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

• the complete structural determination of 3. To overcome this challenge in structural determination, we obtained a single crystal of 3 and performed X-ray diffraction analysis, which unambiguously established the structure of 3 as 5′-desmethylpreterretonin A (Figure 2C and Figure S1 in Supporting

• -5′ desmethyl form of the product from the K187A variant of AdrI, which was created during the in-depth functional analysis of terpene cyclases involved in DMOA-derived meroterpenoid biosynthesis [21], through NMR and single-crystal X-ray crystallographic analyses (Figure 2C and Figure S1 in

• . Finally, the A. oryzae strain expressing insA7 produced two major metabolites 7 and 8. Compound 7 was determined to be the C-5′ desmethyl form of insuetusin A1 [19] using NMR and single-crystal X-ray diffraction analyses (Figure 2C and Figure S1 in Supporting Information File 1; CCDC: 2300695) and was

A laterally-fused N-heterocyclic carbene framework from polysubstituted aminoimidazo[5,1-b]oxazol-6-ium salts

• Andrew D. Gillie,
• Matthew G. Wakeling,
• Bethan L. Greene,
• Louise Male and
• Paul W. Davies

Beilstein J. Org. Chem. 2024, 20, 621–627, doi:10.3762/bjoc.20.54

• the C(oxazole)–N(sulfonamide) bond. No coalescence is observed at up to 110 °C indicating that these motifs might be useful as a robust atropisomeric system. The molecular structure of 13 and 14 have been unambiguously determined by single crystal X-ray diffraction (Scheme 2) [28]. The N–metal

• complexes from 6a. The single crystal X-ray diffraction structures of 13 and 14 have ellipsoids drawn at 50% probability, with hydrogens and solvent omitted for clarity. Selected bond angles and distances: 13: C1–Au: 1.98 Å, Au–Cl: 2.28 Å, N2–Au: 3.65 Å. N1–C1–N3: 102.7°, N3–C1–Au: 129.5°, N1–C1–Au: 127.1

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

• mutagenesis of key enzymes, including terpene cyclases and α-ketoglutarate (αKG)-dependent dioxygenases, that contribute to the structural diversity. Notable progress in genome sequencing has led to the discovery of many novel genes encoding these enzymes, while continued efforts in X-ray crystallographic

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

• of compound 4b has been confirmed by single crystal X-ray data. The next step was to investigate the possibility of obtaining six-membered oxygen-containing spiroheterocycles by interaction of DAS 1 with 2-(bromomethyl)benzyl alcohol (15) (Scheme 6). The synthesis was carried out under the conditions

• . These data are provided free of charge by the joint Cambridge Crystallographic Data Centre and Fachinformationszentrum Karlsruhe Access Structures service https://www.ccdc.cam.ac.uk/structures. Supporting Information File 30: General experimental information, X-ray crystallographic data, synthetic

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

• products 3a–c were comprehensively characterized by IR, 1Н and 13C NMR spectroscopy, HRMS (Supporting Information File 2) as well as by X-ray diffraction analysis. The molecular structure of 3b is shown in Figure 3. The crystal data, details of the data collection and refinements for 3b as well as complete

• , HRMS and X-ray diffraction analysis. Selectively, Fe2+ caused an appearance of new broad long-wavelength absorption bands at 480−530 nm with a contrast naked-eye effect: a visually distinguishable color change of the solutions from yellow to dark orange. The obtained complexes with Fe2+ in acetonitrile

• ™ Impact instrument (electrospray ionization). Melting points were determined on a Fisher–Johns melting point apparatus. X-ray diffraction study The X-ray diffraction dataset of compound 3b was recorded on an Agilent SuperNova diffractometer using a microfocus X-ray radiation source with copper anode and

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

• lead structure with ample space for structural variations. By formally replacing one pyridine moiety of 1,8-naphthyridine 4 by a five-membered thiazole unit, we have identified thiazolo[4,5-b]pyridine 5 as a strong inhibitor of acyl-ACP thioesterase, which has further been confirmed via an X-ray co

