Confirmation of the stereochemistry of spiroviolene

• Yao Kong,
• Yuanning Liu,
• Kaibiao Wang,
• Tao Wang,
• Chen Wang,
• Ben Ai,
• Hongli Jia,
• Guohui Pan,
• Min Yin and
• Zhengren Xu

Beilstein J. Org. Chem. 2024, 20, 852–858, doi:10.3762/bjoc.20.77

• isotope labeling experiments [6], followed by a 2,7-cyclization, afforded C6 cationic intermediate IM-3 with cyclopiane skeleton. Quench of the cation IM-3 with water would give 4, while upon two 1,2-alkyl shifts of IM-3, followed by deprotonation of cation IM-4, would give spiroviolene (1). On the other

• ][20], and fusaterpenol (8, GJ1012E) [17]. A similar 1,2-alkyl shift of IM-10, followed by deprotonation of the formed spirocyclic cation IM-12, afforded 3. Although previous isotope labeling experiments did not support this pathway for spiroviolene cyclization, it should be noted that a subtle

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

• )2 and Xantphos (Scheme 4e). In addition, deuterium labeling experiments were conducted to investigate the H-source of this transformation (for more details, see Supporting Information Information File 1). The isotopic-labeling experiments suggested that both types of protons from the N–H bond of 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

• depictions and related software has lately been portrayed in a quite enjoyable review [15]. A number of computer-readable formats has been developed of which GlycoCT [16] and WURCS [17] are currently the options of choice. None of these software friendly options is even remotely suitable for labeling of

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

• differences in the composition of cell membranes and presence of efflux pumps [9]. Specific protein labeling using a chemical probe can help to identify, characterize, and visualize target proteins [10][11]. The first chemical probe used for A-domains in NRPSs was reported by Marahiel et al. [8]. They

• probes (AA-AMS-BPyne) can selectively label the A-domains corresponding to the amino acid of the ligand in both recombinant enzymes and proteomes. We recently reported that these probes can be used to label the A-domains of endogenous NRPSs in live bacterial cells [17][18][19]. The intracellular labeling

• of the enterobactin synthetase EntF with Sal-AMS-BPyne requires carbonyl cyanide m-chlorophenylhydrazone, which collapses the proton motive force used in most efflux pumps [17]. Under the same conditions, the competitive inhibition of labeling using excess Sal-AMS is not observed, suggesting that the

Using the phospha-Michael reaction for making phosphonium phenolate zwitterions

• Matthias R. Steiner,
• Max Schmallegger,
• Larissa Donner,
• Johann A. Hlina,
• Christoph Marschner,
• Judith Baumgartner and
• Christian Slugovc

Beilstein J. Org. Chem. 2024, 20, 41–51, doi:10.3762/bjoc.20.6

• candidates as well. Ortho-hydroxy-substituted phosphines have been mainly used as chelating ligands for metal complexes until recently [16][17][18]. Further, ortho-hydroxy phosphines have been used for the synthesis of probes in metabolic labeling [19], as a photocatalyst in the defluoroalkylation of

α-(Aminomethyl)acrylates as acceptors in radical–polar crossover 1,4-additions of dialkylzincs: insights into enolate formation and trapping

• Angel Palillero-Cisneros,
• Paola G. Gordillo-Guerra,
• Fernando García-Alvarez,
• Olivier Jackowski,
• Franck Ferreira,
• Fabrice Chemla,
• Joel L. Terán and
• Alejandro Perez-Luna

Beilstein J. Org. Chem. 2023, 19, 1443–1451, doi:10.3762/bjoc.19.103

• . Product 25a is formed on addition of an iPr radical generated by I-atom transfer from iPrI to the Et radical, and is diagnostic for the formation of the latter in the reaction medium. Deuterium labeling experiments were then performed to substantiate the formation of a zinc enolate following radical

Solid-phase total synthesis and structural confirmation of antimicrobial longicatenamide A

• Takumi Matsumoto,
• Takefumi Kuranaga,
• Yuto Taniguchi,
• Weicheng Wang and
• Hideaki Kakeya

Beilstein J. Org. Chem. 2022, 18, 1560–1566, doi:10.3762/bjoc.18.166

• products. For example, the mycolic acid-containing bacterium Tsukamurella pulmonis TP-B0596 can influence the biosynthesis of cryptic natural products [3]. Additionally, we have developed several highly sensitive labeling reagents to detect and identify scarce and cryptic natural products [4]. Integrating

