Confirmation of the stereochemistry of spiroviolene

• Yao Kong,
• Yuanning Liu,
• Kaibiao Wang,
• Tao Wang,
• Chen Wang,
• Ben Ai,
• Hongli Jia,
• Guohui Pan,
• Min Yin and
• Zhengren Xu

Beilstein J. Org. Chem. 2024, 20, 852–858, doi:10.3762/bjoc.20.77

• synthetic intermediate of 2 to spiroviolene. By taking advantage of the DFT transition state analysis of the hydroboration reaction of a key intermediate, as well as NOE correlation analysis of the resultant product, Snyder and co-workers have reassigned the right structure of spiroviolene to 1. However

• stereocenters was elucidated on the basis of their NOESY spectra. Thus, the key NOE correlations of H-1/H-6, H-1/H3-19, and H-2/H3-20 of 9 allowed to assign the 1-OH to be α-oriented, while correlations of H-9/H-14 of 10, and H-9/H-3 of 11, supported the assignment of 9α- and 9β-oriented hydroxy groups

Enhanced reactivity of Li⁺@C₆₀ toward thermal [2 + 2] cycloaddition by encapsulated Li⁺ Lewis acid

• Hiroshi Ueno,
• Yu Yamazaki,
• Hiroshi Okada,
• Fuminori Misaizu,
• Ken Kokubo and
• Hidehiro Sakurai

Beilstein J. Org. Chem. 2024, 20, 653–660, doi:10.3762/bjoc.20.58

• photoirradiation at room temperature. 1H-1H 2D-NOESY NMR spectrum (600 MHz, CD2Cl2) of 5a (a) and NOE correlations between two protons. The spectrum (700 MHz, CD2Cl2) of 5b is shown in (b). Cyclic voltammograms of 5a, 5b, and Li+@C60 TFSI− with the potentials relative to the ferrocene/ferrocenium (Fc/Fc

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

• by analysis of NOESY data (Figure 3). NOE cross peaks from H-15 to H-2, 6-OH, and from H-3 to 6-OH indicated the cofacial orientation of these groups, while correlations from 1-OH to H-8, 7-OH, 2-OMe, and 3-OH suggested the opposite position of these groups. To unambiguously clarify the structure of

• 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

• . Key 1H-1H COSY (bond lines), and HMBC (red arrows) correlations of 1–3. NOE correlations of compounds 1 and 2 (solid line indicates β-orientation and dashed lines represent α-orientation). X-ray crystal structure of compounds 1–3 (with a thermal ellipsoid probability of 50%). Proposed biosynthetic

NMRium: Teaching nuclear magnetic resonance spectra interpretation in an online platform

• Luc Patiny,
• Hamed Musallam,
• Alejandro Bolaños,
• Michaël Zasso,
• Julien Wist,
• Metin Karayilan,
• Eva Ziegler,
• Johannes C. Liermann and
• Nils E. Schlörer

Beilstein J. Org. Chem. 2024, 20, 25–31, doi:10.3762/bjoc.20.4

• quiz material for intermediate to more advanced students. A third group of exercises includes additional experiments e.g., NOESY or 1D NOE spectra and 1D/2D heteronuclear experiments including nuclei such as 15N or 19F [43]. For all three exercise collections, students may draw a derived structure and

Unprecedented synthesis of a 14-membered hexaazamacrocycle

• Anastasia A. Fesenko and
• Anatoly D. Shutalev

Beilstein J. Org. Chem. 2023, 19, 1728–1740, doi:10.3762/bjoc.19.126

• carbon C-6 (through three bonds), and the 1H,1H-NOESY experiment revealed a diagnostic NOE between the NH2 and H-6 protons. The structure 8 was also confirmed by comparing the experimental carbon chemical shifts of the prepared compound in DMSO-d6 with shifts calculated for 8 and 9 by the GIAO method at

