Structure–property relationships in dicyanopyrazinoquinoxalines and their hydrogen-bonding-capable dihydropyrazinoquinoxalinedione derivatives

• Tural N. Akhmedov,
• Ajeet Kumar,
• Daken J. Starkenburg,
• Kyle J. Chesney,
• Khalil A. Abboud,
• Novruz G. Akhmedov,
• Jiangeng Xue and
• Ronald K. Castellano

Beilstein J. Org. Chem. 2024, 20, 1037–1052, doi:10.3762/bjoc.20.92

• , 230−400 mesh from Whatman. Routine 300(75) MHz 1H(13C) NMR spectra were recorded on Varian Mercury 300 or Gemini 300 spectrometers. Routine 500(125) MHz 1H(13C) NMR were recorded on an INOVA 500 spectrometer. 2D NMR spectra were recorded using a 600 MHz Varian instrument. Chemical shifts (δ) are given

• amounts of CH2Cl2 and THF (10 mL), and dried in vacuo to afford a bright orange solid of 1a (0.264 g, 1.14 mmol, 89%). 1H NMR (600 MHz, DMSO-d6) δ 8.30–8.31 (dd, J = 3 Hz, J = 6.6 Hz, 2H), 8.49–8.51 (dd, J = 3 Hz, J = 6.6 Hz, 2H); 13C NMR (150 MHz, DMSO-d6) δ 114.5, 130.4, 136.1, 136.2, 142.7, 147.4; HRMS

• (s, 6H), 8.27 (s, 2H); 13C NMR (125 MHz, DMSO-d6) δ 20.1, 114.2, 127.8, 134.6, 142.3, 146.6, 148.7. The proton NMR in chloroform matches the literature value [25]; HRMS (DART): [M + H]+ calcd for C14H8N6, 261.0883; found, 261.0889; [M + NH4]+, 278.1149; found, 278.1154. Aceanthryleno[1,2-b]pyrazino

One-pot Ugi-azide and Heck reactions for the synthesis of heterocyclic systems containing tetrazole and 1,2,3,4-tetrahydroisoquinoline

• Jiawei Niu,
• Yuhui Wang,
• Shenghu Yan,
• Yue Zhang,
• Xiaoming Ma,
• Qiang Zhang and
• Wei Zhang

Beilstein J. Org. Chem. 2024, 20, 912–920, doi:10.3762/bjoc.20.81

• and 13C NMR, and HRMS analysis. In addition, single crystals of compound 6d and 8c were obtained for X-ray analysis to confirm the structures (Figure 2). Conclusion In conclusion, we have developed a one-pot synthesis with two or three steps for making tetrazolo-pyrazino[2,1-a]isoquinolin-6(5H)-ones

Skeletal rearrangement of 6,8-dioxabicyclo[3.2.1]octan-4-ols promoted by thionyl chloride or Appel conditions

• Martyn Jevric,
• Julian Klepp,
• Johannes Puschnig,
• Oscar Lamb,
• Christopher J. Sumby and
• Ben W. Greatrex

Beilstein J. Org. Chem. 2024, 20, 823–829, doi:10.3762/bjoc.20.74

• separated by 0.21 ppm. In the 13C NMR spectrum of 11a–f, a ≈10 ppm upfield shift for the chloroacetal was seen to δ ≈92 ppm from the C5 acetal present in the starting materials. Only a single diastereomer was formed for all 3,3-disubstituted rearrangement products due to the hindrance on the endo-face, with

• open chain aldehydes present in solution (≈5%) with a doublet at δ 9.6 ppm, with the configuration of the hemiacetal centre confirmed in the solid state by X-ray crystallography on 12a and 12d. The 1H and 13C NMR spectra for 13b,d,e were similar to the starting materials, except that the resonances

• spectra. Supporting Information File 12: 1H and 13C NMR FIDs, HRMS spectra for all new compounds. Funding JP was supported by an Australian Government Research Training Program Scholarship and the Destination Australia Program.

