Intermediates and shunt products of massiliachelin biosynthesis in Massilia sp. NR 4-1

• Till Steinmetz,
• Blaise Kimbadi Lombe and
• Markus Nett

Beilstein J. Org. Chem. 2023, 19, 909–917, doi:10.3762/bjoc.19.69

• -6 to 155.4 ppm (C-1) and 119.8 ppm (C-2) as well as from H-4 to 142.3 ppm (C-3) and 119.8 ppm (C-2). The upfield shifted resonance of H-6 suggested an electron-donating substituent at C-1 and the chemical shift of the latter (δC 155.4 ppm) supported the assignment of an hydroxy function in this

• substituent at C-2 of the phenol moiety. The final carbon atom at 171.9 ppm (C-15) could be attributed to a carboxylic acid function with HMBC correlations from H-13 and H-14, thereby completing the determination of the planar structure of 1. To determine the configuration of 1, we measured its optical

• ) and a proton resonance at δH 3.73 ppm (H-16). Both H-16 and H-14 show HMBC correlations to the carbonyl C-15. It can therefore be concluded that a methyl ester function replaced the carboxylic acid function of compound 1. Measurements of the optical rotation of 2 were not possible due to the low

Synthesis of aliphatic nitriles from cyclobutanone oxime mediated by sulfuryl fluoride (SO₂F₂)

• Xian-Lin Chen and
• Hua-Li Qin

Beilstein J. Org. Chem. 2023, 19, 901–908, doi:10.3762/bjoc.19.68

• interaction between the drug candidate and the target protein, to further improve the efficacy of the potential drug [9]. The nitrile group can also function as a metabolic blocking site to inhibit the oxidative metabolism of molecules to improve metabolic stability in vivo [10]. Consequently, the development

Light-responsive rotaxane-based materials: inducing motion in the solid state

• Adrian Saura-Sanmartin

Beilstein J. Org. Chem. 2023, 19, 873–880, doi:10.3762/bjoc.19.64

• different materials [11]. Towards biocompatible applications [71], the use of visible light irradiation as input which leads to the desired function is a necessary requirement. In this scenario, the incorporation of photosensitizer motifs is a suitable strategy to allow such a performance. Towards this

Photocatalytic sequential C–H functionalization expediting acetoxymalonylation of imidazo heterocycles

• Deepak Singh,
• Shyamal Pramanik and
• Soumitra Maity

Beilstein J. Org. Chem. 2023, 19, 666–673, doi:10.3762/bjoc.19.48

• conversion into ZnBr2 (confirmed by HRMS). These in situ-generated free acetate ions function as a base, deprotonating carbocation III to produce the intermediate IV and AcOH. The first step of cycle-2 involves the oxidation of the excited photocatalyst by aerial oxygen to generate superoxide anion and PC

pH-Responsive fluorescent supramolecular nanoparticles based on tetraphenylethylene-labelled chitosan and a six-fold carboxylated tribenzotriquinacene

• Nan Yang,
• Yi-Yan Zhu,
• Wei-Xiu Lin,
• Yi-Long Lu and
• Wen-Rong Xu

Beilstein J. Org. Chem. 2023, 19, 635–645, doi:10.3762/bjoc.19.45

• %] = 35 μg/mL). (a, c, e) Optical transmittance and (b, d, f) transmittance as a function of [TBTQ-C6] at 293 nm of (a, b) CS-TPE-2% (10 μg/mL), (c, d) CS-TPE-10% (10 μg/mL), and (e, f) CS-TPE-20% (10 μg/mL) with varying concentrations of TBTQ-C6 (0–0.30 mM) and in aqueous solution at pH 5.3. (a, c, e

C3-Alkylation of furfural derivatives by continuous flow homogeneous catalysis

• Grédy Kiala Kinkutu,
• Catherine Louis,
• Myriam Roy,
• Juliette Blanchard and
• Julie Oble