• the combined-culture strategy and new labeling reagents has led to the detection and structural determination of several unprecedented secondary metabolites [5][6][7]. Longicatenamides A–D (1–4, Figure 1) are cyclic hexapeptides isolated from the combined-culture of Streptomyces sp. KUSC_F05 and T

• the evaluation of its antimicrobial activity. The present study confirmed our proposed structure of 1, which was determined by the use of our original labeling reagents [4]. Results and Discussion Although the solution-phase total synthesis of an analogue of longicatenamycin A has been reported [10

Characterization of a new fusicoccane-type diterpene synthase and an associated P450 enzyme

• Jia-Hua Huang,
• Jian-Ming Lv,
• Liang-Yan Xiao,
• Qian Xu,
• Fu-Long Lin,
• Gao-Qian Wang,
• Guo-Dong Chen,
• Sheng-Ying Qin,
• Dan Hu and
• Hao Gao

Beilstein J. Org. Chem. 2022, 18, 1396–1402, doi:10.3762/bjoc.18.144

• Talaromyces wortmannii ATCC 26942. Heterologous expression reveals that TadA catalyzes the formation of a new fusicoccane-type diterpene talaro-7,13-diene. D2O isotope labeling combined with site-directed mutagenesis indicates that TadA might employ a different C2,6 cyclization strategy from the known

• labeling experiments and density functional theory (DFT) calculations are needed so as to gain deeper insight into the cyclization mechanism of 1. Functional analysis of the cytochrome P450 enzyme TadB Due to the significance of tailoring enzymes in terms of structural diversification and bioactivity

Experimental and theoretical studies on the synthesis of 1,4,5-trisubstituted pyrrolidine-2,3-diones

• Nguyen Tran Nguyen,
• Vo Viet Dai,
• Nguyen Ngoc Tri,
• Luc Van Meervelt,
• Nguyen Tien Trung and
• Wim Dehaen

Beilstein J. Org. Chem. 2022, 18, 1140–1153, doi:10.3762/bjoc.18.118

• subunit. View of the molecular structure of compound 10aa with atom labeling. Displacement ellipsoids are drawn at the 30% probability level. The intramolecular hydrogen bond N15–H15···O13 is shown as dashed line. The PES of reaction for the synthesis of 1,4,5-trisubstituted pyrrolidine-2,3-dione 10ab

Electrochemical vicinal oxyazidation of α-arylvinyl acetates

• Yi-Lun Li,
• Zhaojiang Shi,
• Tao Shen and
• Ke-Yin Ye

Beilstein J. Org. Chem. 2022, 18, 1026–1031, doi:10.3762/bjoc.18.103

• , entries 4 and 5). Note that the yield decreased without the addition of water suggesting water may facilitate the formation of the azidoketone (Table 1, entry 6). Interestingly, the H218O labeling experiment confirmed that there was no 18O incorporation in the obtained α-azidoketone (2, for details see

• water to form the desired product E. According to our 18O labeling experiment, the oxygen source of the newly installed carbonyl group probably originates from the vinyl acetate, not from H2O. Conclusion In summary, we have developed an environmentally friendly and efficient electrochemical oxyazidation

Isolation and biosynthesis of daturamycins from Streptomyces sp. KIB-H1544

• Yin Chen,
• Jinqiu Ren,
• Ruimin Yang,
• Jie Li,
• Sheng-Xiong Huang and
• Yijun Yan

Beilstein J. Org. Chem. 2022, 18, 1009–1016, doi:10.3762/bjoc.18.101

• since the 1960s [15][16]. Stable-isotope labeling experiments confirmed that ʟ-tyrosine or ʟ-phenylalanine are involved in the biosynthesis of p-terphenyl as metabolic origin. The precursors undergoing deamination are converted to the corresponding α-keto acid, then a quinone intermediate arises by

Menadione: a platform and a target to valuable compounds synthesis

• Acácio S. de Souza,
• Ruan Carlos B. Ribeiro,
• Dora C. S. Costa,
• Fernanda P. Pauli,
• David R. Pinho,
• Matheus G. de Moraes,
• Fernando de C. da Silva,
• Luana da S. M. Forezi and
• Vitor F. Ferreira

Beilstein J. Org. Chem. 2022, 18, 381–419, doi:10.3762/bjoc.18.43

• reaction mechanisms: free radical autoxidation, cation radical autoxidation, and thermal intersystem crossing (ISC), using 18O2 labeling, spin-trapping, spectroscopic, mass spectrometric, kinetic, and computational techniques. After several experiments, the obtained results have demonstrated that the 2