Discovery and biosynthesis of bacterial drimane-type sesquiterpenoids from Streptomyces clavuligerus

• Dongxu Zhang,
• Wenyu Du,
• Xingming Pan,
• Xiaoxu Lin,
• Fang-Ru Li,
• Qingling Wang,
• Qian Yang,
• Hui-Min Xu and
• Liao-Bin Dong

Beilstein J. Org. Chem. 2024, 20, 815–822, doi:10.3762/bjoc.20.73

• mainly elucidated through comparative 1H and 13C NMR spectra and by comparing analytical data with existing literature reports [28][29] (see Supporting Information File 1, Figures S1–S7). The 1H NMR spectrum of compound 2 exhibited characteristic signals for one olefinic proton at δH (5.48) and four

• comparing the 1H and 13C NMR data with the literature (Figures S11 and S12 in Supporting Information File 1) [41]. Although the chemical structure of compound 8 has been documented, its 1H and 13C NMR data were not fully reported [42]. Therefore, we conducted comprehensive 1D and 2D NMR experiments on it

• differences in 13C NMR (ΔδC = 3.3) (Figures S19–S25, Supporting Information File 1) [43]. Moreover, the key correlation observed between H5 and H7 in the ROESY spectrum provides additional support for the β-configuration of this hydroxy group (Figure S26 and Table S7 in Supporting Information File 1). These

Synthesis and characterization of water-soluble C₆₀–peptide conjugates

• Yue Ma,
• Lorenzo Persi and
• Yoko Yamakoshi

Beilstein J. Org. Chem. 2024, 20, 777–786, doi:10.3762/bjoc.20.71

• most other solvents. C60–oligo-Lys and C60–oligo-Glu were characterized by 1H and 13C NMR. Photoinduced 1O2 generation was observed in the most soluble C60–oligo-Lys conjugate under visible light irradiation (527 nm) to show the potential of this highly water-soluble molecule in biological systems, for

• part (α, β, γ, δ, and ε). The observed splitting of the protons a and b was presumably due to a diastereotopic effect of the methine proton c, similar to the spectrum of the monoadduct. Figure 6a shows the 13C NMR spectra of 5a in D2O and of the monoadduct in CDCl3. Together with the 1H NMR, COSY, HSQC

• –peptide conjugate 5a in D2O (above) and of the precursor monoadduct in CDCl3 (bottom) at 600 MHz. 13C NMR spectrum of C60–peptide conjugate 5a in D2O and of the precursor monoadduct in CDCl3 at 150 MHz (a) and expansion of the sp2 carbon region (b). The asterisks in (a) correspond to a TFA impurity

Substrate specificity of a ketosynthase domain involved in bacillaene biosynthesis

• Zhiyong Yin and
• Jeroen S. Dickschat

Beilstein J. Org. Chem. 2024, 20, 734–740, doi:10.3762/bjoc.20.67

• glutamate decarboxylase, and incubated with BaeJ-KS2. Substrate binding was demonstrated through 13C NMR analysis of the products against the background of various control experiments. Keywords: bacillaene; biosynthesis; enzyme mechanisms; isotopes; trans-AT polyketide synthases; Introduction Polyketides

• conjunction with 13C NMR to investigate substrate acceptance by BaeJ-KS2 from module 4 of the bacillaene PKS. Results and Discussion Synthesis of N-acetylcysteamine thioesters Previous studies have shown that N-acetylcysteamine thioesters (SNAC esters) can be uploaded to KS domains [22][23][24][25]. Therefore

• performed to eliminate any unreacted free 11 in the reaction mixture. The resulting protein preparations were subsequently analysed by 13C NMR spectroscopy. While the signal for the thioester carbonyl group of free 11 dissolved in incubation buffer was observed at δ = 203.33 ppm (Figure 1A), for both

Genome mining of labdane-related diterpenoids: Discovery of the two-enzyme pathway leading to (−)-sandaracopimaradiene in the fungus Arthrinium sacchari

