Sulfur-containing spiroketals from Breynia disticha and evaluations of their anti-inflammatory effect

• Ken-ichi Nakashima,
• Naohito Abe,
• Masayoshi Oyama,
• Hiroko Murata and
• Makoto Inoue

Beilstein J. Org. Chem. 2023, 19, 1604–1614, doi:10.3762/bjoc.19.117

• disticha. The structures of compounds 1–7 were elucidated by extensive 1D and 2D NMR spectroscopic analyses, including 1D total correlation spectroscopy (TOCSY), HSQC, HMBC, double quantum-filtered (DQF)-COSY, heteronuclear two-bond correlation (H2BC), and HSQC-TOCSY experiments, as well as high-resolution

• ) in 1D and 2D ROE spectroscopy (ROESY) suggested that the relative configuration of the aglycone in 1 is identical to that in breynin B (6). The remaining NMR resonances (Table 2) were attributed to a tetrasaccharide based on the observation of four anomeric methine signals at δC 103.2 (C-1′), 104.5

• (C-1′′), 103.3 (C-1′′′), and 111.9 (C-1′′′′). Because the complex overlap of the glycosyl group signals complicated the HSQC, HMBC, and DQF-COSY analyses, 1D total correlation spectroscopy (TOCSY), HSQC-TOCSY, and heteronuclear two-bond correlation (H2BC) experiments were also performed (Figure 2

Cyclodextrins permeabilize DPPC liposome membranes: a focus on cholesterol content, cyclodextrin type, and concentration

• Ghenwa Nasr,
• Hélène Greige-Gerges,
• Sophie Fourmentin,
• Abdelhamid Elaissari and
• Nathalie Khreich

Beilstein J. Org. Chem. 2023, 19, 1570–1579, doi:10.3762/bjoc.19.115

• formulation, a solution containing only liposomes was used as the blank solution. The membrane permeability study by fluorescence spectroscopy The membrane permeability is commonly evaluated by following the leakage of self-quenching probes such as SRB from liposomes [14]. Indeed, a fluorescence auto

Secondary metabolites of Diaporthe cameroonensis, isolated from the Cameroonian medicinal plant Trema guineensis

• Bel Youssouf G. Mountessou,
• Élodie Gisèle M. Anoumedem,
• Blondelle M. Kemkuignou,
• Yasmina Marin-Felix,
• Frank Surup,
• Marc Stadler and
• Simeon F. Kouam

Beilstein J. Org. Chem. 2023, 19, 1555–1561, doi:10.3762/bjoc.19.112

• polyketide 1, and an acetylated alternariol 2 were isolated, along with fifteen known secondary metabolites. Their structures were established by extensive NMR spectroscopy and mass spectrometry analyses, as well as by comparison with literature data of their analogs. Keywords: alternariol; Diaporthe

Morpholine-mediated defluorinative cycloaddition of gem-difluoroalkenes and organic azides

• Tzu-Yu Huang,
• Mario Djugovski,
• Sweta Adhikari,
• Destinee L. Manning and
• Sudeshna Roy

Beilstein J. Org. Chem. 2023, 19, 1545–1554, doi:10.3762/bjoc.19.111

• 19F NMR spectroscopy to monitor the consumption of the gem-difluoro starting material 1, which was completely consumed within 16 h (Figure 3). However, a 48 h time course gave a superior yield (Table 1, entry 13 vs entry 20). We hypothesize this might be due to the volatile nature of the gem

• . Additionally, 30% of the aniline byproduct was also isolated, which explains the modest yields of this reaction and the sluggish nature. To investigate the mechanism of the current transformation, we conducted a series of experiments including a time course of the reaction using 19F NMR spectroscopy (Figure 3

• Equiv of CuSO4 was used as an additive. bModified reaction conditions for benzyl azides: 1 (1 equiv), 2 (1.5 equiv) 0.4 equiv of LiHMDS (1 M in THF), morpholine (0.34–0.4 M), 110 °C, 72 h. Time course profile monitored by 19F NMR spectroscopy. NOESY of 4e confirming the regiochemistry of the product

