski and
• Tetiana Pavlovska

Beilstein J. Org. Chem. 2024, 20, 1831–1838, doi:10.3762/bjoc.20.161

• significant topic. Surprisingly, there has been limited information on 5-deazaalloxazines (dAll) synthesis [20][21][22]. Most known methods employ the cyclization of 6-(arylamino)uracils with one-carbon reagents such as triethyl orthoformate, dimethylformamide dimethylacetal, carbon disulfide, N,N

• characteristic signals of the carbonyl atoms were seen as singlets at 155.6–160.5 ppm. Signals of the carbon atoms of the pyrimido[4,5-b]quinoline ring were located in the resonance region of the carbon atoms of the aryl substituents. Taken together, these data indicate the formation of the 5-arylpyrimido[4,5-b

Hetero-polycyclic aromatic systems: A data-driven investigation of structure–property relationships

• Sabyasachi Chakraborty,
• Eduardo Mayo Yanes and
• Renana Gershoni-Poranne

Beilstein J. Org. Chem. 2024, 20, 1817–1830, doi:10.3762/bjoc.20.160

• -1 houses PBHs, molecules comprising only one type of ring – the aromatic, six-membered, carbon-based benzene. The principal moments of inertia (PMI) plots in Figure 3A show that the two datasets have similar tendencies to form “rod” and “disc”-like structures (i.e., 1D or 2D, respectively). Because

Chiral bifunctional sulfide-catalyzed enantioselective bromolactonizations of α- and β-substituted 5-hexenoic acids

• Sao Sumida,
• Ken Okuno,
• Taiki Mori,
• Yasuaki Furuya and
• Seiji Shirakawa

Beilstein J. Org. Chem. 2024, 20, 1794–1799, doi:10.3762/bjoc.20.158

• without substituents on the carbon–carbon double bond have remained a formidable challenge. To address this limitation, we report herein the asymmetric bromolactonization of 5-hexenoic acid derivatives catalyzed by a BINOL-derived chiral bifunctional sulfide. Keywords: asymmetric catalysis

• to asymmetric halolactonizations, especially for the synthesis of chiral γ-butyrolactones and δ-valerolactones via the reaction of 4-pentenoic acid and 5-hexenoic acid derivatives (Scheme 1). Notably, however, substituents on the carbon–carbon double bond of alkenoic acid substrates are generally

• required to achieve highly enantioselective halolactonizations (Scheme 1a) [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22]. Enantioselective halolactonizations of sterically less hindered alkenoic acid substrates without substituents on the carbon–carbon double bond have

Oxidative fluorination with Selectfluor: A convenient procedure for preparing hypervalent iodine(V) fluorides

• Samuel M. G. Dearman,
• Xiang Li,
• Yang Li,
• Kuldip Singh and
• Alison M. Stuart

Beilstein J. Org. Chem. 2024, 20, 1785–1793, doi:10.3762/bjoc.20.157

• ppm and 7.96 ppm, respectively, for iodine(V) product 6. Similarly, the 13C NMR spectrum showed a major downfield shift for the aromatic carbon attached to iodine from a chemical shift of 105.3 ppm in iodine(III) substrate 10 to 132.4 ppm for difluoroiodane(V) product 6. Since Selectfluor was shown to

• to a trans-configuration because of the bicyclic carbon skeleton. Trifluoroiodane 3, on the other hand, has both trans- and cis-configurations of the fluorine ligands which could play a key role in the reductive elimination step in the fluorination of phenylmagnesium bromide. Trifluoroiodane 3 also

• bicyclic iodane 6 (1.689) compared to monocyclic trifluoroiodanes 20–22 (1.738–1.766) and the ipso carbon atom is slightly less electronegative (−0.355 vs −0.414) resulting in a less polar, but slightly shorter C–I bond in difluoroiodane 6 (2.031(6) Å) compared to trifluoroiodane 20 (2.072(7) Å). As you go

Synthesis and characterization of 1,2,3,4-naphthalene and anthracene diimides

• Adam D. Bass,
• Daniela Castellanos,
• Xavier A. Calicdan and
• Dennis D. Cao

Beilstein J. Org. Chem. 2024, 20, 1767–1772, doi:10.3762/bjoc.20.155

• organic thin-film transistors from heteroacenes. Inspired by these results, we sought to demonstrate the preparation of all-carbon scaffolds, i.e., acenes, that are cata-annulated with cyclic imides. Here, we communicate the successful synthesis of 1,2,3,4-NDIs and -ADIs and the characterization of their

