Synthesis and properties of 6-alkynyl-5-aryluracils

• Ruben Manuel Figueira de Abreu,
• Till Brockmann,
• Alexander Villinger,
• Peter Ehlers and
• Peter Langer

Beilstein J. Org. Chem. 2024, 20, 898–911, doi:10.3762/bjoc.20.80

• of different functional groups was tested. The influence of different functional groups on the physical properties was studied by ultraviolet–visible (UV–vis) and fluorescence spectroscopy, providing new insights into the potential applications of uracil-based structures. Keywords: catalysis; cross

• . Applications and tolerance to a wide range of functional groups have been tested. Furthermore, their physical properties were analyzed by ultraviolet–visible and fluorescence spectroscopy. Results and Discussion Synthesis The synthetic strategy for the desired compounds is based on a four-step sequence

• synthesized by other methods and the single Suzuki reaction on uracil is well studied [42][69][70][71]. Physical properties The photophysical properties of selected derivatives were investigated by steady-state absorption and photoluminescence spectroscopy. The influence of the substitution pattern on the

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

• to cyclopentane skeleton, as well as its stereochemistry, was originally elucidated as 1' as shown in Figure 1, on the basis of detailed analysis of 1D and 2D NMR spectroscopy. Spiroviolene was also found to be produced by several bacterial strains harboring SvS homologs [6][7], as well as putative

Ortho-ester-substituted diaryliodonium salts enabled regioselective arylocyclization of naphthols toward 3,4-benzocoumarins

• Ke Jiang,
• Cheng Pan,
• Limin Wang,
• Hao-Yang Wang and
• Jianwei Han

Beilstein J. Org. Chem. 2024, 20, 841–851, doi:10.3762/bjoc.20.76

• reaction was performed in the presence of 10 mol % Cu(OTf)2 and 1.0 equivalent of K2CO3 in DCE at a temperature of 80 °C. To our delight, the reaction afforded 3,4-benzocoumarin 3aa in a 27% yield (Table 1, entry 1). The structure of 3aa was confirmed through NMR spectroscopy and mass spectra analysis

• isolated as stable solids, whose structures were fully characterized by NMR spectroscopy. As shown in Table 3, we utilized 2-naphthol and 1-naphthol as template substrates to react with various unsymmetrical 2-ester-substituted diaryliodonium salts. Remarkably, iodonium salts 2 proved to be versatile in

Synthesis of new representatives of A₃B-type carboranylporphyrins based on meso-tetra(pentafluorophenyl)porphyrin transformations

• Victoria M. Alpatova,
• Evgeny G. Rys,
• Elena G. Kononova and
• Valentina A. Ol'shevskaya

Beilstein J. Org. Chem. 2024, 20, 767–776, doi:10.3762/bjoc.20.70

• azide substituent in porphyrin 2 with SnCl2·2H2O in MeOH resulted in the formation of porphyrin amino-derivative 3 in 82% yield (Scheme 1). The molecular structures of compounds 2 and 3 were confirmed by a combination of NMR spectroscopy and mass spectrometry. Having synthesized porphyrins 2 and 3 we

• easily converted into hydrophilic charged entities by the protonation of the unsubstituted amino functionalities in their structure providing improved bioconjugation. Spectroscopic data All porphyrin conjugates were structurally characterized by IR, UV–vis, NMR spectroscopy, and mass spectrometry. The IR

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

• 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

Entry to new spiroheterocycles via tandem Rh(II)-catalyzed O–H insertion/base-promoted cyclization involving diazoarylidene succinimides

• Alexander Yanovich,
• Anastasia Vepreva,
• Ksenia Malkova,
• Grigory Kantin and
• Dmitry Dar’in

Beilstein J. Org. Chem. 2024, 20, 561–569, doi:10.3762/bjoc.20.48

• this protocol for spirocyclization and spiroheterocycle formation. The first step of the synthesis, the insertion of rhodium carbene into the O–H bond of 3-bromopropanol, was carried out under standard conditions in the presence of 0.05 mol % Rh2(esp)2 in dry DCM. 1H NMR spectroscopy was used to

