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

• trifluoroacetic acid, followed by coupling with 1,3,5-trimethoxybenzene [18] (Scheme 1A). This process demonstrated tolerance for a wide range of electron-rich and electron-deficient (hetero)aryl iodine(III) compounds. Wirth and colleagues reported the flow synthesis of diaryliodonium(III) trifluoroacetates using

• compared to trifluoroacetic acid, TfOH, HBF4, and p-TsOH, present a wider substrate scope, including acid-sensitive groups, in the preparation of diaryliodonium(III) salts. While the counterion exchange of diaryliodonium(III) chloride with silver acetate was reported [20], this method required heating

• the diaryliodonium(III) salt by irradiating with 365 nm UV light. The counterion exchange in umbelliferone carboxylate salt 7aj with trifluoroacetic acid was rapid, and after 30 s, the completion of the reaction was confirmed by the emergence of strong blue fluorescence emission due to the liberation

(Bio)isosteres of ortho- and meta-substituted benzenes

• H. Erik Diepers and
• Johannes C. L. Walker

Beilstein J. Org. Chem. 2024, 20, 859–890, doi:10.3762/bjoc.20.78

Synthesis and characterization of water-soluble C₆₀–peptide conjugates

• Yue Ma,
• Lorenzo Persi and
• Yoko Yamakoshi

Beilstein J. Org. Chem. 2024, 20, 777–786, doi:10.3762/bjoc.20.71

• , ii) HBTU, DIPEA, in DMF, rt, overnight, and iii) trifluoroacetic acid (TFA)/triisopropylsilane (TIPS)/H2O, rt, 1.5–2 h. AA and PG stand for amino acid and protecting group, respectively. All AAs in 1a–c, 2a–c, and 4a–c were protected. Structure of C60–oligo-Lys (5a), C60–oligo-Glu (5b), and C60–oligo

Development of a chemical scaffold for inhibiting nonribosomal peptide synthetases in live bacterial cells

• Fumihiro Ishikawa,
• Sho Konno,
• Hideaki Kakeya and
• Genzoh Tanabe

Beilstein J. Org. Chem. 2024, 20, 445–451, doi:10.3762/bjoc.20.39

• deprotection of the 5′-OH group using 25% trifluoroacetic acid in tetrahydrofuran. Subsequently, the 5′-OH group of compounds 12a–e were reacted with sulfamoyl chloride in the presence of NaH. Compounds 13a–e were coupled to pre-activated Boc-ʟ-Phe-OSu in the presence of Cs2CO3. Removal of the Boc and TBS

Mechanisms for radical reactions initiating from N-hydroxyphthalimide esters

• Carlos R. Azpilcueta-Nicolas and
• Jean-Philip Lumb

Beilstein J. Org. Chem. 2024, 20, 346–378, doi:10.3762/bjoc.20.35

• photocatalyst 4CzIPN, which typically requires the use of strong H+ donors such as trifluoroacetic acid [49][50][51][52]. While many reports, including Okada’s original work, have suggested that a proton donor can accelerate the fragmentation rate of RAEs [29][49][53], specific values comparing the

Facile approach to N,O,S-heteropentacycles via condensation of sterically crowded 3H-phenoxazin-3-one with ortho-substituted anilines

• Eugeny Ivakhnenko,
• Vasily Malay,
• Pavel Knyazev,
• Nikita Merezhko,
• Nadezhda Makarova,
• Oleg Demidov,
• Gennady Borodkin,
• Andrey Starikov and
• Vladimir Minkin

Beilstein J. Org. Chem. 2024, 20, 336–345, doi:10.3762/bjoc.20.34

• obtained via treatment of 6,8-di-tert-butyl-N-aryl-3H-phenoxazin-3-imines with various arylamines in the presence of an excess of trifluoroacetic acid [9]. The structure of the newly synthesized compounds 5, which are derivatives of a previously unknown 14Н-quinoxaline[2,3-b]phenoxazine system 7a, was