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

• doublets at 107 and 69 ppm, with J = 275.5 Hz, and a singlet at 70.5 ppm (Figure 4c) [42]. In all attempts to prepare bisphos 7a, the singlet and set of doublets were observed, and always in the same approximate ratio. X-ray crystallographic analysis shows C2 rotational symmetry and confirms the identity

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

• and mass spectrometric data. X-ray crystallographic analysis confirmed and established the structures and absolute configurations of compounds 1–3, thus providing the first characterized crystal structure of an ovalicin-type sesquiterpenoid. In the antimicrobial assays, compounds 1–3 showed broad

• compound 1, crystals suitable for X-ray crystal analysis were obtained by slow evaporation of the solvent, which could be analyzed by X-ray diffraction analysis using Cu Kα radiation (Figure 4). The resulting Flack parameter, 0.019(6), allowed the assignment of the absolute configurations of all the

• verified by the COSY and HMBC correlations (Figure 2). The structure and relative configuration of compound 2 were deduced the same as for 1 by NOE correlations (Figure 3). Moreover, the absolute configurations of compound 2 were unambiguous determined by X-ray diffraction with the refined Flack parameter

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

• % isolated yield (Scheme 2) and the structure was confirmed by NMR spectroscopy and X-ray crystallography (Figure 1). To expand the substrate scope of this difluorination method, a range of DBM derivatives 1b–n was synthesized from para-substituted acetophenones, para-substituted benzoyl chlorides and

• . Again, purification by column chromatography gave the products 3 as white crystalline solids and the structures of compounds 3f and 3i were confirmed by X-ray crystallography (Figure 2 and Supporting Information File 1). Molecules 3a, f, and i all exist in the solid state with the dicarbonyl moiety

• submission numbers: 2288841–2288848. Supporting Information File 2: Experimental procedures, characterization data, and copies of 1H, 19F and 13C{1H} NMR spectra. Acknowledgements We thank Dr Dmitry S. Yufit for conducting X-ray crystallographic studies. Parts of this work have already been published in

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

• photophysical and electrochemical analyses and DFT calculations. Therefore, this CT is most likely the origin of the increased Ka value. We also discuss the charged double-layer structure, as determined by X-ray crystallographic analysis. Results and Discussion The size-complementary interaction between CPP2

• observations also agree well with the change in oxidation and reduction potentials upon complex formation observed in the electrochemical analysis. The double-layered structure of the complex was unambiguously determined by single-crystal X-ray analysis (Figure 7), which was performed on a crystal obtained by

• sp2 carbon of [10]CPP within 0.30 nm. HOMO−1, HOMO, LUMO, and LUMO+1 orbitals of [10]CPP⊃[5]CPP2+ (1), [5]CPP2+, and [10]CPP. X-ray crystal structure of [10]CPP⊃[5]CPP2+[B(C6F5)4]2. a) Side and b) top views of ORTEP drawings. The thermal ellipsoids are scaled at the 50% probability level. All hydrogen

Facile approach to N,O,S-heteropentacycles via condensation of sterically crowded 3H-phenoxazin-3-one with ortho-substituted anilines

• Eugeny Ivakhnenko,
• Vasily Malay,
• Pavel Knyazev,
• Nikita Merezhko,
• Nadezhda Makarova,
• Oleg Demidov,
• Gennady Borodkin,
• Andrey Starikov and
• Vladimir Minkin

Beilstein J. Org. Chem. 2024, 20, 336–345, doi:10.3762/bjoc.20.34

• short-term heating of the melted reactants at 220–250 °C is described, and the compounds were characterized by means of single-crystal X-ray crystallography, NMR, UV–vis, and IR spectroscopy, as well as cyclic voltammetry. The reaction with o-amino-, o-hydroxy-, and o-mercapto-substituted arylamines

