NMR Spectroscopy of supramolecular chemistry on protein surfaces

• Peter Bayer,
• Anja Matena and
• Christine Beuck

Beilstein J. Org. Chem. 2020, 16, 2505–2522, doi:10.3762/bjoc.16.203

• substituents binding to Cyt c was also studied by 15N-HSQC titrations [59]. Interestingly, large areas of the protein surface showed chemical shift perturbations, even though the binding curves clearly revealed a 1:1 stoichiometry. Crowley et al. concluded from the NMR data in combination with computational

Formation of an exceptionally stable ketene during phototransformations of bicyclo[2.2.2]oct-5-en-2-ones having mixed chromophores

• Asitanga Ghosh

Beilstein J. Org. Chem. 2020, 16, 2297–2303, doi:10.3762/bjoc.16.190

• 13C NMR data were found to be much more informative (Table 3). In 1H NMR, a doublet and a triplet in the region of δ 6.6–6.9 ppm confirmed the presence of the OPh group while the bridgehead protons of the ketenes appeared at a slightly up-field position with respect to the parent compounds. Ketenes

Azo-dimethylaminopyridine-functionalized Ni(II)-porphyrin as a photoswitchable nucleophilic catalyst

• Jannis Ludwig,
• Julian Helberg,
• Hendrik Zipse and
• Rainer Herges

Beilstein J. Org. Chem. 2020, 16, 2119–2126, doi:10.3762/bjoc.16.179

• ring are strongly dependent on the axial coordination at the central Ni2+ ion (Figure 3, and for details see Tables S1 and S2 in Supporting Information File 1). The analysis of the NMR data revealed that 98.8–99.9% of the cis isomer is coordinated in all solvents, which is expectable because DMAP is a

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

• muyocopronones A (1) and B (2) were isolated from the ethyl acetate layer together with eugenitin (3) [17], and 6-methoxymethyleugenin (4) [18]. The structures of compounds 3 and 4 were identified on the basis of their 1H and 13C NMR data (Figure 1). Muyocopronone A (1) was isolated as yellow amorphous solid

• characterization of the four possible diastereomers of the β-hydroxycarboxylic acid side chain [20]. Based on the obtained NMR data, the relative structure of the side chain of 1 was determined to adopt the (2′R*,3′R*,4′S*) configuration, as determined by the chemical shifts and the coupling constants between H-2

• , 2963, 2934, 2876, 1717, 1674, 1634, 1553, 1456, 1387, 1335, 1314, 1231, 1177, 1121, 1086, 972, 914, 878 cm−1; 1H and 13C NMR data, see Table 1; HRESIMS (m/z): [M + H]+ calcd for C25H31O7, 443.2064; found, 443.2073. Muyocopronone B (2) Yellow amorphous solid; [α]D22 +73 (c 0.1, MeOH); UV (MeOH) λmax

Convenient access to pyrrolidin-3-ylphosphonic acids and tetrahydro-2H-pyran-3-ylphosphonates with multiple contiguous stereocenters from nonracemic adducts of a Ni(II)-catalyzed Michael reaction

• Alexander N. Reznikov,
• Dmitry S. Nikerov,
• Anastasiya E. Sibiryakova,
• Victor B. Rybakov,
• Evgeniy V. Golovin and
• Yuri N. Klimochkin

Beilstein J. Org. Chem. 2020, 16, 2073–2079, doi:10.3762/bjoc.16.174

• -crystal X-ray crystallographic analysis (Figure 4) [51]. All hydrogen atoms and the hydroxy group occupy an axial position, while the remaining substituents are in equatorial positions. This is consistent with the 1H NMR data for other similar tetrahydropyranols 13b–f, therefore, their configuration was

Naphthalene diimide–amino acid conjugates as novel fluorimetric and CD probes for differentiation between ds-DNA and ds-RNA

• Annike Weißenstein,
• Myroslav O. Vysotsky,
• Ivo Piantanida and
• Frank Würthner

Beilstein J. Org. Chem. 2020, 16, 2032–2045, doi:10.3762/bjoc.16.170

• preparative HPLC and treatment with 1 M HCl solution, NDI 5 with three cationic substituents at the imide and bay positions could be obtained in 44% yield. The 1H, 13C NMR data, and high-resolution mass spectra correspond well with the structures of all new compounds synthesised. Spectrophotometric properties

Synthesis of 3(2)-phosphonylated thiazolo[3,2-a]oxopyrimidines

• Ksenia I. Kaskevich,
• Anastasia A. Babushkina,
• Vladislav V. Gurzhiy,
• Dmitrij M. Egorov,
• Nataly I. Svintsitskaya and
• Albina V. Dogadina

