gem-Difluorination of carbon–carbon triple bonds using Brønsted acid/Bu₄NBF₄ or electrogenerated acid

• Mizuki Yamaguchi,
• Hiroki Shimao,
• Kengo Hamasaki,
• Keiji Nishiwaki,
• Shigenori Kashimura and
• Kouichi Matsumoto

Beilstein J. Org. Chem. 2024, 20, 2261–2269, doi:10.3762/bjoc.20.194

• ) was reacted with the Brønsted acid (X equiv) and the fluorine source (Y equiv) in the solvent (4 mL) at temperature of T (°C) for Z hours. The chemical yield of the desired product, (5,5-difluorohexyl)benzene (2a), was evaluated for reaction optimization by using the 19F nuclear magnetic resonance

• in the presence of the substrate. The total electricity of 3.0 F/mol vs 1a was passed to the solution. Interestingly, the result gave the corresponding difluorinated compound 2a in 29% yield in the case of 8 mA, as shown by 19F NMR analysis. In addition, 2a was obtained in 42% yield by 19F NMR

• oxidation of method B was conducted by using 8 mA. The reaction of but-3-yn-1-ylbenzene (1b) in method A gave the corresponding compound 2b in 21% isolated yield (Table 2, entry 1). The 19F NMR result indicated 63% yield. Because of the low molecular weight of 2b, the isolated yield might be somewhat lower

From perfluoroalkyl aryl sulfoxides to ortho thioethers

• Yang Li,
• Guillaume Dagousset,
• Emmanuel Magnier and
• Bruce Pégot

Beilstein J. Org. Chem. 2024, 20, 2108–2113, doi:10.3762/bjoc.20.181

• equiv) was slowly added to the flask with a syringe and the reaction was stirred for another 10 min. At the end of the reaction, 1 mL of chloroform and a known amount of trifluoromethoxybenzene were added to the flask in order to determine the 19F NMR yield. To purify the product, the reaction mixture

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

• ], respectively, while reference [68] provides UV-spectral data of both isomers. 1H, 19F, and 13C NMR data [69][70] are given in Table 2. Chemistry of HFO-1132 Isomerization Iodine-catalyzed cis–trans isomerization of 1,2-difluoroethylene and corresponding equilibrium measurements were described in the 1960s [47

• ]. 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

• for 24 h. Careful investigation of the product structures by 1H and 19F NMR as well as GC–MS revealed exclusive substitution of fluorine rather than hydrogen, leading to a mixture of products in the ratio 0.15:1:1:0.15 (Scheme 25), with a combined yield of 50% for 4-iodotoluene and 75% for methyl 4

A new platform for the synthesis of diketopyrrolopyrrole derivatives via nucleophilic aromatic substitution reactions

• Vitor A. S. Almodovar and
• Augusto C. Tomé

Beilstein J. Org. Chem. 2024, 20, 1933–1939, doi:10.3762/bjoc.20.169

• than the oxygen due to the preferential existence of 4-hydroxypyridine in the pyridin-4-one tautomeric form [37][38][39]. The structures of dyes 3a–f, 4a, 4d and 4f were unambiguously established through their 1H, 13C and 19F NMR and mass spectra. The 1H NMR spectra of the symmetrical compounds

• the protons of the N–CH2C6F5 and N–CH2C6F4XR groups, respectively. All 19F NMR spectra confirmed the selective substitution of the 4-fluorine atoms (in one or in two rings) by the disappearance of the signal corresponding to the resonance of those atoms. Mass spectra of compounds 3a–f, 4a, 4d and 4f

• apparatus. NMR spectra were recorded on a Bruker DRX 300 Avance operating at 300.13 MHz (for 1H NMR), at 75.47 MHz (for 13C NMR) and 282 MHz (for 19F NMR). Deuterated chloroform (CDCl3) was used as the solvent and tetramethylsilane (TMS) as the internal reference. The chemical shifts (δ) are expressed in

Novel oxidative routes to N-arylpyridoindazolium salts

• Oleg A. Levitskiy,
• Yuri K. Grishin and
• Tatiana V. Magdesieva

Beilstein J. Org. Chem. 2024, 20, 1906–1913, doi:10.3762/bjoc.20.166

• -arylpyridoindazolium salts S1–S3 was confirmed with HRMS and 1H, 13C and 19F NMR data; the complete assignment of the signals was performed using 2D NMR methods. The N–N bond formation was additionally confirmed via comparison of the 1H spectra for the salts and their diarylamine precursors. The absence of the signals

