Metal-free nucleophilic trifluoromethylselenolation via an iodide-mediated umpolung reactivity of trifluoromethylselenotoluenesulfonate

• Kevin Grollier,
• Alexis Taponard,
• Arnaud De Zordo-Banliat,
• Emmanuel Magnier and
• Thierry Billard

Beilstein J. Org. Chem. 2020, 16, 3032–3037, doi:10.3762/bjoc.16.252

• THF. Then, compound 2a–n (0.4 mmol, 2 equiv) was added followed by TBAI (0.4 mmol, 2 equiv). The tube is then sealed and the reaction mixture stirred at 40 °C for 4 h. The conversion was checked by 19F NMR spectroscopy with PhOCF3 as internal standard. After completion, the reaction mixture was

• concerning the direct nucleophilic trifluoromethylselenolation. The nucleophilic fluoroalkylselenolation of alkyl bromides. Yields were determined by 19F NMR spectroscopy with PhOCF3 as an internal standard and yields of isolated products are shown in parentheses. aWith 1 equiv of electrophile 2. bStarting

Controlled decomposition of SF₆ by electrochemical reduction

• Sébastien Bouvet,
• Bruce Pégot,
• Stéphane Sengmany,
• Erwan Le Gall,
• Eric Léonel,
• Anne-Marie Goncalves and
• Emmanuel Magnier

Beilstein J. Org. Chem. 2020, 16, 2948–2953, doi:10.3762/bjoc.16.244

• hexafluoride dissolved in various organic solvents. After combining an analytical approach of electrochemistry and 19F NMR spectroscopy, we have succeeded in the total consumption of SF6 in an electrochemical cell. Results and Discussion The first step of this work began with the measurement of the solubility

• . The solubility of SF6 was measured, at 20 °C, by 19F NMR with chlorodifluoromethoxybenzene as internal standard probe. The concentration value for DMF was quite low (0.17 g/L) whereas the one for acetonitrile (2.48 g/L) was convenient for further studies. Acetonitrile is a common nonaqueous solvent in

• also monitored by 19F NMR (Figure 5). After 3 hours experience, unidentified side-products were detected by NMR. Identification of these fleeting species as well as their potential reactivity are under current investigation in our laboratory. The left part of Figure 5 clearly demonstrates the total

Fluorine effect in nucleophilic fluorination at C4 of 1,6-anhydro-2,3-dideoxy-2,3-difluoro-β-D-hexopyranose

• Danny Lainé,
• Vincent Denavit,
• Olivier Lessard,
• Laurie Carrier,
• Charles-Émile Fecteau,
• Paul A. Johnson and
• Denis Giguère

Beilstein J. Org. Chem. 2020, 16, 2880–2887, doi:10.3762/bjoc.16.237

• reactions were monitored using 19F NMR spectroscopy with 2-fluoro-4-nitrotoluene as internal standard. Fluorodeoxygenation of glucopyranose 2 gave galactose 10 (inversion of configuration), as the only diastereoisomer (Table 1, entry 1). Interestingly, the epimer at C4 (compound 3) provided galactose 10

• , entry 1). To our delight, mannose analogue 14 was formed as the major product (44% yield), along with 21% of the talose analogue 12 and the elimination product 15 in 20% yield, as determined after analysis of the 19F NMR spectra of the crude reaction mixture. Figure 2 shows a representative 19F NMR

• 9 from levoglucosan 1. Typical 19F NMR spectrum (470 MHz, CDCl3) of the crude reaction mixture using Et3N·3HF/Et3N (entry 3 of Table 2). Fluorination at C4 of 1,6-anhydro-2,3-difluorohexopyranose analogues. a) Reactions on triflates 13, 16–18, dipole of C–F bonds are displayed in green arrows; b

Synthesis of purines and adenines containing the hexafluoroisopropyl group

• Viacheslav Petrov,
• Rebecca J. Dooley,
• Alexander A. Marchione,
• Elizabeth L. Diaz,
• Brittany S. Clem and
• William Marshall

Beilstein J. Org. Chem. 2020, 16, 2739–2748, doi:10.3762/bjoc.16.224

• isomeric products 3a and 3b (Scheme 2). The major isomer 3a was isolated in a pure form, and the structure was confirmed by X-ray diffraction. It should be pointed out that the 19F NMR spectra of the two isomers were very different. While the resonance corresponding to the CH(CF3)2 group in the spectrum of