Complexes of resorcin[4]arene with secondary amines: synthesis, solvent influence on “in-out” structure, and theoretical calculations of non-covalent interactions

• Waldemar Iwanek

Beilstein J. Org. Chem. 2023, 19, 1525–1536, doi:10.3762/bjoc.19.109

• , these compounds are capable of forming complexes with small organic molecules. The current paper focuses on the synthesis of complexes between R[4]A and secondary aliphatic amines (sec-amines). Through NMR spectroscopy, it was observed that “in-out” complexes are formed depending on the solvent. It was

• amine, and the type of complex formed is influenced by the nature and polarity of the solvent. The stoichiometry and solvent-dependent structure of the “in-out” complexes formed were determined through NMR spectroscopy. Screening tests were carried out using the aISS-xTB2 method, while the final

Cyclization of 1-aryl-4,4,4-trichlorobut-2-en-1-ones into 3-trichloromethylindan-1-ones in triflic acid

• Vladislav A. Sokolov,
• Andrei A. Golushko,
• Irina A. Boyarskaya and
• Aleksander V. Vasilyev

Beilstein J. Org. Chem. 2023, 19, 1460–1470, doi:10.3762/bjoc.19.105

• , the O-protonated forms ArC(=OH+)CH=CHCCl3, which are then cyclized into the target CCl3-indanones. These cations have been studied experimentally by means of NMR spectroscopy in TfOH and theoretically by DFT calculations. Under the same superacidic conditions in TfOH, CCl3-hydroxy ketones (1-aryl

• , we initiated this study on transformations of 1-aryl-4,4,4-trichlorobut-2-en-1-ones under superelectrophilic activation conditions (Scheme 1b). The main goals of this work were the investigation of the protonation of CCl3-enones (1-aryl-4,4,4-trichlorobut-2-en-1-ones) by NMR spectroscopy and DFT

• of enones 2a,e,n with an excess (5 equiv) of AlBr3 or AlCl3 in CH2Cl2 solution at room temperature for 3 days afforded complex mixtures of compounds. Then, the protonation of compounds 1 and 2 in TfOH was investigated by means of NMR spectroscopy. According to the 1H, 13C, and 19F NMR data, hydroxy

Functions of enzyme domains in 2-methylisoborneol biosynthesis and enzymatic synthesis of non-natural analogs

• Binbin Gu,
• Lin-Fu Liang and
• Jeroen S. Dickschat

Beilstein J. Org. Chem. 2023, 19, 1452–1459, doi:10.3762/bjoc.19.104

• isolated and structurally characterised through NMR spectroscopy (Supporting Information File 1, Table S2, Figures S4–S11) as compound 2 (Scheme 2A), a homolog of the 2MIBS side product 2-methylenebornane (6) (Scheme 2C). Analogously, the preparative scale conversion of DA-5 and IA-1 with FPPS and 2MIBS

Application of N-heterocyclic carbene–Cu(I) complexes as catalysts in organic synthesis: a review

• Nosheen Beig,
• Varsha Goyal and
• Raj K. Bansal

Beilstein J. Org. Chem. 2023, 19, 1408–1442, doi:10.3762/bjoc.19.102

• allow to synthesize acylboron compounds [54]. As mentioned earlier, Oro and co-workers [39] used 5 mol % of complex 78a (Scheme 27) for the homogeneous hydrosilylation of acetophenone with HSiEt3 in the presence of KOt-Bu. As indicated by 1H NMR spectroscopy, the conversion was complete in 18 h

Functional characterisation of twelve terpene synthases from actinobacteria

• Anuj K. Chhalodia,
• Houchao Xu,
• Georges B. Tabekoueng,
• Binbin Gu,
• Kizerbo A. Taizoumbe,
• Lukas Lauterbach and
• Jeroen S. Dickschat

