Cholyl 1,3,4-oxadiazole hybrid compounds: design, synthesis and antimicrobial assessment

• Anas J. Rasras,
• Mohamed El-Naggar,
• Nesreen A. Safwat and
• Raed A. Al-Qawasmeh

Beilstein J. Org. Chem. 2022, 18, 631–638, doi:10.3762/bjoc.18.63

• quaternary oxadiazole peaks appeared at around δ = 162.0 and 169.0 ppm. Compound 4f showed a carbonyl peak at δ = 196.7 ppm and for the carbaldehyde carbon in compound 4h a peak at δ = 160.8 ppm was observed. To further characterize the structures, 2D NMR experiments were done for compound 4p as example. The

A study of the photochemical behavior of terarylenes containing allomaltol and pyrazole fragments

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

Beilstein J. Org. Chem. 2022, 18, 588–596, doi:10.3762/bjoc.18.61

• communication we have described for the first time the phototransformation of the 3-hydroxypyran-4-one fragment with the isolation of the resulting substituted α-hydroxy-1,2-diketone in pure form. The structure of the obtained compound 14a was confirmed using 1H, 13C NMR spectroscopy as well as 2D NMR

• : Experimental procedures, characterization data of all products, copies of 1H, 13C, 2D NMR, HRMS spectra of all new compounds, and X-ray crystallographic data.

Terpenoids from Glechoma hederacea var. longituba and their biological activities

• Dong Hyun Kim,
• Song Lim Ham,
• Zahra Khan,
• Sun Yeou Kim,
• Sang Un Choi,
• Chung Sub Kim and
• Kang Ro Lee

Beilstein J. Org. Chem. 2022, 18, 555–566, doi:10.3762/bjoc.18.58

• structure elucidation was performed for the five new compounds (1–5) using 1D and 2D NMR, HRESIMS, DP4+ and ECD calculations, and chemical methods. All the isolates (1–9) were assessed for their antineuroinflammatory activities on nitric oxide (NO) production in lipopolysaccharide (LPS)-activated BV-2 cells

• compounds (1–5) were isolated and characterized from G. hederacea var. longituba (Figure 1). Structures of these compounds were established by 1D and 2D NMR and HRESIMS, comparison of experimental and calculated ECD data, DP4+ analysis, and hydrolysis. Herein, the isolation and structural elucidation of the

• of 2 were similar to those of substolide A except for signals of the methoxy group attached to C-8 and of a monosaccharide at C-6 in 2 [12]. The planar structure of 2 was established based on 2D NMR spectroscopic data (COSY, HSQC, and HMBC). The HMBC correlation from H-1' (δH 4.42) to C-6 (δC 76.6

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

• menadione (10) in trifluoroacetic acid under ethanol reflux conditions (Scheme 26) to synthesize acylhydrazones 81 in 63–91% yield. In view of the different structures that compounds 81a–e could adopt, after analysis by 2D NMR-NOESY spectra, it was found that all products were obtained as E-geometrical

Amamistatins isolated from Nocardia altamirensis

• Till Steinmetz,
• Wolf Hiller and
• Markus Nett

Beilstein J. Org. Chem. 2022, 18, 360–367, doi:10.3762/bjoc.18.40

• Abstract Four new phenolic siderophores were isolated from the actinomycete Nocardia altamirensis along with the known natural product amamistatin B and a putative biosynthetic shunt product. The structures of all compounds were elucidated through 1D and 2D NMR analyses as well as mass spectrometry. The

• the basis of 2D NMR data. In the HMBC spectrum, the singlet methyl protons H3-17 and H3-18 show correlations to C-7, a quaternary carbon at 47.4 ppm (C-8), and an oxymethine carbon at 80.3 ppm (C-9). COSY and HMBC data established the alkyl chain from CH-9 to CH3-16. A correlation between H-9 and C-19