• in the formation of two regioisomers, 4a and 4b (Scheme 3). In this context, the isomers 4a and 4b were separated by column chromatography (see Experimental section), and the structure of both was established by X-ray diffraction. In the 19F NMR spectra of both isomers 4a and 4b, the resonances

• the compounds 5a and 6a relies solely on NMR data. In both cases, the data were consistent with the structures 5a or 6a, carrying NH2 and CH(CF3)2 groups on the same side of the molecule. Indeed, in the 19F NMR spectra of 5a and 6a, the resonance corresponding to CH(CF3)2 was significantly broadened

A heterobimetallic tetrahedron from a linear platinum(II)-bis(acetylide) metalloligand

• Matthias Hardy,
• Marianne Engeser and
• Arne Lützen

Beilstein J. Org. Chem. 2020, 16, 2701–2708, doi:10.3762/bjoc.16.220

• , CD3CN, 298 K) δ [ppm] 4.66–4.47 (m); 19F NMR (470 MHz, CD3CN, 298 K) δ [ppm] −79.4 (CF3SO3−); DOSY (500 MHz, CD3CN, 298 K, τ = 150 ms): D = 3.33∙10−10 m2/s, dh = 33 Å, rh = 1.65 nm; ESI(+)-MS (CH3CN, M = {C320H432Fe4N24P12Pt6}8+) m/z: 1720.141 [M + 4OTf]4+, 1542.718 [Fe(C52H72N4P2Pt)3]2+, 1433.608 [Fe2

Asymmetric Mannich reactions of (S)-N-tert-butylsulfinyl-3,3,3-trifluoroacetaldimines with yne nucleophiles

• Ziyi Li,
• Li Wang,
• Yunqi Huang,
• Haibo Mei,
• Hiroyuki Konno,
• Hiroki Moriwaki,
• Vadim A. Soloshonok and
• Jianlin Han

Beilstein J. Org. Chem. 2020, 16, 2671–2678, doi:10.3762/bjoc.16.217

• ), CH2Cl2 (3 mL), −78 °C, under nitrogen, 2.5 h. Isolated yields of mixture of isomers. Diastereoselectivities were determined by 19F NMR. Large-scale application of the reaction. Removal of the chiral auxiliary. Optimization of reaction conditions.a Supporting Information Supporting Information File 420

Activation of pentafluoropropane isomers at a nanoscopic aluminum chlorofluoride: hydrodefluorination versus dehydrofluorination

• Maëva-Charlotte Kervarec,
• Thomas Braun,
• Mike Ahrens and
• Erhard Kemnitz

Beilstein J. Org. Chem. 2020, 16, 2623–2635, doi:10.3762/bjoc.16.213

• =CHCH2C6D5 (9) and CF3CH=CHC6D5 (8, Scheme 11, middle). In neat silane, 5 and 6 were detected in a ratio of 1:4 (Scheme 11, bottom). Notably, for all conversions (C6D6 and silane, C6D12 and silane, or in neat silane), monitoring of the reaction by 19F NMR spectroscopy led to the observation of the early

• DPX 300 spectrometer. A capillary of trifluorotoluene was employed as an external standard for quantification purposes. The 19F NMR spectra were referenced to PhCF3 (δ = −63.5 ppm) and the chemical shifts in 1H NMR were referenced to residual C6D5H (δ = 7.16 ppm) or C6D11H (δ = 1.38 ppm). Procedure

• mL of HSiEt3 was added using Schlenk techniques to the JYoung NMR tube loaded with ACF. The gases were then condensed using a small glass bulb filled with 0.5 atm of the corresponding gas (0.1 mmol). The reactions were monitored by 1H and 19F NMR spectroscopy. The tubes were kept at 70 °C for 7 days

Catalytic trifluoromethylation of iodoarenes by use of 2-trifluoromethylated benzimidazoline as trifluoromethylating reagent

• Tatsuhiro Uchikura,
• Nanami Kamiyama,
• Taisuke Ishikawa and
• Takahiko Akiyama