Beilstein J. Org. Chem. 2023, 19, 1386–1398, doi:10.3762/bjoc.19.100

• structures were elucidated by NMR spectroscopy, resulting in the discovery of the first terpene synthases for (+)-δ-cadinol and (+)-α-cadinene, besides the first two bacterial (−)-amorpha-4,11-diene synthases. For other terpene synthases with functions reported from bacteria before the products were

• ; biosynthesis; enzymes; NMR spectroscopy; terpenes; Introduction Terpene synthases are remarkable enzymes that can convert acyclic and achiral oligoprenyl pyrophosphates into terpene hydrocarbons or alcohols of high structural complexity. These enzymatic reactions are initiated by ionisation of the substrate

• accepted. A preparative scale incubation of FPP (80 mg, 185 μmol) allowed for the isolation of 10 (5.5 mg, 25 μmol, 14%) for structure elucidation through NMR spectroscopy (Table S2, Figures S3–S10, Supporting Information File 1), confirming the structure of δ-cadinol. The optical rotation of [α]D25

Consecutive four-component synthesis of trisubstituted 3-iodoindoles by an alkynylation–cyclization–iodination–alkylation sequence

• Nadia Ledermann,
• Alae-Eddine Moubsit and
• Thomas J. J. Müller

Beilstein J. Org. Chem. 2023, 19, 1379–1385, doi:10.3762/bjoc.19.99

• compounds 5 in yields between 11–69% after chromatographic workup. The structures of the products were unambiguously confirmed by 1H and 13C NMR spectroscopy, as well as by mass spectrometry. Assuming that four new bonds are being formed in this one-pot process, the range of yield from 11 to 69% (after

• -trisubstitued indoles 8 in good yield (Scheme 4). The 1,2,3-trisubstitued indoles 8 were unambiguously confirmed by 1H and 13C NMR spectroscopy, as well as by mass spectrometry and elemental analysis. Miura et al. could show that 1-alkyl-2,3-diarylindoles constitute a class of blue-emissive indole derivatives

Organic thermally activated delayed fluorescence material with strained benzoguanidine donor

• Alexander C. Brannan,
• Elvie F. P. Beaumont,
• Nguyen Le Phuoc,
• George F. S. Whitehead,
• Mikko Linnolahti and
• Alexander S. Romanov

Beilstein J. Org. Chem. 2023, 19, 1289–1298, doi:10.3762/bjoc.19.95

• , and 1H/13C NMR spectroscopy. Proton NMR shows a complicated set of overlapping multiplets indicating that the reaction results in the formation of various isomers (rotamers) which are different by relative orientation of the benzoguanidine donor moieties with respect to each other (Figure 2, see

Selective construction of dispiro[indoline-3,2'-quinoline-3',3''-indoline] and dispiro[indoline-3,2'-pyrrole-3',3''-indoline] via three-component reaction

• Ziying Xiao,
• Fengshun Xu,
• Jing Sun and
• Chao-Guo Yan

Beilstein J. Org. Chem. 2023, 19, 1234–1242, doi:10.3762/bjoc.19.91

• structures of the obtained dispiro compounds 3a–m were fully characterized by IR, HRMS, 1H and 13C NMR spectroscopy. Because of the three chiral carbon atoms in the product, several diastereomers might be formed in the reaction. However, TLC monitoring and 1H NMR spectra of the crude products clearly

Unravelling a trichloroacetic acid-catalyzed cascade access to benzo[f]chromeno[2,3-h]quinoxalinoporphyrins

• Chandra Sekhar Tekuri,
• Pargat Singh and
• Mahendra Nath

Beilstein J. Org. Chem. 2023, 19, 1216–1224, doi:10.3762/bjoc.19.89

• spectroscopy. The preliminary photophysical results revealed a significant red-shift in their absorption and emission spectra as compared to the meso-tetrakis(4-methylphenyl)porphyrins due to the extended π-conjugation. Keywords: bathochromic shift; benzo[f]chromeno[2,3-h]quinoxalinoporphyrins; catalysis