• by X-ray crystallography and are shown in Figure 2 (i.e., 4f) and Figures S1 and S2, Supporting Information File 1 (i.e., 4c,d). The geometry of the phenoxazine-3-one fragment of 4c,d,f coincides with that found for 6,8-di-tert-butyl-3H-phenoxazin-3-one (1) [6]. A strong hydrogen bridge, N(15)–H···O

• molecular structure of 5c was also determined using X-ray crystallography (Figure 4). We assumed that the scope of the reaction shown in Scheme 3 could be expanded via replacement of one of the amino groups of o-phenylenediamine by another strong nucleophilic center. It was earlier found [23] that

Spatial arrangements of cyclodextrin host–guest complexes in solution studied by ¹³C NMR and molecular modelling

• Konstantin Lebedinskiy,
• Ivan Barvík,
• Zdeněk Tošner,
• Ivana Císařová,
• Jindřich Jindřich and
• Radim Hrdina

Beilstein J. Org. Chem. 2024, 20, 331–335, doi:10.3762/bjoc.20.33

• modelling and solid-state X-ray analysis, provides a detailed description of the spatial arrangement of cyclodextrin host–guest complexes in solution. The chiral cavity of the cyclodextrin molecule creates an anisotropic environment for the guest molecule resulting in a splitting of its prochiral carbon

• calorimetry [13]. Single crystals for many host–guest complexes have been prepared, and their structure elucidated by X-ray crystallography [14][15]. Conformations of host–guest complexes in solution have been studied by 2D NMR experiments [11] (NOESY, ROESY) or proposed computationally [16][17] based on

• -cyclodextrins. Compounds 1, 6 and 8 are commercial, compounds 2–5 [21] and 7 [22] were prepared according to published procedures. Compound 2 (as a free amine) crystallized in the supramolecular capsule of two α-cyclodextrins, and the mono-crystal was subjected to X-ray analysis. This experiment was performed

Elucidating the glycan-binding specificity and structure of Cucumis melo agglutinin, a new R-type lectin

• Jon Lundstrøm,
• Emilie Gillon,
• Valérie Chazalet,
• Nicole Kerekes,
• Antonio Di Maio,
• Ten Feizi,
• Yan Liu,
• Annabelle Varrot and
• Daniel Bojar

Beilstein J. Org. Chem. 2024, 20, 306–320, doi:10.3762/bjoc.20.31

• confirmed and quantified this binding specificity in solution. Finally, we solved the high-resolution structure of the CMA1 N-terminal domain using X-ray crystallography, supporting our functional findings at the molecular level. Our study provides a comprehensive understanding of CMA1, laying the

• experiments, thermal shift assays, and high-resolution X-ray crystallography not only confirms its classification as a functional R-type lectin but also provides a deep dive into its unique glycan-binding profile and high-resolution 3D structure. Overall, we present a deeply characterized new lectin with a

• no binding to unsubstituted galactose, we rather hypothesized the existence of specific interactions made with the C2-substituents, that did not exist in other R-type lectins such as RCA1. To determine this, we set out to resolve the detailed three-dimensional structure of CMA1 via X-ray

Synthesis of π-conjugated polycyclic compounds by late-stage extrusion of chalcogen fragments

• Aissam Okba,
• Pablo Simón Marqués,
• Kyohei Matsuo,
• Naoki Aratani,
• Hiroko Yamada,
• Gwénaël Rapenne and
• Claire Kammerer

Beilstein J. Org. Chem. 2024, 20, 287–305, doi:10.3762/bjoc.20.30

• , were synthesized as direct soluble precursors of PBIs 6a,b, along with the corresponding oxides, namely sulfoxides 4a,b and sulfone 5 (Scheme 4). An X-ray crystal structure of the extended thiepine 3b confirmed its bent structure, with a protrusion of the sulfur atom out of the π-surface (Figure 1). As

• hydride resulted in the formation of the oxepine ring by a double substitution reaction, to yield the desired dinaphthooxepine 33. The non-planar character of dinaphthooxepine bisimides was confirmed by X-ray crystal structure, and stability towards thermal or photoactivation was also established. Cyclic