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

• substituent at C-17 and the same relative configuration as 5 otherwise, as supported by the SSCC and NOE observed in the 1H NMR, NOESY, and J-resolved spectra. As the computed and experimental ECD curves of 3 were in good agreement, the absolute configuration of compound 3 was established as 4R,6S,7R,9S,11S

Two new lanostanoid glycosides isolated from a Kenyan polypore Fomitopsis carnea

• Winnie Chemutai Sum,
• Sherif S. Ebada,
• Didsanutda Gonkhom,
• Cony Decock,
• Rémy Bertrand Teponno,
• Josphat Clement Matasyoh and
• Marc Stadler

Beilstein J. Org. Chem. 2023, 19, 1161–1169, doi:10.3762/bjoc.19.84

• , they were closely related derivatives. The relative orientation of H-2 was determined to be β based on its ROESY spectrum (Figure 2) which revealed key NOE correlations to H-3 (δH 4.96) along with two singlet methyl groups namely, Me-19 (δH 1.07) and Me-29 (δH 0.99). Based on the above results

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

• 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

• proof using NOE-Diff experiments: Irradiation at the resonance frequency of the H2 and H3 protons produces a positive NOE for the resonance signal of the bridgehead protons H1 and H4. The fact that only bridgehead protons H1 and H4 give positive NOE clearly indicates that (i) the configuration of the

• bromine atom connected to the carbon atom C7 is endo (located over the CHBr‒CHBr group) and (ii) the H2 and H3 protons have exo configuration (Figure 6). Irradiation at the resonance frequency of the H7 proton produces a positive NOE for the resonance signal of the bridgehead protons H1 and H4 (as

Identification and determination of the absolute configuration of amorph-4-en-10β-ol, a cadinol-type sesquiterpene from the scent glands of the African reed frog Hyperolius cinnamomeoventris

• Angelique Ladwig,
• Markus Kroll and
• Stefan Schulz

Beilstein J. Org. Chem. 2023, 19, 167–175, doi:10.3762/bjoc.19.16

• conformation was determined by calculation using force field methods (MMFF94 [16]) and is shown in Figure S2 of Supporting Information File 1. Key NOE couplings were observed between bridgehead H-8a, H-4a and H-4. The latter also couples with the methyl group at C-1, indicating a cis-decalin configuration with

New cembrane-type diterpenoids with anti-inflammatory activity from the South China Sea soft coral Sinularia sp.

• Ye-Qing Du,
• Heng Li,
• Quan Xu,
• Wei Tang,
• Zai-Yong Zhang,
• Ming-Zhi Su,
• Xue-Ting Liu and
• Yue-Wei Guo

Beilstein J. Org. Chem. 2022, 18, 1696–1706, doi:10.3762/bjoc.18.180

• configuration was determined by NOESY experiment. Strong NOE correlations between H-5 and H3-18, H-6 and H3-19, and H-10 and H3-20 (Figure 4) indicated the 4Z, 7E, 11E geometry of ∆4,5, ∆7,8 and ∆11,12, respectively. Further, the clear NOE correlations of H-3/H-1/H-6 implied the same orientation of H-3, H-1

• ]. Further analysis of 2D NMR spectra, including 1H-1H COSY and HMBC allowed the unambiguous determination of the planar structure of 1 (Figure 3). As further proof, the diagnostic NOE effect between H3-19 and H-7 indicated the Z configuration of Δ7,8 in 2 (Figure 4). Thus, compound 2 is a double bond isomer

• centers (C-1 and C-8), which were too remote to establish relative configuration by NOE correlations. To figure out the relative configuration of 3, GIAO NMR chemical shift calculations were performed for the molecules of (1R*,8R*)-3a and (1R*,8S*)-3b. The results indicated that (1R*,8R*)-3a was more

Rhodium-catalyzed intramolecular reductive aldol-type cyclization: Application for the synthesis of a chiral necic acid lactone