Beilstein J. Org. Chem. 2020, 16, 1947–1954, doi:10.3762/bjoc.16.161

• diffraction analysis along with 1H and 13C NMR spectral studies. Unfortunately, the majority of reports on the synthesis of thiazolopyrimidines relied on 1H NMR data to prove the structure of the obtained compounds [18][33][34][35]. There are no systematic data on 13C NMR spectroscopy of thiazolopyrimidines

Selective preparation of tetrasubstituted fluoroalkenes by fluorine-directed oxetane ring-opening reactions

• Clément Q. Fontenelle,
• Thibault Thierry,
• Romain Laporte,
• Emmanuel Pfund and
• Thierry Lequeux

Beilstein J. Org. Chem. 2020, 16, 1936–1946, doi:10.3762/bjoc.16.160

• reaction from acetate derivative 12. Supporting Information The experimental section describing the preparation of all new compounds, the copies of the NMR data (1H NMR, 13C NMR, 19F NMR), HOESY and NOESY experiments and crystallographic data for compounds 1d, 4d and 25. The CIF files of 1d, 4d and 25

Three new O-isocrotonyl-3-hydroxybutyric acid congeners produced by a sea anemone-derived marine bacterium of the genus Vibrio

• Dandan Li,
• Enjuro Harunari,
• Tao Zhou,
• Naoya Oku and
• Yasuhiro Igarashi

Beilstein J. Org. Chem. 2020, 16, 1869–1874, doi:10.3762/bjoc.16.154

• completed the structure of 4 as O-isocrotonyl-3-hydroxybutyric acid (Figure 2). A close similarity of the NMR data for 1–3 (Table 1 and Table 2) allowed the same sequence of structure analysis. The compounds 1 and 2 were found to have extra C1 and C2 extensions on the butyric acid units, while in 3, an

• major conformers of the PGME amide derivatives between the β,β-substituted carboxylic acids (top) and the α,α-substituted carboxylic acids (bottom), showing an orientational inversion of the PGME groups. NMR data for 1 and 2 in CDCl3. NMR data for 3 and 4 in CDCl3. Supporting Information Supporting

Polarity effects in 4-fluoro- and 4-(trifluoromethyl)prolines

• Vladimir Kubyshkin

Beilstein J. Org. Chem. 2020, 16, 1837–1852, doi:10.3762/bjoc.16.151

• direct dipole–dipole interaction between the substituent and the main chain groups could have an effect onto the conformation. Here, the NMR data for the model compounds 1–4 were collected in three solvents with distinct dielectric properties (Table 1). The results were interpreted by comparing the

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

• performing the reaction at a temperature below −15 °C yielded the compound β-4Ac-Man-CEP, with no traces of the α-anomer. The configuration was then retained throughout the rest of the synthesis, as indicated by the NMR data of MPC-1 and MPC-2 (Supporting Information File 1). Conclusion We report herein the

Rearrangement of o-(pivaloylaminomethyl)benzaldehydes: an experimental and computational study

• Csilla Hargitai,
• Györgyi Koványi-Lax,
• Tamás Nagy,
• Péter Ábrányi-Balogh,
• András Dancsó,
• Gábor Tóth,
• Judit Halász,
• Angéla Pandur,
• Gyula Simig and
• Balázs Volk

Beilstein J. Org. Chem. 2020, 16, 1636–1648, doi:10.3762/bjoc.16.136

• 24 h at room temperature led to dimer-like product 23a in 58% yield, obviously via the intermediate cation 22a (Scheme 8). The structure of 23a was supported by NMR data and also by single-crystal X-ray measurement (Figure 3). Nevertheless, HPLC–MS analysis of the crude product mixture showed, in

• possible in case of a RR–SS diastereomer (23b), with only one of the aromatic hydrogen atoms of the isoindoline moiety [H(7)] located in close proximity above the middle of the other aromatic ring. It can be concluded after all that the NMR data also made it possible to assign the RS–SR diastereomeric

• C14H17NO4 (263.29): N, 5.32; H, 6.51; C, 63.87; found: N, 5.38; H, 6.44; C, 63.77%; NMR data are identical with those published earlier [1]. Method B: This compound was prepared according to general procedure II using 1a [2] (1.00 g, 3.80 mmol) and TFA (29 µL, 43 mg, 0.38 mmol). The title compound (592 mg

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

• of 13a-C, 13-C and 15-C (signals highlighted in green, Figure 3). It is noteworthy that in the reduction process of the DHBER 2 precursors, a single diastereoisomer of the corresponding THBERs 3 is produced according to 1H and 13C NMR data. In particular, the NOE correlation between C13−H and C13a−H

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

• ). Specific optical rotation was measured in chloroform (c = 0.6), giving [α]D +40.5. The molecular formula C29H42O6 was established based on 13C NMR data and HRAPCIMS measurements, yielding m/z 487.3054 [M + H]+ (Supporting Information File 1). The double bond equivalent (DBE) was calculated to be nine and

