Copper-catalyzed domino cyclization of anilines and cyclobutanone oxime: a scalable and versatile route to spirotetrahydroquinoline derivatives

• Qingqing Jiang,
• Xinyi Lei,
• Pan Gao and
• Yu Yuan

Beilstein J. Org. Chem. 2025, 21, 749–754, doi:10.3762/bjoc.21.58

• ) trifluoroacetate (Cu(TFA)2) as the catalyst (20 mol %) under ambient air at 80 °C for 12 hours; the product 3aa was isolated by chromatographic purification (Table 1, entry 1). The use of other solvents, including acetonitrile (MeCN), tetrahydrofuran (THF), toluene, acetone and methanol (MeOH), resulted in

•  1, entry 3). When iron(II) sulfate (FeSO4) and iron trifluoromethanesulfonate (Fe(OTf)2) were used as the catalyst instead of copper(II) trifluoroacetate (Cu(TFA)2), the yields of the product were decreased (Table 1, entries 4 and 5). Using palladium(II) acetate (Pd(OAc)2) as the catalyst provided a

• conditions, we proceeded to investigate the generality of this Cu-catalyzed system. Initially, a series of anilines bearing diverse substituents was examined, and the results are summarized in Scheme 2. When copper(II) trifluoroacetate was employed as the catalyst, para-halogen-substituted anilines 1b–e

Synthesis of electrophile-tethered preQ₁ analogs for covalent attachment to preQ₁ RNA

• Laurin Flemmich and
• Ronald Micura

Beilstein J. Org. Chem. 2025, 21, 483–489, doi:10.3762/bjoc.21.35

• were required to obtain the corresponding mesylate 3b. Similar to 11, compound 12 was isolated as its trifluoroacetate salt. Selective Boc protection of the aliphatic amine gave 13, which was selectively O-mesylated to give compound 14. Compound 14 was found to slowly undergo intramolecular cyclization

Advances in the use of metal-free tetrapyrrolic macrocycles as catalysts

• Mandeep K. Chahal

Beilstein J. Org. Chem. 2024, 20, 3085–3112, doi:10.3762/bjoc.20.257

• zero due to too strong association of trifluoroacetate with protonated porphyrin. DFT calculations suggested that the O–O bond in O2 becomes polarized upon binding in {(H4TPP2+)·(TB−)·O2}, which facilitates

Synthesis of fluoroalkenes and fluoroenynes via cross-coupling reactions using novel multihalogenated vinyl ethers

• Yukiko Karuo,
• Keita Hirata,
• Atsushi Tarui,
• Kazuyuki Sato,
• Kentaro Kawai and
• Masaaki Omote

Beilstein J. Org. Chem. 2024, 20, 2691–2703, doi:10.3762/bjoc.20.226

• 2a in good yields (Table 1, entries 9–11). Cross-coupling with palladium bis(trifluoroacetate), which is more reactive than palladium diacetate, gave the corresponding product in high yield of 96% (Table 1, entry 12). Without the addition of triphenylphosphine, the reaction proceeded in only 12

• mol %), cesium carbonate (1.5 equiv), palladium bis(trifluoroacetate) (5 mol %) in THF (2.0 mL) was added the respective boronic acid derivative 4 (2.0 equiv). The reaction solution was refluxed for 3.5 h. The reaction mixture was quenched by the addition of water (40 mL) at 0 °C and extracted with

Hypervalent iodine-mediated cyclization of bishomoallylamides to prolinols

• Smaher E. Butt,
• Konrad Kepski,
• Jean-Marc Sotiropoulos and
• Wesley J. Moran

Beilstein J. Org. Chem. 2024, 20, 2455–2460, doi:10.3762/bjoc.20.209

• , the iodane moiety in 12 is eliminated by an intramolecular attack by the amide nitrogen to form the aziridinium 13. Finally, ring-opening by SN2 attack of trifluoroacetate leads to the final product 14 [20]. In this case, the kinetic pyrrolidine product is obtained due to the electron-withdrawing

Phenylseleno trifluoromethoxylation of alkenes

• Clément Delobel,
• Armen Panossian,
• Gilles Hanquet,
• Frédéric R. Leroux,
• Fabien Toulgoat and
• Thierry Billard

