Evaluating the halogen bonding strength of a iodoloisoxazolium(III) salt

• Dominik L. Reinhard,
• Anna Schmidt,
• Marc Sons,
• Julian Wolf,
• Elric Engelage and
• Stefan M. Huber

Beilstein J. Org. Chem. 2024, 20, 2401–2407, doi:10.3762/bjoc.20.204

• )AuCl was applied with a catalyst loading of 2 mol %, activated by an equal amount of the DAI salt. Due to solubility issues, the reaction had to be performed in methylene chloride instead of chloroform. The gold-catalyzed cyclization reaction (Scheme 2) was followed via 1H NMR spectroscopy (Figure 3

• ]. For all catalyst systems, decomposition of the −BArF24 anion was observed via 1H and 19F NMR spectroscopy, which is known to happen in the presence of activated gold complexes [29]. The stability of the DAI cations was checked with 1H NMR: the characteristic doublets belonging to the respective

Efficient one-step synthesis of diarylacetic acids by electrochemical direct carboxylation of diarylmethanol compounds in DMSO

• Hisanori Senboku and
• Mizuki Hayama

Beilstein J. Org. Chem. 2024, 20, 2392–2400, doi:10.3762/bjoc.20.203

• proton in triphenylmethane (3, Scheme 4, bottom). Further, the yield was determined to be 67% by 1H NMR spectroscopy. These results indicated that the triphenylmethyl anion species generated by electroreductive C(sp3)–O bond cleavage acted not as nucleophile toward carbon dioxide but as base, performing

• MgSO4. Evaporation of the solvent gave a residue that was analyzed by 1H NMR spectroscopy, during which 1,4-dinitrobenzene was used as an internal standard for quantification of the substances. The products diphenylacetic acid (2a) [30][31], (4-methylphenyl)phenylacetic acid (2d) [32], (4-methoxyphenyl

Synthesis, electrochemical properties, and antioxidant activity of sterically hindered catechols with 1,3,4-oxadiazole, 1,2,4-triazole, thiazole or pyridine fragments

• Daria A. Burmistrova,
• Andrey Galustyan,
• Nadezhda P. Pomortseva,
• Kristina D. Pashaeva,
• Maxim V. Arsenyev,
• Oleg P. Demidov,
• Mikhail A. Kiskin,
• Andrey I. Poddel’sky,
• Nadezhda T. Berberova and
• Ivan V. Smolyaninov

Beilstein J. Org. Chem. 2024, 20, 2378–2391, doi:10.3762/bjoc.20.202

• , compounds 6–9 are products of alkylation of the nitrogen atom of the heterocycle. Thiones 6–9 were obtained in 40–79% yield (Scheme 1,b). The structures of synthesized compounds were confirmed by the spectral methods IR-, 1H NMR, 13C{1H} NMR spectroscopy (Figures S1–S18 in Supporting Information File 1

Asymmetric organocatalytic synthesis of chiral homoallylic amines

• Nikolay S. Kondratyev and
• Andrei V. Malkov

Beilstein J. Org. Chem. 2024, 20, 2349–2377, doi:10.3762/bjoc.20.201

• active catalytic species in COBI-catalysed allylations, chemical equilibria in a solution containing catalyst 72, triflic acid, and aldimine 73 were investigated by low-temperature NMR spectroscopy (Scheme 15). Protonation of oxazaborolidine 70 with triflic acid resulted in an 8.3:1 mixture of 71 and 72

Tandem diazotization/cyclization approach for the synthesis of a fused 1,2,3-triazinone-furazan/furoxan heterocyclic system

• Yuri A. Sidunets,
• Valeriya G. Melekhina and
• Leonid L. Fershtat

Beilstein J. Org. Chem. 2024, 20, 2342–2348, doi:10.3762/bjoc.20.200

• , indicating that the developed tandem protocol does not depend on the presence of the N-oxide moiety in the parent heterocycle. All synthesized triazinones 1 and 7 were fully characterized by IR, 1H and 13C NMR spectroscopy, and high-resolution mass spectrometry. The structure of compounds 1b and 7h was

