Synthesis and characterisation of new antimalarial fluorinated triazolopyrazine compounds

• Kah Yean Lum,
• Jonathan M. White,
• Daniel J. G. Johnson,
• Vicky M. Avery and
• Rohan A. Davis

Beilstein J. Org. Chem. 2023, 19, 107–114, doi:10.3762/bjoc.19.11

• studies (Supporting Information File 1, S51, S52, and S54), which confirmed the structure assignment. Compounds 4–6 were known OSM compounds that displayed good selective activity with IC50 values of <1 µM [16][21], whereas 7–9 are new ether derivatives without a phenyl ring that were synthesised for SAR

• -ray crystallographic studies and confirmed the NMR-based structure assignment. Key COSY, HMBC, and ROESY correlations, and ORTEP drawing of compound 18 are shown in Figure 1. All compounds were tested for their antimalarial activity against P. falciparum 3D7 (chloroquine-sensitive strain) and Dd2

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

• 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

Diels–Alder reaction of β-fluoro-β-nitrostyrenes with cyclic dienes

• Savva A. Ponomarev,
• Roman V. Larkovich,
• Alexander S. Aldoshin,
• Andrey A. Tabolin,
• Sema L. Ioffe,
• Jonathan Groß,
• Till Opatz and
• Valentine G. Nenajdenko

Beilstein J. Org. Chem. 2021, 17, 283–292, doi:10.3762/bjoc.17.27

• and stereoisomers, respectively) 3d in 40% overall yield. Two pairs of regioisomers were partially separated by column chromatography with sufficiently slow elution and analyzed by 1H NMR spectroscopy. The structure assignment was made as depicted in Scheme 5. The structures of two pairs of

• react. The activation parameters of the reaction of nitrostyrene 1h with CPD were estimated. In addition, the synthetic utility of the norbornenes obtained was demonstrated. All the structures obtained in this work were elucidated by NMR spectroscopy and elemental analysis or HRMS. The structure

• assignment of norbornenes 2 by 1H (a) and NOE (b) NMR spectroscopy. 13C NMR spectrum of the mixture of exo- and endo-isomers of norbornene 2l. The predicted reaction pathway for the Diels–Alder reaction of nitrostyrene 1h with CPD is displayed. The path leading to the endo-2h isomer has a lower lying

Unexpected one-pot formation of the 1H-6a,8a-epiminotricyclopenta[a,c,e][8]annulene system from cyclopentanone, ammonia and dimethyl fumarate. Synthesis of highly strained polycyclic nitroxide and EPR study

• Sergey A. Dobrynin,
• Igor A. Kirilyuk,
• Yuri V. Gatilov,
• Andrey A. Kuzhelev,
• Olesya A. Krumkacheva,
• Matvey V. Fedin,
• Michael K. Bowman and
• Elena G. Bagryanskaya

Beilstein J. Org. Chem. 2019, 15, 2664–2670, doi:10.3762/bjoc.15.259

• dipole and dipolarophile (Figure 3). Nitroxide Oxidation of 1 with m-CPBA afforded the nitroxide 6 with 48% yield (Scheme 3). It is noteworthy that the oxidation of the amino group is accompanied by the stereospecific hydroxylation at position 4 of the 2,3,4,7-tetrahydroazepine ring. The structure

• assignment was based on the single-crystal X-ray analysis (Figure 4) and a possible mechanism for this hydroxylation is shown in Scheme 4. Oxidation of amines with peracids is known to proceed through oxoammonium cation formation [12]. The close proximity of this reactive group to the allyl hydrogen results

Synthesis of 1-azaspiro[4.4]nonan-1-oxyls via intramolecular 1,3-dipolar cycloaddition

• Yulia V. Khoroshunova,
• Denis A. Morozov,
• Andrey I. Taratayko,
• Polina D. Gladkikh,
• Yuri I. Glazachev and
• Igor A. Kirilyuk

Beilstein J. Org. Chem. 2019, 15, 2036–2042, doi:10.3762/bjoc.15.200

• 8a–c (racemic mixtures; Scheme 2). The structure assignment was performed on the basis of 1H and 13C NMR spectra and 1H,1H and 13C,1H correlations (see Supporting Information File 1); the spectral data are in agreement with the literature on similar systems [6]. To decrease the tarring, the reaction

A novel method for heterocyclic amide–thioamide transformations

• Walid Fathalla,
• Ibrahim A. I. Ali and
• Pavel Pazdera

Beilstein J. Org. Chem. 2017, 13, 174–181, doi:10.3762/bjoc.13.20

• ) as an excellent new thiating reagent in high yield, Scheme 1. The structure assignment of the prepared N-cyclohexyl dithiocarbamate cyclohexylammonium salt (2) is based on 1H and 13C NMR spectral and physicochemical analysis. The 1H NMR spectrum displays a broad singlet signal at 8.01 ppm associated

• reaction mixture was evapourated and ethanol was added successively to give the desired product C2. The structure assignment of the prepared heterocyclic thioamides C1–13 is based on 1H and 13C NMR spectral and physicochemical analyses. The 1H NMR spectrum of 2-(4-methoxyphenyl)quinazoline-4(3H)-thione (C5