• Fumito Sato,
• Terutaka Sonohara,
• Shunta Fujiki,
• Akihiro Sugawara,
• Yohei Morishita,
• Taro Ozaki and
• Teigo Asai

Beilstein J. Org. Chem. 2024, 20, 714–720, doi:10.3762/bjoc.20.65

• HREIMS spectrum. The 1H and 13C NMR spectra of 1 were identical to those of sandaracopimaradiene [30][31]. As the specific rotation of compound 1 was in good agreement with the reported data ([α]D24 −14.3 (c 0.97, CHCl3) in this study; [α]D25 −10.29 (c 0.65, CHCl3) in the literature [31]), compound 1 was

New variochelins from soil-isolated Variovorax sp. H002

• Jabal Rahmat Haedar,
• Aya Yoshimura and
• Toshiyuki Wakimoto

Beilstein J. Org. Chem. 2024, 20, 692–700, doi:10.3762/bjoc.20.63

• from 1. The 1H NMR spectrum showed additional olefinic proton signals at δH 5.35, as compared with that of 1. In line with this, two sp2 carbon signals at δC 130.6 and 131.0 were detected in the 13C NMR spectrum, demonstrating the presence of an olefin in 4. The comparative analysis of the MS/MS

• phase for 30 minutes to yield variochelins A (1, 10.0 mg), B (2, 20.1 mg), C (3, 3.0 mg), D (4, 2.1 mg), and E (5, 5.3 mg). Variochelin A (1) HRESIMS m/z: [M − 2H]2−, calcd for C47H83O17N11, 535.7911; found, 535.7912, Δ 0.2 ppm for C47H83O17N11; −7.5, (c 1.78, MeOH), 1H and 13C NMR chemical shifts see

• Table S1 (Supporting Information File 1). Variochelin B (2) HRESIMS m/z: [M − H]− calcd for C49H87O17N11, 1100.6209; found, 1100.6218, Δ 0.8 ppm for; C49H87O17N11; −11.1, (c 0.23, MeOH), 1H and 13C NMR chemical shifts see Table S1 (Supporting Information File 1). Variochelin C (3) HRESIMS m/z: [M − H

Evaluation of the enantioselectivity of new chiral ligands based on imidazolidin-4-one derivatives

• Jan Bartáček,
• Karel Chlumský,
• Jan Mrkvička,
• Lucie Paloušová,
• Miloš Sedlák and
• Pavel Drabina

Beilstein J. Org. Chem. 2024, 20, 684–691, doi:10.3762/bjoc.20.62

• catalysed by copper(II) complex of ligand IV. Asymmetric aldol reactions of various aldehydes with ketones catalysed by compound IV. Supporting Information Supporting Information File 62: General information and experimental data of prepared compounds, copies of 1H and 13C NMR spectra and DFT calculations

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

• by the higher HOMO level of 3 compared to that of 4. The products were characterized by spectroscopic and spectrometric analyses (Figures S3–S11 in Supporting Information File 1). 1H, and 13C NMR spectra clearly indicated the formation of [2 + 2] monoadducts. 7Li NMR spectra showed a sharp singlet

• Hz, 3H), 3.88 (s, 3H), 5.07 (qd, J = 6.9 8.7 Hz, 1H), 5.38 (d, J = 8.7 Hz, 1H), 7.12 (d, J = 8.7 Hz, 2H), 7.92 (d, J = 8.8 Hz, 2H); 13C NMR (100 MHz, CD2Cl2) δ 19.83, 47.39, 55.80, 58.72, 70.58, 73.03, 115.10, 119.84 (q, JCF = 320 Hz, CF3), 129.96, 130.56, 136.89, 136.93, 139.24, 139.66, 140.23

• filtration. 1H NMR (700 MHz, CD2Cl2) δ 3.87 (s, 3H), 4.59 (dd, J = 10.8 Hz, 13.8 Hz, 1H), 4.69 (dd, J = 8.6 Hz, 13.8 Hz, 1H), 5.89 (dd, J = 8.6, 10.7 Hz, 1H), 7.12 (d, J = 8.8 Hz, 2H), 7.95 (d, J = 8.7 Hz, 2H); 13C NMR (176 MHz, CD2Cl2) δ 37.94, 49.75, 55.65, 64.70, 74.90, 114.85, 120.07 (q, JCF = 321 Hz