A facile three-component route to powerful 5-aryldeazaalloxazine photocatalysts

• Ivana Weisheitelová,
• Radek Cibulka,
• Marek Sikorski and
• Tetiana Pavlovska

Beilstein J. Org. Chem. 2024, 20, 1831–1838, doi:10.3762/bjoc.20.161

• named using ChemDraw. Nuclear magnetic resonance (NMR) spectra were recorded on an Agilent 400-MR DDR2 (399.94 MHz for 1H, 100.58 MHz for 13C, 376.50 MHz for 19F) or on a JNM-ECZ500R NMR spectrometer, JEOL Resonance, (500.16 MHz for 1H, 125.77 MHz for 13C, 470.60 MHz for 19F) at 298 K unless otherwise

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

• tetrafluoroborate, BF4−) to form difluoroiodane 6. The formation of difluoroiodane 6 was identified by a singlet at −23.0 ppm in the 19F NMR spectrum. As expected, the aromatic signals in the 1H NMR spectrum shifted downfield from a doublet at 7.21 ppm and a triplet at 7.56 ppm for iodine(III) substrate 10 to 7.71

• 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

• deposition numbers CCDC: 2351949 and 2351950. Supporting Information File 18: Experimental procedures, characterisation data, DFT calculations and 1H, 13C and 19F NMR spectra and crystallographic data. Funding SMGD and AMS thank the School of Chemistry, University of Leicester, for their generous support

Benzylic C(sp³)–H fluorination

• Alexander P. Atkins,
• Alice C. Dean and
• Alastair J. J. Lennox

Beilstein J. Org. Chem. 2024, 20, 1527–1547, doi:10.3762/bjoc.20.137

• fluoride. Manganese-catalysed benzylic C(sp3)–H fluorination with AgF and Et3N·3HF and proposed mechanism. 19F NMR yields in parentheses. Iridium-catalysed photocatalytic benzylic C(sp3)–H fluorination with nucleophilic fluoride and N-acyloxyphthalamide HAT reagent. Iridium-catalysed photocatalytic

Tetrabutylammonium iodide-catalyzed oxidative α-azidation of β-ketocarbonyl compounds using sodium azide

• Christopher Mairhofer,
• David Naderer and
• Mario Waser

Beilstein J. Org. Chem. 2024, 20, 1510–1517, doi:10.3762/bjoc.20.135

• pronucleophile, followed by a phase-transfer-catalyzed nucleophilic substitution by the azide. Furthermore, we also obtained a first proof-of-concept for the conceptually analogous α-nitration by using NaNO2 under otherwise identical conditions. Experimental General details 1H, 13C and 19F NMR spectra were

• Research Center “RERI uasb”. All NMR spectra were referenced on the solvent residual peak (CDCl3: δ = 7.26 ppm for 1H NMR, δ = 77.16 ppm for 13C NMR,19F NMR unreferenced). IR spectra were recorded on a Bruker Alpha II FTIR spectrometer with diamond ATR-module using the OPUS software package. HRMS spectra

Auxiliary strategy for the general and practical synthesis of diaryliodonium(III) salts with diverse organocarboxylate counterions

• Naoki Miyamoto,
• Daichi Koseki,
• Kohei Sumida,
• Elghareeb E. Elboray,
• Naoko Takenaga,
• Ravi Kumar and
• Toshifumi Dohi

Beilstein J. Org. Chem. 2024, 20, 1020–1028, doi:10.3762/bjoc.20.90

• details and copies of 1H, 13C, and 19F NMR spectra. Acknowledgements T.D. thanks for the generous gift of fluoroalcohols from Central Glass Co., Ltd. Funding N.T. and T.D. acknowledge support from JSPS KAKENHI Grant Number 20K06980 (N.T.) and 19K05466 (T.D.), JST CREST grant number JPMJCR20R1 (T.D.), and

Direct synthesis of acyl fluorides from carboxylic acids using benzothiazolium reagents

• Lilian M. Maas,
• Alex Haswell,
• Rory Hughes and
• Matthew N. Hopkinson

Beilstein J. Org. Chem. 2024, 20, 921–930, doi:10.3762/bjoc.20.82

• equiv of NaH in DCM under conditions similar to our previous reports on the deoxygenative trifluoromethylthiolation of carboxylic acids [31]. 19F NMR analysis of the crude reaction mixture after 2 h at rt revealed no conversion towards the desired acyl fluoride product 2a, however, 30% of thioester 3a

• was formed (internal standard: PhCF3, Table 1, entry 1). Pleasingly, changing the base to K2CO3 led to the formation of 2a in 7% 19F NMR yield (Table 1, entry 2), while the selectivity of the reaction could be switched significantly upon employing organic amine bases (Table 1, entries 3 and 4). Using

• 2.0 equiv of diisopropylethylamine (DIPEA), 2a could be obtained in quantitative 19F NMR yield although a reduction to 1.5 equiv led to a significant drop in efficiency, delivering the acyl fluoride in only 30% 19F NMR yield together with 45% of thioester 3a (Table 1, entries 4 and 5). At this stage