• 1H NMR spectroscopy data, one of its components was the product of the migration of the double bond of the benzylidene fragment into the succinimide cycle – compound 22. Finally, a compound with a longer side chain 24, obtained from 2-(2-bromoethoxy)ethanol (23), underwent exclusively isomerization

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

• ], the signals of methine protons of E-isomers should be in the region of approximately 5.90 ppm [14]. Other IR, 1Н and 13С NMR spectroscopy and HRMS data confirming the structure of the synthesized compounds 1 and 2a–c are presented in Supporting Information File 2. Nonacylated compound 1 showed long

• 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

Switchable molecular tweezers: design and applications

• Pablo Msellem,
• Maksym Dekthiarenko,
• Nihal Hadj Seyd and
• Guillaume Vives

Beilstein J. Org. Chem. 2024, 20, 504–539, doi:10.3762/bjoc.20.45

• attached functional arms. The formation of new hydrogen bonds between -OMe groups and protonated pyridine stabilizes a "W"-shaped open conformation. The conformation switch can be easily followed by NMR spectroscopy in solution. Remarkably, the water-soluble tweezers 1, when functionalized with hydrophobic

• . Using the same architecture, the group explored the control of magnetic properties by the mechanical motion of the tweezers using Cu(II)–salphen complexes [43]. The magnetic properties of tweezers 13 were studied by EPR spectroscopy and SQUID magnetometry. In the open state, the large intramolecular

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

• pursuit are equally significant. One of the efficient approaches for finding new secondary metabolites from microorganisms is physicochemical (PC) screening. This approach involves the screening of the physicochemical properties of potential compounds, such as UV spectroscopy, mass spectrometry, and color

• ppm) in the 13C NMR spectra. Infrared (IR) spectroscopy was carried out using an FT-4600 Fourier transform infrared spectrometer (JASCO P-2200 Polarimeter, Japan). The UV spectra were measured using a SpectraMax QuickDrop micro-volume spectrophotometer (Molecular Devices, LLC., San Jose, USA) at

Synthesis of 2,2-difluoro-1,3-diketone and 2,2-difluoro-1,3-ketoester derivatives using fluorine gas

• Alexander S. Hampton,
• David R. W. Hodgson,
• Graham McDougald,
• Linhua Wang and
• Graham Sandford

Beilstein J. Org. Chem. 2024, 20, 460–469, doi:10.3762/bjoc.20.41

• gave no noticeable conversion on analysis by 19F NMR spectroscopy, and a large excess of fluorine led to formation of a dark brown tar from which no useful product could be isolated. On the bases of these failed attempts, coupled with our previous experiences with the DBM scaffold [16][17][36], we used

• product 3a so we next sought to optimize this process at a preparative scale by varying the reaction stoichiometry. We found that 2.3 equiv of fluorine and 1.1 equiv of quinuclidine gave 99% conversion of 1a with 2a and 3a being the only products observed by 19F NMR spectroscopy in a 16:120 ratio (see

• % isolated yield (Scheme 2) and the structure was confirmed by NMR spectroscopy and X-ray crystallography (Figure 1). To expand the substrate scope of this difluorination method, a range of DBM derivatives 1b–n was synthesized from para-substituted acetophenones, para-substituted benzoyl chlorides and

(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 allene resulted in the formation of (Z)-1,2-dibromo-1,1,4,4,4-pentafluorobut-2-ene (13) in 92% yield, which was isolated as a colorless liquid and fully characterized by NMR spectroscopy (Scheme 10). The 19F NMR spectrum showed two signals with the integrated intensity ratio 3:2, a doublet for a

Mechanisms for radical reactions initiating from N-hydroxyphthalimide esters

• Carlos R. Azpilcueta-Nicolas and
• Jean-Philip Lumb

Beilstein J. Org. Chem. 2024, 20, 346–378, doi:10.3762/bjoc.20.35

• ). Importantly, electron paramagnetic resonance (EPR) spectroscopy at 25 °C supported the formation of species 107. However, NMR measurements at −40 °C showed the accumulation of BiIII complex 131, which can be prepared separately in a stoichiometric experiment. As such, two different pathways may lead to the C

Facile approach to N,O,S-heteropentacycles via condensation of sterically crowded 3H-phenoxazin-3-one with ortho-substituted anilines

