Synthesis of new dihydroberberine and tetrahydroberberine analogues and evaluation of their antiproliferative activity on NCI-H1975 cells

• Giacomo Mari,
• Lucia De Crescentini,
• Serena Benedetti,
• Francesco Palma,
• Stefania Santeusanio and
• Fabio Mantellini

Beilstein J. Org. Chem. 2020, 16, 1606–1616, doi:10.3762/bjoc.16.133

• ). From the comparison between the 1H NMR spectra of DHBER 2a and THBER 3a, it can also be noted as the chemical shifts of 6-C, and 8-C protons, which are the closest to the N-7 nitrogen atom are significantly shifted downfield (assigned by 2D-NMR analysis, see Supporting Information File 1). For example

Antibacterial scalarane from Doriprismatica stellata nudibranchs (Gastropoda, Nudibranchia), egg ribbons, and their dietary sponge Spongia cf. agaricina (Demospongiae, Dictyoceratida)

• Cora Hertzer,
• Stefan Kehraus,
• Nils Böhringer,
• Fontje Kaligis,
• Robert Bara,
• Dirk Erpenbeck,
• Gert Wörheide,
• Till F. Schäberle,
• Heike Wägele and
• Gabriele M. König

Beilstein J. Org. Chem. 2020, 16, 1596–1605, doi:10.3762/bjoc.16.132

• ]. The planar structure of 12-deacetoxy-4-demethyl-11,24-diacetoxy-3,4-methylenedeoxoscalarin was established by extensive 1D and 2D NMR experiments (1H, 13C, 1H,1H-COSY, DEPT, HSQC and HMBC, see Table 1, Figure S8, Supporting Information File 1). The 13C NMR spectrum showed 29 resonances attributable to

• the 2D NMR data and comparison to literature values [53] suggested that the compound belongs to the family of scalarane sesterterpenoids, with similarities to the deoxoscalarin-like molecule 12,24-diacetoxydeoxoscalarin, previously isolated from a Korean sponge of the genus Spongia [53]. The two

One-step route to tricyclic fused 1,2,3,4-tetrahydroisoquinoline systems via the Castagnoli–Cushman protocol

• Aleksandar Pashev,
• Nikola Burdzhiev and
• Elena Stanoeva

Beilstein J. Org. Chem. 2020, 16, 1456–1464, doi:10.3762/bjoc.16.121

• with the use of succinic anhydride. The results are evidence of an unexplored method for the access of the aforementioned tricyclic annelated systems incorporating a bridgehead nitrogen atom. The structures and relative configurations of the new compounds were established by means of 1D and 2D NMR

• ), the 1-ethyl derivative 20 did not react at all with the anhydrides 5–7. The structures of compounds 25 and 26 were confirmed by 2D NMR spectroscopy and singe-crystal X-ray analysis (Figure 3). The piperidine moiety is planar to a significant extent due to the combined influence of the aromatic ring

• . The structure of 27 was proven by a combination of 1D and 2D NMR spectra, and IR spectroscopy. The reactivity of thiodiacetic anhydride 8 towards the imines 19 and 20 was different to that of the anhydrides 5–7. The targeted 11b-methyl and 11b-ethyl-4-oxo-2-thiabenzo[a]quinolizidinones 28 and 29

Diversity-oriented synthesis of 17-spirosteroids

• Benjamin Laroche,
• Thomas Bouvarel,
• Martin Louis-Sylvestre and
• Bastien Nay

Beilstein J. Org. Chem. 2020, 16, 880–887, doi:10.3762/bjoc.16.79

• structure and stereochemistry of the products were determined by 2D NMR analysis. Taking 16b as an example, the key NOESY correlations between proton H-4' at 2.79 ppm and steroid protons H-12 at 1.33/1.65 ppm demonstrated that H-4' is on the α-face of the cyclohexene (Figure 3a). The endo character of the

Two antibacterial and PPARα/γ-agonistic unsaturated keto fatty acids from a coral-associated actinomycete of the genus Micrococcus