Beilstein J. Org. Chem. 2023, 19, 582–592, doi:10.3762/bjoc.19.43

• changing the redox state of the aldehyde function, we have developed a number of directed Ru(0)-catalyzed C3-functionalizations of furfurylimines, such as alkylation [21], arylation [22], alkenylation [23] and acylation [24], as well as an Ir-catalyzed directed C3-silylation (Scheme 1a) [25]. These batch

Phenanthridine–pyrene conjugates as fluorescent probes for DNA/RNA and an inactive mutant of dipeptidyl peptidase enzyme

• Josipa Matić,
• Tana Tandarić,
• Marijana Radić Stojković,
• Filip Šupljika,
• Zrinka Karačić,
• Ana Tomašić Paić,
• Lucija Horvat,
• Robert Vianello and
• Lidija-Marija Tumir

Beilstein J. Org. Chem. 2023, 19, 550–565, doi:10.3762/bjoc.19.40

• as a function of temperature. The absorbance scale was normalized. Tm values were the midpoints of the transition curves determined from the maximum of the first derivative and checked graphically by the tangent method. The ΔTm values were calculated subtracting Tm of the free nucleic acid from Tm of

Computational studies of Brønsted acid-catalyzed transannular cycloadditions of cycloalkenone hydrazones

• Manuel Pedrón,
• Jana Sendra,
• Irene Ginés,
• Tomás Tejero,
• Jose L. Vicario and
• Pedro Merino

Beilstein J. Org. Chem. 2023, 19, 477–486, doi:10.3762/bjoc.19.37

• by the tethers, the entropy effects caused by them has also been studied. The analysis of the evolution of the electron localization function along the reaction revealed the highly concerted character of the reaction. Keywords: DFT; distortion model; hydrazones; transannular cycloadditions

• also carried out an analysis of the electron localization function (ELF) [31][32] and the charge transfer along the reaction coordinate to determine the different stages and the polarity of the reaction. Results and Discussion The enantioselective intermolecular cycloaddition between hydrazones and

• we found, in both cases, values lower than 0.4, typical for nonpolar processes. To assess the concertedness of the reaction we carried out an analysis of the electron localization function (ELF) [31][32]. The ELF analysis applied to an IRC represents the evolution of the electron density (electron

Recommendations for performing measurements of apparent equilibrium constants of enzyme-catalyzed reactions and for reporting the results of these measurements

• Robert N. Goldberg,
• Robert T. Giessmann,
• Peter J. Halling,
• Carsten Kettner and
• Hans V. Westerhoff

Beilstein J. Org. Chem. 2023, 19, 303–316, doi:10.3762/bjoc.19.26

• activity coefficient γ, which is a function of the ionic strength and temperature. The transformed molar Gibbs energy of a biochemical reaction ΔrG′ also equals 0 at equilibrium and the standard transformed molar Gibbs energy change ΔrG′° = −RTlogeK′, where K′ is written in terms of the ratio of the

• laboratory determinations of mass. Thus, if one uses molality based values of K when calculating the value of a standard molar enthalpy of reaction ΔrH° from values of K as a function of temperature T, one avoids the need for a correction due to the temperature dependence of the density of the solvent

• equilibrium measurements on enzyme-catalyzed reactions are now described. Method 1: As a function of time, measure the approach to equilibrium from opposite directions of reaction, i.e., measure QF (forward direction) and QR (reverse direction). If the enzyme loses activity before the reaction reaches

Strategies to access the [5-8] bicyclic core encountered in the sesquiterpene, diterpene and sesterterpene series

• Cécile Alleman,
• Charlène Gadais,
• Laurent Legentil and
• François-Hugues Porée

Beilstein J. Org. Chem. 2023, 19, 245–281, doi:10.3762/bjoc.19.23

• commercial cyclopentenone 69. Protection of the alcohol function was mandatory prior to the cyclization as the free alcohol substrate failed to cyclize. As proposed by the authors, interaction between the free alcohol 70 and the molybdenum metal center may explain the reaction inhibition. Thus, after

• protection of the alcohol function as a silyl ether leading to diene 71, the RCM was performed in refluxing hexane and dactylol (72) was isolated in 17% overall yield after silyl ether removal [18][37]. Asteriscanolide (2), isolated in 1985 from the hexane extract of the plant Astericus aquaticus, is a