• together with the 13C NMR data, giving evidence for one C–C and two C–O double bonds, thus suggested a structure with six rings. The presence of a hydroxy group and ester functionalities was deduced from characteristic IR absorptions at 3416, 1732 and 1234 cm−1 (Supporting Information File 1) [39][40][53

• 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

4-Hydroxy-3-methyl-2(1H)-quinolone, originally discovered from a Brassicaceae plant, produced by a soil bacterium of the genus Burkholderia sp.: determination of a preferred tautomer and antioxidant activity

• Dandan Li,
• Naoya Oku,
• Yukiko Shinozaki,
• Yoichi Kurokawa and
• Yasuhiro Igarashi

Beilstein J. Org. Chem. 2020, 16, 1489–1494, doi:10.3762/bjoc.16.124

• ; HRESITOFMS (m/z): [M + Na]+ calcd for C10H9NNaO2, 198.0526, found: 198.0525 ; 1H and 13C NMR data are shown in Table 1. Evaluation of Fe3+ binding activity The iron-binding activity was evaluated by the CAS assay developed by Schwyn and Neilands [45]. Compound 1 (2.5 mg) in DMSO (20 μL) was mixed with a blue

• luminol chemiluminescence by 1. 1H (500 MHz) and 13C (125 MHz) NMR data of compound 1 in DMSO-d6 (297 K). Supporting Information Supporting Information File 60: Synthetic procedure of 1, UV, IR, 1H NMR, 13C NMR, COSY, HSQC, HMBC spectra for natural and synthetic 1, and UV, IR, 1H NMR, 13C NMR spectra for

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

• (19) with anhydrides 5–7. Reagents and conditions: xylene, inert atmosphere, 120 °C, 6 h. Reactions of 1-alkyl-3,4-dihydroisoquinolines 19 and 20 with anhydride 8. Reagents and conditions: xylene, inert atmosphere, 120 °C, 6 h. Suggested mechanism for the formation of products 25–27. NMR data and

A cyclopeptide and three oligomycin-class polyketides produced by an underexplored actinomycete of the genus Pseudosporangium

• Shun Saito,
• Kota Atsumi,
• Tao Zhou,
• Keisuke Fukaya,
• Daisuke Urabe,
• Naoya Oku,
• Md. Rokon Ul Karim,
• Hisayuki Komaki and
• Yasuhiro Igarashi

Beilstein J. Org. Chem. 2020, 16, 1100–1110, doi:10.3762/bjoc.16.97

• experimental 1H and 13C NMR data of 1 presented a higher chemical shift similarity to those for 1b and thereby the (S)-configuration was suggested for C-2. Indeed, the DP4+ analysis [25] gave 100% probability for structure 1b and 0.0% probability for structure 1a (Table S2, Supporting Information File 2). This

• (0.48) nm; ECD (1 × 10−4 M, MeCN) λext (Δε) 217.0 (+17.3), 235.5 (−10.8) nm; IR (ATR) νmax 3328, 1722 cm−1; for 1H and 13C NMR data, see Table 1; HRESITOFMS (m/z): [M − H]− calcd for C27H27N4O6, 503.1931; found, 503.1936. Pseudosporamicin A (2): white amorphous powder; [α]D25 −23 (c 0.50, MeOH); UV

• (MeOH) λmax (log ε) 218 (4.65) nm; IR (ATR) νmax 3366, 1713, 1635 cm−1; for 1H and 13C NMR data, see Table 2; HRESITOFMS (m/z) [M − H]− calcd for C47H75O12, 831.5259; found, 831.5255. Pseudosporamicin B (3): white amorphous powder; [α]D25 −9.3 (c 0.50, MeOH); UV (MeOH) λmax (log ε) 223 (4.56) nm; IR

Bipyrrole boomerangs via Pd-mediated tandem cyclization–oxygenation. Controlling reaction selectivity and electronic properties

• Liliia Moshniaha,
• Marika Żyła-Karwowska,
• Joanna Cybińska,
• Piotr J. Chmielewski,
• Ludovic Favereau and
• Marcin Stępień

Beilstein J. Org. Chem. 2020, 16, 895–903, doi:10.3762/bjoc.16.81

• below 1 equiv (Table 1, entries 16 and 22). Structure The identity of the α-oxygenated products, cRnO, was determined on the basis of high-resolution mass spectrometry and 1H and 13C NMR data. In particular, the 1H NMR spectrum of cNMI2O revealed the absence of the pyrrolic α-H resonances, whereas the