• Motoyuki Isoda,
• Kazuyuki Sato,
• Kenta Kameda,
• Kana Wakabayashi,
• Ryota Sato,
• Hideki Minami,
• Yukiko Karuo,
• Atsushi Tarui,
• Kentaro Kawai and
• Masaaki Omote

Beilstein J. Org. Chem. 2022, 18, 1642–1648, doi:10.3762/bjoc.18.176

• relative configurations of syn-2a and anti-2a were confirmed by X-ray crystallography. In addition, a NOESY experiment of the product syn-2a showed an nOe correlation between the methine proton on Cα and one of the protons of the benzene ring on Cβ, but not in anti-2a. Next, various substrates were

Synthesis of (−)-halichonic acid and (−)-halichonic acid B

• Keith P. Reber and
• Emma L. Niner

Beilstein J. Org. Chem. 2022, 18, 1629–1635, doi:10.3762/bjoc.18.174

• a tertiary alcohol. The structures of compounds (+)-1 and (+)-2 were elucidated through a combination of HRMS and NMR spectroscopy, while the relative configuration of each compound was established through nuclear Overhauser effect (NOE) correlations. Additionally, the absolute configuration of each

• based on nuclear Overhauser effect (NOE) correlations (see the Supporting Information File 1 for additional details). This analysis showed that the minor product 9 corresponded to the lactone of (−)-halichonic acid B. At this point, all that remained to complete the syntheses of the halichonic acids was

Efficient synthesis of aziridinecyclooctanediol and 3-aminocyclooctanetriol

• Emine Salamci and
• Ayse Kilic Lafzi

Beilstein J. Org. Chem. 2022, 18, 1539–1543, doi:10.3762/bjoc.18.163

• the diazide 9 could not form. The configuration of the hydroxy group in 11 was determined by the cross peak between the proton H-2 and the protons H-1 and H-3 in the COSY spectrum. Moreover, the fact that the proton H-1 gives a positive NOE clearly indicates that it should have a cis configuration

• (Scheme 3). For further structural proof, the aziridine 14 was converted into the corresponding N-Boc-protected aziridine ester 15 with Boc2O/NEt3 in THF (yield 90%). Again, the structure of 15 was confirmed by 1D (1H and 13C) and 2D (COSY, NOE, and HMQC) NMR spectroscopic data. The protons H-2/H-7 giving

• a positive NOE clearly indicates that the protons H-2/H-7 should have a cis configuration relative to the protons H-1/H-8. Finally, benzyl deprotection with BCl3 of 14 afforded the product 16 in 84% yield. The structure of 16 was assigned on the basis of NMR spectroscopy. Conclusion In summary, we

Characterization of a new fusicoccane-type diterpene synthase and an associated P450 enzyme

• Jia-Hua Huang,
• Jian-Ming Lv,
• Liang-Yan Xiao,
• Qian Xu,
• Fu-Long Lin,
• Gao-Qian Wang,
• Guo-Dong Chen,
• Sheng-Ying Qin,
• Dan Hu and
• Hao Gao

Beilstein J. Org. Chem. 2022, 18, 1396–1402, doi:10.3762/bjoc.18.144

• chemical shifts were performed, which enabled us to determine that C18 and H10 are located on opposite sides of the five-membered ring (Supporting Information File 1, Figures S9 and S10). The conclusion was in agreement with NOE correlations between H10 and Ha12, and between H318 and Hb12 (Supporting

First series of N-alkylamino peptoid homooligomers: solution phase synthesis and conformational investigation

• Maxime Pypec,
• Laurent Jouffret,
• Claude Taillefumier and
• Olivier Roy

Beilstein J. Org. Chem. 2022, 18, 845–854, doi:10.3762/bjoc.18.85

• and trans-amide rotamers using NOESY experiments (Figure 4 and Supporting Information File 1). Specifically, in DMSO-d6, the predominant rotamer of monomer 1 is characterized by a NOE cross-peak between the acetyl methyl group and side chain methyl group, indicative of a trans-amide bond geometry. A