• Amit Raj Sharma,
• Enjuro Harunari,
• Naoya Oku,
• Nobuyasu Matsuura,
• Agus Trianto and
• Yasuhiro Igarashi

Beilstein J. Org. Chem. 2020, 16, 297–304, doi:10.3762/bjoc.16.29

• correlations for 1 and 2. Spin system simulation for the C8–C9 double bond of 2. Natural keto fatty acids of various origins. PPAR activation by 1 and 2. 1H and 13C NMR data for compounds 1 and 2 in CDCl3. Supporting Information Supporting Information File 204: ESIMS-TOF, UV, IR, 1D, and 2D NMR spectra of 1

Absolute configurations of talaromycones A and B, α-diversonolic ester, and aspergillusone B from endophytic Talaromyces sp. ECN211

• Ken-ichi Nakashima,
• Junko Tomida,
• Takao Hirai,
• Yoshiaki Kawamura and
• Makoto Inoue

Beilstein J. Org. Chem. 2020, 16, 290–296, doi:10.3762/bjoc.16.28

• was correlated to a carbonyl carbon signal at δC 170.2 (C-12), which suggested the presence of a methyl carboxylate group. These substructures, as revealed by 1D and 2D NMR spectroscopic analyses and 1H and 13C chemical shifts, suggested that 1 was related to the diversonolic esters, but with a

Ultrasonic-assisted unusual four-component synthesis of 7-azolylamino-4,5,6,7-tetrahydroazolo[1,5-a]pyrimidines

• Yana I. Sakhno,
• Maryna V. Murlykina,
• Oleksandr I. Zbruyev,
• Anton V. Kozyryev,
• Svetlana V. Shishkina,
• Dmytro Sysoiev,
• Vladimir I. Musatov,
• Sergey M. Desenko and
• Valentyn A. Chebanov

Beilstein J. Org. Chem. 2020, 16, 281–289, doi:10.3762/bjoc.16.27

• 2D NMR experiments), and X-ray diffraction analysis. The signals in the 1H and 13C NMR spectra of some of the compounds 4 were duplicated. This could have been caused by two reasons, namely by free rotation of the azolyl fragment in the position 7 or by the presence of a second diastereomer. To

• the presence of two isomers of 4. The 1H NMR and 13C NMR spectra of triazolyl derivatives 4p–u were more complicated, both due to the duplication of the signals and the fast decomposition of the compounds 4p–u in solutions. Therefore, 2D NMR and, in some cases, 13C NMR spectra were overcrowded and

Combination of multicomponent KA² and Pauson–Khand reactions: short synthesis of spirocyclic pyrrolocyclopentenones

• Riccardo Innocenti,
• Elena Lenci,
• Gloria Menchi and
• Andrea Trabocchi

Beilstein J. Org. Chem. 2020, 16, 200–211, doi:10.3762/bjoc.16.23

• and showing stability towards harsh acidic conditions. The structural assignment of compound 36 was assessed by detailed 1D and 2D NMR studies, and corroborated with molecular modeling calculations. NOESY-1D experiments carried out with a mixing time of 500 ms allowed to identify the unique rotamer

Reversible photoswitching of the DNA-binding properties of styrylquinolizinium derivatives through photochromic [2 + 2] cycloaddition and cycloreversion

• Sarah Kölsch,
• Heiko Ihmels,
• Jochen Mattay,
• Norbert Sewald and
• Brian O. Patrick

Beilstein J. Org. Chem. 2020, 16, 111–124, doi:10.3762/bjoc.16.13

• cyclobutane at 4.89–5.00 ppm [42][43][44][45][46]. Unfortunately, detailed 2D NMR and spectroscopic analyses did not allow a conclusive assignment of the configuration of the products. Even in the ROESY NMR spectra, only unspecific correlations were detected. However, as both products could be obtained as

Microwave-assisted synthesis of 2-substituted 4,5,6,7-tetrahydro-1,3-thiazepines from 4-aminobutanol

• María C. Mollo,
• Natalia B. Kilimciler,
• Juan A. Bisceglia and
• Liliana R. Orelli