• Eugeny Ivakhnenko,
• Vasily Malay,
• Pavel Knyazev,
• Nikita Merezhko,
• Nadezhda Makarova,
• Oleg Demidov,
• Gennady Borodkin,
• Andrey Starikov and
• Vladimir Minkin

Beilstein J. Org. Chem. 2024, 20, 336–345, doi:10.3762/bjoc.20.34

• short-term heating of the melted reactants at 220–250 °C is described, and the compounds were characterized by means of single-crystal X-ray crystallography, NMR, UV–vis, and IR spectroscopy, as well as cyclic voltammetry. The reaction with o-amino-, o-hydroxy-, and o-mercapto-substituted arylamines

• reaction products as 12H-quinoxaline[2,3-b]phenoxazines was confirmed through DFT calculations, X-ray crystallography, and NMR spectroscopy. Electronic absorption spectra (Table 2 and Figures 5–7) and electrochemical properties (Table 3) of the heteropentacyclic compounds 4a–h, 5a–c, 6a,b, and 10c revealed

• 15N NMR spectroscopy (NMR spectra of compounds 4a–h, 5a–c, 6a,b, and 10c are given in Figures S13–S43, Supporting Information File 1), mass spectrometry (Figures S44–S56, Supporting Information File 1), IR and UV–vis spectroscopy, as well as elemental analysis. The NMR spectra were recorded on the

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

• complex of 1 with α-CD. Interatomic distances within the host–guest complex were measured using rotating-frame nuclear Overhauser effect spectroscopy (ROESY) measurements. For the complex of 1 with α-CD, the cross-peak in the 2D ROESY spectrum between proton 5 of the glucose moiety of the host α-CD and

Elucidating the glycan-binding specificity and structure of Cucumis melo agglutinin, a new R-type lectin

• Jon Lundstrøm,
• Emilie Gillon,
• Valérie Chazalet,
• Nicole Kerekes,
• Antonio Di Maio,
• Ten Feizi,
• Yan Liu,
• Annabelle Varrot and
• Daniel Bojar

Beilstein J. Org. Chem. 2024, 20, 306–320, doi:10.3762/bjoc.20.31

• ) spectroscopy to derive binding constants for the interaction between CMA1 and GalNAc. A single cycle kinetics approach was applied, resulting in a measured KD of 1.66 ± 0.08 µM (Figure 3d,e). Inhibiting binding of CMA1 to the GalNAc chip through a dilution series of N-acetyllactosamine (LacNAc) via multicycle

• raised by 1 °C/min from 25 to 100 °C, and fluorescence readings were taken at each step. Surface plasmon resonance spectroscopy Experiments were performed using a Biacore X100 instrument (Cytiva) at 25 °C in HBS-T running buffer (10 mM HEPES pH 7.4, 150 mM NaCl and 0.05% Tween 20). Biotinylated PAA

Synthesis of π-conjugated polycyclic compounds by late-stage extrusion of chalcogen fragments

• Aissam Okba,
• Pablo Simón Marqués,
• Kyohei Matsuo,
• Naoki Aratani,
• Hiroko Yamada,
• Gwénaël Rapenne and
• Claire Kammerer

Beilstein J. Org. Chem. 2024, 20, 287–305, doi:10.3762/bjoc.20.30

• using a high-pressure mercury lamp equipped with a sharp cut filter (λ > 380 nm), which resulted in a smooth conversion into the PBI product 6a within 20 min. Interestingly, the sulfoxide derivative exhibited enhanced kinetics, as confirmed by UV–vis spectroscopy and NMR experiments. The latter was also

• ” is particularly interesting, since the as-prepared π-extended structures can undergo in-depth structural characterization and electronic investigations in situ at the single molecule scale, thanks to scanning probe microscopy and spectroscopy. The synthetic route relying on O-extrusion was thus

Unveiling the regioselectivity of rhodium(I)-catalyzed [2 + 2 + 2] cycloaddition reactions for open-cage C₇₀ production

• Cristina Castanyer,
• Anna Pla-Quintana,
• Anna Roglans,
• Albert Artigas and
• Miquel Solà

