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

• 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

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

• and the reaction mixture was stirred at room temperature for 3 h. After concentrating the mixture, the residue was purified by column chromatography on silica gel using a mixture of petroleum ether/ethyl acetate 30:1 (v/v) as the eluent to afford products 2. The yields were determined by 19F NMR

• 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

• 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

• -acetyl groups. The disaccharide fraction was isolated by gel permeation chromatography on Bio-Beads S-X3 (toluene) and analyzed by 1H NMR spectroscopy to give the anomeric ratio (α/β). Individual anomers of disaccharides were then separated by silica gel chromatography to give the yield. Model

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

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

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

• toward the desired product 3-(allyloxy)propanenitrile was observed after stirring the reaction mixture for 24 h at room temperature. Analyzing the reaction mixture with 1H NMR spectroscopy revealed the formation of a minor amount of a novel compound characterized by two multiplets centered at 3.31 and

• purified by recrystallization whereby the solvents used vary depending on the parent Michael acceptor (for details, see Supporting Information File 1). Yields are not optimized and given in Table 1. The synthesized zwitterions were investigated via 1H, 13C and 31P NMR spectroscopy. All synthesized

Facile access to pyridinium-based bent aromatic amphiphiles: nonionic surface modification of nanocarbons in water

• Lorenzo Catti,
• Shinji Aoyama and
• Michito Yoshizawa

Beilstein J. Org. Chem. 2024, 20, 32–40, doi:10.3762/bjoc.20.5

• mV) compared to the other derivatives in neutral water, owing to the basic imidazole groups (Table 1). The protonation behavior of the imidazole groups on (PA-Im)n·(C60)m in D2O (0.5 mM based on PA-Im) was monitored by 1H NMR spectroscopy, showing significant down-field shifts of the imidazole ring

NMRium: Teaching nuclear magnetic resonance spectra interpretation in an online platform

• Luc Patiny,
• Hamed Musallam,
• Alejandro Bolaños,
• Michaël Zasso,
• Julien Wist,
• Metin Karayilan,
• Eva Ziegler,
• Johannes C. Liermann and
• Nils E. Schlörer

Beilstein J. Org. Chem. 2024, 20, 25–31, doi:10.3762/bjoc.20.4

• ; structure elucidation; Introduction For the validation of molecular structures, nuclear magnetic resonance (NMR) spectroscopy is an indispensable methodology in the daily routine of synthetic chemistry laboratories. Arguably, NMR experiments serve as the ‘eye of the synthetic chemist’ because they allow a

• rapid and comparatively easy deduction of structural features with the only requirement being the molecule's solubility in deuterated solvents. Therefore, NMR spectroscopy is of ubiquitous presence in many disciplines today. At the same time, with the high throughput analysis of samples that has been a

• common approach in academic laboratories, the ability of chemists to conduct the interpretation of experimental results becomes crucial. In addition, NMR spectroscopy is one of the methods that has been delivering digital experimental raw data for a long time. However, the way the spectra are interpreted

Cycloaddition reactions of heterocyclic azides with 2-cyanoacetamidines as a new route to C,N-diheteroarylcarbamidines

• Pavel S. Silaichev,
• Tetyana V. Beryozkina,
• Vsevolod V. Melekhin,
• Valeriy O. Filimonov,
• Andrey N. Maslivets,
• Vladimir G. Ilkin,
• Wim Dehaen and
• Vasiliy A. Bakulev

Beilstein J. Org. Chem. 2024, 20, 17–24, doi:10.3762/bjoc.20.3

• effect on the yield of the final compounds 3 observed. The structures of compounds 3a–u were confirmed by IR, 1H and 13C NMR spectroscopy (Figures S1‒S44 in Supporting Information File 1) as well as by high-resolution mass spectrometry (HRMS). X-ray data obtained for compound 3g gave us final proof of

1-Butyl-3-methylimidazolium tetrafluoroborate as suitable solvent for BF₃: the case of alkyne hydration. Chemistry vs electrochemistry

• Marta David,
• Elisa Galli,
• Richard C. D. Brown,
• Marta Feroci,
• Fabrizio Vetica and
• Martina Bortolami