Synthesis of novel [1,2,4]triazolo[1,5-b][1,2,4,5]tetrazines and investigation of their fungistatic activity

• Anna V. Korotina,
• Svetlana G. Tolshchina,
• Rashida I. Ishmetova,
• Natalya P. Evstigneeva,
• Natalya A. Gerasimova,
• Natalya V. Zilberberg,
• Nikolay V. Kungurov,
• Gennady L. Rusinov,
• Oleg N. Chupakhin and
• Valery N. Charushin

Beilstein J. Org. Chem. 2022, 18, 243–250, doi:10.3762/bjoc.18.29

• labeling proteins and visualizing cancer due to the ability of s-tetrazine to fast and biocompatible ligation with alkenes via the inverse electron demand Diels–Alder reactions [29][30][31]. At the same time, azolo-annulated 1,2,4,5-tetrazines remain to be a scarcely studied class of compounds, mainly due

Ready access to 7,8-dihydroindolo[2,3-d][1]benzazepine-6(5H)-one scaffold and analogues via early-stage Fischer ring-closure reaction

• Irina Kuznetcova,
• Felix Bacher,
• Daniel Vegh,
• Hsiang-Yu Chuang and
• Vladimir B. Arion

Beilstein J. Org. Chem. 2022, 18, 143–151, doi:10.3762/bjoc.18.15

• interchanged. However, to our delight only the formation of the desired species 1a occurred, as evidenced by two-dimensional NMR measurements (for atom labeling scheme used for assignment of resonances see Figure S1 in Supporting Information File 1) and confirmed by SC-XRD (Figure 2), being in agreement with

Iron-catalyzed domino coupling reactions of π-systems

• Austin Pounder and
• William Tam

Beilstein J. Org. Chem. 2021, 17, 2848–2893, doi:10.3762/bjoc.17.196

• of the scope of the reaction, substrates bearing an electron-rich functionality were less reactive than substrates with electron-deficient groups. Isotopic labeling revealed the oxygen functionality installed came from the peroxide initiator rather than the water present, suggesting the water plays

Exfoliated black phosphorous-mediated CuAAC chemistry for organic and macromolecular synthesis under white LED and near-IR irradiation

• Azra Kocaarslan,
• Zafer Eroglu,
• Önder Metin and
• Yusuf Yagci

Beilstein J. Org. Chem. 2021, 17, 2477–2487, doi:10.3762/bjoc.17.164

• has set a milestone as a new and effective method for the synthesis of macromolecules [11]. Initiation of this reaction photocatalytically provides many advantages for the synthetic methodologies including bioconjugation, labeling, surface functionalization, dendrimer synthesis, polymer synthesis, and

Synthesis of O⁶-alkylated preQ₁ derivatives

• Laurin Flemmich,
• Sarah Moreno and
• Ronald Micura

Beilstein J. Org. Chem. 2021, 17, 2295–2301, doi:10.3762/bjoc.17.147

• cofactor for methyl group transfer resulting in cytosine methylation. This recently discovered riboswitch-ribozyme activity opens new avenues for the development of RNA labeling tools based on tailored O6-alkylated preQ1 derivatives. Here, we report a robust synthesis for this class of pyrrolo[2,3-d

• solved by a hydration reaction sequence on a well-soluble dimethoxytritylated precursor via in situ oxime formation. The synthetic path now provides a solid foundation to access O6-alkylated 7-aminomethyl-7-deazaguanines for the development of RNA labeling tools based on the preQ1 class-I riboswitch

• (preQ1) [1]. Thus far, present-day riboswitches have only been known to bind – but not to be able to react – with their ligands [2][3]. This new finding now opens exciting avenues for the development of RNA labeling tools [4], in particular, for RNA methylation, and more generally, for RNA alkylation. To

On the application of 3d metals for C–H activation toward bioactive compounds: The key step for the synthesis of silver bullets

• Renato L. Carvalho,
• Amanda S. de Miranda,
• Mateus P. Nunes,
• Roberto S. Gomes,
• Guilherme A. M. Jardim and
• Eufrânio N. da Silva Júnior

Beilstein J. Org. Chem. 2021, 17, 1849–1938, doi:10.3762/bjoc.17.126

Sustainable manganese catalysis for late-stage C–H functionalization of bioactive structural motifs