Beilstein J. Org. Chem. 2020, 16, 2442–2447, doi:10.3762/bjoc.16.198

• , hexafluorobenzene was added as an internal standard and the mixture analyzed by 19F NMR spectroscopy for the calculation of the NMR yield. Then, the crude products were purified by preparative TLC to give pure products 3. Trifluoromethylation of aryl halides. Scope of aryl iodides. Yields determined by 19F NMR

• spectroscopy and used ligand is given in parenthesis. Scope of heteroaryl iodides. Yields determined by 19F NMR spectroscopy and used ligand is given in parenthesis. Time course of the trifluoromethylation reaction. Proposed mechanism of the catalytic cycle. Screening for reaction conditionsa. Screening for

Chan–Evans–Lam N1-(het)arylation and N1-alkеnylation of 4-fluoroalkylpyrimidin-2(1H)-ones

• Viktor M. Tkachuk,
• Oleh O. Lukianov,
• Mykhailo V. Vovk,
• Isabelle Gillaizeau and
• Volodymyr A. Sukach

Beilstein J. Org. Chem. 2020, 16, 2304–2313, doi:10.3762/bjoc.16.191

• ). Structural determination of compound 3а was performed by IR and 1Н, 13С, and 19F NMR spectroscopy as well as by LCMS and HRMS analysis. Performing the reaction with substrate 1а under the optimum conditions (see Table 1, entry 18), we examined a variety of (het)aryl- and alkenylboronic acids 2b–w as coupling

Regioselective cobalt(II)-catalyzed [2 + 3] cycloaddition reaction of fluoroalkylated alkynes with 2-formylphenylboronic acids: easy access to 2-fluoroalkylated indenols

• Tatsuya Kumon,
• Miroku Shimada,
• Jianyan Wu,
• Shigeyuki Yamada and
• Tsutomu Konno

Beilstein J. Org. Chem. 2020, 16, 2193–2200, doi:10.3762/bjoc.16.184

• determined by 19F NMR spectroscopy. The values in parentheses are the isolated yield of 3. aAtropisomers of 3fA and 5fA were detected. b3.0 equiv of 2 were used. cThe reaction was carried out using 3.0 equiv of 2 in the presence of 20 mol % each of Co(acac)2·2H2O and dppp at 110 °C in a sealed tube

• . Synthesis of the fluoroalkylated indenone 6 and the indanone 7 from the indenol 3aA. The yields were determined by 19F NMR spectroscopy. The values in parentheses are the isolated yields. Stereochemical assignment of 5aA and 7 based on NMR techniques. The cross-peaks were observed through HMBC measurements

• . Proposed reaction mechanism. Screening for the reaction conditions of the cobalt-catalyzed [2 + 3] cycloaddition using the fluoroalkylated alkyne 1a and 2-formylphenylboronic acid (2A). Supporting Information Supporting Information File 454: Experimental procedures, characterization data (1H, 13C, 19F NMR

Lipophilicity trends upon fluorination of isopropyl, cyclopropyl and 3-oxetanyl groups

• Benjamin Jeffries,
• Zhong Wang,
• Robert I. Troup,
• Anaïs Goupille,
• Jean-Yves Le Questel,
• Charlene Fallan,
• James S. Scott,
• Elisabetta Chiarparin,
• Jérôme Graton and
• Bruno Linclau

Beilstein J. Org. Chem. 2020, 16, 2141–2150, doi:10.3762/bjoc.16.182

• fluorinated isobutanol, cyclopropylmethanol and 3-oxetanylmethanol derivatives are given in Figure 5. They were measured by a 19F NMR-based method developed by our group [22][27], which is suitable for measuring the octanol/water partition coefficients P of (fluorinated) non-UV active substrates. As expected

Reactions of 3-aryl-1-(trifluoromethyl)prop-2-yn-1-iminium salts with 1,3-dienes and styrenes

• Thomas Schneider,
• Michael Keim,
• Bianca Seitz and
• Gerhard Maas

Beilstein J. Org. Chem. 2020, 16, 2064–2072, doi:10.3762/bjoc.16.173

• °C, 19F NMR monitoring of the reaction’s progress indicated the appearance of a second product beside the 1,4-cyclohexadien-1-iminium salt 4-Ch. Further investigations revealed that the new product was the dihydrofluorene 7, resulting from 4-Ch by an intramolecular electrophilic aromatic substitution