Synthesis and reactivity of the di(9-anthryl)methyl radical

• Tomohiko Nishiuchi,
• Kazuma Takahashi,
• Yuta Makihara and
• Takashi Kubo

Beilstein J. Org. Chem. 2024, 20, 2254–2260, doi:10.3762/bjoc.20.193

• spectroscopy under ambient conditions. The CV of DAntM species showed a reversible wave at E1/2 = −0.20 V (V vs Fc/Fc+) (Figure 5a) [39]. This redox potential is close to that of TAntM radical and cation [17]. Additionally, at a scan rate of 0.1 V s−1, the current peak intensity on the anodic side (from

Metal-free double azide addition to strained alkynes of an octadehydrodibenzo[12]annulene derivative with electron-withdrawing substituents

• Naoki Takeda,
• Shuichi Akasaka,
• Susumu Kawauchi and
• Tsuyoshi Michinobu

Beilstein J. Org. Chem. 2024, 20, 2234–2241, doi:10.3762/bjoc.20.191

• . Chemical shifts of NMR were reported in ppm relative to the residual solvent peak at 7.26 ppm for 1H NMR spectroscopy and 77.6 ppm for 13C NMR spectroscopy. Coupling constants (J) were given in Hz. The resonance multiplicity was described as s (singlet), t (triplet), and m (multiplet). FTIR spectra were

Selective hydrolysis of α-oxo ketene N,S-acetals in water: switchable aqueous synthesis of β-keto thioesters and β-keto amides

• Haifeng Yu,
• Wanting Zhang,
• Xuejing Cui,
• Zida Liu,
• Xifu Zhang and
• Xiaobo Zhao

Beilstein J. Org. Chem. 2024, 20, 2225–2233, doi:10.3762/bjoc.20.190

• by other acids such as H2SO4 and CF3SO3H, the reaction showed poor effectiveness due to the poor solubility of 1a in water (Table 1, entries 4 and 5). Most notably, 2a was an inseparable mixture of keto and enol isomers, reaching a keto/enol ratio of 5:4 as determined by 1H NMR spectroscopy. Thus

• . Reaction conditions A: 1 (0.25 mmol), DBSA (87.9 mg, 0.25 mmol), H2O (1 mL), reflux, 5 h. Isolated yield is stated. Keto/enol ratio of 2 was determined by 1H NMR spectroscopy. Synthesis of β-keto amides 3. Reaction conditions B: 1 (0.25 mmol), NaOH (0.75 mmol, 30 mg), H2O (1 mL), reflux, 24 h. Isolated

• yield is stated. Keto/enol ratio of 3 was determined by 1H NMR spectroscopy. Gram-scale hydrolysis reactions of 1a. Proposed mechanism for formation of β-keto thioesters 2 and β-keto amides 3. Optimization of the reaction conditions. EcoScale calculations and results for the synthesis of 2a and 3a [75

Electrochemical allylations in a deep eutectic solvent

• Sophia Taylor and
• Scott T. Handy

Beilstein J. Org. Chem. 2024, 20, 2217–2224, doi:10.3762/bjoc.20.189

• spectroscopy to determine that the deposited metal was tin, with traces of other metals consistent with the purity of the initial tin source. The tin recovery was 99% of the theoretical. To explore recycling of this recovered tin, 1 mmol was used in a 0.5 mmol scale allylation of anisaldehyde under the

• funnel with the aid of 10 mL of deionized (DI) water followed by 20 mL of diethyl ether. The organic layer was separated, dried with anhydrous magnesium sulfate, filtered, and the solvent removed in vacuo to afford the crude product, which was first analyzed by 1H NMR spectroscopy and then purified using

• sulfate, filtered, and the solvent removed in vacuo to afford the crude product, which was first analyzed by 1H NMR spectroscopy and then purified using flash column chromatography. The graphite electrodes were not polished in between reactions, but were rinsed with DI water and then acetone. General Sn

Natural resorcylic lactones derived from alternariol

• Joachim Podlech

Beilstein J. Org. Chem. 2024, 20, 2171–2207, doi:10.3762/bjoc.20.187

• from an unidentified endophytic fungus [124] and later from colletotrichum sp. [125], Lachnum abnorme [126], Diaporthe phragmitis [127] and a further D. sp. [128], and deviantly from the flower buds of the banana species Musa nana [129]. Its structure was determined by NMR spectroscopy [126] and