Isolation and structure determination of a new analog of polycavernosides from marine Okeania sp. cyanobacterium

• Kairi Umeda,
• Naoaki Kurisawa,
• Ghulam Jeelani,
• Tomoyoshi Nozaki,
• Kiyotake Suenaga and
• Arihiro Iwasaki

Beilstein J. Org. Chem. 2024, 20, 645–652, doi:10.3762/bjoc.20.57

• geometry of the remaining double bond at C-18 was established to be trans by comparing the 13C NMR chemical shifts at C-16 and C-21 between 1 and polycavernoside D (5) (Table S1 in Supporting Information File 1) [5]. In addition, a 4J long-range coupling between δH 1.95 (H-26) and δH 2.18 (H-24) and three

• (100 MHz). 1H NMR chemical shifts (referenced to the residual solvent signal of CHD2OD: δ 3.31, CHCl3: δ 7.26) were assigned using a combination of data from COSY and HMQC experiments. Similarly, 13C NMR chemical shifts (referenced to the solvent signal CD3OD: δ 49.0, CDCl3: δ 77.16) were assigned

Production of non-natural 5-methylorsellinate-derived meroterpenoids in Aspergillus oryzae

• Jia Tang,
• Yixiang Zhang and
• Yudai Matsuda

Beilstein J. Org. Chem. 2024, 20, 638–644, doi:10.3762/bjoc.20.56

• ). After large-scale cultivation, 3 was isolated and subjected to nuclear magnetic resonance (NMR) analysis, which suggested that 3 is the C-5′ desmethyl form of preterretonin A [17]. However, several missing signals in the 13C NMR spectrum, likely due to keto–enol tautomerization in the D-ring, hindered

HPW-Catalyzed environmentally benign approach to imidazo[1,2-a]pyridines

• Luan A. Martinho and
• Carlos Kleber Z. Andrade

Beilstein J. Org. Chem. 2024, 20, 628–637, doi:10.3762/bjoc.20.55

• reproducible. Unsuccessful substrates for these reactions were also detected (Scheme 4). The use of 2-amino-3-hydroxypyridine provided a complex mixture of products (1H and 13C NMR analysis). When 6-amino-2-thiouracil was used, only the starting materials were recovered. Regarding the aldehyde component, the

Chemical and biosynthetic potential of Penicillium shentong XL-F41

• Ran Zou,
• Xin Li,
• Xiaochen Chen,
• Yue-Wei Guo and
• Baofu Xu

Beilstein J. Org. Chem. 2024, 20, 597–606, doi:10.3762/bjoc.20.52

• m/z 341.1862 [M − H]− (calcd for C20H25N2O3, 341.1870). Spectroscopic analysis, including 1H NMR, 13C NMR (Table 1), and DEPT, revealed that compound 1 contains three methyl groups, one of which is oxygenated, four methines, three saturated non-protonated carbons, and two ketone carbonyl carbons (δC

• substructure at C-14 with a methine at C-16, indicated by the methoxy group. The position of the methoxy substituent was established by HMBC correlations, and the 13C NMR data suggested that compound 1 includes a 4-oxo-2,3-dihydro-(1H)-quinolin-3-yl fragment. The planar structure was established from HMBC

• 335.1719 [M + Na]+ (calcd for C19H24N2O2Na+, 335.1730) and m/z 311.1755 [M − H]− (calcd for C19H23N2O2, 311.1765). Spectroscopic analysis using 1H NMR, 13C NMR, and DEPT (Table 2) indicated that compound 2 comprises two methyl groups, five methines, five saturated non-protonated carbons, and one ketone