• -delocalization. As part of our previous work constructing heteroacenes bearing cata-imide groups, we investigated the 9,10-diaza analog of compound 8-Hex (9, Figure 5). It is interesting to note that the all-carbon scaffold in 8-Hex results in a narrower bandgap than that of 9, with Δλmax = 85 nm. This

Synthesis of polycyclic aromatic quinones by continuous flow electrochemical oxidation: anodic methoxylation of polycyclic aromatic phenols (PAPs)

• Hiwot M. Tiruye,
• Solon Economopoulos and
• Kåre B. Jørgensen

Beilstein J. Org. Chem. 2024, 20, 1746–1757, doi:10.3762/bjoc.20.153

• short distance between the electrodes, and easily reproduceable conditions. The electrochemical oxidation of phenols has been performed with platinum anodes [37][41], and carbon/platinum worked well for the oxidation of toluene dissolved in methanol with tetraethylammonium tosylate (Et4NOTs) as a

• the four-electron oxidation product 1,1-dimethoxynaphthalen-2(1H)-one (2). Best results were obtained with a carbon/platinum electrode pair, although stainless steel (SS) could also be used as cathode. The experiments were conducted with a 3:1 mixture of methanol/tetrahydrofuran (optimization not

• cell equipped with a platinum-coated cathode and a carbon-filled PPS (polyphenylene sulfide) micro-channel anode separated by a polyetheretherketone (PEEK) gasket [40]. Further experimental details and characterization of new compounds are given in Supporting Information File 1. General procedure A

Syntheses and medicinal chemistry of spiro heterocyclic steroids

• Laura L. Romero-Hernández,
• Ana Isabel Ahuja-Casarín,
• Penélope Merino-Montiel,
• Sara Montiel-Smith,
• José Luis Vega-Báez and
• Jesús Sandoval-Ramírez

Beilstein J. Org. Chem. 2024, 20, 1713–1745, doi:10.3762/bjoc.20.152

• reaction of mestranol acetate (34) catalysed by a palladium(II) complex, in the presence of p-benzoquinone under carbon monoxide. The authors propose an initial addition of the acetate C=O group onto the triple bond coordinated to palladium, followed by a MeOH attack onto the resulting oxycarbenium, and a

• yields (82–85%) (Scheme 28). The authors proposed a free radical mechanism facilitated by hydrogen peroxide, generating a primary radical at the terminal nitrogen atom -CO-HN• which then adds to the carbon atom of the imino group. The reaction mechanism was substantiated by theoretical calculations

• -oxathiaphospholane steroids In 2012, Krstić et al. reported the synthesis of spiro-1,3,2-oxathiaphospholane steroids using Lawesson’s reagent (LR) as a thionating and phosphorylating agent in the reaction with 17α-hydroxyprogesterone (107) [58]. The reaction was conducted in toluene, dichloromethane, or carbon

Chemo-enzymatic total synthesis: current approaches toward the integration of chemical and enzymatic transformations

• Ryo Tanifuji and
• Hiroki Oguri

Beilstein J. Org. Chem. 2024, 20, 1693–1712, doi:10.3762/bjoc.20.151

• (Scheme 7 and Scheme 8) [68]. This chemo-enzymatic total synthesis represents a pioneering approach, as it ingeniously integrates biosynthetic intermediate mimics, synthesized through multiple steps, into the biosynthetic pathway. A cascade of stereoselective carbon chain elongation and regioselective

• TylGI loads a methylmalonyl-CoA onto the acyl carrier protein (ACP) in module 1. The ketosynthase-like decarboxylase (KSQ) domain catalyzes the decarboxylation of the loaded methylmalonyl moiety, and subsequent modules 2 and 3 extend the carbon chain using two molecules of malonyl-CoA. The β

• -ketoreductase (KR) and dehydratase (DH) domains, sequentially catalyze the carbonyl reduction and dehydration of the extended polyketide chains to provide thioester 62 connecting to the ACP domain of module 3. TylGII then iterates similar conversions including carbon chain extension reaction, carbonyl reduction

Oxidation of benzylic alcohols to carbonyls using N-heterocyclic stabilized λ³-iodanes