• C35H53N5O7 by the [M + H]+ ion at m/z 656.4019 (calcd for C35H54N5O7, 656.4023). Analysis of 1D and 2D NMR spectra confirmed that the aldehyde group in position 25 is missing. Therefore, compound 3 represents the N-desformyl analogue of 1. Compound 4 (1.9 mg) was obtained as a reddish oil. Its molecular

Glycosylated coumarins, flavonoids, lignans and phenylpropanoids from Wikstroemia nutans and their biological activities

• Meifang Wu,
• Xiangdong Su,
• Yichuang Wu,
• Yuanjing Luo,
• Ying Guo and
• Yongbo Xue

Beilstein J. Org. Chem. 2022, 18, 200–207, doi:10.3762/bjoc.18.23

• including its absolute configuration was elucidated based on a combination of 1D and 2D NMR, UV, IR, HRESIMS spectroscopic data, as well as chemical transformation. Compounds 1–17 were first isolated from the plant species W. nutans, while compounds 1–3, 8, and 11 were reported from the genus Wikstroemia

• structures were established by extensive spectroscopic analyses, including 1D, 2D NMR spectroscopy, and HRESIMS. The relative and absolute structure of 1 was unambiguously determined based on ROESY experiments and chemical transformation. In the vitro bioassays, compounds 1–17 showed a mild inhibitory effect

• samples were scanned from 190 to 400 nm in 1 nm steps. IR spectra were obtained using a Tensor 27 spectrophotometer with KBr pellets. 1D and 2D NMR spectra were acquired on Bruker DRX-600 and DRX-800 spectrometers with TMS as internal standard. Chemical shifts (δ) were expressed in ppm with reference to

Tenacibactins K–M, cytotoxic siderophores from a coral-associated gliding bacterium of the genus Tenacibaculum

• Yasuhiro Igarashi,
• Yiwei Ge,
• Tao Zhou,
• Amit Raj Sharma,
• Enjuro Harunari,
• Naoya Oku and
• Agus Trianto

Beilstein J. Org. Chem. 2022, 18, 110–119, doi:10.3762/bjoc.18.12

• while only a single set experiment was possible for 2 due to its limited availability. Structures of tenacibactins K–M (1–3). Key 2D-NMR correlations for 1–3. (a) Partial 1H NMR spectra of 1 at 25 and 50 °C in DMSO-d6; (b) magnified HMBC spectrum of 1 at 25 °C in CDCl3/CD3OD 3:7. MS/MS spectrum of 1

Efficient and regioselective synthesis of dihydroxy-substituted 2-aminocyclooctane-1-carboxylic acid and its bicyclic derivatives

• İlknur Polat,
• Selçuk Eşsiz,
• Uğur Bozkaya and
• Emine Salamci

Beilstein J. Org. Chem. 2022, 18, 77–85, doi:10.3762/bjoc.18.7

• -functional theory (DFT) computations were used to explain the reaction mechanism for the ring opening of the epoxide and the formation of five-membered lactones. The stereochemistry of the synthesized compounds was determined by 1D and 2D NMR spectroscopy. The configuration of methyl 6-hydroxy-9-oxo-8

• expected product 9 failed. The product 8 was obtained as the major product in 80% yield, and the expected product 9 was formed as the minor product in 4% yield. We propose that diol isomer mixture 9 can be formed by solvolysis. The presence of the lactone ring in 8 was determined by 2D NMR spectroscopic

• . However, all attempts to isolate isomer mixture 11 failed. Again, we suggest that diol isomer mixture 11 can be formed by solvolysis. The presence of the lactone ring in 10 was determined by 2D NMR spectroscopic data (COSY and HMQC). The diagonal peak at 4.19 ppm has cross peaks with the protons

Isolation and characterization of new phenolic siderophores with antimicrobial properties from Pseudomonas sp. UIAU-6B