• aldehydes and dimedone in chloroform at 65 °C. The optical properties of the newly prepared porphyrins have been investigated by using UV–vis and emission spectroscopy and the results are presented in this paper. Results and Discussion Synthesis The required precursors, copper(II) 2,3-diamino-5,10,15,20

Enabling artificial photosynthesis systems with molecular recycling: A review of photo- and electrochemical methods for regenerating organic sacrificial electron donors

• Grace A. Lowe

Beilstein J. Org. Chem. 2023, 19, 1198–1215, doi:10.3762/bjoc.19.88

• excited state. Hence, Stern–Volmer plots derived from quenching measurements and photosensitizer excited-state lifetimes measured by transient spectroscopy are crucial to understanding and optimizing the system as a whole [18]. Recently, Kientz et al. demonstrated that the dark regeneration of oxidatively

• catalysts in an acetonitrile/water mixture [46]. They used combinations of deuterated solvents and 1H NMR spectroscopy to confirm that water was the main source of the protons for the regeneration. Furthermore, they successfully replaced ruthenium photosensitizers with organic dyes so that the system used

Cyanothioacetamides as a synthetic platform for the synthesis of aminopyrazole derivatives

• Valeriy O. Filimonov,
• Alexandra I. Topchiy,
• Vladimir G. Ilkin,
• Tetyana V. Beryozkina and
• Vasiliy A. Bakulev

Beilstein J. Org. Chem. 2023, 19, 1191–1197, doi:10.3762/bjoc.19.87

• pyrazoles has been thus synthesized. The structure of the reaction products was studied using NMR spectroscopy and mass spectrometry and confirmed by X-ray diffraction analysis. Keywords: aminopyrazoles; 2-cyanothioacetamides; enamines; hydrazines; Introduction Compounds containing a pyrazole cycle

• -diaminopyrazoles 4a–c (Scheme 2). The structures of compounds 4a–c were confirmed by 1H and 13C NMR spectroscopy data, as well as high-resolution mass spectrometry (HRMS). Compound 4a was previously obtained by another method [18]. The spectral characteristics of diaminopyrazole 4a reported in [18] correspond to

• group during the reaction. The structures of compounds 5a–e were confirmed by 1H and 13C NMR spectroscopy and HRMS, as well as X-ray diffraction analysis of a single crystal of compound 5b. The involvement of arylhydrazines 3b,c in the reaction with enamines 2a–d similarly leads to the formation of 1

Exploring the role of halogen bonding in iodonium ylides: insights into unexpected reactivity and reaction control

• Carlee A. Montgomery and
• Graham K. Murphy

Beilstein J. Org. Chem. 2023, 19, 1171–1190, doi:10.3762/bjoc.19.86

• have been evaluated extensively through both qualitative and quantitative means. Methods of evaluation have included X-ray crystallography and spectroscopy (e.g., microwave, IR, Raman, NMR, NQR), as well as through computational determination of their electrostatic VS,max potentials (Figure 2), their

Photoredox catalysis harvesting multiple photon or electrochemical energies

• Mattia Lepori,
• Simon Schmid and
• Joshua P. Barham

Beilstein J. Org. Chem. 2023, 19, 1055–1145, doi:10.3762/bjoc.19.81

• obtained by transient absorption spectroscopy with femtosecond pulsed laser excitation and were 2–3 orders of magnitude greater (e.g., keT (*PC1•−) = 6.8 × 1010 s−1) than the diffusion rate in DMSO (kdiff = 4.0 × 108 s−1 of 0.12 M 1d) confirming a preassociation of PC1•− and the substrate prior to PET

• reducing enough to engage the model substrate perfluorooctyl iodide and instead *[FeII(btz)3]2+ was verified as the key catalytic species by transient absorption spectroscopy; even though the strongly reducing α-amino alkyl radical intermediate might also engage in the reduction of alkyl halides or act as