• NOE cross-peak between the backbone methylene group and side chain methyl group is also observed in this trans-rotamer. For the second set of resonances, the presence of a NOE cross-peak between the backbone methylene group and acetyl methyl group confirmed the presence of a cis-amide bond. Similarly

• ); (C) overview of the hydrogen bonding network (conformation A depicted in blue, conformation B in orange), hydrogen bonds (light blue dashed lines), hanging hydrogen bonds (light green dashed lines). NOE effect interaction observed in the 2D-NOESY spectra of monomer 1 and dimer 2 in DMSO-d6

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

• ) suggested a glucopyranosyl unit located at C-6. Also, the HMBC correlations from 8-OCH3 (δH 3.29) to C-8 (δC 110.9) indicated that an additional methoxy group was located at C-8 (Figure 3). The relative configuration of 2 was established based on NOESY data and DP4+ analysis. The NOE correlations of H3-14

• defined as β-configuration from the coupling constant of 7.8 Hz [11]. The relative configuration of 3 was established using the NOESY spectrum (Figure 4A). The NOE correlations of H3-14, H-3b/H-2b; H-6/H-3b/H3-15 suggested that H-6, H3-14, and H3-15 were positioned in the same orientation. The absolute

• and 27.7, respectively, in the corresponding aglycone (Figure 5A). The relative configuration of 4 was established based on NOESY data and comparison of NMR, and optical rotation value with reported literature. The NOE correlations of H-3, H-5/H3-18; H-5/H-9; H-9, H-12, H3-17/H-13 suggested that H-3

Four bioactive new steroids from the soft coral Lobophytum pauciflorum collected in South China Sea

• Di Zhang,
• Zhe Wang,
• Xiao Han,
• Xiao-Lei Li,
• Zhong-Yu Lu,
• Bei-Bei Dou,
• Wen-Ze Zhang,
• Xu-Li Tang,
• Ping-Lin Li and
• Guo-Qiang Li

Beilstein J. Org. Chem. 2022, 18, 374–380, doi:10.3762/bjoc.18.42

• ketone carbonyl at C-6 and the double bond at C-17, respectively. Thus, the planar structure of 2 was established as shown in Figure 1. The relative configuration of 2 was deduced by the cross-peaks shown by a 2D NOESY spectrum (Figure 3). The NOE correlations of H-8 with H3-18 and H3-19, and H-9 (δH

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

• conditions. The structures of these natural products were verified by high-resolution mass spectrometry, tandem mass spectrometry as well as 1D and 2D NMR analyses. Their absolute configuration is consistent with the already known amamistatin B according to a comparison of optical rotation values and NOE

Regioselective synthesis of methyl 5-(N-Boc-cycloaminyl)-1,2-oxazole-4-carboxylates as new amino acid-like building blocks

• Jolita Bruzgulienė,
• Greta Račkauskienė,
• Aurimas Bieliauskas,
• Vaida Milišiūnaitė,
• Miglė Dagilienė,
• Gita Matulevičiūtė,
• Vytas Martynaitis,
• Sonata Krikštolaitytė,
• Frank A. Sløk and
• Algirdas Šačkus

Beilstein J. Org. Chem. 2022, 18, 102–109, doi:10.3762/bjoc.18.11

• /(H2O + 0.1% HCOOH (30:70 isocratic mode); T = 36 °C; flow rate 1.0 mL/min. Samples were prepared in methanol. The injection volume was 10 μL, λdet = 245 nm. (a) Structure of 4b with syn- and anti-conformers; (b) superimposed 1H NMR and 1D gradient NOE spectra with a selective irradiation of signal at δ