• Emmanuel T. Oluwabusola,
• Olusoji O. Adebisi,
• Fernando Reyes,
• Kojo S. Acquah,
• Mercedes De La Cruz,
• Larry L. Mweetwa,
• Joy E. Rajakulendran,
• Digby F. Warner,
• Deng Hai,
• Rainer Ebel and
• Marcel Jaspars

Beilstein J. Org. Chem. 2021, 17, 2390–2398, doi:10.3762/bjoc.17.156

• from the Oyun river in North Central Nigeria. The structure of the new compounds, pseudomonin A–C (1–3) and pseudomobactin A and B (4 and 5) isolated alongside two known compounds, pseudomonine (6) and salicylic acid (7), were elucidated based on high-resolution mass spectrometry, 1D and 2D NMR

• secondary metabolites 1–5 including pseudomonin A–C (1–3) and pseudomobactins A and B (4 and 5). The two known compounds, pseudomonine (6) and salicylic acid (7) were also isolated as the major constituents of the extracts and their structures were determined by analysis of HRESIMS, 1D and 2D NMR data (see

• that revealed a molecular ion at m/z 237.0874 (calcd for C11H13N2O4−, 237.0880). A thorough analysis of 1H and 2D NMR data (see Table 1 and Supporting Information File 1) showed four aromatic methines, two aliphatic methines, one methyl, and four quaternary carbons signals at δC 162.9 (C-1), 113.2 (C-6

Phenolic constituents from twigs of Aleurites fordii and their biological activities

• Kyoung Jin Park,
• Won Se Suh,
• Da Hye Yoon,
• Chung Sub Kim,
• Sun Yeou Kim and
• Kang Ro Lee

Beilstein J. Org. Chem. 2021, 17, 2329–2339, doi:10.3762/bjoc.17.151

• absolute configuration. The planar structure of 3 was further confirmed by analysis of 2D NMR data, including COSY, HSQC, and HMBC (Figure 2). The determination of the stereochemistry for the sugar unit of 3 was conducted following the same method as for compound 2. The structure of the aglycone 3a

• and 13C NMR spectral data of 15 and 16 in CD3OD. Effects of isolated compounds on NO production in LPS-activated BV-2 cells. Effects of isolated compounds on NGF secretion in C6 cells. Supporting Information Supporting Information File 260: Copies of NMR spectra including 1D and 2D NMR and HRMS data

A study on selective transformation of norbornadiene into fluorinated cyclopentane-fused isoxazolines

• Zsanett Benke,
• Attila M. Remete and
• Loránd Kiss

Beilstein J. Org. Chem. 2021, 17, 2051–2066, doi:10.3762/bjoc.17.132

• catalyst-dependent (Table 1). In the presence of HG-2, the main product was dicoupled (±)-8c accompanied by the unseparable mixture of monocoupled products (±)-8a and (±)-8b. Despite the partial signal overlap, 2D NMR analysis of the (±)-8a and (±)-8b mixture was possible, and the structure of both (±)-8a

Analogs of the carotane antibiotic fulvoferruginin from submerged cultures of a Thai Marasmius sp.

• Birthe Sandargo,
• Leon Kaysan,
• Rémy B. Teponno,
• Christian Richter,
• Benjarong Thongbai,
• Frank Surup and
• Marc Stadler

Beilstein J. Org. Chem. 2021, 17, 1385–1391, doi:10.3762/bjoc.17.97

• antibiotic fulvoferruginin (1), fulvoferruginins B–F (2–6). The structures of these sesquiterpenoids were elucidated using HRESIMS, 1D and 2D NMR, as well as CD spectroscopy. Assessing the bioactivity, fulvoferruginin emerged as a potent cytotoxic agent of potential pharmaceutical interest. Keywords

• due to two methylenes at δC 38.8 (C-8) and 39.2 (C-9); three methines at δC 46.4 (C-11), 58.4 (C-6), and 77.6 (C-7) as well as two quaternary carbons at δC 45.6 (C-8) and 82.8 (C-10). Correlating 1D data with 2D NMR experiments (1H,1H COSY, 1H,13C HMBC, 1H,1H ROESY, see Figure 2) led to an underlying