Synthesis of imidazo[4,5-e][1,3]thiazino[2,3-c][1,2,4]triazines via a base-induced rearrangement of functionalized imidazo[4,5-e]thiazolo[2,3-c][1,2,4]triazines

• Dmitry B. Vinogradov,
• Alexei N. Izmest’ev,
• Angelina N. Kravchenko,
• Yuri A. Strelenko and
• Galina A. Gazieva

Beilstein J. Org. Chem. 2023, 19, 1047–1054, doi:10.3762/bjoc.19.80

• . However, we also detected by 1H NMR spectroscopy the formation of other minor products, presumably derivatives of a new heterocyclic system, imidazo[4,5-e][1,3]thiazino[2,3-c][1,2,4]triazines 5a,b (Scheme 2). To prepare the new compounds 5, the solvent, amount of KOH, reaction time, and temperature were

• with excess hydrochloric acid and further evaporation of the solvent at 40 °C led to decomposition products, two of which were isolated and characterized by NMR spectroscopy including 2D experiments and HRMS data. The target acids 5k,m were obtained using equivalent amounts of HCl at room temperature

• in the thiazine ring leads to the cleavage of the triazine C–N bond. Further proton transfer gives product 9. The structures of the synthesized compounds 3a,b,j and 5a–k,m were confirmed by IR, 1H and 13C NMR spectroscopy, and high-resolution mass spectrometry. the potassium salts 3c–i,k,m were

The effect of dark states on the intersystem crossing and thermally activated delayed fluorescence of naphthalimide-phenothiazine dyads

• Liyuan Cao,
• Xi Liu,
• Xue Zhang,
• Jianzhang Zhao,
• Fabiao Yu and
• Yan Wan

Beilstein J. Org. Chem. 2023, 19, 1028–1046, doi:10.3762/bjoc.19.79

• states. Femtosecond transient absorption spectroscopy (fs-TA) was rarely used for the study of the photophysics of the TADF emitters [12][34][35][36][37], since it suffers from the limitation of the time window of detection (up to a few ns). On the other hand, nanosecond transient absorption spectroscopy

• [38][39][40][41][42][43][44] and, more recently, time-resolved electron paramagnetic resonance (TREPR) spectroscopy [33][39][44][45][46] were also applied to study TADF mechanisms, but the examples are limited. Therefore, much room is left for studies of the photophysical mechanism of the TADF

• different aryl substituents, which contain both electron-donating and -withdrawing moieties. Although we reported NI-PTZ analogous dyads recently, they were not studied by fs-TA spectroscopy and the molecular structures are different from the current dyads [39][47]. The photophysical processes of the dyads

CO₂ complexation with cyclodextrins

• Cecilie Høgfeldt Jessen,
• Jesper Bendix,
• Theis Brock Nannestad,
• Heloisa Bordallo,
• Martin Jæger Pedersen,
• Christian Marcus Pedersen and
• Mikael Bols

Beilstein J. Org. Chem. 2023, 19, 1021–1027, doi:10.3762/bjoc.19.78

• get more information about the CO2 content in the crystal samples we also analyzed the crystals by thermogravimetric analysis. The crystal samples where heated to 26–200 °C at different rates and weight loss observed while the gas release was monitored by IR spectroscopy. Two distinguished weight

The unique reactivity of 5,6-unsubstituted 1,4-dihydropyridine in the Huisgen 1,4-diploar cycloaddition and formal [2 + 2] cycloaddition

• Xiu-Yu Chen,
• Hui Zheng,
• Ying Han,
• Jing Sun and
• Chao-Guo Yan

Beilstein J. Org. Chem. 2023, 19, 982–990, doi:10.3762/bjoc.19.73

• -dihydropyridines derived from the condensation of acetylacetone also afforded the expected product 4o in 65% yield. The chemical structures of the obtained isoquinoline[2,1-h][1,7]naphthyridines 4a–o were fully characterized by various spectroscopy methods and further confirmed by determination of the single