Beilstein J. Org. Chem. 2024, 20, 272–279, doi:10.3762/bjoc.20.28

• we analyzed by UV–vis spectroscopy. This peak was assigned as a bis(fulleroid) compound by comparing the spectra with the UV–vis absorption pattern exhibited by previously characterized C70 bis(fulleroids) reported by Murata et al. [43][48]. In addition, a minor peak at a retention time of 20 minutes

• column chromatography, giving an inseparable mixture of different isomers. The oxygenation process was confirmed by HRMS, which gave a single peak at m/z = 1170.0756 corresponding to [3a + Na]+. On analyzing carefully the mixture by 1H NMR spectroscopy, we observed three different sets of three methyl

Additive-controlled chemoselective inter-/intramolecular hydroamination via electrochemical PCET process

• Kazuhiro Okamoto,
• Naoki Shida and
• Mahito Atobe

Beilstein J. Org. Chem. 2024, 20, 264–271, doi:10.3762/bjoc.20.27

• in vacuo and the resulting residue was subjected to 1H NMR spectroscopy or column chromatography. A divided-cell experiment was performed using an H-type cell (4G glass filter). Compound 1 (0.2 mmol), Bu4NPF6 (387 mg, 1 mmol), phosphate base (90 mg, 0.2 mmol), CH2Cl2 (10 mL), and methyl vinyl ketone

• was removed by filtration through a short silica gel pad under reduced pressure. The filtrate was concentrated in vacuo and the resulting residue was subjected to 1H NMR spectroscopy or column chromatography. Application of amidyl radical species generated by PCET. (A) Effect of phosphate base on the

Substitution reactions in the acenaphthene analog of quino[7,8-h]quinoline and an unusual synthesis of the corresponding acenaphthylenes by tele-elimination

• Ekaterina V. Kolupaeva,
• Narek A. Dzhangiryan,
• Alexander F. Pozharskii,
• Oleg P. Demidov and
• Valery A. Ozeryanskii

Beilstein J. Org. Chem. 2024, 20, 243–253, doi:10.3762/bjoc.20.24

• nitrobenzene. For example, quinoquinoline 5 reacts with chloranil upon heating in toluene to give a dark brown, high-melting product, in which, however, the methylene bridge remains unchanged. According to 1H NMR spectroscopy and combustion analysis data, this is complex 9 with a composition close to the ratio

• /data_request/cif. Supporting Information File 14: Additional experimental and XRD information, synthetic procedures, copies of NMR spectral data for new compounds. Acknowledgements We thank the Scientific and Educational Laboratory of Resonance Spectroscopy (Department of Natural and High Molecular Compounds

Photochromic derivatives of indigo: historical overview of development, challenges and applications

• Gökhan Kaplan,
• Zeynel Seferoğlu and
• Daria V. Berdnikova

Beilstein J. Org. Chem. 2024, 20, 228–242, doi:10.3762/bjoc.20.23

• (λirr = 660 nm). The excited state dynamics of 18c was later studied in detail by Nagasawa and co-workers using femtosecond time-resolved transient absorption spectroscopy [44]. In 2022, Qiao and co-workers attempted to extend the thermal relaxation half-life of compound 18c by addition of cations such

• the Z-isomers in comparison with the E-forms [62]. In 2018, Nagasawa and co-workers provided a detailed investigation of the influence of solvent polarity and intermolecular hydrogen bonding on the photoisomerization of N,N'-diacetylindigo (9a) by transient absorption spectroscopy [63]. In principle

• -donating group, 19a) to 6.8 h (in the presence of electron-withdrawing group, 19f) depending on the effect of the substituents in the aryl groups. Further insights into the photoisomerization mechanism of N,N'-diarylindigos were provided in 2022 using steady-state and time-resolved spectroscopy experiments

Chiral phosphoric acid-catalyzed transfer hydrogenation of 3,3-difluoro-3H-indoles

• Yumei Wang,
• Guangzhu Wang,
• Yanping Zhu and
• Kaiwu Dong

Beilstein J. Org. Chem. 2024, 20, 205–211, doi:10.3762/bjoc.20.20

• spectroscopy and the ee values were determined by chiral HPLC. Structures of bioactive fluorinated indole derivatives. Proposed mechanism for the transfer hydrogenation reaction. Synthesis of chiral indolines via asymmetric reduction. Substrate scope of 3,3-difluoro-3H-indoles. Experiment at 2 mmol scale