• ) and side view (b) of the X-ray crystal structure of thiepine 3b showing its bent conformation. Thermal ellipsoids are shown at the 50% probability level, and all hydrogen atoms as well as propyl groups on imide substituents have been omitted for clarity. Reprinted with permission from [57]. Copyright

Synthesis of spiropyridazine-benzosultams by the [4 + 2] annulation reaction of 3-substituted benzoisothiazole 1,1-dioxides with 1,2-diaza-1,3-dienes

• Wenqing Hao,
• Long Wang,
• Jinlei Zhang,
• Dawei Teng and
• Guorui Cao

Beilstein J. Org. Chem. 2024, 20, 280–286, doi:10.3762/bjoc.20.29

• investigated the performance of other organic and inorganic bases, but they did not improve the yield (Table 1, entries 8–12). The structure of spiropyridazine-benzosultam 3aa was determined by 1H NMR, 13C NMR, HRMS analysis and single-crystal X-ray crystallography [33]. Further experiments conducted with

• spiropyridazine-benzosultams. The electronic effects of substituents and the influence of steric hindrance on the reaction were explored. The configuration of the product was determined by X-ray single crystal diffraction. This method has the advantages of mild reaction conditions, wide substrate scope, and high

Substitution reactions in the acenaphthene analog of quino[7,8-h]quinoline and an unusual synthesis of the corresponding acenaphthylenes by tele-elimination

• Ekaterina V. Kolupaeva,
• Narek A. Dzhangiryan,
• Alexander F. Pozharskii,
• Oleg P. Demidov and
• Valery A. Ozeryanskii

Beilstein J. Org. Chem. 2024, 20, 243–253, doi:10.3762/bjoc.20.24

• in a 2:1 ratio leads to the formation of co-crystals, in which, as judged by the X-ray data, the supramolecular organization is again in action (Figure 4). Two molecules of the base are almost parallel to each other (the distance between the π-systems of two molecular planes is 3.551 Å with the

Photochromic derivatives of indigo: historical overview of development, challenges and applications

• Gökhan Kaplan,
• Zeynel Seferoğlu and
• Daria V. Berdnikova

Beilstein J. Org. Chem. 2024, 20, 228–242, doi:10.3762/bjoc.20.23

• melting point of indigo is bifurcated intra- and intermolecular hydrogen bonding [11], and face-to-face π–π stacking of parallel aromatic rings (Figure 2) [12]. Single crystal X-ray diffraction analysis showed that the indigo molecule is almost planar and exists in the E-conformation. The central C=C bond

• used in the synthesis of indigo [4]. a) Intramolecular (a = 2.26 Å) and intermolecular (b = 2.11 Å) hydrogen bonds in indigo, b) crystal packing of indigo in the solid state obtained from the single-crystal X-ray diffraction data, CCDC 796873 [12], c) photos of indigo in the solid state and solutions

• of indigo in 1) DMSO, 2) DMF, 3) N-methyl-2-pyrrolidone. Bond length in the indigo molecule obtained from the single crystal X-ray analysis [12], the typical bond lengths in organic compounds [15] and the main resonance structures of indigo. The structure of the indigo chromophore (H-chromophore

Comparison of glycosyl donors: a supramer approach

• Anna V. Orlova,
• Nelly N. Malysheva,
• Maria V. Panova,
• Nikita M. Podvalnyy,
• Michael G. Medvedev and
• Leonid O. Kononov

Beilstein J. Org. Chem. 2024, 20, 181–192, doi:10.3762/bjoc.20.18

• treated with 90% aq trifluoroacetic acid in CH2Cl2 to give diol 7 (70% yield) that was formed due to migration of a chloroacetyl group from O-7 to O-9. The structure of diol 7 was established by NMR spectroscopy, high-resolution mass spectrometry and X-ray diffraction analysis (see the Experimental

• NMR (282 MHz, acetone-d6, δ, ppm) −77.1; HRESIMS (m/z): [M + Na]+ calcd for C22H24Cl2F3NNaO10S, 644.0342; found, 644.0349 . For the details of the single crystal X-ray analysis data for compound 7 (CCDC 1843708) see Supporting Information File 1 and Supporting Information File 2. Typical glycosylation