Fates of imine intermediates in radical cyclizations of N-sulfonylindoles and ene-sulfonamides

• Hanmo Zhang,
• E. Ben Hay,
• Stephen J. Geib and
• Dennis P. Curran

Beilstein J. Org. Chem. 2015, 11, 1649–1655, doi:10.3762/bjoc.11.181

• ), and the crystal structure of 27 was solved to make the structure assignment ironclad. An ORTEP representation of this structure is shown in Figure 5. A likely pathway from 22 to 25 is shown in Figure 6. Radical cyclization and sulfonyl radical elimination give the imine 28, which then apparently

The chemical behavior of terminally tert-butylated polyolefins

• Dagmar Klein,
• Henning Hopf,
• Peter G. Jones,
• Ina Dix and
• Ralf Hänel

Beilstein J. Org. Chem. 2015, 11, 1246–1258, doi:10.3762/bjoc.11.139

• Information File 1) already hinted that the cycloadduct 37 had been produced; the structure assignment was confirmed by X-ray structural analysis. The structure of 37 involves two independent molecules, one of which is shown in Figure 4. The molecules are closely similar, with an rms deviation of only 0.09 Å

Five-membered ring annelation in [2.2]paracyclophanes by aldol condensation

• Henning Hopf,
• Swaminathan Vijay Narayanan and
• Peter G. Jones

Beilstein J. Org. Chem. 2014, 10, 2021–2026, doi:10.3762/bjoc.10.210

• , both at room temperature), only two of the possible six isomers (see above) are actually formed. To these we assign structures 12 and 15 (product ratio 30:70), i.e., the aldols are syn,endo,endo- and anti,endo,endo-isomers. For the former compound the structure assignment follows from single-crystal X

• the same type of distortions as discussed above for 12 (see Table 2). This result clearly confirms our previous structure assignment of 15 as an anti-isomer. Although structures 13 and 14 for the initial aldol products cannot be excluded from the dehydration experiment, this alternative seems unlikely

The preparation of several 1,2,3,4,5-functionalized cyclopentane derivatives

• André S. Kelch,
• Peter G. Jones,
• Ina Dix and
• Henning Hopf

Beilstein J. Org. Chem. 2013, 9, 1705–1712, doi:10.3762/bjoc.9.195

• the originally added solvent (by NMR analysis). The exact structure assignment of 30 is hampered by the fact that no pure isomer was available. We assume, however, that the isomeric composition is not changed by the LAH reduction (i.e. 4:1 as in the case of the esters 26/27). The signals for the cis

Polar reactions of acyclic conjugated bisallenes

• Reiner Stamm and
• Henning Hopf

Beilstein J. Org. Chem. 2013, 9, 36–48, doi:10.3762/bjoc.9.5

• structure assignment (see Supporting Information File 1). The oxidation of the sterically more shielded 12 was even slower than that of 11: after 3 days at room temperature only 47% of the substrate had reacted. According to spectroscopic analysis (see Supporting Information File 1) the ketone 47 had been

• valuable for structure assignment; they clearly show that the products obtained possess a conjugated triene chromophore. The formation of the monochlorides very likely proceeds via the carbocationic intermediates 49/50 and 52/53 (R = CH3). For the generation of the aromatic isomers of the substrate we

Stereoselective synthesis of trans-fused iridoid lactones and their identification in the parasitoid wasp Alloxysta victrix, Part II: Iridomyrmecins

• Robert Hilgraf,
• Nicole Zimmermann,
• Lutz Lehmann,
• Armin Tröger and
• Wittko Francke

Beilstein J. Org. Chem. 2012, 8, 1256–1264, doi:10.3762/bjoc.8.141

• following a strategy similar to our route leading to trans-fused dihydronepetalactones [1]. The realization of this task and the unambiguous structure assignment of the natural products Y and Z is subject of the present paper. Results and Discussion Upon coupled gas chromatography/mass spectrometry (GC/MS

• retention times between B and B' on the cyclodextrin column, the enantiomers could be well distinguished under the experimental conditions. Structure assignment of volatile components Y and Z in the parasitoid wasp Alloxysta victrix Comparison of mass spectra and GC retention times of synthetic

Chemo-enzymatic modification of poly-N-acetyllactosamine (LacNAc) oligomers and N,N-diacetyllactosamine (LacDiNAc) based on galactose oxidase treatment

• Christiane E. Kupper,
• Ruben R. Rosencrantz,
• Birgit Henßen,
• Helena Pelantová,
• Stephan Thönes,
• Anna Drozdová,
• Vladimir Křen and
• Lothar Elling

Beilstein J. Org. Chem. 2012, 8, 712–725, doi:10.3762/bjoc.8.80

• terminal C-6 and H-6 (87.98 and 4.861 ppm in 3a, 88.14 and 4.955 ppm in 3b) indicate the presence of a geminal diol (the hydrate was formed). The NMR structure assignment of 7a and 7b was achieved as described for the above-mentioned products 3a and 3b. The α,β-unsaturated aldehyde structure of compounds