Synthesis of photo- and ionochromic N-acylated 2-(aminomethylene)benzo[b]thiophene-3(2Н)-ones with a terminal phenanthroline group

• Vladimir P. Rybalkin,
• Sofiya Yu. Zmeeva,
• Lidiya L. Popova,
• Irina V. Dubonosova,
• Olga Yu. Karlutova,
• Oleg P. Demidov,
• Alexander D. Dubonosov and
• Vladimir A. Bren

Beilstein J. Org. Chem. 2024, 20, 552–560, doi:10.3762/bjoc.20.47

• were isolated preparatively and fully characterized by IR, 1H, and 13C NMR spectroscopy as well as HRMS and XRD methods. The reverse thermal reaction was catalyzed by protonic acids. N-Acylated compounds exclusively with Fe2+ formed nonfluorescent complexes with a contrast naked-eye effect: a color

• products 3a–c were comprehensively characterized by IR, 1Н and 13C NMR spectroscopy, HRMS (Supporting Information File 2) as well as by X-ray diffraction analysis. The molecular structure of 3b is shown in Figure 3. The crystal data, details of the data collection and refinements for 3b as well as complete

• reaction occurred catalytically in the presence of HClO4. A special technique for the preparative synthesis of photoproducts was developed. For the first time in the course of studying N→O acylotropic migrations, O-acylated photoproducts were comprehensively characterized by IR, 1H and 13C NMR spectroscopy

Synthesis and biological profile of 2,3-dihydro[1,3]thiazolo[4,5-b]pyridines, a novel class of acyl-ACP thioesterase inhibitors

• Jens Frackenpohl,
• David M. Barber,
• Guido Bojack,
• Birgit Bollenbach-Wahl,
• Ralf Braun,
• Rahel Getachew,
• Sabine Hohmann,
• Kwang-Yoon Ko,
• Karoline Kurowski,
• Bernd Laber,
• Rebecca L. Mattison,
• Thomas Müller,
• Anna M. Reingruber,
• Dirk Schmutzler and
• Andrea Svejda

Beilstein J. Org. Chem. 2024, 20, 540–551, doi:10.3762/bjoc.20.46

• ) to afford 6-bromo-5-(2-fluorophenyl)-2,3-dihydro[1,3]thiazolo[4,5-b]pyridine (13b, 596 mg, 59%). 1H NMR (600 MHz, CDCl3, δ) 4.56 (s, 2H), 6.88 (br s, 1H), 7.11–7.16 (m, 1H), 7.21 (td, J = 7.5; 1.1 Hz, 1H), 7.31 (s, 1H), 7.34 (td, J = 7.4; 1.9 Hz, 1H), 7.36–7.41 (m, 1H); 13C NMR (151 MHz, CDCl3, δ

• ), 7.07 (s, 1H), 7.09–7.12 (m, 1H), 7.19–7.21 (m, 1H), 7.32–7.36 (m, 2H); 13C NMR (151 MHz, CDCl3, δ) 17.96 (CH3), 17.99 (CH3), 48.8 (CH2), 115.6 (CH), 115.7 (CH), 121.0 (C), 121.8 (C), 124.15 (CH), 124.18 (CH), 129.59 (CH), 129.64 (CH), 130.2 (CH), 131.40 (CH), 131.43 (CH), 145.6 (C), 158.9 (C), 159.2 (C

• (m, 2H); 13C NMR (151 MHz, CDCl3, δ) 18.41 (CH3), 18.44 (CH3), 24.7 (CH3), 49.3 (CH2), 115.7 (CH), 115.8 (CH), 124.09 (CH), 124.12 (CH), 125.2 (C), 127.8 (C), 129.9 (CH), 130.0 (CH), 131.37 (CH), 131.40 (CH), 132.1 (CH), 147.0 (C), 149.6 (C), 158.9 (C), 160.6 (C), 170.6 (C); HRESIMS (m/z): [M + H