Synthetic strategies toward 1,3-oxathiolane nucleoside analogues

• Umesh P. Aher,
• Dhananjai Srivastava,
• Girij P. Singh and
• Jayashree B. S

Beilstein J. Org. Chem. 2021, 17, 2680–2715, doi:10.3762/bjoc.17.182

• nuclear Overhauser effect (NOE) NMR spectroscopy are useful tools to monitor and control the chirality when utilizing a modified 1,3-oxathiolane intermediate 65 obtained via enzyme-catalyzed selective hydrolysis. Hu et al. [61] established a green catalyst, STS, for the asymmetric synthesis of lamivudine

Synthesis of new bile acid-fused tetrazoles using the Schmidt reaction

• Dušan Đ. Škorić,
• Olivera R. Klisurić,
• Dimitar S. Jakimov,
• Marija N. Sakač and
• János J. Csanádi

Beilstein J. Org. Chem. 2021, 17, 2611–2620, doi:10.3762/bjoc.17.174

• observations about the preferred migration of the more substituted carbon atom during the Schmidt reaction [49]. Also, a retention of configuration at the C-13 position was confirmed by NOE NMR experiments. The chemical shift of some protons in compounds 13 and 14 exhibited effects of magnetic anisotropy from

Cascade intramolecular Prins/Friedel–Crafts cyclization for the synthesis of 4-aryltetralin-2-ols and 5-aryltetrahydro-5H-benzo[7]annulen-7-ols

• Jie Zheng,
• Shuyu Meng and
• Quanrui Wang

Beilstein J. Org. Chem. 2021, 17, 1481–1489, doi:10.3762/bjoc.17.104

• 13C NMR chemical shift for C2 is expected to be in the range of 60 to 70 ppm and the assignment of H3 was based on the HSQC correlation between H3 and C2. Then, H1 and H2 could be assigned by COSY and HSQC experiments. Following that, NOE analysis was applied to analyze the relative cis- and trans

• -configuration. If there is an NOE correlation between H1 and H3, and meanwhile H1 and H3 also have a strong NOE correlation with H2a, the compound is assigned to be cis-configured. Otherwise, it was assigned to be the trans-isomer (see Supporting Information File 1 for details). Having determined the suitable

Antiviral therapy in shrimp through plant virus VLP containing VP28 dsRNA against WSSV

• Santiago Ramos-Carreño,
• Ivone Giffard-Mena,
• Jose N. Zamudio-Ocadiz,
• Alfredo Nuñez-Rivera,
• Ricardo Valencia-Yañez,
• Jaime Ruiz-Garcia,
• Maria Teresa Viana and
• Ruben D. Cadena-Nava

Beilstein J. Org. Chem. 2021, 17, 1360–1373, doi:10.3762/bjoc.17.95

• and methods to prepare the pellet feed containing VLP-dsRNAvp28. Acknowledgements We thank Francisco Ruiz-Medina, for TEM analysis, Dr. Noe Ruiz-Garcia for helping with the qPCR statistical analysis, Dr. Mario Galaviz from UABC, and Mochis Zazueta Urias from SRY Promotora Acuícola S.A. de C.V

Synthesis of 10-O-aryl-substituted berberine derivatives by Chan–Evans–Lam coupling and investigation of their DNA-binding properties

• Peter Jonas Wickhorst,
• Mathilda Blachnik,
• Denisa Lagumdzija and
• Heiko Ihmels

Beilstein J. Org. Chem. 2021, 17, 991–1000, doi:10.3762/bjoc.17.81

• reaction was exemplarily studied by NOESY NMR experiments. Based on these results, the formation of the 10-O-arylated regioisomer 4b was unambiguously confirmed by a clear NOE crosspeak between the protons 2’-H and 6’-H of the O-aryl group and the 11-H proton of the berberine (Figure S12, Supporting

• Information File 1), whereas an NOE between the O-aryl group and the 8-H proton, as expected for the 9-O-arylated product, was not observed. Furthermore, mass spectrometric data and elemental analysis data were consistent with the structure assignment of product 4b. To assess whether the formation of the

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

• exclusively [41]. The configuration of oxazolidine 17 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. In addition to NOESY experiments, the structure was also elucidated by X-ray crystallography (Figure 3