• in α-position to the keto function. This terminal double bond prefigures the late RCM cyclization. trans-Hydrindanone 87 was isolated as a single diastereomer and possesses 5 out of the 10 stereogenic centers of nitidasin (93). In parallel, (−)-citronellene (88) was converted into derivative 89

Total synthesis of insect sex pheromones: recent improvements based on iron-mediated cross-coupling chemistry

• Eric Gayon,
• Guillaume Lefèvre,
• Olivier Guerret,
• Adrien Tintar and
• Pablo Chourreu

Beilstein J. Org. Chem. 2023, 19, 158–166, doi:10.3762/bjoc.19.15

• functionality indeed affords the terminal oxidized function of the pheromone molecule (alkoxy acetate in 2 or 3, Scheme 4a and 4b, or formyl group in 1, Scheme 4c). As a representative target, we developed the total synthesis of the codling moth sex pheromone, (8E,10E)-dodecadien-1-ol (4), featuring the

1,4-Dithianes: attractive C2-building blocks for the synthesis of complex molecular architectures

• Bram Ryckaert,
• Ellen Demeyere,
• Frederick Degroote,
• Hilde Janssens and
• Johan M. Winne

Beilstein J. Org. Chem. 2023, 19, 115–132, doi:10.3762/bjoc.19.12

• rapid build-up of target molecules (see Scheme 1a) [7]. Once the important skeletal carbon–carbon bonds have been formed around the thioketal carbon, the sulfur-heterocycle can perform its primary function as a temporary protecting group and be chemoselectively hydrolyzed to afford a carbonyl functional

Preparation of β-cyclodextrin/polysaccharide foams using saponin

• Max Petitjean and
• José Ramón Isasi

Beilstein J. Org. Chem. 2023, 19, 78–88, doi:10.3762/bjoc.19.7

• ]. Saponins, because of their amphiphilic nature, are known as natural surfactants [9]. They have been used as natural detergents, foaming agents, stabilizers, emulsifiers and wetting agents, for example [10]. The micelles produced will be different in size and shape as a function of the type of saponin

• show the sorption isotherms at low solute concentrations. The c-LBG 20Pow matrix sorption behaviour was fitted following the Hill function, but this model does not represent well the absorption process in the low concentration region. For c-XG and c-CS, a wider 1-N concentration range where saponins

• simple hydrogel scaffold for the sorption of 1-naphthol. An aqueous sorbate mixture of five phenolic compounds has been also tested to assess the differences in the sorption behaviours of the different matrices. The absorbed amount changes as a function of the cyclodextrin/polysaccharide ratio, and the

NaI/PPh₃-catalyzed visible-light-mediated decarboxylative radical cascade cyclization of N-arylacrylamides for the efficient synthesis of quaternary oxindoles

• Dan Liu,
• Yue Zhao and
• Frederic W. Patureau

Beilstein J. Org. Chem. 2023, 19, 57–65, doi:10.3762/bjoc.19.5

• ethers and N-heteroarenes by using a novel catalytic system based on sodium iodide (NaI) and triphenylphosphine (PPh3), suggested to function as an electron donor–acceptor (EDA) complex [55][56][57][58][59][60]. Compared to previously reported radical reactions, this novel catalytic system has the key

Combining the best of both worlds: radical-based divergent total synthesis

• Kyriaki Gennaiou,
• Antonios Kelesidis,
• Maria Kourgiantaki and
• Alexandros L. Zografos

Beilstein J. Org. Chem. 2023, 19, 1–26, doi:10.3762/bjoc.19.1

• libraries. But how big should this chemical space be, so as to actually address our needs? A general consensus has emerged, supporting that “it is not actually the library size but rather the library diversity in terms of molecular structure and function which is fundamental for a successful drug discovery

• further oxidized, and thus producing the respective benzylic cation. Intramolecular cyclization in the cationic position under participation of the methyl ester function provided the core for (+)-grandilodine C (191) and (+)-lapidilectine B (192), while allylation of the benzylic position allowed