Beilstein J. Org. Chem. 2024, 20, 2434–2441, doi:10.3762/bjoc.20.207

• finally be reopened by trifluoroacetate (Scheme 3). Although the selenylated compounds 2 are of interest, the presence of the PhSe moiety allows other transformations to be considered. First, the oxidative elimination of the selenyl moiety to generate a double bond was first studied. However, regardless

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

• ][9][10][11], yielding phenylacetic acids. For example, Troupel et al. successfully performed electrochemical reduction of benzyl ethers and several esters such as acetate, trifluoroacetate, benzoate, and dibenzyl carbonate derived from benzyl alcohols, including 1-phenylethanol compounds, in the

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

• containing 1 g L−1 of a sample, 10 g L−1 of dithranol, and 1 g L−1 of sodium trifluoroacetate were mixed at a ratio of 1:1:1, and then 1 μL aliquot of this mixture was deposited onto a sample target plate. UV–vis absorption spectra were recorded on a JASCO V-670 spectrophotometer. Fluorescence spectra were

Solvent-dependent chemoselective synthesis of different isoquinolinones mediated by the hypervalent iodine(III) reagent PISA

• Ze-Nan Hu,
• Yan-Hui Wang,
• Jia-Bing Wu,
• Ze Chen,
• Dou Hong and
• Chi Zhang

Beilstein J. Org. Chem. 2024, 20, 1914–1921, doi:10.3762/bjoc.20.167

• Na2SO4 (Table 1, entries 3 and 4). Next, different commercially available iodanes were employed as oxidants, such as PIDA, phenyliodine(III) bis(trifluoroacetate) (PIFA), N-tosyliminobenzyliodinane (PhINTs), iodosylbenzene (PhIO), and Koser’s reagent (HTIB) (Table 1, entries 5–9). Of the reagents tested

Synthesis of 4-functionalized pyrazoles via oxidative thio- or selenocyanation mediated by PhICl₂ and NH₄SCN/KSeCN

• Jialiang Wu,
• Haofeng Shi,
• Xuemin Li,
• Jiaxin He,
• Chen Zhang,
• Fengxia Sun and
• Yunfei Du

Beilstein J. Org. Chem. 2024, 20, 1453–1461, doi:10.3762/bjoc.20.128

• NH4SCN (Table 1, entries 4–6). Next, other oxidants including phenyliodine(III) diacetate (PIDA), phenyliodine(III) bis(trifluoroacetate) (PIFA), iodosobenzene (PhIO), and NCS were applied, and the results indicated that PhICl2 was the most effective oxidant (Table 1, entries 7–10). Later on, when the

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

• conditions afforded the ditrigger iodonium salt 4l in 88% yield, demonstrating the versatility of the process for the synthesis of multivalent precursors. Furthermore, phenyliodine(III) bis(trifluoroacetate) was used as a starting material under the optimized reaction conditions and the corresponding phenyl

• (TMP)iodonium(III) trifluoroacetate (4m) was obtained in 91% yield. These aryl(TMP)iodonium(III) acetates were recently utilized by our group for the arylation of phenols [13] and N-alkoxyamides [26][29], exhibiting excellent reactivity and aryl group selectivity. In subsequent experiments, we sought

Carbonylative synthesis and functionalization of indoles

• Alex De Salvo,
• Raffaella Mancuso and
• Xiao-Feng Wu

Beilstein J. Org. Chem. 2024, 20, 973–1000, doi:10.3762/bjoc.20.87

• indole derivatives were obtained by catalyzing the reaction with 5 mol % of Pd(tfa)2 (palladium(II) trifluoroacetate) and 1.5 equivalents of p-benzoquinone as oxidant in a 1:5 DMSO/MeOH solvent mixture at a temperature between 0 °C and 15 °C and, for a time between 48 and 120 hours depending on the

Enantioselective synthesis of β-aryl-γ-lactam derivatives via Heck–Matsuda desymmetrization of N-protected 2,5-dihydro-1H-pyrroles

• Arnaldo G. de Oliveira Jr.,
• Martí F. Wang,
• Rafaela C. Carmona,
• Danilo M. Lustosa,
• Sergei A. Gorbatov and
• Carlos R. D. Correia