Beilstein J. Org. Chem. 2020, 16, 32–38, doi:10.3762/bjoc.16.5

• -acylpyrrolidines. In order to ascertain the structure of compound 4a, we compared its NMR spectra with those of N-thiobenzoylpyrrolidine (Scheme 1) [60], confirming further the identity of the tetrahydrothiazepine by analysis of its 2D NMR spectra (see Supporting Information File 1). Using the optimized

Pigmentosins from Gibellula sp. as antibiofilm agents and a new glycosylated asperfuran from Cordyceps javanica

• Soleiman E. Helaly,
• Wilawan Kuephadungphan,
• Patima Phainuphong,
• Mahmoud A. A. Ibrahim,
• Kanoksri Tasanathai,
• Suchada Mongkolsamrit,
• Janet Jennifer Luangsa-ard,
• Souwalak Phongpaichit,
• Vatcharin Rukachaisirikul and
• Marc Stadler

Beilstein J. Org. Chem. 2019, 15, 2968–2981, doi:10.3762/bjoc.15.293

• -forming S. aureus. The structure elucidation and determination of the absolute configuration were accomplished using a combination of spectroscopy, including 1D and 2D NMR, HRMS, Mosher ester analysis, and comparison of calculated/experimental ECD spectra. A chemotaxonomic investigation of the secondary

• olefinic sp2 carbon atoms at 98.7 (C-8/C-8′) and 114.7 (C-5/C-5′), respectively, assigned to four methine units, suggested the presence of a dihydro-α-naphthopyrone moiety in 2. Comprehensive analysis of the 2D NMR data, including HSQC, COSY, and HMBC, confirmed the structure of 2 as follows: COSY

• of the 2D NMR data revealed that beauverolide Jb (6) comprised a leucine moiety instead of isoleucine in beauverolide Ja (see NMR data in the Experimental section and Figures S30–S34 in Supporting Information File 1). Chemotaxonomic investigation In order to investigate the distribution patterns of

One-pot synthesis of substituted pyrrolo[3,4-b]pyridine-4,5-diones based on the reaction of N-(1-(4-hydroxy-6-methyl-2-oxo-2H-pyran-3-yl)-2-oxo-2-arylethyl)acetamide with amines

• Valeriya G. Melekhina,
• Andrey N. Komogortsev,
• Boris V. Lichitsky,
• Vitaly S. Mityanov,
• Artem N. Fakhrutdinov,
• Arkady A. Dudinov,
• Vasily A. Migulin,
• Yulia V. Nelyubina,
• Elizaveta K. Melnikova and
• Michail M. Krayushkin

Beilstein J. Org. Chem. 2019, 15, 2840–2846, doi:10.3762/bjoc.15.277

• for the synthesis of pyrrolo[3,4-b]pyridin-5-one derivatives 1.a Supporting Information Supporting Information File 582: Experimental procedures, characterization data of all products, copies of 1H, 13C, 2D NMR, and HRMS spectra of all compounds, and X-ray data for compound 1e.

Design, synthesis and investigation of water-soluble hemi-indigo photoswitches for bioapplications

• Daria V. Berdnikova

Beilstein J. Org. Chem. 2019, 15, 2822–2829, doi:10.3762/bjoc.15.275

• ROESY 2D NMR techniques. The carbon NMR signal assignments were performed by means of HSQC and HMBC 2D NMR techniques. Mass spectra (ESI) were recorded on a Finnigan LCQ Deca mass spectrometer. Elemental analysis was performed with a HEKAtech EUROEA combustion analyser by Mr. Rochus Breuer (Universität

Skeletocutins M–Q: biologically active compounds from the fruiting bodies of the basidiomycete Skeletocutis sp. collected in Africa

• Tian Cheng,
• Clara Chepkirui,
• Cony Decock,
• Josphat C. Matasyoh and
• Marc Stadler

Beilstein J. Org. Chem. 2019, 15, 2782–2789, doi:10.3762/bjoc.15.270

• . Compound 2 (skeletocutin N, Table 1 and Figure 2) was obtained as a white solid, with the molecular formula C30H46O6 and eight degrees of unsaturation determined from HRESIMS data. The 1D and 2D NMR data for 2 revealed a similar structure to 1, with the difference being the size of the carbon chain in the