A new analog of dihydroxybenzoic acid from Saccharopolyspora sp. KR21-0001

• Rattiya Janthanom,
• Yuta Kikuchi,
• Hiroki Kanto,
• Tomoyasu Hirose,
• Arisu Tahara,
• Takahiro Ishii,
• Arinthip Thamchaipenet and
• Yuki Inahashi

Beilstein J. Org. Chem. 2024, 20, 497–503, doi:10.3762/bjoc.20.44

• determined as C12H13NO7S (requiring seven degrees of unsaturation) from the [M + H]+ ion at m/z 316.0484 (calcd. for C12H14NO7S, 316.0485) by HRESIMS. The 1H and 13C NMR spectral data of 1 are listed in Table 1. The 1H NMR and heteronuclear single quantum coherence (HSQC) data indicated the presence of two

• sp2 methines, one sp3 methine, one sp3 methylene, and one methyl group. The 13C NMR data showed the resonances of twelve carbons, which were classified into six olefinic carbons (including two oxygenated carbons: δC 151.0 and 145.2), three carbonyl carbons, one sp3 methine carbon, one sp3 methylene

• of 0.5 mL·min−1 and gradient elution with MeOH/H2O with 0.1% FA. Structure elucidation Spectra from 1H NMR at 500 MHz and 13C NMR at 125 MHz were measured in CD3OD using a JNM-ECA500 (JEOL Ltd., Tokyo Japan). Chemical shifts were referenced to CD3OD (3.31 ppm) in the 1H NMR spectra and CD3OD (49.0

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

• )], four aliphatic methylenes, four methines (with two oxygenated and one olefinic), and four exchangeable protons. The 13C NMR spectroscopic data (Table 1) displayed all 16 resonances which were classified by DEPT experiments into the categories of four methyls (including one methoxy), four methylenes

• should be mentioned that compound 3 was the first sulfur-containing ovalicin sesquiterpenoid, which was previously isolated from Sporothrix sp. FO-4649, but its absolute configuration was not explicitly represented, and their 1H and 13C NMR data were incomplete [10]. Thus, a full assignment of the NMR

• –6.10). Then, compound 2 (13.7 mg) was isolated by CC on Si gel (CH2Cl2/MeOH, 250:1 to 50:1) and preparative TLC (plate: 20 × 20 cm, developing solvent: ether/acetone 2:1) from Fr. 6.3 (578 mg). Pseudallene A (1): colorless crystals (MeOH); mp 115–117 °C; [α]D25 +20.0 (c 0.4, MeOH); 1H and 13C NMR data

(E,Z)-1,1,1,4,4,4-Hexafluorobut-2-enes: hydrofluoroolefins halogenation/dehydrohalogenation cascade to reach new fluorinated allene

• Nataliia V. Kirij,
• Andrey A. Filatov,
• Yurii L. Yagupolskii,
• Sheng Peng and
• Lee Sprague

Beilstein J. Org. Chem. 2024, 20, 452–459, doi:10.3762/bjoc.20.40

• of stereoisomers in 2:1 ratio. After isolation by distillation, 2,3-dibromo-1,1,1,4,4,4-hexafluorobutane (2) was characterized by 1H, 19F, 13C NMR and mass spectra. We studied the reaction of dibromoalkane 2 with various bases such as DBU, Hünig’s base (iPr2NEt), and potassium hydroxide (Table 1). In

• obtained by us fully correspond to the literature data [19][20]. The 1H and 19F NMR spectra of compounds 7a,b also corresponded to the data given in the literature [21][22]. We present here the spectral data for isomer 6a, as well as the missing data of 13C NMR spectra for iodoolefins 7a,b. It should be

• 11 had an allene structure. It was also important to note that the reaction proceeded more selectively in ether, which significantly reduced the amount of byproducts. Pure final alcohol 10 was isolated by column chromatography on SiO2 in 46% yield and 1H, 19F and 13C NMR spectra were in full

Mono or double Pd-catalyzed C–H bond functionalization for the annulative π-extension of 1,8-dibromonaphthalene: a one pot access to fluoranthene derivatives