Beilstein J. Org. Chem. 2024, 20, 940–949, doi:10.3762/bjoc.20.84

• in the er. Pd(acac)2 and Pd(MeCN)2(OTs)2 were also tested without significant improvements. Despite the fact that palladium acetate slightly better performed as shown in Table 1, we decided to continue with palladium trifluoroacetate due to its higher reactivity in forming palladium complexes with N

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

• section and Supporting Information File 1 for the details). Diol 7 was converted into glycosyl donor 2 by O-trifluoroacetylation with trifluoroacetic anhydride and sodium trifluoroacetate under previously developed [36][55] conditions. Supramer analysis As we know that the concentrations of reactants can

• characterization Methyl (phenyl 4,9-bis-O-chloroacetyl-3,5-dideoxy-2-thio-5-trifluoroacetamido-7,8-bis-O-trifluoroacetyl-ᴅ-glycero-β-ᴅ-galacto-nonulopyranosid)onate (2) To the solution of diol 7 (124.9 mg, 0.2 mmol, dried in vacuo at 0.1 Torr for 1 h) in (CF3CO)2O (4 mL), sodium trifluoroacetate (25 mg, freshly

• previously [33]. The residue was dissolved in anhydrous MeOH (3 mL per 0.1 mmol of sialyl donor) and MeONa (0.3 mL of 1 M solution in MeOH per 0.1 mmol of sialyl donor) followed by ethyl trifluoroacetate (0.1 mL per 0.1 mmol of sialyl donor) was added. The reaction mixture was kept at room temperature

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

• 1-butyl-3-methylimidazolium cation unchanged, anion variation also affected the reaction yield. Indeed, in the presence of triflate, acetate or trifluoroacetate anions the desired product was obtained only in trace amounts (Table 3, entries 10–12). This could be explained by the fact that these

Visible-light-induced nickel-catalyzed α-hydroxytrifluoroethylation of alkyl carboxylic acids: Access to trifluoromethyl alkyl acyloins

• Feng Chen,
• Xiu-Hua Xu,
• Zeng-Hao Chen,
• Yue Chen and
• Feng-Ling Qing

Beilstein J. Org. Chem. 2023, 19, 1372–1378, doi:10.3762/bjoc.19.98

• the synthesis of trifluoromethyl aromatic acyloins. Maekawa’s group [24] developed a tandem reaction of the reductive coupling between arylaldehydes and ethyl trifluoroacetate in the presence of magnesium and chlorotrimethylsilane, followed by desilylation to produce the trifluoromethyl aromatic

Phenanthridine–pyrene conjugates as fluorescent probes for DNA/RNA and an inactive mutant of dipeptidyl peptidase enzyme

• Josipa Matić,
• Tana Tandarić,
• Marijana Radić Stojković,
• Filip Šupljika,
• Zrinka Karačić,
• Ana Tomašić Paić,
• Lucija Horvat,
• Robert Vianello and
• Lidija-Marija Tumir

Beilstein J. Org. Chem. 2023, 19, 550–565, doi:10.3762/bjoc.19.40

• trifluoroacetate salt of the deprotected amino acid was obtained as yellow oil after evaporation of the solvent. The deprotected compound was then dissolved in anhydrous acetonitrile (3 mL) and appropriate pyrenecarboxylic acid, HBTU, HOBt and Et3N were added. The reaction was stirred at room temperature for 20

Identification and determination of the absolute configuration of amorph-4-en-10β-ol, a cadinol-type sesquiterpene from the scent glands of the African reed frog Hyperolius cinnamomeoventris

• Angelique Ladwig,
• Markus Kroll and
• Stefan Schulz

Beilstein J. Org. Chem. 2023, 19, 167–175, doi:10.3762/bjoc.19.16

• concept proved to be difficult to achieve, but by optimization of different parameters of this Domino reaction, the required enantiomerically almost pure ketones 9–11 were obtained (Table 1). The Mannich reaction worked best using diisopropylammonium trifluoroacetate as the catalyst [22]. The isolation of

• –Alder reactions. DIA TFA: diisopropylammonium trifluoroacetate. Supporting Information Supporting Information File 8: Numbering scheme, experimental procedures, 1H, 13C and 2D NMR spectra, and mass spectra. Acknowledgements We thank Serdar Dilek for technical assistance and Miguel Vences for fruitful