• isolated and identified as fulvoferruginin (1), utilizing HRESIMS and 1D/2D NMR experiments (see Table S3 in Supporting Information File 1). The methyl group C-14 of fulvoferruginin B (2) results in an additional stereocenter at C-11. The proton at C-11 (δH 2.72) exhibited 1H,1H ROESY correlations with H-5

Synthesis of multiply fluorinated N-acetyl-D-glucosamine and D-galactosamine analogs via the corresponding deoxyfluorinated glucosazide and galactosazide phenyl thioglycosides

• Vojtěch Hamala,
• Lucie Červenková Šťastná,
• Martin Kurfiřt,
• Petra Cuřínová,
• Martin Dračínský and
• Jindřich Karban

Beilstein J. Org. Chem. 2021, 17, 1086–1095, doi:10.3762/bjoc.17.85

• conversion and debenzylation. The values [Hz] of selected coupling constants. Boldfaced values illustrate the trends discussed in the text. Supporting Information Supporting Information File 89: Experimental procedures and spectral data. Supporting Information File 90: Copies of 1H, 13C, 19F, and 2D NMR

Stereoselective synthesis and transformation of pinane-based 2-amino-1,3-diols

• Ákos Bajtel,
• Mounir Raji,
• Matti Haukka,
• Ferenc Fülöp and
• Zsolt Szakonyi

Beilstein J. Org. Chem. 2021, 17, 983–990, doi:10.3762/bjoc.17.80

• 9 ring system (Scheme 1). The absolute configuration of compound 9 was determined by 2D NMR spectroscopic techniques. Clear NOE signals were observed between the H-7a and Me-10 as well as the Ha-9 and Me-10 protons. Beside NOESY experiments, the structure was also elucidated by X-ray crystallography

• configuration depicted in Scheme 2. Beside 2D NMR spectroscopic studies, the absolute configuration of compound 12 was determined by its transformation into the corresponding aminodiols 13 and 14, comparing the products with those obtained from the regioisomer 9 (discussed in Scheme 3). Synthesis and

• of the five components 15A–E were determined by 2D NMR spectroscopic techniques (NOESY and HMBC). Since this finding is quite unusual in the case of Schiff’ bases, we decided to study the ring/chain tautomeric mixture (15A–E) in the reaction of 13 with benzaldehyde by 1H NMR spectroscopy. When a time

Total synthesis of pyrrolo[2,3-c]quinoline alkaloid: trigonoine B

• Takashi Nishiyama,
• Erina Hamada,
• Daishi Ishii,
• Yuuto Kihara,
• Nanase Choshi,
• Natsumi Nakanishi,
• Mari Murakami,
• Kimiko Taninaka,
• Noriyuki Hatae and
• Tominari Choshi

Beilstein J. Org. Chem. 2021, 17, 730–736, doi:10.3762/bjoc.17.62

• structures of the compounds were elucidated through 1D and 2D NMR spectroscopy. It was determined that trigonoine A was a β-carboline alkaloid containing a 2,8-diazabicyclo[3.3.1]nonane ring system, while trigonoine B (1) was formed by a combination of 2,3-dihydroquinolin-4-one and 3H-pyrrolo[2,3-c]quinoline

Stereoselective syntheses of 3-aminocyclooctanetriols and halocyclooctanetriols

• Emine Salamci and
• Yunus Zozik

Beilstein J. Org. Chem. 2021, 17, 705–710, doi:10.3762/bjoc.17.59

• converted into the corresponding triacetate 11 with acetic anhydride in pyridine and 4-(dimethylamino)pyridine (DMAP) (yield 76%). To determine the exact configurations of the substituents in 11, we made full assignments for the H-3 and the acetoxy protons with the help of the 1D and 2D NMR experiments