• Thomas J. Kuczmera,
• Pim Puylaert and
• Boris J. Nachtsheim

Beilstein J. Org. Chem. 2024, 20, 1677–1683, doi:10.3762/bjoc.20.149

• was added, no significant shifts in the NMR spectral signals were detected, probably due to the poor solubility of the iodane. Conversely, with the addition of the red tetrazine salt 1c, a significant downfield shift was observed for the alpha-carbon protons from 3.51 ppm to 4.55 ppm, as illustrated

Methyltransferases from RiPP pathways: shaping the landscape of natural product chemistry

• Maria-Paula Schröder,
• Isabel P.-M. Pfeiffer and
• Silja Mordhorst

Beilstein J. Org. Chem. 2024, 20, 1652–1670, doi:10.3762/bjoc.20.147

• cyanoborohydride as a mild reducing agent, and paraformaldehyde as a methylating agent [36]. Methanol can be used as the methylating reagent in other methods. Here, a palladium on carbon (Pd/C) catalyst processes the dehydrogenation of the alcohol to form the corresponding aldehyde. The subsequently formed imine

• donates its methyl group to yield the mono-N-methylated amino acid. Common reagents for this reaction include iodomethane (MeI), cyanamide (CH2N2), and dimethyl sulphate ((CH3O)2SO2). A similar logic can be followed to methylate the Cα-carbon, with reaction conditions ranging from mild to very harsh

• pathways Methyltransferases can be classified based on various factors, such as their substrates (small molecule MTs, protein MTs, or RNA/DNA MTs), the atom that accepts the methyl group (oxygen = O-MTs, nitrogen = N-MTs, carbon = C-MTs, sulphur = S-MTs, or halide = H-MTs), metal or cofactor dependence

Polymer degrading marine Microbulbifer bacteria: an un(der)utilized source of chemical and biocatalytic novelty

• Weimao Zhong and
• Vinayak Agarwal

Beilstein J. Org. Chem. 2024, 20, 1635–1651, doi:10.3762/bjoc.20.146

• -linked homopolymer of N-acetyl-β-ᴅ-glucosamine (GlcNAc), the second most abundant biomass on earth after cellulose (Figure 4). Approximately 1011 tons of chitin are produced annually in nature, about 70% of which originate from the ocean. Most of the chitin is recycled by bacteria and fungi as carbon and

• group in 25 is rare. Feeding [1-13C]acetate to the culture resulted the enrichment of C1, C3, C5, C7, and C9 carbons, which verified the origin of the carbon skeleton as being fatty acid-derived. Feeding experiments with ʟ-[methyl-13C]methionine yielded only enrichment of C11 methyl, indicating that

New triazinephosphonate dopants for Nafion proton exchange membranes (PEM)

• Fátima C. Teixeira,
• António P. S. Teixeira and
• C. M. Rangel

Beilstein J. Org. Chem. 2024, 20, 1623–1634, doi:10.3762/bjoc.20.145

• chlorine atoms by different nucleophiles. The devised strategy involved the attack of the O or N atoms of the arylphosphonate nucleophile at the position of the chlorine atom of triazine, at its 2, 4 and 6 carbon positions (Figure 1). Most of these nucleophiles bearing a phosphonate group were not

• chlorine atom bonded to a carbon atom in the proposed structure. Other synthetic attempts were carried out with different reaction conditions, but they usually gave complex mixtures, whose compounds could not be separated, and the trisubstituted triazine derivative was not achieved. The reaction of

• the 31P atoms is observed as a singlet for both phosphorus atoms (Figure 2) and the carbon atom bonded to the chlorine atom is observed at 167.8 ppm. Also, the reaction with diethyl [hydroxy(4-aminophenyl)methyl]phosphonate (14) only afforded the disubstituted derivative TP3 (Scheme 5), despite the

Generation of multimillion chemical space based on the parallel Groebke–Blackburn–Bienaymé reaction

• Evgen V. Govor,
• Vasyl Naumchyk,
• Ihor Nestorak,
• Dmytro S. Radchenko,
• Dmytro Dudenko,
• Yurii S. Moroz,
• Olexiy D. Kachkovsky and
• Oleksandr O. Grygorenko

Beilstein J. Org. Chem. 2024, 20, 1604–1613, doi:10.3762/bjoc.20.143

• partition coefficient logarithm (log P), H-bond acceptor/donor count (HAcc/HDon), fraction of sp3-hybrid carbon atoms (F(sp3)), and rotatable bond count (RotB) are shown in Figure 5. It is apparent that the GBB chemical space contains many drug-like (69,043,101 molecules, 25%) and “beyond-Ro5” compounds (75