Electrochemical Friedel–Crafts-type amidomethylation of arenes by a novel electrochemical oxidation system using a quasi-divided cell and trialkylammonium tetrafluoroborate

• Hisanori Senboku,
• Mizuki Hayama and
• Hidetoshi Matsuno

Beilstein J. Org. Chem. 2022, 18, 1040–1046, doi:10.3762/bjoc.18.105

• likely nucleophile in this reaction medium was the trifluoroacetate ion, which was produced by electrochemical reduction of TFA at the cathode, although we could not detect the coupling product of trifluoroacetate and the corresponding N-acyliminium ion due to the high solubility in water. In addition to

• TFA, iPr2NEt was also included in this reaction medium, and they probably formed the corresponding ammonium trifluoroacetate in the reaction medium. The thus-generated trifluoroacetate ion could also react with N-acyliminium ions of DMA. Therefore, to avoid the reaction of the cathodic product with N

• and yield of 2 were observed. These results indicate that DMA was selectively oxidized at the anode to generate the corresponding N-acyliminium ions, which were trapped by trifluoroacetate ions preventing the desired amidomethylation in the presence of TFA. The exchange of the proton source from TFA

Menadione: a platform and a target to valuable compounds synthesis

• Acácio S. de Souza,
• Ruan Carlos B. Ribeiro,
• Dora C. S. Costa,
• Fernanda P. Pauli,
• David R. Pinho,
• Matheus G. de Moraes,
• Fernando de C. da Silva,
• Luana da S. M. Forezi and
• Vitor F. Ferreira

Beilstein J. Org. Chem. 2022, 18, 381–419, doi:10.3762/bjoc.18.43

• developed based on other oxidizing agents, such as cobalt(III) fluoride [85], phenyliodine(III) bis(trifluoroacetate) (PIFA) [86] and tert-butyl hydroperoxide [87] (Table 3). In 1999, Tomatsu and co-workers performed the synthesis of menadione (10) through demethylation of 2-methyl-1,4-dimethoxynaphthalene

• published an alternative and sustainable methodology, using phenyliodine(III) bis(trifluoroacetate) (PIFA) as an oxidizing agent of the demethylation reaction [86]. The hypervalent iodine(III) proved to be a good oxidizing agent in the formation of 10 (92% yield) (Table 3, entry 2). According to the authors

Regioselective synthesis of methyl 5-(N-Boc-cycloaminyl)-1,2-oxazole-4-carboxylates as new amino acid-like building blocks

• Jolita Bruzgulienė,
• Greta Račkauskienė,
• Aurimas Bieliauskas,
• Vaida Milišiūnaitė,
• Miglė Dagilienė,
• Gita Matulevičiūtė,
• Vytas Martynaitis,
• Sonata Krikštolaitytė,
• Frank A. Sløk and
• Algirdas Šačkus

Beilstein J. Org. Chem. 2022, 18, 102–109, doi:10.3762/bjoc.18.11

• asymmetric unit of the crystal of 6b consists of two (2S)-2-[4-(methoxycarbonyl)-1,2-oxazol-5-yl]piperidin-1-ium cations and two 2,2,2-trifluoroacetate anions (2C10H15N2O3+·2C2F3O2−) (Figure 5; Table 1, Supporting Information File 1 in Tables S1–S3). The substituted piperidinium moieties are in chair

• sets of signals with different intensities were observed due to the existence of two Boc-group rotational conformers. The X-ray structure of (2S)-2-[4-(methoxycarbonyl)-1,2-oxazol-5-yl]piperidin-1-ium trifluoroacetate (6b) finally supported this structure analysis. Examples of amino-functionalized 1,2

The PIFA-initiated oxidative cyclization of 2-(3-butenyl)quinazolin-4(3H)-ones – an efficient approach to 1-(hydroxymethyl)-2,3-dihydropyrrolo[1,2-a]quinazolin-5(1H)-ones

• Alla I. Vaskevych,
• Nataliia O. Savinchuk,
• Ruslan I. Vaskevych,
• Eduard B. Rusanov,
• Oleksandr O. Grygorenko and
• Mykhailo V. Vovk

Beilstein J. Org. Chem. 2021, 17, 2787–2794, doi:10.3762/bjoc.17.189

• of them (pathway a) includes the formation of the nitrene cation 11 [41][42][44][45][53] under action of PIFA as an oxidant. A subsequent electrophilic attack at the double bond provides aziridinium cation 12 that undergoes selective ring opening with the trifluoroacetate anion to give intermediate