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

• gives first insights into the optical properties. It was observed that the photophysical properties could be partially modulated by the chosen substituents. Experimental General information Nuclear magnetic resonance spectra (1H/13C/19F NMR) were recorded on a Bruker AVANCE 300 III, 250II, or 500. The

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

• and characterization data of all products, copies of 1H, 13C, 19F NMR spectra of all compounds. Acknowledgements The authors thank the Research Center of Analysis and Test of the East China University of Science and Technology for the help on the characterization and Professor Zhen-Jiang Xu from SIOC

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

• carborane A3B-porphyrin were also synthesized based on the amino-substituted A3B-porphyrin. The structures of the prepared carboranylporphyrins were determined by UV–vis, IR, 1H, 19F, 11B NMR spectroscopic data and MALDI mass spectrometry. Keywords: bioconjugation; carboranes; fluorine; porphyrin; SNAr

• substituent of porphyrins 3, 5, 11, 12, 14, 18–20, 23, 24, and 26 were also observed supporting the structures of these compounds (see Supporting Information File 1, experimental and Figures S1–S14 for details). The 19F NMR spectra were also in good agreement with the structures of the synthesized compounds

• functionality was supported by the design of conjugates containing maleimide and biotin substituents. The structures of prepared carboranylporphyrins were determined by UV–vis, IR, 1H 19F, 11B NMR spectroscopic data and MALDI mass spectrometry. Synthesis of porphyrins 2 and 3. Synthesis of carborane

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

• reaction of compound 1a with Selectfluor in acetonitrile (MeCN) gave high yields of the monofluorinated product 2a with no difluorinated product being observed by 19F NMR analysis of the product mixture after 5 h (Scheme 1). In contrast, attempts to fluorinate 1a with one equivalent of fluorine gas in MeCN

• 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

• the crude yields of fluorinated products were estimated by 19F NMR integration (monofluoro product 2a, δF −189.9 ppm; difluoro product 3a, δF −102.7 ppm) (Table 1, entry 3). Using excess fluorine or DABCO (entries 5 and 6 in Table 1) led to the formation of tars, while 0.1 equiv of DABCO (entry 7

(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

• .20.40 Abstract A series of 2,3-dihalo-1,1,1,4,4,4-hexafluorobutanes and 2-halo-1,1,1,4,4,4-hexafluorobut-2-enes were prepared from commercially available hydrofluoroolefins 1,1,1,4,4,4-hexafluorobut-2-enes and their 1H, 19F and 13C chemical shifts measured. Some reactions of synthesized 2-halo

• of stereoisomers in 2:1 ratio. After isolation by distillation, 2,3-dibromo-1,1,1,4,4,4-hexafluorobutane (2) was characterized by 1H, 19F, 13C NMR and mass spectra. We studied the reaction of dibromoalkane 2 with various bases such as DBU, Hünig’s base (iPr2NEt), and potassium hydroxide (Table 1). In

• all cases, except the reaction in diglyme (Table 1, entry 5), a mixture of (E)- and (Z)-2-bromo-1,1,1,4,4,4-hexafluorobut-2-enes (3a,b) in a ratio of 2:1 was formed. The configuration of the isomers was determined by the 5JFFcis coupling constant in the 19F{H} NMR spectrum (ca. 0 Hz for (Z)-isomer and

Mono or double Pd-catalyzed C–H bond functionalization for the annulative π-extension of 1,8-dibromonaphthalene: a one pot access to fluoranthene derivatives

• Nahed Ketata,
• Linhao Liu,
• Ridha Ben Salem and
• Henri Doucet

Beilstein J. Org. Chem. 2024, 20, 427–435, doi:10.3762/bjoc.20.37

• from Acros. KOPiv (95%) was purchased from Doug Discovery. These compounds were not purified before use. All reagents were weighed and handled in air. All reactions were carried out under an inert atmosphere with standard Schlenk techniques. 1H, 19F and 13C NMR spectra were recorded on Bruker Avance

• data of synthesized compounds. Supporting Information File 44: Copies of 1H, 19F, and 13C NMR spectra. Acknowledgements We are grateful to Dr. Elsa Caytan for NMR experiments. Part of this work has been performed using the PRISM core facility (Biogenouest, Univ Rennes, Univ Angers, INRAE, CNRS, FRANCE

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

• -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

• 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

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

• after immersion in a 1:10 (v/v) mixture of 85% aq H3PO4 and 95% aq EtOH. 1H, 13C, and 19F NMR spectra of solutions in CDCl3 and acetone-d6 were recorded on a Bruker AVANCE-600 instrument at 600 MHz for 1H and 151 MHz for 13C or on a Bruker AM-300 instrument at 300 MHz for 1H, 75 MHz for 13C, and 282 MHz