• reaction of propyn-1-iminium salt 1a with styrene in acetonitrile was considered first and was monitored by 19F NMR spectroscopy. Whereas no reaction appeared to occur at room temperature, a slow transformation into two fluorine-containing products was observed at 70 °C, which after neutralization and work

• interest to know whether it would react with propyn-1-iminium salts 1 as a styrene or a 1,3-diene. With 3-(4-bromophenyl)propyn-1-iminium salt 1c in acetonitrile, no reaction was observed at 20 °C, but within two hours at 45 °C, an unclean reaction took place, which became evident by a multitude of 19F NMR

Selective preparation of tetrasubstituted fluoroalkenes by fluorine-directed oxetane ring-opening reactions

• Clément Q. Fontenelle,
• Thibault Thierry,
• Romain Laporte,
• Emmanuel Pfund and
• Thierry Lequeux

Beilstein J. Org. Chem. 2020, 16, 1936–1946, doi:10.3762/bjoc.16.160

• of 0 °C instead of 20 °C, for 30 min, complete conversion was achieved and the three products E,Z-9 and 10 were present in a 62:8:26 ratio as determined by 19F NMR, the remaining 4% being attributed to acetylated analogues of 9 (Table 3, entry 1). After purification, two products were obtained as a

• heterocyclic ether 10, the addition of TBAB as a bromide source was explored. To our delight, after 30 min at 0 °C, the crude 19F NMR showed that only 4% of 10 and 96% of 9 as an 84:16 E/Z mixture had formed (Table 3, entry 2). Separation of the two E/Z isomers proved challenging by column chromatography and a

• ) and CSA (2 equiv) an 84% conversion into mainly brominated lactone 15 (79%) with traces of hydroxylated lactone 14, and of bromoalkene Z-13 was determined by crude 19F NMR. The remaining 8% appeared to be the β-chloromethyllactone 19 (see Scheme 7 below), an analogue of 15 as determined by NMR

Polarity effects in 4-fluoro- and 4-(trifluoromethyl)prolines

• Vladimir Kubyshkin

Beilstein J. Org. Chem. 2020, 16, 1837–1852, doi:10.3762/bjoc.16.151

• analogues in complex biological systems such as peptides and proteins, especially in 19F NMR labelling, where fluorinated prolines can serve as spectroscopic probes. Potential areas for the application of fluorinated prolines are numerous, and include the design of molecular recognition systems [101

Pauson–Khand reaction of fluorinated compounds

• Jorge Escorihuela,
• Daniel M. Sedgwick,
• Alberto Llobat,
• Mercedes Medio-Simón,
• Pablo Barrio and
• Santos Fustero

Beilstein J. Org. Chem. 2020, 16, 1662–1682, doi:10.3762/bjoc.16.138

• -aldol reaction affording the final product (Scheme 34). This mechanism was experimentally supported by the beneficial effect of water and the observation of HF-loss by 19F NMR. The catalytic version of this process was also studied. The best results in terms of efficiency and stereoselectivity were

Fluorohydration of alkynes via I(I)/I(III) catalysis

• Jessica Neufeld,
• Constantin G. Daniliuc and
• Ryan Gilmour

Beilstein J. Org. Chem. 2020, 16, 1627–1635, doi:10.3762/bjoc.16.135

• organocatalyst, Selectfluor® was employed as the terminal oxidant, and an amine/HF complex enlisted as the fluoride source (please see Supporting Information File 1 for full details). The reaction was performed in CHCl3 at ambient temperature and the crude reaction mixtures were analysed by 19F NMR spectroscopy

• , carbonyl and alkynyl group are optimally preorganised with a C5 linker. With this in mind, the amide derivatives 12 and 13 were exposed to the standard reaction conditions. Curiously, the reactions were extremely ineffective yielding the respective α-fluoroketones in only 15% yield as determined by 19F NMR

• spectroscopical yields determined by 19F NMR analysis of the crude reaction mixtures using ethyl fluoroacetate as an internal standard. (A) Hammett plot varying the para-substitution on the alkyne (ρ ≈ 0). (B) Hammett plot varying the para-substitution on the catalyst (ρ < 0). An overview of the I(I)/I(III