• singlet (δ = 3.37 ppm, H2-2), a quintet (δ = 1.58 ppm, H2-21), a triplet (δ = 2.45 ppm, H2-22) for three methylene groups, and a triplet for a methine unit (δ = 7.13 ppm, H-4) were observed in the 1H NMR spectrum of 3. Analysis of 1D and 2D NMR data for 3 indicated a similar structure to 1, with a

• . Peaks for m/z = 537.3058 ([M + H]+), 559.2877 ([M + Na]+), 519.2953 ([M + H − H2O])+, and 1095.5860 ([2M + Na]+) were observed in the mass spectrum. The 1D and 2D NMR data of 4 were similar to those of 3, with the difference being the presence of a tricarboxylic acid moiety instead of a dicarboxylic

Nanangenines: drimane sesquiterpenoids as the dominant metabolite cohort of a novel Australian fungus, Aspergillus nanangensis

• Heather J. Lacey,
• Cameron L. M. Gilchrist,
• Andrew Crombie,
• John A. Kalaitzis,
• Daniel Vuong,
• Peter J. Rutledge,
• Peter Turner,
• John I. Pitt,
• Ernest Lacey,
• Yit-Heng Chooi and
• Andrew M. Piggott

Beilstein J. Org. Chem. 2019, 15, 2631–2643, doi:10.3762/bjoc.15.256

• ), three methyl groups (C-13, C-14, C-15) and three hydroxy groups (1-OH, 6-OH, 9-OH). Detailed analysis of the 2D NMR data for 1 (Table S3 in Supporting Information File 1) confirmed the presence of a drimane sesquiterpenoid lactone scaffold. A search of the literature revealed 1 to be almost identical to

• oxymethylene H2-12 were also shifted upfield by ≈1 ppm compared to those in 2, suggesting the pendant oxygen atom was no longer attached to a carbonyl carbon. A detailed analysis of the 2D NMR data for 9 (Table S11 in Supporting Information File 1) confirmed the structure to be the seco analogue of 2, as shown

• File 565: Details of cultivation media, fractionation schemes, NMR spectra and tabulated 2D NMR data for all compounds, detailed X-ray crystallographic details and CCDC deposition numbers, bioassay procedures and genomic data. Supporting Information File 566: Crystal structure information files for

Chiral terpene auxiliaries V: Synthesis of new chiral γ-hydroxyphosphine oxides derived from α-pinene

• Anna Kmieciak and
• Marek P. Krzemiński

Beilstein J. Org. Chem. 2019, 15, 2493–2499, doi:10.3762/bjoc.15.242

• hydrolyzed with a 5% aqueous solution of NaOH. GC analysis of the isolated alcohol confirmed the presence of (1R,4S,5R)-apopinenol (18) and (1R,4R,5R)-16 in a ratio of 79.5:20.5. The structures and stereochemistry of both diastereomeric alcohols 16 and 18 were confirmed by 2D NMR spectra. All protons in 16

Sugar-derived oxazolone pseudotetrapeptide as γ-turn inducer and anion-selective transporter

• Sachin S. Burade,
• Sushil V. Pawar,
• Tanmoy Saha,
• Navanath Kumbhar,
• Amol S. Kotmale,
• Manzoor Ahmad,
• Pinaki Talukdar and
• Dilip D. Dhavale

Beilstein J. Org. Chem. 2019, 15, 2419–2427, doi:10.3762/bjoc.15.234

• presence and absence of valinomycin (1 µM) across EYPC-LUVslucigenin (D). Synthesis of linear azido ester dipeptide 5 and tetrapeptide 7. Synthesis of oxazolone pseudopeptides 1, 2a and 2b. Supporting Information Supporting Information File 200: Experimental procedures, 1H and 13C NMR data, HRMS and 2D

• NMR spectra. Acknowledgements We are thankful to the Science and Engineering Research Board (SERB), New Delhi (File no. EMR/2014/000873) for financial support and Central Instrumentation Facility (CIF), SPPU, Pune for analytical services. S.S.B. thanks CSIR, S.P, T.S., and M.A. thank the UGC, A.K

Isolation and biosynthesis of an unsaturated fatty acid with unusual methylation pattern from a coral-associated bacterium Microbulbifer sp.