• assigned using 1H NMR and 2D NMR spectroscopic data. The position of the chlorine atom in 25 was confirmed with the help of the COSY spectra. The diagonal peak at 4.26 ppm has cross peaks with the protons resonating at 2.15 and 5.62 ppm, respectively. Analysis of these cross peaks shows that the cross peak

• of chlorocyclooctanetriol 20. Synthesis of chlorocyclooctanetriols 23 and 24. Supporting Information Supporting Information File 234: Experimental section, 1H and 13C NMR spectra for all new compounds, as well as selected 2D NMR spectra. Acknowledgements We would like to thank Professor Cavit Kazaz

Unexpected rearrangements and a novel synthesis of 1,1-dichloro-1-alkenones from 1,1,1-trifluoroalkanones with aluminium trichloride

• Beatrice Lansbergen,
• Catherine S. Meister and
• Michael C. McLeod

Beilstein J. Org. Chem. 2021, 17, 404–409, doi:10.3762/bjoc.17.36

• ketone. When the 4-methoxy derivative 5n was treated with AlCl3 using our standard conditions, none of the expected 1,1-dichloroalkenone 6n was obtained. Instead, the acid chloride 13 was isolated in an excellent yield (Scheme 5). The structure of this product was elucidated using 2D-NMR experiments

Synthesis of legonmycins A and B, C(7a)-hydroxylated bacterial pyrrolizidines

• Wilfred J. M. Lewis,
• David M. Shaw and
• Jeremy Robertson

Beilstein J. Org. Chem. 2021, 17, 334–342, doi:10.3762/bjoc.17.31

• pxaAB gene cluster in E. coli, and analysis of the metabolites by differential 2D NMR spectroscopy, led to the isolation and characterization of pyrrolizixenamide A (9) and, subsequently, pyrrolizixenamides B–D (10–12). Ultimately, an analogous biosynthetic pathway to that proposed for the legonmycins

Regioselective chemoenzymatic syntheses of ferulate conjugates as chromogenic substrates for feruloyl esterases

• Olga Gherbovet,
• Fernando Ferreira,
• Apolline Clément,
• Mélanie Ragon,
• Julien Durand,
• Sophie Bozonnet,
• Michael J. O'Donohue and
• Régis Fauré

Beilstein J. Org. Chem. 2021, 17, 325–333, doi:10.3762/bjoc.17.30

• (t), doublet of doublets (dd), doublet of doublets of doublets (ddd), broad (br), and quadruplet of triplets (qt) as abbreviations. Analyses and assignments were made using 1D (1H, 13C, and J-modulated spin–echo (Jmod)) and 2D NMR experiments (COSY and HSQC). High-resolution mass spectrometry (HRMS

1,2,3-Triazoles as leaving groups in S_NAr–Arbuzov reactions: synthesis of C6-phosphonated purine derivatives

• Kārlis-Ēriks Kriķis,
• Irina Novosjolova,
• Anatoly Mishnev and
• Māris Turks

Beilstein J. Org. Chem. 2021, 17, 193–202, doi:10.3762/bjoc.17.19

• 1H,13C-HSQC 2D NMR experiments for representative products of each compound class. Crystallographic diffraction data were collected with a NoniusKappa CCD diffractometer (Mo Kα, λ = 0.71073 Å) equipped with a low-temperature Oxford Cryosystems Cryostream Plus device. HPLC analysis was performed using

Chemical constituents of Chaenomeles sinensis twigs and their biological activity

• Joon Min Cha,
• Dong Hyun Kim,
• Lalita Subedi,
• Zahra Khan,
• Sang Un Choi,
• Sun Yeou Kim and
• Chung Sub Kim

Beilstein J. Org. Chem. 2020, 16, 3078–3085, doi:10.3762/bjoc.16.257

• together with 11 known phytochemicals through chromatographic methods. The chemical structure of the new isolate 1 was determined by conventional 1D and 2D NMR data analysis, ECD experiment, hydrolysis followed by a modified Mosher’s method, and LC–MS analysis. The characterized compounds’ biological