Synthetic study toward tridachiapyrone B

• Morgan Cormier,
• Florian Hernvann and
• Michaël De Paolis

Beilstein J. Org. Chem. 2022, 18, 1741–1748, doi:10.3762/bjoc.18.183

• deprotonation of 2-(α’-methoxy-γ-pyrone)-1,3-dithiane. The resulting vinylogous enolate intermediate was trapped with the electrophile 3, amounting to the one-pot preparation of compound 4, having a masked carbonyl function connecting both key fragments [27][28]. Isolated and characterized by Schmitz [17], the

Navigating and expanding the roadmap of natural product genome mining tools

• Friederike Biermann,
• Sebastian L. Wenski and
• Eric J. N. Helfrich

Beilstein J. Org. Chem. 2022, 18, 1656–1671, doi:10.3762/bjoc.18.178

• sequences that are conserved across different types of enzymes and that have a specific function) are used to identify RiPP BGCs beyond family borders as they are present in the BGCs of approximately 50% of all RiPP families [35]. BGCs without conserved signature sequences are almost impossible to identify

• gene annotations representing the different genomes are aligned to compare the genomes not on a sequence level, but instead on the gene-function level [86]. Whole genome alignments are performed to detect single diverging gene loci that are subsequently expanded by their genomic neighborhood to detect

A new route for the synthesis of 1-deazaguanine and 1-deazahypoxanthine

• Raphael Bereiter,
• Marco Oberlechner and
• Ronald Micura

Beilstein J. Org. Chem. 2022, 18, 1617–1624, doi:10.3762/bjoc.18.172

• -, and 7-deazapurine mutations of RNA have been fundamental to shed light on their structure, catalysis, and function [13][14][15]. However, difficulties in these fields arise from the lack of efficient synthetic protocols for various deaza-nucleosides and nucleobases. This is particularly true for the

New triazole-substituted triterpene derivatives exhibiting anti-RSV activity: synthesis, biological evaluation, and molecular modeling

• Elenilson F. da Silva,
• Krist Helen Antunes Fernandes,
• Denise Diedrich,
• Jessica Gotardi,
• Marcia Silvana Freire Franco,
• Carlos Henrique Tomich de Paula da Silva,
• Ana Paula Duarte de Souza and
• Simone Cristina Baggio Gnoatto

Beilstein J. Org. Chem. 2022, 18, 1524–1531, doi:10.3762/bjoc.18.161

• ) acids (Figure 1) have demonstrated various antiviral activities, such as by HIV protease inhibition (IC50 = 8 and 9 μM) [22]. In addition, compound 1 has demonstrated some anti-SARS-CoV activity (EC50 = 10 μM; SI = >10) by having an inhibitory effect on the 3CL protease function [21][23]. Moreover

Supramolecular approaches to mediate chemical reactivity

• Pablo Ballester,
• Qi-Qiang Wang and
• Carmine Gaeta

Beilstein J. Org. Chem. 2022, 18, 1463–1465, doi:10.3762/bjoc.18.152

• Molecular Sciences, CAS Key Laboratory of Molecular Recognition and Function, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China University of Chinese Academy of Sciences, Beijing 100049, China Dipartimento di Chimica e Biologia “A. Zambelli”, Università di Salerno, I-84084 Fisciano

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

• analyze the function of TadA, we introduced tadA into the quadruple auxotrophic host Aspergillus oryzae NSAR1 (niaD−, sC−, ∆argB, adeA−) (Supporting Information 1, Tables S1 and S2) [26], which has been widely used for biosynthesis of fungi-derived natural products due to its genetic tractability [27

Preparation of an advanced intermediate for the synthesis of leustroducsins and phoslactomycins by heterocycloaddition

