Using the phospha-Michael reaction for making phosphonium phenolate zwitterions

• Matthias R. Steiner,
• Max Schmallegger,
• Larissa Donner,
• Johann A. Hlina,
• Christoph Marschner,
• Judith Baumgartner and
• Christian Slugovc

Beilstein J. Org. Chem. 2024, 20, 41–51, doi:10.3762/bjoc.20.6

• = 3.9 Hz) [30]. Compared to the parent phosphine 1 (155.9 ppm, 2JPC = 19.3 Hz) [35] a pronounced down-field shift occurred upon adduct formation, which suggests a considerable contribution of a quinonic resonance structure as benzoquinones exhibit 13C NMR shifts of about 188 ppm and hydroquinones of

Chemistry of polyhalogenated nitrobutadienes, 17: Efficient synthesis of persubstituted chloroquinolinyl-1H-pyrazoles and evaluation of their antimalarial, anti-SARS-CoV-2, antibacterial, and cytotoxic activities

• Viktor A. Zapol’skii,
• Isabell Berneburg,
• Ursula Bilitewski,
• Melissa Dillenberger,
• Katja Becker,
• Stefan Jungwirth,
• Aditya Shekhar,
• Bastian Krueger and
• Dieter E. Kaufmann

Beilstein J. Org. Chem. 2022, 18, 524–532, doi:10.3762/bjoc.18.54

• ring system in the dienes 4a,l–o (Scheme 4). The obtained 5-aminopyrazoles 5a,l–o show the following 13C NMR shifts of the pyrazole ring and the dichloromethyl group: 149.5–149.9 ppm (C-NHR), 114.7–116.1 ppm (C-NO2), 147.0–147.2 ppm (C=N), and 62.2–62.3 ppm (CHCl2). On the other hand, the dienes 4b–k

• the butadiene chain is more likely due to the possibility of a rotation around the C1–C2 bond in 4b–k. The 3-aminopyrazoles 5b–k show considerable differences of the 13C shifts of C-NO2-, C-CHCl2- and CHCl2-groups in comparison with the corresponding 13C shifts of 5-aminopyrazoles 5a,l–o. The 13C NMR

• shifts of the pyrazole ring and the dichloromethyl group of 3-aminopyrazoles 5b–k are 151.1–154.0 ppm (C-NRR1), 120.6–122.2 ppm (C-NO2), 136.7–136.9 ppm (C-CHCl2), and 57.5–57.7 ppm (CHCl2). The obtained 13C NMR data of pyrazoles 5 match the calculated NMR shifts (Table S1 in Supporting Information File

1,2,3-Triazoles as leaving groups: S_NAr reactions of 2,6-bistriazolylpurines with O- and C-nucleophiles

• Dace Cīrule,
• Irina Novosjolova,
• Ērika Bizdēna and
• Māris Turks

Beilstein J. Org. Chem. 2021, 17, 410–419, doi:10.3762/bjoc.17.37

• 2205 cm−1 for product 5c. These results differ from the absorption in the range of 2260–2240 cm−1, which would be characteristic for a cyano group attached to sp3-hybridized carbon [82]. On the other hand, 13C NMR shifts of the C(2’’) position of purine–malononitrile conjugate 5a and ethyl cyanoacetate

Mesoionic tetrazolium-5-aminides: Synthesis, molecular and crystal structures, UV–vis spectra, and DFT calculations

• Vladislav A. Budevich,
• Sergei V. Voitekhovich,
• Alexander V. Zuraev,
• Vadim E. Matulis,
• Vitaly E. Matulis,
• Alexander S. Lyakhov,
• Ludmila S. Ivashkevich and
• Oleg A. Ivashkevich

Beilstein J. Org. Chem. 2021, 17, 385–395, doi:10.3762/bjoc.17.34

• and 12b: 161.1 and 151.9 ppm for compound 12a and 153.2 and 151.1 ppm for compound 12b. It is known that the 13C NMR shifts for the endocyclic C5 atom in 2,5-disubstituted tetrazoles is located downfield (162–167 ppm and 151.9 ppm for 2-methyl-5H-tetrazole) from the corresponding signal of the 1,5

Cation-induced ring-opening and oxidation reaction of photoreluctant spirooxazine–quinolizinium conjugates

• Phil M. Pithan,
• Sören Steup and
• Heiko Ihmels

Beilstein J. Org. Chem. 2020, 16, 904–916, doi:10.3762/bjoc.16.82

• ). Moreover, the 13C NMR signal of C2’ also exhibited a downfield shift from δC = 100.7 to 170.8. Thereby, both the 1H and the 13C NMR shifts of the indolinium–naphthoxazole unit were in good agreement with the reported ones of similar derivatives [17][73][74][75][76]. At the same time, the addition of 2

New terpenoids from the fermentation broth of the edible mushroom Cyclocybe aegerita

• Frank Surup,
• Florian Hennicke,
• Nadine Sella,
• Maria Stroot,
• Steffen Bernecker,
• Sebastian Pfütze,
• Marc Stadler and
• Martin Rühl

Beilstein J. Org. Chem. 2019, 15, 1000–1007, doi:10.3762/bjoc.15.98

• -H3 and 1-Hb indicated methyl C-12 being on the opposite site of the molecular plane as 2-H and 9-H. This assignment was confirmed by the comparison of the 13C NMR shifts to pasteurestin A and B [6][7]. Since the absolute stereochemistry has been demonstrated for pasteurestins A and B by total