• structures of both bicyclic compounds 5a–o and 6a–o were fully characterized by various spectroscopy methods. The single crystal structures of compounds 5a (Figure 2) and 6f (Figure 3) were successfully determined by X-ray diffraction analysis. From Figure 2 (compound 5a), it can be seen that the

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

• correlation spectroscopy (COSY; Figure 3). The first spin system is part of a 2,3-substituted phenol moiety featuring proton signals at δH 7.15 (H-5), 6.70 (H-6) and 6.69 ppm (H-4; Table 1). Three aromatic carbon atoms could be assigned due to heteronuclear multiple bond correlation (HMBC) correlations from H

A fluorescent probe for detection of Hg²⁺ ions constructed by tetramethyl cucurbit[6]uril and 1,2-bis(4-pyridyl)ethene

• Xiaoqian Chen,
• Naqin Yang,
• Yue Ma,
• Xinan Yang and
• Peihua Ma

Beilstein J. Org. Chem. 2023, 19, 864–872, doi:10.3762/bjoc.19.63

• cucurbit[6]uril (TMeQ[6]) and 1,2-bis(4-pyridyl)ethene (G) were used to construct a supramolecular fluorescent probe G@TMeQ[6]. The host–guest interaction between TMeQ[6] and G was investigated using 1H NMR spectroscopy, single-crystal X-ray diffraction and various experimental techniques. The results show

• detection methods include atomic absorption spectroscopy, mass spectrometry, emission spectroscopy and electrochemical methods [4][5][6][7]. These detection methods are expensive and time-consuming, and the detection of samples becomes extremely difficult. Therefore, it is of great significance to construct

• detection of heavy metal ions. Results and Discussion The interactions of G with TMeQ[6] UV–vis spectroscopy analysis The binding interaction between G and TMeQ[6] in aqueous solution was studied using UV–vis absorption spectroscopy. Figure 2a shows that the absorbance of G decreases with the addition of

Synthesis of substituted 8H-benzo[h]pyrano[2,3-f]quinazolin-8-ones via photochemical 6π-electrocyclization of pyrimidines containing an allomaltol fragment

• Constantine V. Milyutin,
• Andrey N. Komogortsev,
• Boris V. Lichitsky,
• Mikhail E. Minyaev and
• Valeriya G. Melekhina

Beilstein J. Org. Chem. 2023, 19, 778–788, doi:10.3762/bjoc.19.58

• result, both products could be isolated and characterized using 1H, 13C NMR spectroscopy and mass spectrometry. Moreover, the structure of product 11a was also confirmed by single-crystal X-ray diffraction analysis. It might be noted that precipitated crystals of 11a contained two polymorph modifications

• 11g–j were confirmed by 1H, 13C NMR spectroscopy and high-resolution mass spectrometry. In the 1H NMR spectra of the products, characteristic singlets corresponding to the protons of the dihydropyranone fragment in the region δ 5.3–5.4 ppm and the protons of the hydroxy group in the region δ 5.4–5.5

Bromination of endo-7-norbornene derivatives revisited: failure of a computational NMR method in elucidating the configuration of an organic structure

• Demet Demirci Gültekin,
• Arif Daştan,
• Yavuz Taşkesenligil,
• Cavit Kazaz,
• Yunus Zorlu and
• Metin Balci

Beilstein J. Org. Chem. 2023, 19, 764–770, doi:10.3762/bjoc.19.56

• temperatures yielding mixtures of addition products. The structural elucidations of the formed compounds were achieved by NMR spectroscopy. Particularly, the γ-gauche effect and long-range couplings were instrumental in assigning the stereochemistry of the adducts. However, in a recent paper, Novitskiy and

• erroneous mechanistic pathway. Keywords: bromination; computational NMR; γ-gauche effect; NMR; NOE-Diff experiments; Introduction Nuclear magnetic resonance (NMR) spectroscopy is one of the most important analytical tools used to determine the structure of organic compounds. NMR not only confirms the