Beilstein J. Org. Chem. 2023, 19, 1966–1981, doi:10.3762/bjoc.19.147

• was analysed using NMR spectroscopy. Initially the reaction was carried out without added water, in the presence of a large excess of BF3·Et2O (5 equiv) (as often reported in literature, see as an example [104]). The reaction was conducted for 5 h at 80 °C using either “stock” (undried) BMIm-BF4

Aldiminium and 1,2,3-triazolium dithiocarboxylate zwitterions derived from cyclic (alkyl)(amino) and mesoionic carbenes

• Nedra Touj,
• François Mazars,
• Guillermo Zaragoza and
• Lionel Delaude

Beilstein J. Org. Chem. 2023, 19, 1947–1956, doi:10.3762/bjoc.19.145

• on 13C NMR spectroscopy (see below). We suspect that deleterious hydrophilic effects caused the subsequent decomposition of the CAAC·CS2 and MIC·CS2 zwitterions when an aqueous work-up was applied. Structural analysis Several analytical techniques were employed to characterize the nine aldiminium and

• lower energies is a likely consequence of the greater donicity of CAACs and MICs vs NHCs. Hence, the ν̃ CS2 values recorded on IR spectroscopy constitute a more sensitive probe than the δ CS2 values obtained from 13C NMR spectroscopy to help discriminate the various types of dithiocarboxylate adducts

• carbenes with a strong base, followed by their nucleophilic addition onto carbon disulfide. The nine products obtained were characterized by 1H and 13C NMR spectroscopy, FTIR spectroscopy, HR–ESI mass spectrometry, and elemental analysis. Moreover, the molecular structures of two CAAC·CS2 and two MIC·CS2

Beyond n-dopants for organic semiconductors: use of bibenzo[d]imidazoles in UV-promoted dehalogenation reactions of organic halides

• Kan Tang,
• Megan R. Brown,
• Chad Risko,
• Melissa K. Gish,
• Garry Rumbles,
• Phuc H. Pham,
• Oana R. Luca,
• Stephen Barlow and
• Seth R. Marder

Beilstein J. Org. Chem. 2023, 19, 1912–1922, doi:10.3762/bjoc.19.142

• lower for a given reaction time (compare entries 12 and 15 to 11 and 14 in Table 1) and the sole detected product is toluene rather than bibenzyl. Furthermore, in one of the cases of complete conversion (Table 1, entry 14), 1H NMR spectroscopy indicated that the reductant-based side product is a salt of

N-Boc-α-diazo glutarimide as efficient reagent for assembling N-heterocycle-glutarimide diads via Rh(II)-catalyzed N–H insertion reaction

• Grigory Kantin,
• Pavel Golubev,
• Alexander Sapegin,
• Alexander Bunev and
• Dmitry Dar’in

Beilstein J. Org. Chem. 2023, 19, 1841–1848, doi:10.3762/bjoc.19.136

• the reaction mixture). The structure of the main reaction product 9i was confirmed by 2D HSQC NMR spectroscopy. To evaluate the influence of the catalyst on chemoselectivity of the reaction with indole (ratio 6a/9a) we have performed additional testing with Rh2(TFA)4 and Rh2(OAc)4, which differ from

Unprecedented synthesis of a 14-membered hexaazamacrocycle

• Anastasia A. Fesenko and
• Anatoly D. Shutalev

Beilstein J. Org. Chem. 2023, 19, 1728–1740, doi:10.3762/bjoc.19.126

• , according to NMR spectroscopic data, the isolated product was a mixture of the desired macrocycle 5 and a noticeable amount of an impurity (Scheme 2) whose formation was not mentioned in the cited reference. The structure of the concomitant impurity was established using 1D and 2D NMR spectroscopy. The 1H

• under reflux for 23 h. After the reaction had completed (monitored by 1H NMR spectroscopy), the obtained solution was concentrated under water pump vacuum upon heating in a water bath at 65 °C. The product was extracted from the resulting dense brown oil by trituration 4 times with a mixture of ether