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

• treated with 90% aq trifluoroacetic acid in CH2Cl2 to give diol 7 (70% yield) that was formed due to migration of a chloroacetyl group from O-7 to O-9. The structure of diol 7 was established by NMR spectroscopy, high-resolution mass spectrometry and X-ray diffraction analysis (see the Experimental

• CFCl3 (δF 0.0). Assignments of the signals in the NMR spectra were performed using 2D-spectroscopy (COSY, HSQC, HMBC) and DEPT-135 experiments. For the copies of NMR spectra for all new compounds see Supporting Information File 1. High resolution mass spectra (electrospray ionization, HRESIMS) were

• cotton wool plug and concentrated under reduced pressure. The residue was dried in vacuo, dissolved in toluene (2 mL) and separated by gel permeation chromatography on a Bio-Beads S-X3 column (toluene). The first eluted fraction contained disaccharides 4, which was analyzed by NMR spectroscopy to give

Perspectives on push–pull chromophores derived from click-type [2 + 2] cycloaddition–retroelectrocyclization reactions of electron-rich alkynes and electron-deficient alkenes

• Michio Yamada

Beilstein J. Org. Chem. 2024, 20, 125–154, doi:10.3762/bjoc.20.13

• 1H nuclear magnetic resonance (NMR) spectroscopy. Their investigation revealed that the product plays a pivotal role as an autocatalyst in the kinetics, as illustrated in Scheme 8 [104][105][106]. The traditional model posits that an alkyne (A) and TCNE (designated as B in Scheme 8) initially form a

• manner, ultimately affording 27 with 90% yield. The formation of intermediates 24, 25, and 26 was elucidated through 1H NMR analysis, of which 24 and 26 were successfully isolated and characterized. A comprehensive analysis of the [2 + 2] CA–RE reaction activation parameters via 1H NMR spectroscopy

• ) [142]. In these conjugates, the push–pull chromophores and the C60 unit were effectively spatially isolated from each other – a feat achieved through the strategic incorporation of a pyrrolidine ring as the connecting bridge. Thorough examinations via steady-state fluorescence spectroscopy in toluene

Photoinduced in situ generation of DNA-targeting ligands: DNA-binding and DNA-photodamaging properties of benzo[c]quinolizinium ions

• Julika Schlosser,
• Olga Fedorova,
• Yuri Fedorov and
• Heiko Ihmels

Beilstein J. Org. Chem. 2024, 20, 101–117, doi:10.3762/bjoc.20.11

• the amine 2b gave the corresponding amide 2g in 28% yield. The chloro-substituted derivative 2e was synthesized in a Sandmeyer-reaction from 2b in 20% yield. The products 2a–g were identified and fully characterized by NMR spectroscopy (1H, 13C, COSY, HSQC, and HMBC), elemental analyses, and mass

• because of their low water solubility. The styrylpyridine derivatives 2a–g were irradiated in oxygen-saturated solutions in MeCN, H2O, MeOH, or MeCN/H2O with a high-pressure Hg lamp (λ > 220 nm), and the course of the photocyclization reaction was monitored by absorption spectroscopy (Figure 2). In

• within the binding site. The binding mode of the benzo[c]quinolizinium derivatives 3c,e–g with DNA was further examined with circular dichroism (CD) and linear dichroism (LD) spectroscopy (Figure 6 and Supporting Information File 1, Figures S12–S14). Hence, with increasing ligand-DNA ratio (LDR) weak

Optimizing reaction conditions for the light-driven hydrogen evolution in a loop photoreactor

• Pengcheng Li,
• Daniel Kowalczyk,
• Johannes Liessem,
• Mohamed M. Elnagar,
• Dariusz Mitoraj,
• Radim Beranek and
• Dirk Ziegenbalg

Beilstein J. Org. Chem. 2024, 20, 74–91, doi:10.3762/bjoc.20.9

• photocatalyst is referred to as Pt-PCN. The surface morphology, chemical composition, and elemental distribution of the Pt-PCN were analyzed using a ZEISS LEO 1550 VP scanning electron microscope (SEM) equipped with energy dispersive spectroscopy (EDS) from Ametek, USA. The SEM was operated at an acceleration