• Nahed Ketata,
• Linhao Liu,
• Ridha Ben Salem and
• Henri Doucet

Beilstein J. Org. Chem. 2024, 20, 427–435, doi:10.3762/bjoc.20.37

• from Acros. KOPiv (95%) was purchased from Doug Discovery. These compounds were not purified before use. All reagents were weighed and handled in air. All reactions were carried out under an inert atmosphere with standard Schlenk techniques. 1H, 19F and 13C NMR spectra were recorded on Bruker Avance

• data of synthesized compounds. Supporting Information File 44: Copies of 1H, 19F, and 13C NMR spectra. Acknowledgements We are grateful to Dr. Elsa Caytan for NMR experiments. Part of this work has been performed using the PRISM core facility (Biogenouest, Univ Rennes, Univ Angers, INRAE, CNRS, FRANCE

Spatial arrangements of cyclodextrin host–guest complexes in solution studied by ¹³C NMR and molecular modelling

• Konstantin Lebedinskiy,
• Ivan Barvík,
• Zdeněk Tošner,
• Ivana Císařová,
• Jindřich Jindřich and
• Radim Hrdina

Beilstein J. Org. Chem. 2024, 20, 331–335, doi:10.3762/bjoc.20.33

• 2026/5, 121 16 Praha, Czech Republic Department of Inorganic Chemistry, Faculty of Science, Charles University, Hlavova 8, 128 43 Praha, Czech Republic 10.3762/bjoc.20.33 Abstract 13C NMR spectroscopic analyses of Cs symmetric guest molecules in the cyclodextrin host cavity, combined with molecular

• signals in 13C NMR spectra. This signal split can be correlated to the distance of the guest atoms from the wall of the host cavity and to the spatial separation of binding sites preferred by pairs of prochiral carbon atoms. These measurements complement traditional solid-state analyses, which rely on the

• crystallization of host–guest complexes and their crystallographic analysis. Keywords: anisotropy; 13C NMR; cyclodextrin; host–guest complexes; Introduction Complexation of organic and inorganic compounds with α-, β-, or γ-cyclodextrins and their derivatives [1] is an established tool used in medicine for drug

Discovery of unguisin J, a new cyclic peptide from Aspergillus heteromorphus CBS 117.55, and phylogeny-based bioinformatic analysis of UngA NRPS domains

• Sharmila Neupane,
• Marcelo Rodrigues de Amorim and
• Elizabeth Skellam

Beilstein J. Org. Chem. 2024, 20, 321–330, doi:10.3762/bjoc.20.32

• compound 1 was elucidated by 1D and 2D NMR and HRESIMS/MS. Unguisin B was identified by the 1H and 13C NMR data with the reported data [1][5]. Compound 1 was obtained as a white amorphous solid optically active, with +23.4 (c 0.1, MeOH). Its molecular formula was established as C41H56N8O7 by HRMS ([M + H

• . The 1H and 13C NMR spectra of 1 revealed the presence of seven amide NH signals between δH 7.43 and 8.44 ppm supported by the amide carbonyl signals at δC 173.1, 172.6, 172.6, 172.1, 172.1, 171.1 and 171.0 ppm (Table 1). An additional NH signal at δH 10.82 ppm and four aromatic signals at δH 7.50

• powder, +37 (c 0.1, EtOH) [lit +40 (c 1.0, EtOH)] [5]; for the 1H and 13C NMR spectroscopic data, see Table S2 in Supporting Information File 1. By comparison with literature data this compound was identified as unguisin B (2) [1][5], further corroborating the identification of the new unguisin J (1

Synthesis of spiropyridazine-benzosultams by the [4 + 2] annulation reaction of 3-substituted benzoisothiazole 1,1-dioxides with 1,2-diaza-1,3-dienes

• Wenqing Hao,
• Long Wang,
• Jinlei Zhang,
• Dawei Teng and
• Guorui Cao

Beilstein J. Org. Chem. 2024, 20, 280–286, doi:10.3762/bjoc.20.29

• investigated the performance of other organic and inorganic bases, but they did not improve the yield (Table 1, entries 8–12). The structure of spiropyridazine-benzosultam 3aa was determined by 1H NMR, 13C NMR, HRMS analysis and single-crystal X-ray crystallography [33]. Further experiments conducted with