• sialylation reaction. TFA = CF3CO; ClAc = ClCH2CO. Synthesis of sialyl donor 2. SR values and types of supramers in solutions of sialyl donors 1 and 2 at different concentrations. Supporting Information Supporting Information File 3: Copies of NMR spectra for all new compounds, single crystal X-ray analysis

Tandem Hock and Friedel–Crafts reactions allowing an expedient synthesis of a cyclolignan-type scaffold

• Viktoria A. Ikonnikova,
• Cristina Cheibas,
• Oscar Gayraud,
• Alexandra E. Bosnidou,
• Nicolas Casaretto,
• Gilles Frison and
• Bastien Nay

Beilstein J. Org. Chem. 2024, 20, 162–169, doi:10.3762/bjoc.20.15

• ortho-methoxy substituents as previously observed by others [22][23], and demonstrating the high rotational barrier constraining the aryl substituent. This structure was unambiguously confirmed by X-ray crystallographic analysis (Figure 1). During this work we have been intrigued by the possible direct

• -donor substituents, while highly electron-deficient substituents (CN, NO2) precluded the cyclization. Overall, this sequence led to valuable 1-aryltetralines structurally related to medicinally relevant cyclolignan natural products. X-ray crystallographic structure of product 6 (CCDC 2301977). The

Perspectives on push–pull chromophores derived from click-type [2 + 2] cycloaddition–retroelectrocyclization reactions of electron-rich alkynes and electron-deficient alkenes

• Michio Yamada

Beilstein J. Org. Chem. 2024, 20, 125–154, doi:10.3762/bjoc.20.13

• successfully characterized through single-crystal X-ray crystallography. A mechanistic investigation of the [2 + 2] CA–RE reactions involving DCV compounds was undertaken by Diederich et al. in 2010 [77]. Their investigation unveiled that the reaction between 1 and arylated DCV derivatives followed second

• determined the absolute configurations of these atropisomers through the X-ray crystallographic analyses of (Sa)-59 and (Ra)-60. Surprisingly, heating the enantiomers of 69 and 60 at 80 °C for 3 h resulted in negligible thermally induced racemization. Meanwhile, in O2-free toluene solution under illumination

Visible-light-induced radical cascade cyclization: a catalyst-free synthetic approach to trifluoromethylated heterocycles

• Chuan Yang,
• Wei Shi,
• Jian Tian,
• Lin Guo,
• Yating Zhao and
• Wujiong Xia

Beilstein J. Org. Chem. 2024, 20, 118–124, doi:10.3762/bjoc.20.12

• indole ring (3m and 3n) furnished the products in moderate yields. The structure of compound 3m (4-Br) was confirmed by X-ray single crystal diffraction (CCDC: 2304916). Reactions of substrates with a longer carbon chain and a branched chain also proceeded well and afforded the products in 43% (3o) and

• Supporting Information Supporting Information File 35: Characterization data and copies of spectra. Supporting Information File 36: Crystallographic information file (cif) of X-ray structure for compound 3m. Funding We are grateful for the financial support from the Science and Technology Plan of Shenzhen

Electron-beam-promoted fullerene dimerization in nanotubes: insights from DFT computations

• Laura Abella,
• Gerard Novell-Leruth,
• Josep M. Ricart,
• Josep M. Poblet and
• Antonio Rodríguez-Fortea

Beilstein J. Org. Chem. 2024, 20, 92–100, doi:10.3762/bjoc.20.10

• with irreversible C–C fusions [7]. In phase 1, a [2 + 2] cycloadduct C120 dimer is formed, which was initially proposed to be with Cs symmetry, in contrast to the X-ray structure for the C120 dimer that shows D2h symmetry [3][9]. In phase 2, irreversible structural rearrangements occur leading to a