• -methoxylglucopyranoside] (5) was isolated from Alternaria alternata and its structure was determined by NMR spectroscopy. It showed no antibacterial activity [138]. Lysilactones A–C (7–9) bearing β-glucopyranoside moieties were first isolated from Lysimachia clethroides, where lysilactone B is mentioned in this review

• determined by NMR spectroscopy and unambiguously confirmed by total syntheses [44][177]. It showed cytotoxic activity against SW1116 cells with an IC50 value of 12 μg/mL [168]. Chlorinated alternariol derivatives (Figure 9) together with the respective redox-modified natural products (Figure 20, vide infra

Novel truxene-based dipyrromethanes (DPMs): synthesis, spectroscopic characterization and photophysical properties

• Shakeel Alvi and
• Rashid Ali

Beilstein J. Org. Chem. 2024, 20, 2163–2170, doi:10.3762/bjoc.20.186

• derivatives were successfully characterized and their structures were established by means of the 1H and 13C NMR spectroscopy, besides further confirmation by mass spectrometry (see Supporting Information File 1). The UV–vis absorption, emission and time-resolved fluorescence spectra Emission and absorption

O,S,Se-containing Biginelli products based on cyclic β-ketosulfone and their postfunctionalization

• Kateryna V. Dil and
• Vitalii A. Palchykov

Beilstein J. Org. Chem. 2024, 20, 2143–2151, doi:10.3762/bjoc.20.184

• in our study (Table 1, entries 1–6), but in any case, we received a mixture of regioisomeric products 2a/2a’ (3:1 to 2:1) confirmed by 2D NMR spectroscopy (see Supporting Information File 1, Figures S1–S6). Classical conditions for Biginelli reaction (reflux in ethanolic HCl) gave only 23% yield

Efficacy of radical reactions of isocyanides with heteroatom radicals in organic synthesis

• Akiya Ogawa and
• Yuki Yamamoto

Beilstein J. Org. Chem. 2024, 20, 2114–2128, doi:10.3762/bjoc.20.182

• . Because of this conjugation, the aromatic ring at the N of the 1,1-addition product 4 (R = Ar, E = PhS) geometrically isomerizes faster than the NMR timescale, so that the two thio groups of 4 are observed to be equivalent in NMR spectroscopy. In the case of diphenyl diselenide as a representative organic

Understanding X-ray-induced isomerisation in photoswitchable surfactant assemblies

• Beatrice E. Jones,
• Camille Blayo,
• Jake L. Greenfield,
• Matthew J. Fuchter,
• Nathan Cowieson and
• Rachel C. Evans

Beilstein J. Org. Chem. 2024, 20, 2005–2015, doi:10.3762/bjoc.20.176

• effect, but also as the medium for structural rearrangements. Effect of acidification The effect of acidification on isomerisation was further investigated using UV–vis absorbance spectroscopy, where excess hydrobromic acid (HBr) was added to AzoTAB and AAPTAB samples (25 μM) that had been preirradiated

• the samples ex-situ for 3.5 hours to achieve a Z-rich PSS, where the percentage isomerised has been determined previously using 1H NMR spectroscopy [20]. The 10 wt % sample was measured over 800 X-ray exposures of 250 ms each. The initial Z-rich PSS SAXS pattern shows a strong interaction peak at Q

• (10 and 90 wt %), and the samples were heated to 60 °C, whilst stirring until homogenous. Samples were left to cool to room temperature whilst stirring. For the photoisomerisation studies using UV–vis absorbance spectroscopy, samples were irradiated to the PSS in a custom-built LED light box with UV

1,2-Difluoroethylene (HFO-1132): synthesis and chemistry

• Liubov V. Sokolenko,
• Taras M. Sokolenko and
• Yurii L. Yagupolskii

Beilstein J. Org. Chem. 2024, 20, 1955–1966, doi:10.3762/bjoc.20.171

• ]. Additionally, when the reaction was performed using DMSO-d6 (or CD3CN) and CH3ONa, H/D exchange occurred already at ambient temperature (25 °C, 20 h) [78]. The formation of CDF=CDF was confirmed by NMR spectroscopy, namely by the change of signal multiplicity in the 19F NMR spectra of E- and Z-isomers of 1,2