• Amit Raj Sharma,
• Enjuro Harunari,
• Tao Zhou,
• Agus Trianto and
• Yasuhiro Igarashi

Beilstein J. Org. Chem. 2019, 15, 2327–2332, doi:10.3762/bjoc.15.225

• of tuberculostearic acid in Mycobacterium. Possible methylation mechanism for compound 1. 1H and 13C NMR data for compound 1 in CDCl3. Incorporation of 13C-labeled precursors into 1. Supporting Information Supporting Information File 466: 1D and 2D NMR spectra of 1; 13C NMR spectra of 13C-labeled 1.

Multiple threading of a triple-calix[6]arene host

• Veronica Iuliano,
• Roberta Ciao,
• Emanuele Vignola,
• Carmen Talotta,
• Patrizia Iannece,
• Margherita De Rosa,
• Annunziata Soriente,
• Carmine Gaeta and
• Placido Neri

Beilstein J. Org. Chem. 2019, 15, 2092–2104, doi:10.3762/bjoc.15.207

• dialkylammonium axles. The formation of pseudo[2]rotaxane, pseudo[3]rotaxane, and pseudo[4]rotaxane by threading one, two, and three, respectively, calix-wheels of 6 has been studied by 1D and 2D NMR, DOSY, and ESI-FT-ICR MS/MS experiments. The use of a directional alkylbenzylammonium axle led to the

• axle 7+ was studied by HR-ESI-FT-ICR mass spectrometry and 1D/2D NMR (Figure 3). A 1:1 mixture of 6 and 7+·TFPB− in CHCl3 was stirred at 298 K for 15 min, until the solution was clarified, and then used for mass spectrometry analysis. An ESI-FT-ICR mass spectrum of this solution (Figure 3, bottom

• →29.2 ppm. Thus, these data clearly indicated that the calix[6]arene threaded by dibenzylammonium axles adopted a cone-conformation. A close inspection of the region between 4.8 and 5.2 ppm in the 1D and 2D NMR spectra, revealed the presence of the triple-threaded (7+)36 pseudo[4]rotaxane as a less

Genome mining in Trichoderma viride J1-030: discovery and identification of novel sesquiterpene synthase and its products

• Xiang Sun,
• You-Sheng Cai,
• Yujie Yuan,
• Guangkai Bian,
• Ziling Ye,
• Zixin Deng and
• Tiangang Liu

Beilstein J. Org. Chem. 2019, 15, 2052–2058, doi:10.3762/bjoc.15.202

• by genome mining and determined the structure of its corresponding products. One new 5/6 bicyclic sesquiterpene and its esterified derivative were characterised by GC–MS and 1D and 2D NMR spectroscopy. To the best of our knowledge, this is the first well-identified sesquiterpene synthase from T

• characterised by GC–MS and 1D and 2D NMR, revealing a 5/6 bicyclic sesquiterpene and its C-11 esterified structure. Based on a literature search, to our knowledge, this is the first report of the characterisation of a sesquiterpene synthase in T. viride. In addition, this study demonstrates the effectiveness of

• and 2D NMR spectroscopy (Table 1, Table S4, and Figures S4–S15, Supporting Information File 1). Compound 1 was a new compound with a known skeleton [35], isolated as a white powder. 1H and 13C NMR data showed four methyl groups at δH 1.87 (t, J = 1.2 Hz, 3H,), δH 0.96 (s, 3H), δH 0.83 (s, 3H), and δH

Bipolenins K–N: New sesquiterpenoids from the fungal plant pathogen Bipolaris sorokiniana

• Chin-Soon Phan,
• Hang Li,
• Simon Kessler,
• Peter S. Solomon,
• Andrew M. Piggott and
• Yit-Heng Chooi