Efficient syntheses of 25,26-dihydrodictyostatin and 25,26-dihydro-6-epi-dictyostatin, two potent new microtubule-stabilizing agents

• María Jiménez,
• Wei Zhu,
• Andreas Vogt,
• Billy W. Day and
• Dennis P. Curran

Beilstein J. Org. Chem. 2011, 7, 1372–1378, doi:10.3762/bjoc.7.161

• by Pettit and coworkers [5][6], its complete stereostructure was proposed by Paterson and Wright in 2004 [7]. The structure assignment phase was finalized in 2004 when total syntheses by Paterson and our group confirmed the assignment [8][9]. The two synthetic samples of dictyostatin provided

Functionalization of anthracene: A selective route to brominated 1,4-anthraquinones

• Kiymet Berkil Akar,
• Osman Cakmak,
• Orhan Büyükgüngör and
• Ertan Sahin

Beilstein J. Org. Chem. 2011, 7, 1036–1045, doi:10.3762/bjoc.7.118

•  2). The compounds were easily separated by column chromatography and are readily crystallizable materials. Structure assignment for compounds 10 and 11 was carried out by comparison with authentic compounds [1]. To elucidate the mechanistic details and to explore the origin of selectivity, we also

Rh-Catalyzed rearrangement of vinylcyclopropane to 1,3-diene units attached to N-heterocycles

• Franca M. Cordero,
• Carolina Vurchio,
• Stefano Cicchi,
• Armin de Meijere and
• Alberto Brandi

Beilstein J. Org. Chem. 2011, 7, 298–303, doi:10.3762/bjoc.7.39

• into 19 under the reaction conditions. However, in the absence of the catalyst, heating of diene 18 under otherwise identical conditions did not induce any isomerization of 18 to 19, which confirms that Rh also catalyzes the 1,5-hydrogen shift in 18. The structure assignment was easily made on the

Preparation and NMR spectra of four isomeric diformyl[2.2]paracyclophanes (cyclophanes 66)

• Ina Dix,
• Henning Hopf,
• Thota B. N. Satyanarayana and
• Ludger Ernst

Beilstein J. Org. Chem. 2010, 6, 932–937, doi:10.3762/bjoc.6.104

• , and were characterized by their spectroscopic data. The individual isomers can now be easily identified from their 1H NMR spectra even if only one of them is present. Keywords: cyclophanes; diformyl[2.2]paracyclophanes; layered compounds; NMR spectroscopy; structure assignment; Introduction

Comparison of zwitterionic N-alkylaminomethanesulfonic acids to related compounds in the Good buffer series

• Robert D. Long,
• Newton P. Hilliard Jr,
• Suneel A. Chhatre,
• Tatiana V. Timofeeva,
• Andrey A. Yakovenko,
• Daniel K. Dei and
• Enoch A. Mensah

Beilstein J. Org. Chem. 2010, 6, No. 31, doi:10.3762/bjoc.6.31

• = 4.8), 3.76 (4H, t, J = 4.8), 3.8 (2H, s); 13C NMR (125 MHz, D2O/TSP): δ 54.7 (t), 69.2 (t), 75.8 (s). Anal. Calcd for C5H11NO4S·0.5Na: C, 31.24%; H, 5.51%; N, 7.29%; Na, 5.98%; O, 33.30%; S, 16.68%. Found: C, 31.05%; H, 6.13%; N, 7.63%; S, 16.66%. Structure assignment supported by single crystal X-ray

• , t, J = 6.3), 3.81 (2H, s). 13C NMR (62.9 MHz, MeOD): δ 52.5, 54.0, 59.2, 60.7, 74.2. Anal. Calcd for C7H17N2NaO5S·H2O: C, 31.81%; H, 6.48%; N, 10.60%; Na, 8.70%; O, 30.27%; S, 12.13%. Found: C, 30.72%; H, 6.48%; N, 10.22%; S, 10.82%. Structure assignment supported by single crystal X-ray structure

Stereoselective synthesis of (2S,3S,4Z)-4-fluoro- 1,3-dihydroxy- 2-(octadecanoylamino)octadec- 4-ene, [(Z)-4-fluoroceramide], and its phase behavior at the air/water interface

• Gergana S. Nikolova and
• Günter Haufe

Beilstein J. Org. Chem. 2008, 4, No. 12, doi:10.3762/bjoc.4.12

• aldol reaction. Supporting Information Supporting Information File 32: General methods, synthesis of the compounds and spectroscopic structure assignment.

8-epi-Salvinorin B: crystal structure and affinity at the κ opioid receptor

• Thomas A. Munro,
• Katharine K. Duncan,
• Richard J. Staples,
• Wei Xu,
• Lee-Yuan Liu-Chen,
• Cécile Béguin,
• William A. Carlezon Jr. and
• Bruce M. Cohen

Beilstein J. Org. Chem. 2007, 3, No. 1, doi:10.1186/1860-5397-3-1

• later identified the byproduct mentioned above as 8-epi-diol 3.[15] Characterization data was given, but the basis of the structure assignment was not stated. The first structure elucidation of one of these compounds was of 8-epi-salvinorin A (1b).[16] The trans-diaxial H-8 coupling constant found in