Tying a knot between crown ethers and porphyrins

• Maksym Matviyishyn and
• Bartosz Szyszko

Beilstein J. Org. Chem. 2023, 19, 1630–1650, doi:10.3762/bjoc.19.120

• anion. The formed receptor: ion-pair 1:1 complex 4-CsF was stable in solution, as evidenced by 1H NMR spectroscopy. The binding constant Ka = 3.8·105 M−1 in CHCl3/MeOH 9:1 was reported. The XRD analysis in the solid state provided further proof of the binding mode, demonstrating the significant

• , interacting with the calixpyrrole macrocycle through hydrogen bonds. The water molecule was bound near the fluoride and was further stabilised through hydrogen bonding to the oxygen atoms in the central part of the receptor. This selective fluoride binding was evidenced with the help of 1H NMR spectroscopy

• to a dimer 37 was achieved using N,N-dimethylformamide, dimethyl sulfoxide, or acetonitrile. Interestingly, the dissolution of compound 37 in CHCl3, MeOH, or EtOH resulted in the interconversion to 36 within 1–2 days, as evidenced by 1H NMR spectroscopy. The Ravikanth group has developed an

A series of perylene diimide cathode interlayer materials for green solvent processing in conventional organic photovoltaics

• Kathryn M. Wolfe,
• Shahidul Alam,
• Eva German,
• Fahad N. Alduayji,
• Maryam Alqurashi,
• Frédéric Laquai and
• Gregory C. Welch

Beilstein J. Org. Chem. 2023, 19, 1620–1629, doi:10.3762/bjoc.19.119

• adding a methanol/water mixture; thus, no lengthy purification steps were required for any of the syntheses. Yields of 52.4%, 80.2%, 58.1%, and 68.3% were obtained for PDIN-FB, PDIN-B, CN-PDIN-FB, and CN-PDIN-B, respectively. All compounds were structurally characterized using 1H NMR spectroscopy, 13C

• NMR spectroscopy, mass spectrometry, and elemental analysis. See Supporting Information File 1 for full synthetic and characterization details. Optical properties Using UV–visible spectroscopy, the optical properties for PDIN-FB, PDIN-B, CN-PDIN-FB, and CN-PDIN-FB in both solution and film form were

Sulfur-containing spiroketals from Breynia disticha and evaluations of their anti-inflammatory effect

• Ken-ichi Nakashima,
• Naohito Abe,
• Masayoshi Oyama,
• Hiroko Murata and
• Makoto Inoue

Beilstein J. Org. Chem. 2023, 19, 1604–1614, doi:10.3762/bjoc.19.117

• analysis based on 2D NMR spectroscopy has previously been described. He et al. reported that epibreynin D, which bears the same aglycone moiety as compounds 2 and 7, exhibits anti-inflammatory effects in mice and rat models [12]. To investigate the anti-inflammatory effects of the sulfur-containing

Secondary metabolites of Diaporthe cameroonensis, isolated from the Cameroonian medicinal plant Trema guineensis

• Bel Youssouf G. Mountessou,
• Élodie Gisèle M. Anoumedem,
• Blondelle M. Kemkuignou,
• Yasmina Marin-Felix,
• Frank Surup,
• Marc Stadler and
• Simeon F. Kouam

Beilstein J. Org. Chem. 2023, 19, 1555–1561, doi:10.3762/bjoc.19.112

• polyketide 1, and an acetylated alternariol 2 were isolated, along with fifteen known secondary metabolites. Their structures were established by extensive NMR spectroscopy and mass spectrometry analyses, as well as by comparison with literature data of their analogs. Keywords: alternariol; Diaporthe

Morpholine-mediated defluorinative cycloaddition of gem-difluoroalkenes and organic azides

• Tzu-Yu Huang,
• Mario Djugovski,
• Sweta Adhikari,
• Destinee L. Manning and
• Sudeshna Roy

Beilstein J. Org. Chem. 2023, 19, 1545–1554, doi:10.3762/bjoc.19.111

• 19F NMR spectroscopy to monitor the consumption of the gem-difluoro starting material 1, which was completely consumed within 16 h (Figure 3). However, a 48 h time course gave a superior yield (Table 1, entry 13 vs entry 20). We hypothesize this might be due to the volatile nature of the gem