• Anaïs Rousseau,
• Guillaume Vincent and
• Cyrille Kouklovsky

Beilstein J. Org. Chem. 2022, 18, 1385–1395, doi:10.3762/bjoc.18.143

• both fragments for the synthesis of an advanced intermediate. The synthetic strategy for the synthesis of the central fragment takes advantage of the proximity between the terminal amino function and the hydroxy function at C9. It was anticipated that both functions could arise from the cleavage of a N

• have therefore completed a quick, efficient and selective access to the central core of leustroducsins/phoslactomycins using an asymmetric nitroso Diels–Alder reaction. This fragment displays a ketone function that will be used for coupling with the lactone fragment 3 by generation of the tertiary

• coupling revealed the incompatibility of the lactone function; therefore, it was reduced with DIBAL-H then transformed into 19 by a one pot acetalization–desilylation procedure (91:9 mixture of diastereomers) [17]. Hydrozirconation followed by treatment with iodine furnished the target vinyl iodide 20

Synthesis of C6-modified mannose 1-phosphates and evaluation of derived sugar nucleotides against GDP-mannose dehydrogenase

• Sanaz Ahmadipour,
• Alice J. C. Wahart,
• Jonathan P. Dolan,
• Laura Beswick,
• Chris S. Hawes,
• Robert A. Field and
• Gavin J. Miller

Beilstein J. Org. Chem. 2022, 18, 1379–1384, doi:10.3762/bjoc.18.142

• unknown; b) previously disclosed C6–Me and C6–amido structure-to-function tools for GMD; c) C6-modified GDP-Mans of type 8 and 9, targeted in this work. Structure of 16 with ADPs rendered at the 50% probability level. Acetyl group disorder is omitted for clarity. Atom colour scheme: carbon = black, oxygen

• = red, phosphorus = purple, chlorine = green, hydrogen = pink. C6–Cl is the gg rotamer (from the Cl6–C6–C5–O5 torsion angle). GMD function with probe 19 over 120 min (GMD (100 µg/mL), GDP sugars (50 µM), NAD+ (200 µM)). Dotted trace dictates expected fluorescence output following spiking with GDP-Man 1

On drug discovery against infectious diseases and academic medicinal chemistry contributions

• Yves L. Janin

Beilstein J. Org. Chem. 2022, 18, 1355–1378, doi:10.3762/bjoc.18.141

• chances of being identified in the course of screenings. In 2004, the Molecular Library Initiative sponsored by the NIH also tried to address such issues and provide probes to determine the function and therapeutic potential of all the human genes. Aside from considerations on the selectivity and drug

• for simplified analogues, hopefully retaining the function of the biologically active compound, is very relevant when considering its potential in medicinal chemistry [279][280][281]. Start from leads obtained from previous research A second research direction for chemists is to start from previously

• consider the much less studied novobiocin (62) depicted in Figure 10. This compound is another naturally occurring antibiotic which was isolated in 1955 [311]. It turned out to be the first inhibitor of the bacterial ATP-ase function of gyrases found and it was actually instrumental in the discovery of

Cyclodextrin-based Schiff base pro-fragrances: Synthesis and release studies

• Attila Palágyi,
• Jindřich Jindřich,
• Juraj Dian and
• Sophie Fourmentin

Beilstein J. Org. Chem. 2022, 18, 1346–1354, doi:10.3762/bjoc.18.140

• – cinnamaldehyde, cyclamen aldehyde, lilial, benzaldehyde, anisaldehyde, vanillin, hexanal, heptanal, citral, and 5-methylfurfural. Subsequently, the rate of release of the volatile compound from selected pro-fragrances, as a function of the environment (solvent, pH), was studied by 1H NMR spectroscopy (for

• influence of adding hygroscopic salts (MgSO4, LiClO4, or Ca(ClO4)2), triethyl orthoformate, or activated molecular sieves to the reaction. These compounds could function as desiccants removing the water formed during the reaction, as well as catalysts; nevertheless, the conversion to the final imine needed

• dissolution of the pro-fragrance, which influenced the equilibrium between dissociation and formation reactions. The integrals of the imine group signal at 8.30 ppm measured at various time intervals were depicted as a function of time for all the samples with pH from 3 to 12.8. Data were fitted by a