Beilstein J. Org. Chem. 2019, 15, 2020–2028, doi:10.3762/bjoc.15.198

• suggested that 1 was the 9-hydroxy analogue of 5, which was further confirmed by detailed analysis of key 2D NMR correlations (Figure 2). Compound 1 was previously reported in 1970 as a semi-synthetic analogue of 9-hydroxyprehelminthosporol [18], but has not been previously isolated and characterised from a

• quaternary carbon (δC 74.8) in 3. This suggested that 3 was the 6-hydroxy analogue of 5, which was further confirmed by detailed analysis of key 2D NMR correlations (Figure 2). The absolute configurations of the stereocentres in 3 were established to be identical to 1 and 2 based on the analysis of proton

• with reduction of the lactone ring to the dialcohol and dihydroxylation of the Δ2,12 double bond. Detailed analysis of the 2D NMR data for 4 (Figure 2) confirmed the seco-sativene-type scaffold. The relative configurations at C-1, C-3, C-6, C-7 and C-13 were determined to be the same as those of 1–3

Morphology-tunable and pH-responsive supramolecular self-assemblies based on AB₂-type host–guest-conjugated amphiphilic molecules for controlled drug delivery

• Yang Bai,
• Cai-ping Liu,
• Di Chen,
• Long-hai Zhuo,
• Huai-tian Bu and
• Wei Tian

Beilstein J. Org. Chem. 2019, 15, 1925–1932, doi:10.3762/bjoc.15.188

• . 1H NMR spectra of β-CD-BM2-based supramolecular self-assemblies in DMSO-d6 (a), D2O (b) and DCl/D2O (c), respectively. 2D NMR NOESY spectra in D2O (a) and D2O/DCl (b), UV–vis spectra (c) and fluorescence spectra (d) of β-CD-BM2-based supramolecular self-assemblies at pH 7.4 and 5.0. Cumulative

Complexation of chiral amines by resorcin[4]arene sulfonic acids in polar media – circular dichroism and diffusion studies of chirality transfer and solvent dependence

• Bartosz Setner and
• Agnieszka Szumna

Beilstein J. Org. Chem. 2019, 15, 1913–1924, doi:10.3762/bjoc.15.187

• noted otherwise, all reactions were carried out under an atmosphere of air. 1H and 13C NMR spectra were recorded at 303 K on Bruker 400 MHz and at 298 K on Varian VNMRS 600 MHz instruments with a residual solvent signal as an internal standard. All 2D NMR spectra were recorded at 298 K on a Varian 600

Bambusuril analogs based on alternating glycoluril and xylylene units

• Tomáš Lízal and
• Vladimír Šindelář

Beilstein J. Org. Chem. 2019, 15, 1268–1274, doi:10.3762/bjoc.15.124

• of these protons because of its non-equivalent nature. The structures of conformers 1a-1 and 1a-2 were further confirmed by 2D NMR experiments. We performed 2D exchange spectrometry (EXSY) NMR experiments to confirm that there is a change of conformation on the NMR timescale [17]. This technique

New α- and β-cyclodextrin derivatives with cinchona alkaloids used in asymmetric organocatalytic reactions

• Iveta Chena Tichá,
• Simona Hybelbauerová and
• Jindřich Jindřich

Beilstein J. Org. Chem. 2019, 15, 830–839, doi:10.3762/bjoc.15.80

• to 8.16 ppm of H-14' of triazole) and 126.13 ppm of C-14' triazole is correlated to the signal at 4.57 ppm of the quinidine part. Additional 2D NMR spectra (COSY, HSQC, HMBC, ROESY) are included in Supporting Information File S2 and Supporting Information File S3. Moreover, we also investigated a

• alkaloid attachment to the CD skeleton through the triazole by 2D NMR measurements. This thorough investigation revealed no triple bond and a new triazole hydrogen signal while correlating carbon C6 of the substituted glucose unit with the triazole. Therefore, the prepared CD derivatives are substituted on

• subsequently applied as catalysts in enantioselective reactions. We fully characterized the series of new 16 cinchona–CD derivatives including non-methylated and permethylated CDs by 2D NMR, MS, IR spectroscopy and we optimized their preparation (less than 3 h and up to 95% isolated yield). We applied them in