• glucopyranosyl unit was confirmed to be located at C-2 through a glycosidic bond by the HMBC cross-peak between H-2 and C-1′ (Figure 2A). The intensive analysis of the 1D and 2D NMR data of compound 1 including COSY, HSQC, and HMBC analyses led to the elucidation of the planar structure of 1 (Figure 2A and

• . sinensis twigs and their structures were characterized by intensive 1D and 2D NMR data analysis, ECD experiment, modified Mosher’s method, and LC–MS analysis. The 12 phytochemicals were evaluated for their anticancer, antineuroinflammatory, and neurotrophic effects and the active compounds 8–11 could be

Thermodynamic and electrochemical study of tailor-made crown ethers for redox-switchable (pseudo)rotaxanes

• Henrik Hupatz,
• Marius Gaedke,
• Hendrik V. Schröder,
• Julia Beerhues,
• Arto Valkonen,
• Fabian Klautzsch,
• Sebastian Müller,
• Felix Witte,
• Kari Rissanen,
• Biprajit Sarkar and
• Christoph A. Schalley

Beilstein J. Org. Chem. 2020, 16, 2576–2588, doi:10.3762/bjoc.16.209

• clarity), b) NDIC7 (CH3CN molecule omitted for clarity) and c) NDIC8. a) Synthesis of the [2]rotaxane NDIRot. b) Stacked 1H NMR spectra (700 MHz, CDCl3, 298 K) of NDIC8 (top), NDIRot (middle), and A1·BArF24 (bottom). The signal assignment was done by 2D NMR spectroscopy. UV–vis–NIR spectra obtained by

Access to highly substituted oxazoles by the reaction of α-azidochalcone with potassium thiocyanate

• Mysore Bhyrappa Harisha,
• Pandi Dhanalakshmi,
• Rajendran Suresh,
• Raju Ranjith Kumar and
• Shanmugam Muthusubramanian

Beilstein J. Org. Chem. 2020, 16, 2108–2118, doi:10.3762/bjoc.16.178

• ). All the synthesized compounds 4a–l were confirmed by 1D and 2D NMR, IR spectroscopy and HRMS techniques. Additional evidence of the structures of these compounds was obtained based on the single-crystal X-ray analysis of 4h [71] (Figure 4). The nitrogen end of the thiocyanate attacks the azirine to

Muyocopronones A and B: azaphilones from the endophytic fungus Muyocopron laterale

• Ken-ichi Nakashima,
• Junko Tomida,
• Tomoe Tsuboi,
• Yoshiaki Kawamura and
• Makoto Inoue

Beilstein J. Org. Chem. 2020, 16, 2100–2107, doi:10.3762/bjoc.16.177

• esters of 1. 1H and 13C NMR spectroscopic data for 1 and 2a. Supporting Information Supporting Information File 536: Preparations of MTPA diesters 2a and 2b, phylograms of ECN-279 and related species, and copies of 1D and 2D NMR data for 1 and 2. Acknowledgements The authors thank Mr. Koichi Kaburagi

Nonenzymatic synthesis of anomerically pure, mannosyl-based molecular probes for scramblase identification studies

• Giovanni Picca,
• Markus Probst,
• Simon M. Langenegger,
• Oleg Khorev,
• Peter Bütikofer,
• Anant K. Menon and
• Robert Häner

Beilstein J. Org. Chem. 2020, 16, 1732–1739, doi:10.3762/bjoc.16.145

• configuration at the anomeric position and to prove the working principle of our synthetic strategy, we used 2D NMR experiments. Coupled HSQC measurements revealed the 1JCH coupling constants of our compounds and thereby the absolute configuration at the anomeric center of the carbohydrate [40][41][42]. For MPC