• in the latter (Figure 1). Dimer 1-Cs is at our computational settings (PBE/PW), more than 15 kcal mol−1 higher in energy than dimer 1-D2h, the one characterized by X-ray crystallography in the solid state, both in the gas phase and inside the CNT. Similar lower stabilities for dimer 1-Cs are also

Multi-redox indenofluorene chromophores incorporating dithiafulvene donor and ene/enediyne acceptor units

• Christina Schøttler,
• Kasper Lund-Rasmussen,
• Line Broløs,
• Philip Vinterberg,
• Ema Bazikova,
• Viktor B. R. Pedersen and
• Mogens Brøndsted Nielsen

Beilstein J. Org. Chem. 2024, 20, 59–73, doi:10.3762/bjoc.20.8

• containing acetylenic acceptor motifs at both ends of the IF core and hence no DTF donor unit. Compound 23 also undergoes a reversible, second reduction to form the dianion. This compound should gain aromaticity upon either reduction or oxidation as illustrated in Figure 9. X-ray crystallographic analysis

• Crystals suitable for single-crystal X-ray diffraction studies were obtained for compounds 25, 26, and 29. Their structures are shown in Figure 10, top, and their respective crystal packings below. All three compounds pack in a herringbone manner in the crystal structure, with the major difference that

• after the experiment. A 0.1 M solution of NBu4PF6 was used as electrolyte. All solutions were purged with Ar prior to measurements. Crystallography All single crystal X-ray diffraction data for compounds 25, 26, and 29 were collected on a Bruker D8 VENTURE diffractometer equipped with a Mo Kα X-ray (λ

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

• molecules were determined by single-crystal X-ray crystallography. The bonding situation in the solid state together with NMR data suggests an important contribution of an ylidic resonance structure in these molecules. The phosphonium phenolates are characterized by UV–vis absorptions peaking around 360 nm

• product of interest 2a. Compound 2a was identified by a combination of NMR spectroscopic methods and single-crystal X-ray structure analysis (vide infra) as the zwitterionic phospha-Michael adduct of 1 and acrylonitrile, formally stabilized by proton transfer from the phenol group to the initially formed

• in these cases (Supporting Information File 1, Figures S54 and S74). Crystal structures The solid-state structures of 2a and 2f were determined by single-crystal X-ray diffraction. The crystals were grown from concentrated solutions in toluene. A representation of the molecular structure of 2a is

Cycloaddition reactions of heterocyclic azides with 2-cyanoacetamidines as a new route to C,N-diheteroarylcarbamidines

• Pavel S. Silaichev,
• Tetyana V. Beryozkina,
• Vsevolod V. Melekhin,
• Valeriy O. Filimonov,
• Andrey N. Maslivets,
• Vladimir G. Ilkin,
• Wim Dehaen and
• Vasiliy A. Bakulev

Beilstein J. Org. Chem. 2024, 20, 17–24, doi:10.3762/bjoc.20.3

• effect on the yield of the final compounds 3 observed. The structures of compounds 3a–u were confirmed by IR, 1H and 13C NMR spectroscopy (Figures S1‒S44 in Supporting Information File 1) as well as by high-resolution mass spectrometry (HRMS). X-ray data obtained for compound 3g gave us final proof of

• , 174.5; IR (ATR, KBr, cm−1): ν 3400, 3359, 3255, 1625, 1602, 1563, 1554, 1508, 1495, 1483, 1455, 1436, 1425, 1402, 1385, 1356, 1332, 1319, 1303, 1283, 1257, 1215, 1151, 1095, 1067, 1053, 1035, 1011; HRMS–ESI-TOF (m/z): [M + H]+ calcd for C13H14N7S+, 300.1026; found, 300.1031. X-ray structure

• (sigma) = 0.0978) which were used in all calculations. The final R1 was 0.0693 (I > 2σ(I)) and wR2 was 0.1849 (all data). The refined twin ratio was 0.6748(18):0.3252(18). The experiment was accomplished on the automated X-ray diffractometer «Xcalibur Ruby» with CCD detector following standard procedures