NHC-catalyzed enantioselective synthesis of β-trifluoromethyl-β-hydroxyamides

• Alyn T. Davies,
• Mark D. Greenhalgh,
• Alexandra M. Z. Slawin and
• Andrew D. Smith

Beilstein J. Org. Chem. 2020, 16, 1572–1578, doi:10.3762/bjoc.16.129

• : Experimental procedures, product characterization data (mp, NMR, IR, HRMS, [α]D, HPLC), and spectra (1H, 13C, and 19F NMR, HPLC). Supporting Information File 336: Crystallographic details for 12. Acknowledgements We thank the EPSRC UK National Mass Spectrometry Facility at Swansea University. Funding We thank

Photoredox-catalyzed silyldifluoromethylation of silyl enol ethers

• Vyacheslav I. Supranovich,
• Vitalij V. Levin and
• Alexander D. Dilman

Beilstein J. Org. Chem. 2020, 16, 1550–1553, doi:10.3762/bjoc.16.126

• analyzed by 19F NMR spectroscopy. A series of typical photocatalysts (for example, iridium catalysts) were ineffective in promoting the reaction. Rewardingly, a gold catalyst, [AuCl(μ-dppm)]2 [25][26][27], provided reasonable yields of 3a after one day of irradiation along with a full conversion of the

• . Yield determined by 19F NMR spectroscopy using an internal standard. Proposed mechanism of the fluoroalkylation reaction. Supporting Information Supporting Information File 332: Full experimental details, compound characterization, and copies of NMR spectra.

Heterogeneous photocatalysis in flow chemical reactors

• Christopher G. Thomson,
• Ai-Lan Lee and
• Filipe Vilela

Beilstein J. Org. Chem. 2020, 16, 1495–1549, doi:10.3762/bjoc.16.125

Synthesis of new fluorescent molecules having an aggregation-induced emission property derived from 4-fluoroisoxazoles

• Kazuyuki Sato,
• Akira Kawasaki,
• Yukiko Karuo,
• Atsushi Tarui,
• Kentaro Kawai and
• Masaaki Omote

Beilstein J. Org. Chem. 2020, 16, 1411–1417, doi:10.3762/bjoc.16.117

• fluorescence data for 4-fluoroisoxazoles 3b and 3c, and non-fluorinated compound 2ca. Optical properties of BKIs and F-BKIs. Supporting Information Supporting Information File 68: General procedures and analytical data, including copies of 1H NMR, 13C NMR and 19F NMR spectra. Acknowledgements We wish to

Photocatalytic trifluoromethoxylation of arenes and heteroarenes in continuous-flow

• Alexander V. Nyuchev,
• Ting Wan,
• Borja Cendón,
• Carlo Sambiagio,
• Job J. C. Struijs,
• Michelle Ho,
• Moisés Gulías,
• Ying Wang and
• Timothy Noël

Beilstein J. Org. Chem. 2020, 16, 1305–1312, doi:10.3762/bjoc.16.111

• trifluoromethoxylation methodologies. Effect of KH2PO4 – other substrates. a Conditions as for entry 15 (Table 2), 1 h residence time; b conditions as for entry 14 (Table 2), 18 h reaction time; c 0.5 equiv KH2PO4, CH3CN/CH2Cl2 1:1; d 2 equiv KH2PO4. 19F NMR yields are reported. A) Properties and B) synthesis of CF3O

• -bearing arenes; C) trifluoromethoxylation using the “second” Ngai reagent. Optimization of residence time. 19F NMR yields are reported. Scope of photoredox trifluoromethoxylation in continuous-flow. In case of different products, the major isomer is shown. The position of the CF3O group in the minor

• isomer is marked with a star. 19F NMR yields are reported. a CH3CN/CH2Cl2 3:2, 0.08 M; b CH3CN/CH2Cl2 1:1, 0.05 M; c CH3CN/CH2Cl2 5:3, 0.05 M; d CH3CN/CH2Cl2 3:2, 0.02 M; e CH3CN/CH2Cl2 5:4, 0.057 M. Reaction optimization under flow conditions. Influence of bases on the photoredox trifluoromethoxylation