Regioselective alkylation of a versatile indazole: Electrophile scope and mechanistic insights from density functional theory calculations

• Pengcheng Lu,
• Luis Juarez,
• Paul A. Wiget,
• Weihe Zhang,
• Krishnan Raman and
• Pravin L. Kotian

Beilstein J. Org. Chem. 2024, 20, 1940–1954, doi:10.3762/bjoc.20.170

• spectroscopy (see Supporting Information File 1). From the yield of products 8 and 9, we decided to explore new reaction conditions to improve the yields of the N1-substituted indazole analogs. As shown in Scheme 2, compound 12 was prepared by treating ethanol (10) with tosyl chloride (11) in the presence of 4

The Groebke–Blackburn–Bienaymé reaction in its maturity: innovation and improvements since its 21st birthday (2019–2023)

• Cristina Martini,
• Muhammad Idham Darussalam Mardjan and
• Andrea Basso

Beilstein J. Org. Chem. 2024, 20, 1839–1879, doi:10.3762/bjoc.20.162

• a [1,5]-H shift [19], indazolo[3’,2’:2,3]imidazo[1,5-c]quinazolin-6(5H)-one 18 (Scheme 7) [20]. The favorable host–guest interaction between 14 and the reactants (demonstrated by 2D NMR and FTIR spectroscopy as well as by scanning electron micrography), combined with the acidity of the succinyl

Oxidative fluorination with Selectfluor: A convenient procedure for preparing hypervalent iodine(V) fluorides

• Samuel M. G. Dearman,
• Xiang Li,
• Yang Li,
• Kuldip Singh and
• Alison M. Stuart

Beilstein J. Org. Chem. 2024, 20, 1785–1793, doi:10.3762/bjoc.20.157

• studies of hypervalent iodine(V) fluorides in solution The stability of hypervalent iodine(V) fluorides 6, 20, 21 and 22 was studied in dry acetonitrile-d3 by 1H and 19F NMR spectroscopy over 7 days under an argon atmosphere. All four hypervalent iodine(V) fluorides were stable for the 7-day period. When

Synthesis and characterization of 1,2,3,4-naphthalene and anthracene diimides

• Adam D. Bass,
• Daniela Castellanos,
• Xavier A. Calicdan and
• Dennis D. Cao

Beilstein J. Org. Chem. 2024, 20, 1767–1772, doi:10.3762/bjoc.20.155

• sodium hydroxide, followed by acidification with HCl, yielded a mixture of carboxylic acids and anhydrides 5, as evidenced by 1H NMR spectroscopy (Figure S13 in Supporting Information File 1). Gratifyingly, purification of these mixtures was not necessary as they could be used directly for imidization

Synthesis of polycyclic aromatic quinones by continuous flow electrochemical oxidation: anodic methoxylation of polycyclic aromatic phenols (PAPs)

• Hiwot M. Tiruye,
• Solon Economopoulos and
• Kåre B. Jørgensen

Beilstein J. Org. Chem. 2024, 20, 1746–1757, doi:10.3762/bjoc.20.153

• indicated, are given in Supporting Information File 1. The optical properties of the PAPs were investigated by UV–vis absorption spectroscopy in 10−5 M solutions in CH2Cl2, as depicted in Figure 1. The UV–vis spectra of these compounds exhibited strong absorption in the region of 250–370 nm. These

A fiber-optic spectroscopic setup for isomerization quantum yield determination

• Anouk Volker,
• Jorn D. Steen and
• Stefano Crespi

Beilstein J. Org. Chem. 2024, 20, 1684–1692, doi:10.3762/bjoc.20.150

• actinometry, thus demonstrating the reliability of our setup. Keywords: isomerization; molecular photoswitches; photochemistry; photon flux; UV–vis spectroscopy; Introduction Photoswitches are molecules that can undergo a light-driven structural rearrangement to populate a metastable state of the initial

• of each isomer, as illustrated by Equation 1. The value for c at the PSS can be found using other spectroscopic methods, such as NMR spectroscopy [17] or the TEM (for Thulstrup, Eggers, and Michl) method [34][35]. With a known value for c, the spectrum of the second component can be found by a simple