Nucleofugal behavior of a β-shielded α-cyanovinyl carbanion

• Rudolf Knorr and
• Barbara Schmidt

Beilstein J. Org. Chem. 2018, 14, 3018–3024, doi:10.3762/bjoc.14.281

• performed with methyllithium or methylmagnesium bromide and gas-volumetric control of the liberated methane (ca. 25 mL/mmol at 22 °C). All 1H and 13C NMR shifts δ were referenced with internal Me4Si. NMR abbreviations were as follows: d = doublet, m = multiplet, q = quartet, quat = quaternary, s = singlet

Secondary metabolome and its defensive role in the aeolidoidean Phyllodesmium longicirrum, (Gastropoda, Heterobranchia, Nudibranchia)

• Alexander Bogdanov,
• Cora Hertzer,
• Stefan Kehraus,
• Samuel Nietzer,
• Sven Rohde,
• Peter J. Schupp,
• Heike Wägele and
• Gabriele M. König

Beilstein J. Org. Chem. 2017, 13, 502–519, doi:10.3762/bjoc.13.50

• the bulky substituents on ring D. NOE correlations were observed between α-oriented H-14 and H-17 demonstrating β-orientation of the gorgosterol side chain. 13C NMR shifts for the carbons of the side chain (C-20 to C-30: δC 36.3, 21.4, 33.3, 26.9, 52.2, 33.4, 22.7, 21.9, 15.8, 14.7, 22.2) were almost

• downfield resonances resulting from the lack of a carbon–carbon double bond. Instead, two characteristic 13C NMR shifts at δC 66.4 and 62.3, attributable to an epoxide moiety were present. 13C NMR data of 12 and the specific optical rotation were identical with those reported by Bowden et al. [37], ([α]D20

• 13C NMR resonance of C-30 was shifted downfield to δC 82.1 compared with the reported value of δC 69.2 for the same carbon in bisglaucumlide B (24). The 13C NMR shift of the methyl group CH3-38 was more shielded (δC 16.6) than the reported resonance (δC 20.0) for 24. The 13C NMR shifts of C-2 and C-21

Pyridinoacridine alkaloids of marine origin: NMR and MS spectral data, synthesis, biosynthesis and biological activity

• Louis P. Sandjo,
• Victor Kuete and
• Maique W. Biavatti

Beilstein J. Org. Chem. 2015, 11, 1667–1699, doi:10.3762/bjoc.11.183

• are also discussed. Pyridoacridines were found to have a large spectrum of bioactivity and this review highlights and compares the pharmacophores that are responsible for the observed bioactivity. Keywords: biosynthesis; 13C NMR shifts; pharmacophores; pyridoacridines; synthesis; Introduction In

Dipolar addition to cyclic vinyl sulfones leading to dual conformation tricycles

• Steven S. Y. Wong,
• Michael G. Brant,
• Christopher Barr,
• Allen G. Oliver and
• Jeremy E. Wulff

Beilstein J. Org. Chem. 2013, 9, 1419–1425, doi:10.3762/bjoc.9.159

• conformers, we calculated the 13C NMR shifts for our geometry-optimized structures, and compared these to the shifts obtained experimentally for the two conformations (Table 2). These agreed exceptionally well for those carbons not connected to the sulfone (relativistic effects were not well handled by our

Triterpenoid saponins from the roots of Acanthophyllum gypsophiloides Regel

• Elena A. Khatuntseva,
• Vladimir M. Men’shov,
• Alexander S. Shashkov,
• Yury E. Tsvetkov,
• Rodion N. Stepanenko,
• Raymonda Ya. Vlasenko,
• Elvira E. Shults,
• Genrikh A. Tolstikov,
• Tatjana G. Tolstikova,
• Dimitri S. Baev,
• Vasiliy A. Kaledin,
• Nelli A. Popova,
• Valeriy P. Nikolin,
• Pavel P. Laktionov,
• Anna V. Cherepanova,
• Tatiana V. Kulakovskaya,
• Ekaterina V. Kulakovskaya and
• Nikolay E. Nifantiev

Beilstein J. Org. Chem. 2012, 8, 763–775, doi:10.3762/bjoc.8.87

• NMR (Table 2) spectra of 1 and 2. Furthermore, the presence of these aglycons was unambiguously confirmed by the good agreement between 13C NMR shifts of aglycon moieties of 1 and 2 and signals of aglycons for described bidesmosides comprising quillaic acid [21] and gypsogenin [21]. Analysis of COSY

Highly substituted benzannulated cyclooctanol derivatives by samarium diiodide-induced cyclizations

• Jakub Saadi,
• Irene Brüdgam and
• Hans-Ulrich Reissig

Beilstein J. Org. Chem. 2010, 6, 1229–1245, doi:10.3762/bjoc.6.141

• constrained and rigid, can be formed only when carboxyl and hydroxyl groups are at the same face of the eight-membered ring (Figure 1). This analysis was further supported by high similarity of NMR-spectroscopic data (1H and 13C NMR shifts and relative signal patterns) with those of compound 17a and at the

Synthesis of spiroannulated and 3-arylated 1,2,4-trioxanes from mesitylol and methyl 4-hydroxytiglate by photooxygenation and peroxyacetalization

• Axel G. Griesbeck,
• Lars-Oliver Höinck and
• Jörg M. Neudörfl

Beilstein J. Org. Chem. 2010, 6, No. 61, doi:10.3762/bjoc.6.61

• connecting C-3 and C-6. In Table 3 the yields of the peroxyacetalization reactions, the characteristic 13C NMR shifts of the peracetal carbon C-3 and two significant bond lengths are listed. It is clear that the electronic nature of the substituent on the aryl group does not significantly change the bond