Metal-catalyzed coupling/carbonylative cyclizations for accessing dibenzodiazepinones: an expedient route to clozapine and other drugs

• Amina Moutayakine and
• Anthony J. Burke

Beilstein J. Org. Chem. 2024, 20, 193–204, doi:10.3762/bjoc.20.19

• = 8 Hz, Ar, 1H), 6.79–6.83 (t, J = 8 Hz, Ar, 1H), 6.85–6.87 (d, J = 8 Hz, Ar, 1H), 7.09–7.13 (m, Ar, 3H), 7.49–7.51 (d, J = 8 Hz, Ar, 1H); 13C NMR (CDCl3, 100 MHz) δ 110.42, 114.41, 116.47, 119.48, 119.70, 127.00, 127.04, 128.39, 132.62, 142.45, 143.03; HRESIMS (m/z): [M + H+] calcd for C12H11BrN2

• °C; 1H NMR (DMSO-d6, 400 MHz) δ 6.87–7.00 (m, Ar, 6H), 7.31–7.35 (t, J = 8 Hz, Ar, 1H), 7.66–7.68 (d, J = 8 Hz, Ar,1H), 7.84 (s, Ar, 1H), 9.85 (s, Ar, 1H); 13C NMR (CDCl3, 100 MHz) δ 119.52, 120.23, 121.17, 121.73, 123.24, 123.40, 124.95, 130.29, 132.56, 133.67, 140.43, 150.92, 168.40; ESIMS (m/z

Comparison of glycosyl donors: a supramer approach

• Anna V. Orlova,
• Nelly N. Malysheva,
• Maria V. Panova,
• Nikita M. Podvalnyy,
• Michael G. Medvedev and
• Leonid O. Kononov

Beilstein J. Org. Chem. 2024, 20, 181–192, doi:10.3762/bjoc.20.18

• = 11.7, J4,5 = 10.3, J4,3e = 4.8, 1H, H-4), 7.27 (d, JNH,5 = 9.9, 1H, NH), 7.33–7.49 (m, 5H, Ph); 13C NMR (75 MHz, CDCl3, δ, ppm, J, Hz) 37.0 (C-3), 40.1 (CH2Cl), 40.3 (CH2Cl), 49.8 (C-5), 53.1 (OMe), 62.5 (C-9), 70.1 (C-4), 71.5, 71.8 (C-6, C-7), 75.5 (C-8), 88.2 (C-2), 114.1 (q, JC,F = 285, CF3), 114.2

• ); 13C NMR (75 MHz, CDCl3, δ, ppm, J, Hz) 25.0 (Me), 26.2 (Me), 37.7 (C-3), 40.3 (CH2Cl), 40.6 (CH2Cl), 50.2 (C-5), 52.7 (OMe), 65.2 (C-9), 70.5 (C-4), 70.7 (C-7), 71.2 (C-6), 74.7 (C-8), 88.7 (C-2), 108.6 (CMe2), 115.3 (q, JC,F = 288, CF3), 128.5, 129.0, 130.2, 136.1 (Ph), 157.8 (q, JC,F = 38, COCF3

• –7.42 (m, 1H, p-Ph), 7.61–7.63 (m, 2H, o-Ph), 8.74 (d, JNH,5 = 8.1 Hz, 1H, NH); 13C NMR (151 MHz, acetone-d6, δ, ppm, J, Hz) 38.2 (C-3), 41.5 (CH2Cl), 41.8 (CH2Cl), 50.9 (C-5), 52.7 (OMe), 69.0 (C-9), 69.4 (C-8), 70.2 (C-7), 71.8 (C-4), 72.3 (C-6), 90.3 (C-2), 117.0 (q, JC,F = 288, CF3), 129.8, 130.6