• for 19F NMR. The 1H chemical shifts are given relative to the signal of the residual CHCl3 (δH 7.27) or acetone-d5 (δH 2.05), the 13C chemical shifts were measured relative to the signal of CDCl3 (δC 77.0) or acetone-d6 (δC 29.92). The 19F chemical shifts are given relative to the external signal of

• (q, JC,F = 285, CF3), 115.2 (q, JC,F = 288, CF3), 127.6, 129.6, 130.6, 136.0 (Ph), 156.4 (q, JC,F = 45, COCF3), 156.9 (q, JC,F = 44, COCF3), 158.0 (q, JC,F = 39, COCF3), 166.2, 167.5, 168.4 (COCH2Cl, CO2Me); 19F NMR (282 MHz, CDCl3, δ, ppm) −76.8 (NHCOCF3), −75.7, −75.2 (OCOCF3); HRESIMS (m/z): [M

Visible-light-induced radical cascade cyclization: a catalyst-free synthetic approach to trifluoromethylated heterocycles

• Chuan Yang,
• Wei Shi,
• Jian Tian,
• Lin Guo,
• Yating Zhao and
• Wujiong Xia

Beilstein J. Org. Chem. 2024, 20, 118–124, doi:10.3762/bjoc.20.12

• . The addition of a typical radical scavenger – TEMPO (2,2,6,6-tetramethylpiperidin-1-yloxyl) significantly inhibited the reaction (as shown in Scheme 3), suggesting the involvement of radical species during the reaction process. Moreover, the radical trapping product was detected and confirmed via 19F

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

• quiz material for intermediate to more advanced students. A third group of exercises includes additional experiments e.g., NOESY or 1D NOE spectra and 1D/2D heteronuclear experiments including nuclei such as 15N or 19F [43]. For all three exercise collections, students may draw a derived structure and

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

• and anion of the IL as the length of the side alkyl chain increases, which makes the BF4‒/water interaction more effective. Although Saihara and co-workers demonstrated that BF4‒ hydrolysis generates HF, which reacts with the surrounding glass container yielding SiF62‒ (signal at −130 ppm in 19F NMR

• spectrum) [106], we never detected such a peak in 19F NMR spectra of the neat IL, analysed after reaction work-up, keeping it under vacuum to completely eliminate diethyl ether traces before NMR analysis. It should be mentioned that the solution was kept in the NMR tubes only for the time necessary to

• -chelate. In fact, the following convincing peaks were found in the NMR spectra: a singlet at 6.11 ppm, along with a quartet at 4.68 ppm (1H NMR spectrum), a peak at 83.3 ppm (13C NMR spectrum) and a singlet at −139.1 ppm (19F NMR spectrum) [109]. A simple washing with distilled water gave the

Substituent-controlled construction of A₄B₂-hexaphyrins and A₃B-porphyrins: a mechanistic evaluation

• Seda Cinar,
• Dilek Isik Tasgin and
• Canan Unaleroglu

Beilstein J. Org. Chem. 2023, 19, 1832–1840, doi:10.3762/bjoc.19.135

• -tosylimines. Experimental General method: All reagents and solvents were purchased from Sigma-Aldrich, Fisher Scientific, or Acros Organics and were used without further purification. 1H NMR (400 MHz), 13C NMR (100 MHz), and 19F NMR (376 MHz) spectra were recorded on a Bruker 400, Ultra Shield high

• -performance digital FT-NMR spectrometer. Data for 1H NMR, 13C NMR, and 19F NMR are reported as follows: chemical shift (δ, ppm), multiplicity (s = singlet, d = doublet, t = triplet, m = multiplet, q= quartet, bs = broad singlet, dd = doublet of doublets, td = triplet of doublets, qd = quartet of doublets

A novel recyclable organocatalyst for the gram-scale enantioselective synthesis of (S)-baclofen

• Gyula Dargó,
• Dóra Erdélyi,
• Balázs Molnár,
• Péter Kisszékelyi,
• Zsófia Garádi and
• József Kupai

Beilstein J. Org. Chem. 2023, 19, 1811–1824, doi:10.3762/bjoc.19.133

• 22.8, 14.2 ppm; 19F NMR −63.1 ppm; HRESI(+)-MS (m/z): [M + H+] calcd for C94H144F6N5O7, 1569.0970; found, 1569.957. General procedure for the solvent screening of stereoselective Michael addition of acetylacetone to trans-β-nitrostyrene First, trans-β-nitrostyrene (12, 11.9 mg, 0.08 mmol) and the