• . Additionally, 30% of the aniline byproduct was also isolated, which explains the modest yields of this reaction and the sluggish nature. To investigate the mechanism of the current transformation, we conducted a series of experiments including a time course of the reaction using 19F NMR spectroscopy (Figure 3

• Equiv of CuSO4 was used as an additive. bModified reaction conditions for benzyl azides: 1 (1 equiv), 2 (1.5 equiv) 0.4 equiv of LiHMDS (1 M in THF), morpholine (0.34–0.4 M), 110 °C, 72 h. Time course profile monitored by 19F NMR spectroscopy. NOESY of 4e confirming the regiochemistry of the product

Complexes of resorcin[4]arene with secondary amines: synthesis, solvent influence on “in-out” structure, and theoretical calculations of non-covalent interactions

• Waldemar Iwanek

Beilstein J. Org. Chem. 2023, 19, 1525–1536, doi:10.3762/bjoc.19.109

• , these compounds are capable of forming complexes with small organic molecules. The current paper focuses on the synthesis of complexes between R[4]A and secondary aliphatic amines (sec-amines). Through NMR spectroscopy, it was observed that “in-out” complexes are formed depending on the solvent. It was

• amine, and the type of complex formed is influenced by the nature and polarity of the solvent. The stoichiometry and solvent-dependent structure of the “in-out” complexes formed were determined through NMR spectroscopy. Screening tests were carried out using the aISS-xTB2 method, while the final

Cyclization of 1-aryl-4,4,4-trichlorobut-2-en-1-ones into 3-trichloromethylindan-1-ones in triflic acid

• Vladislav A. Sokolov,
• Andrei A. Golushko,
• Irina A. Boyarskaya and
• Aleksander V. Vasilyev

Beilstein J. Org. Chem. 2023, 19, 1460–1470, doi:10.3762/bjoc.19.105

• , the O-protonated forms ArC(=OH+)CH=CHCCl3, which are then cyclized into the target CCl3-indanones. These cations have been studied experimentally by means of NMR spectroscopy in TfOH and theoretically by DFT calculations. Under the same superacidic conditions in TfOH, CCl3-hydroxy ketones (1-aryl

• , we initiated this study on transformations of 1-aryl-4,4,4-trichlorobut-2-en-1-ones under superelectrophilic activation conditions (Scheme 1b). The main goals of this work were the investigation of the protonation of CCl3-enones (1-aryl-4,4,4-trichlorobut-2-en-1-ones) by NMR spectroscopy and DFT

• of enones 2a,e,n with an excess (5 equiv) of AlBr3 or AlCl3 in CH2Cl2 solution at room temperature for 3 days afforded complex mixtures of compounds. Then, the protonation of compounds 1 and 2 in TfOH was investigated by means of NMR spectroscopy. According to the 1H, 13C, and 19F NMR data, hydroxy

Functions of enzyme domains in 2-methylisoborneol biosynthesis and enzymatic synthesis of non-natural analogs

• Binbin Gu,
• Lin-Fu Liang and
• Jeroen S. Dickschat

Beilstein J. Org. Chem. 2023, 19, 1452–1459, doi:10.3762/bjoc.19.104

• isolated and structurally characterised through NMR spectroscopy (Supporting Information File 1, Table S2, Figures S4–S11) as compound 2 (Scheme 2A), a homolog of the 2MIBS side product 2-methylenebornane (6) (Scheme 2C). Analogously, the preparative scale conversion of DA-5 and IA-1 with FPPS and 2MIBS

Application of N-heterocyclic carbene–Cu(I) complexes as catalysts in organic synthesis: a review

• Nosheen Beig,
• Varsha Goyal and
• Raj K. Bansal

Beilstein J. Org. Chem. 2023, 19, 1408–1442, doi:10.3762/bjoc.19.102

• allow to synthesize acylboron compounds [54]. As mentioned earlier, Oro and co-workers [39] used 5 mol % of complex 78a (Scheme 27) for the homogeneous hydrosilylation of acetophenone with HSiEt3 in the presence of KOt-Bu. As indicated by 1H NMR spectroscopy, the conversion was complete in 18 h