• count; F(sp3) – fraction of sp3-hybrid carbon atoms; RotB – rotatable bond count); compounds complying with specific Lipinski/Veber rules (MW ≤ 500, log P ≤ 5, HDon ≤ 5, HAcc ≤ 10, RotB ≤ 10 [38][41]) as well as compounds with F(sp3) > 0.5 are highlighted in blue, the rest of the compounds are shown in

Supramolecular assemblies of amphiphilic donor–acceptor Stenhouse adducts as macroscopic soft scaffolds

• Ka-Lung Hung,
• Leong-Hung Cheung,
• Yikun Ren,
• Ming-Hin Chau,
• Yan-Yi Lam,
• Takashi Kajitani and
• Franco King-Chi Leung

Beilstein J. Org. Chem. 2024, 20, 1590–1603, doi:10.3762/bjoc.20.142

• kV, equipped with a Gatan 794 CCD camera. TEM samples were prepared by depositing sample solutions (5.0 μL) onto a carbon grid (micro to nano, EMR carbon support film on copper, 400 square mesh) for 20 s. The sample solution was removed by blotting, and UranyLess EM stain solution (5.0 μL, Electron

• conductive carbon adhesive tape and air-dried for 48 h before measurement. SLS The scattering intensity of the samples was determined by SLS measurements using a Wyatt Technology DynaPro NanoStar. The scattering intensity was recorded as a parameter signifying the assembly size since the objects in solution

Electrocatalytic hydrogenation of cyanoarenes, nitroarenes, quinolines, and pyridines under mild conditions with a proton-exchange membrane reactor

• Koichi Mitsudo,
• Atsushi Osaki,
• Haruka Inoue,
• Eisuke Sato,
• Naoki Shida,
• Mahito Atobe and
• Seiji Suga

Beilstein J. Org. Chem. 2024, 20, 1560–1571, doi:10.3762/bjoc.20.139

• ][34][35][36][37][38][39][40][41][42][43]. The PEM reactor included a membrane electrode assembly (MEA) consisting of a PEM and an electro-catalyst supported on carbon (Figure 1). Humidified hydrogen gas (H2) or H2O was injected into the anodic chamber and the substrate passed through the cathodic

Mining raw plant transcriptomic data for new cyclopeptide alkaloids

• Draco Kriger,
• Michael A. Pasquale,
• Brigitte G. Ampolini and
• Jonathan R. Chekan

Beilstein J. Org. Chem. 2024, 20, 1548–1559, doi:10.3762/bjoc.20.138

• ]. These RiPP natural products encompass a wide range of structural scaffolds including cyclopeptide alkaloids that contain a phenolic ether-linkage and the lyciumin-type peptides that are composed of a crosslink between the Trp-indole-N and the carbon in another amino acid side chain or peptide backbone

• alkaloids, containing both Ziziphus and Ceanothus genera. In addition to the subclass defining Tyr-phenol-O to carbon linkage, the cyclopeptide alkaloids of this family are typically oxidatively decarboxylated and N-methylated (Figure 1, adouetine X and Figure 3, ceanothine B) [19][20][21]. Our

• tryptophan at the position for cyclization, indicating they may correspond to the stephanotic acid-type burpitides like moroidin (Trp-indole-C to carbon crosslink, Figure 3) [4]. Amaranthaceae family The Amaranthaceae family is home to the known moroidin producer, Celosia argentea var. cristata (Cockscomb

Benzylic C(sp³)–H fluorination

• Alexander P. Atkins,
• Alice C. Dean and
• Alastair J. J. Lennox

Beilstein J. Org. Chem. 2024, 20, 1527–1547, doi:10.3762/bjoc.20.137

• of agrochemicals contain fluorine, and that almost a quarter of drug molecules approved by the FDA between 2018 and 2022 contained at least one fluorine atom, for example belzutifan and quinofumelin, Figure 1A [4][5]. The fluorination of functionalised carbon centres is a reliable strategy to

• incorporate fluorine into compounds of interest, with regio and site selectivity pre-determined by the nature of the functionalised carbon. However, the development of C(sp3)–H fluorination methods represents a more sustainable and versatile approach, as there is no requirement to pre-functionalise the

• bond formation for substrates bearing primary benzylic positions, attributed to the faster rate of SN2 at the less hindered carbon. The scope was limited to substrates bearing secondary benzylic sites, with various functional groups tolerated. However, substrates bearing electron-donating substituents