• molecular switch by UV–vis absorption spectroscopy in operando. We provide all the information necessary to build the setup as well as the scripts and examples to retrieve the quantum yields of forward and backward isomerization of a molecular photoswitch following the evolution of the absorption in the low

Oxidation of benzylic alcohols to carbonyls using N-heterocyclic stabilized λ³-iodanes

• Thomas J. Kuczmera,
• Pim Puylaert and
• Boris J. Nachtsheim

Beilstein J. Org. Chem. 2024, 20, 1677–1683, doi:10.3762/bjoc.20.149

• : 3.61 Å [31]). Beginning with the electron-deficient and thereby highly reactive NHIs 1a and 1c, we explored the potential for a ligand-exchange process on the iodane via 1H NMR spectroscopy by combining equimolar quantities of NHI and n-octanol (2). When the tetrazole-substituted hydroxy(aryl)iodane 1a

• with common iodine(III) reagents by 1H NMR spectroscopy (Figure 4). After 60 h the measurements revealed a higher yield of aldehyde 4a using 1a (68%) compared to 1c (30%) under the influence of AlCl3. As a comparison, the use of PIDA (5b) and IBA (5c) with the additive resulted in a significantly lower

• , respectively) in CD3CN (500 µL) was monitored via 1H NMR spectroscopy. Substrate scope of aldehydes and ketones synthesized from the corresponding alcohols. Isolated yields. Reaction conditions: 1a (700 µmol), alcohol (500 µmol), and method A HCl (37%, 500 µmol) in EtOAc (2.5 mL) or method B TBACl (500 µmol

Ring opening of photogenerated azetidinols as a strategy for the synthesis of aminodioxolanes

• Henning Maag,
• Daniel J. Lemcke and
• Johannes M. Wahl

Beilstein J. Org. Chem. 2024, 20, 1671–1676, doi:10.3762/bjoc.20.148

• chosen as a preferred solvent because it is known to facilitate Norrish–Yang-cyclizations and allows simple analysis by nuclear magnetic resonance (NMR) spectroscopy [10]. Our results are summarized in Table 1. When p-toluenesulfonyl (Ts) was used as a PG at nitrogen, azetidine 3a was obtained in 81

• added to 3a (Scheme 3a). Formation of hemiketal 8 was expected to occur, which would facilitate ring opening by a 5-exo-tet cyclization. While we did observe the formation of hemiketal 8 by NMR spectroscopy, we were unable to detect any ring-opened products 9, even when adding Lewis acids or Brønsted

Polymer degrading marine Microbulbifer bacteria: an un(der)utilized source of chemical and biocatalytic novelty

• Weimao Zhong and
• Vinayak Agarwal

Beilstein J. Org. Chem. 2024, 20, 1635–1651, doi:10.3762/bjoc.20.146

• determined using a combination of NMR spectroscopy and chemical derivatization experiments, adding new members to this class of imidazole-containing natural products such as the nocarimidazoles A and B reported from a marine-derived actinomycete Nocardiopsis sp. before [126]. Compound 21 was determined to be

New triazinephosphonate dopants for Nafion proton exchange membranes (PEM)

• Fátima C. Teixeira,
• António P. S. Teixeira and
• C. M. Rangel

Beilstein J. Org. Chem. 2024, 20, 1623–1634, doi:10.3762/bjoc.20.145

• conduction properties of new membranes were evaluated by electrochemical impedance spectroscopy (EIS) at 60 °C at different relative humidity (RH) conditions. The results showed higher proton conductivities than recast Nafion membrane and similar or better proton conductivities than commercial Nafion N115

• , for example, to the performance of fuel cells. The study of the protonic conductivities of the new modified membranes were determined, in-plane, at 60 ºC, in different relative humidity (RH) conditions (40, 60 and 80%), through electrochemical impedance spectroscopy (EIS) (Figure 5). A prepared recast

• characterization of the dopants was carried out by Fourier-transform infrared spectroscopy (FTIR), nuclear magnetic resonance (NMR) spectroscopy and mass spectrometry (MS). 1H, 13C and 31P NMR characterization was done using different one- and two-dimensional techniques, and were obtained on a Bruker Avance III HD