• Jongwoo Son

Beilstein J. Org. Chem. 2021, 17, 1733–1751, doi:10.3762/bjoc.17.122

• , fluorinations, allylations, alkynylations, alkenylations, and fluorescent labeling with BODIPY. Moreover, manganese catalysis exhibits excellent functional group tolerance in late-stage C–H functionalization, indicating a robust and versatile catalytic system. Several challenges still remain since there are

Chemical approaches to discover the full potential of peptide nucleic acids in biomedical applications

• Nikita Brodyagin,
• Martins Katkevics,
• Venubabu Kotikam,
• Christopher A. Ryan and
• Eriks Rozners

Beilstein J. Org. Chem. 2021, 17, 1641–1688, doi:10.3762/bjoc.17.116

Methodologies for the synthesis of quaternary carbon centers via hydroalkylation of unactivated olefins: twenty years of advances

• Thiago S. Silva and
• Fernando Coelho

Beilstein J. Org. Chem. 2021, 17, 1565–1590, doi:10.3762/bjoc.17.112

• -substituted β-diketones 2a and 2b (61 and 70% yield, respectively). Notably, the unsaturated carbocycles expected from palladium β-hydride elimination were not observed, indicating that an oxidant was not required in the reaction medium to regenerate the Pd(II) species. Later, deuterium-labeling experiments

A straightforward conversion of 1,4-quinones into polycyclic pyrazoles via [3 + 2]-cycloaddition with fluorinated nitrile imines

• Greta Utecht-Jarzyńska,
• Karolina Nagła,
• Grzegorz Mlostoń,
• Heinz Heimgartner,
• Marcin Palusiak and
• Marcin Jasiński

Beilstein J. Org. Chem. 2021, 17, 1509–1517, doi:10.3762/bjoc.17.108

• of 3-trifluoromethylpyrazole derivative 9d. The labeling scheme of the asymmetric unit is shown. Anisotropic displacement parameters of nonhydrogen atoms are drawn as ellipsoids with a 50% probability level. N atoms in blue, O atoms in red, C atoms in grey, H atoms as small white spheres. Structure

Icilio Guareschi and his amazing “1897 reaction”

• Gian Cesare Tron,
• Alberto Minassi,
• Giovanni Sorba,
• Mara Fausone and
• Giovanni Appendino

Beilstein J. Org. Chem. 2021, 17, 1335–1351, doi:10.3762/bjoc.17.93

• irreversible one-electron oxidation at 0.80 V, in accordance with the involvement of oxygen in the reaction. Remarkably, when the glutarimide was labeled with deuterium in position 3, the deuterium labeling was transferred to the hydrocarbon liberated in the reaction, showing that hydrogen abstraction was

Synthesis of (Z)-3-[amino(phenyl)methylidene]-1,3-dihydro-2H-indol-2-ones using an Eschenmoser coupling reaction

• Lukáš Marek,
• Lukáš Kolman,
• Jiří Váňa,
• Jan Svoboda and
• Jiří Hanusek

Beilstein J. Org. Chem. 2021, 17, 527–539, doi:10.3762/bjoc.17.47

• of 3-bromooxindoles with thiobenzamides. The Eschenmoser coupling reaction of 3-bromooxindole (1a) with thioacetamides. The synthesis of alternative 3-substituted oxindoles and their Eschenmoser coupling reaction with thiobenzamide (2a). A survey and labeling of synthesized 3-[amino(phenyl

Identification of volatiles from six marine Celeribacter strains

• Anuj Kumar Chhalodia,
• Jan Rinkel,
• Dorota Konvalinkova,
• Jörn Petersen and
• Jeroen S. Dickschat

Beilstein J. Org. Chem. 2021, 17, 420–430, doi:10.3762/bjoc.17.38

• interaction. Isotopic labeling experiments demonstrated that also in laboratory cultures roseobacter group bacteria efficiently degrade DMSP into sulfur volatiles [22][23], but also from other sulfur sources including 2,3-dihydroxypropane-1-sulfonic acid (DHPS, Scheme 1C) labeling was efficiently incorporated

• identical to (E)-42. Feeding experiments with isotopically labeled precursors The biosynthesis of sulfur volatiles in C. marinus was investigated in a series of feeding experiments with isotopically labeled precursors. Feeding of (methyl-2H3)methionine resulted in the efficient incorporation of labeling

• incorporation of labeling into two or three of the sulfur atoms in 41 (Figure 3D; also here the signal at m/z = 213 represents inseparable unlabeled 41). In this experiment, the base peak did not change which allowed the localization of labeling specifically in the MeS group of 41. The fact that no