N-Sulfinylpyrrolidine-containing ureas and thioureas as bifunctional organocatalysts

• Viera Poláčková,
• Dominika Krištofíková,
• Boglárka Némethová,
• Renata Górová,
• Mária Mečiarová and
• Radovan Šebesta

Beilstein J. Org. Chem. 2021, 17, 2629–2641, doi:10.3762/bjoc.17.176

• were obtained as their trifluoroacetate salts. (S)-2-((3-((R)-tert-Butylsulfinyl)thioureido)methyl)pyrrolidin-1-ium 2,2,2-trifluoroacetate ((S,R)-C1) −17.8 (c 1.0, MeOH); 1H NMR (300 MHz, CDCl3) δ 9.53 (s, 1H), 9.40 (s, 1H), 9.16 (s, 1H), 9.01 (s, 1H), 4.33–4.17 (m, 2H), 3.63–3.31 (m, 3H), 2.30–2.00

• ; found, 264.1200; [M − CF3COOH + Na]+ calcd, 286.1018; found, 286.1019. (S)-2-((3-((S)-tert-Butylsulfinyl)thioureido)methyl)pyrrolidin-1-ium 2,2,2-trifluoroacetate ((S,S)-C1) +34.2 (c 1.0, MeOH); 1H NMR (600 MHz, D2O) δ 3.93–3.87 (m, 1H), 3.81–3.74 (m, 2H), 3.61–3.57 (m, 1H), 3.28–3.13 (m, 3H), 2.15

• ]+ calcd for C12H22F3N3O3S2, 264.1199; found, 264.1198; [M − CF3COOH + Na]+ calcd, 286.1018; found, 286.1016. (S)-2-((3-((R)-tert-Butylsulfinyl)ureido)methyl)pyrrolidin-1-ium 2,2,2-trifluoroacetate ((S,R)-C2) −38.8 (c 1.0, MeOH); 1H NMR (300 MHz, D2O) δ 7.22 (bs, 1H), 7.05 (bs, 1H), 6.87 (bs, 1H), 3.72

Advances in mercury(II)-salt-mediated cyclization reactions of unsaturated bonds

• Sumana Mandal,
• Raju D. Chaudhari and
• Goutam Biswas

Beilstein J. Org. Chem. 2021, 17, 2348–2376, doi:10.3762/bjoc.17.153

• using mercuric trifluoroacetate Hg(TFA)2 at room temperature was performed. The reaction proceeds primarily through stereoselective cyclization to give α-ᴅ-C-glycopyranosyl amino acid derivative 14 as the major product [43]. Nevertheless, C-mannopyranosyl derivatives cannot be achieved in a similar

• -containing mixture of diastereomeric alicyclic derivatives 59. The tetrahydropyrimidin-4(1H)-one-mercuri trifluoroacetate derivative 59 on successive treatment with NaBr and LiBH4 gives a mixture of tetrahydropyrimidin-4(1H)-one derivatives 60 in the diastereomeric ratio of 63:37 after separation by column

• , or mercuric trifluoroacetate as shown in Scheme 41 [97]. Alkyne carboxylic acids also undergo oxymercuration reactions to form furan- and pyran-like derivatives. When γ-alkyne carboxylic derivative 140 was refluxed with HgO the cyclization took place to give product 141 in almost quantitative yields

Synthesis of O⁶-alkylated preQ₁ derivatives

• Laurin Flemmich,
• Sarah Moreno and
• Ronald Micura

Beilstein J. Org. Chem. 2021, 17, 2295–2301, doi:10.3762/bjoc.17.147

• & 112.6 (C(arom, DMTr)), 74.5 (CAr3(DMTr)), 70.3 (CAr3(DMTr)), 55.3 (H3CO(DMTr)), 53.4 (H3CO(6)), 38.9 (H2CC(7)) ppm; ESIMS (m/z): [M + H]+ calcd, 798.3650; found, 798.3629. O6-Methyl preQ1 (trifluoroacetate salt) (2). Compound 6 (120 mg, 150 µmol) was dissolved in 500 µL dichloromethane. Trifluoroacetic