Synthesis of C₇₀-fragment buckybowls bearing alkoxy substituents

• Yumi Yakiyama,
• Shota Hishikawa and
• Hidehiro Sakurai

Beilstein J. Org. Chem. 2020, 16, 681–690, doi:10.3762/bjoc.16.66

• depths of 5b at the specific focused carbons. Supporting Information Supporting Information File 7: CIF files of compounds 5a–c. Supporting Information File 8: 1H and 13C NMR data of 3a, 3b, 4a, 4b and 5a–c, simulated UV–vis spectra of 5a, 5b and 5c. Funding This work was supported by a Grant-in-Aid

Microwave-assisted efficient and facile synthesis of tetramic acid derivatives via a one-pot post-Ugi cascade reaction

• Yong Li,
• Zheng Huang,
• Jia Xu,
• Yong Ding,
• Dian-Yong Tang,
• Jie Lei,
• Hong-yu Li,
• Zhong-Zhu Chen and
• Zhi-Gang Xu

Beilstein J. Org. Chem. 2020, 16, 663–669, doi:10.3762/bjoc.16.63

• Supporting Information File 250: General information, general experimental procedure, characterization data, and copies of 1H and 13C NMR spectra. Acknowledgements We would like to thank Ms H.Z. Liu for obtaining the LC–MS and NMR data. Funding The authors would like to thank the Science and Technology

Regio- and stereoselective synthesis of new ensembles of diversely functionalized 1,3-thiaselenol-2-ylmethyl selenides by a double rearrangement reaction

• Svetlana V. Amosova,
• Andrey A. Filippov,
• Nataliya A. Makhaeva,
• Alexander I. Albanov and
• Vladimir A. Potapov

Beilstein J. Org. Chem. 2020, 16, 515–523, doi:10.3762/bjoc.16.47

• ). The monitoring results are presented in Figure 1 and Table 1. The reaction was studied in the time interval from 0.25 to 6 h. Having assigned the 1H NMR data for compounds 1 and 4, we found signals of an unknown compound, which was easily identified after 0.5 h (at 46% conversion of thiaselenole 1) as

• potassium selenocyanate. The reaction pathway for the formation of compounds 4 and 5. Synthesis of new ensembles of 1,3-thiaselenol-2-ylmethyl selenides 6a–l (77Se NMR data are included). The synthesis of vinyl selenides 7a,b through nucleophilic addition of 1,3-thiaselenol-2-ylmethylselenolate anion to

• alkyl propiolates (77Se NMR data are included). One-pot synthesis of diselenide 8 from thiaselenole 1 (77Se NMR data are included). Synthesis of compounds 6a–j from diselenide 8. Results the reaction of thiaselenole 1 with KSeCN based on 1H NMR spectroscopy monitoring (Figure 1).a Supporting

Aerobic synthesis of N-sulfonylamidines mediated by N-heterocyclic carbene copper(I) catalysts

• Faïma Lazreg,
• Marie Vasseur,
• Alexandra M. Z. Slawin and
• Catherine S. J. Cazin

Beilstein J. Org. Chem. 2020, 16, 482–491, doi:10.3762/bjoc.16.43

• in this manner (Scheme 10). The latter was then reacted with tosyl azide. An immediate colour change resulted and based on 1H NMR data, two new species were formed. They were identified as the sulfonyltriazole and an unstable organometallic compound, presumably the triazolylcopper(I) complex C. These

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

• adduct ion peak at m/z 357.0572, attributable to the molecular formula C16H14O8Na (calcd 357.0586), suggesting that 2 had one more oxygen atom relative to 1. The 1H and 13C NMR data for 2 were substantially similar to those of 1, with the exception that 2 exhibited oxymethylene signals (δH 4.73 (2H, s

• , with thermal ellipsoids indicating 50% probability. b) Electronic circular dichroism spectrum of 5. 1H (400 MHz) and 13C (100 MHz) NMR data for 1 and 2 in CDCl3. Supporting Information Supporting Information File 265: A phytogenic tree for ECN211 and related species and NMR spectra of 1 and 2

Synthesis of 4-(2-fluorophenyl)-7-methoxycoumarin: experimental and computational evidence for intramolecular and intermolecular C–F···H–C bonds

• Vuyisa Mzozoyana,
• Fanie R. van Heerden and
• Craig Grimmer

Beilstein J. Org. Chem. 2020, 16, 190–199, doi:10.3762/bjoc.16.22

• crystal structure and solution-state NMR data of the coumarin 6 were studied to examine any C–F···H–C hydrogen bond interactions. DFT calculations were performed to determine the preferred conformations of the structure that might exhibit a C–F···H–C hydrogen bond. Results and Discussion Synthesis of 2

• these observations (Figure 1 and Figure 3) is that, in solution, rotation of the fluorophenyl ring (about C4–C1’) is permitted but that the average geometry of coumarin 6 has the fluorine atom closer to H5 than H3. The theoretical NMR data for twenty-four conformations of coumarin 6 were obtained from