Development of fluorinated benzils and bisbenzils as room-temperature phosphorescent molecules

• Shigeyuki Yamada,
• Takuya Higashida,
• Yizhou Wang,
• Masato Morita,
• Takuya Hosokai,
• Kaveendra Maduwantha,
• Kaveenga Rasika Koswattage and
• Tsutomu Konno

Beilstein J. Org. Chem. 2020, 16, 1154–1162, doi:10.3762/bjoc.16.102

• procedures for the synthesis and characterization of fluorinated benzils 2a and 2b, fluorinated bisbenzils 3a and 3b, and nonfluorinated bisbenzil 3c. 1H, 13C, and 19F NMR spectra of 2a, 2b, and 3a–c. Cartesian coordinates of the optimized geometries of 1a, 1c, 2a, and 3a obtained from DFT calculations

Synthesis of esters of diaminotruxillic bis-amino acids by Pd-mediated photocycloaddition of analogs of the Kaede protein chromophore

• Esteban P. Urriolabeitia,
• Pablo Sánchez,
• Alexandra Pop,
• Cristian Silvestru,
• Eduardo Laga,
• Ana I. Jiménez and
• Carlos Cativiela

Beilstein J. Org. Chem. 2020, 16, 1111–1123, doi:10.3762/bjoc.16.98

• isomers, the transoid (in which the two cyclopalladated oxazolones are in an anti arrangement) and the cisoid (syn arrangement). The presence of the two isomers in 3 is clear from the observation of two sets of signals due to the CF3CO2– ligand in the 19F NMR spectra. The major isomer shows one singlet

• stereoisomer, despite the presence of two isomers in the starting materials 3. The 1H NMR and 13C NMR spectra clearly showed the chemical equivalence of the two ortho-palladated fragments, while 19F NMR spectra showed the equivalence of the bridging trifluoroacetate ligands. This means that only the transoid

• universal attenuated total reflectance (UATR) accessory made of thallium bromide-iodide crystals (KRS-5). The 1H, 13C{1H} and 19F NMR spectra were recorded on Bruker Avance-300 and -400 spectrometers (δ in ppm; J in Hz). All spectra were recorded at room temperature in solution, using CDCl3 as deuterated

Copper-based fluorinated reagents for the synthesis of CF₂R-containing molecules (R ≠ F)

• Louise Ruyet and
• Tatiana Besset

Beilstein J. Org. Chem. 2020, 16, 1051–1065, doi:10.3762/bjoc.16.92

• substrates. Based on 19F NMR studies, the authors suggested the following mechanism: first the in situ generation of a CuCF2H complex from TMSCF2H in equilibrium with the corresponding cuprate (Cu(CF2H)2−) occurred followed by the reaction with terminal alkynes under basic conditions. The resulting

• either from the pre-isolated (K(DMF))Cu(Ot-Bu)2 or in situ from CuCl, t-BuOK in DMF in a nearly quantitative yield. The copper reagent was used for the pentafluoroethylation of a panel of (hetero)aryl iodides and bromides (up to 99% 19F NMR yield) and its synthetic utility was further demonstrated with

• , pyrimidine and quinolone derivatives, for instance, when the PhenCuCF2CF3 complex was used as the pentafluoroethyl source (24 examples, up to 99% 19F NMR yield and up to 93% isolated yield, Scheme 15). Note that a complete mechanistic study was recently reported to explain the reactivity of this well

Towards triptycene functionalization and triptycene-linked porphyrin arrays

• Gemma M. Locke,
• Keith J. Flanagan and
• Mathias O. Senge

Beilstein J. Org. Chem. 2020, 16, 763–777, doi:10.3762/bjoc.16.70

• , triptycene-H), 7.03 (d, 4H, pyrrole-H), 6.62 ppm (s, 4H, pyrrole-H); 13C NMR (151 MHz, CDCl3) δ 146.4, 144.7, 143.5, 135.0, 134.3, 132.3, 131.6, 130.9, 126.3, 126.2, 125.6, 122.5, 119.0, 92.3, 86.4, 29.8; 11B NMR (128 MHz, CDCl3) δ 0.32 (t, J = 28.7 Hz); 19F NMR (377 MHz, CDCl3) δ −145.04 (dd, J = 57.5, 28.7