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

Tandem Hock and Friedel–Crafts reactions allowing an expedient synthesis of a cyclolignan-type scaffold

• Viktoria A. Ikonnikova,
• Cristina Cheibas,
• Oscar Gayraud,
• Alexandra E. Bosnidou,
• Nicolas Casaretto,
• Gilles Frison and
• Bastien Nay

Beilstein J. Org. Chem. 2024, 20, 162–169, doi:10.3762/bjoc.20.15

• Hock cleavage step under acidic conditions (Scheme 2 and Table 1). In the presence of trifluoroacetic acid (TFA, 1 equiv; Table 1, entry 1) or BF3·OEt2 (1 equiv; Table 1, entry 2), the rearrangement of 2 and 2’ led to a complex mixture of products including aldehyde 3, the typical product of the Hock

Controlling the reactivity of La@C₈₂ by reduction: reaction of the La@C₈₂ anion with alkyl halide with high regioselectivity

• Yutaka Maeda,
• Saeka Akita,
• Mitsuaki Suzuki,
• Michio Yamada,
• Takeshi Akasaka,
• Kaoru Kobayashi and
• Shigeru Nagase

Beilstein J. Org. Chem. 2023, 19, 1858–1866, doi:10.3762/bjoc.19.138

• not be eluted under typical fullerene HPLC separation conditions, trifluoroacetic acid was added to the reaction mixture. Notably, La@C2v-C82 is produced after the addition of trifluoroacetic acid to the La@C2v-C82 anion [20]. After removing the solvent under vacuum, the electrolyte was removed by

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

• applied between the catalytic and lipophilic units to avoid a decrease in the catalytic activity. The demethylated cinchona squaramide 6 was reacted with O-p-toluenesulfonyl-N-Boc-ethanolamine. The protecting group was removed using trifluoroacetic acid, followed by a neutralization step, gaining the

• , trifluoroacetic acid (5.74 mL, 75 mmol, 63 equiv) was added dropwise. The reaction mixture was stirred at room temperature for 1 h. Then, it was cooled to 0 °C, and a 40% NaOH(aq) solution was added to set the pH to 13. To this mixture, water (60 mL) was added, and it was extracted with DCM/MeOH 20:1 (60 mL

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

• with trifluoroacetic acid (TFA) resulted in a cationic 40-H+. Cyclic voltammetry and differential pulse voltammetry were performed to investigate the electrochemical properties of 40-H+. The cation exhibited two reversible oxidations and two to three reductions. The redox potentials were influenced by

N-Sulfenylsuccinimide/phthalimide: an alternative sulfenylating reagent in organic transformations

• Fatemeh Doraghi,
• Seyedeh Pegah Aledavoud,
• Mehdi Ghanbarlou,
• Bagher Larijani and
• Mohammad Mahdavi

Beilstein J. Org. Chem. 2023, 19, 1471–1502, doi:10.3762/bjoc.19.106

• -(alkyl/arylthio)succinimides 1 led to aryl sulfides 104 (Scheme 43) [77]. The cross-coupling reaction involves protonation of the succinimide moiety by trifluoroacetic acid (TFA) to create electrophilic thio intermediate I. Nucleophilic attack of arene 103 on I led to target product 104. Also, TFA

Synthesis of ether lipids: natural compounds and analogues

• Marco Antônio G. B. Gomes,
• Alicia Bauduin,
• Chloé Le Roux,
• Romain Fouinneteau,
• Wilfried Berthe,
• Mathieu Berchel,
• Hélène Couthon and
• Paul-Alain Jaffrès

Beilstein J. Org. Chem. 2023, 19, 1299–1369, doi:10.3762/bjoc.19.96

• sodium cyanoborohydride and trifluoroacetic acid to yield the thermodynamic product 32.4 or sodium cyanoborohydride and trimethylchlorosilane (a bulkier reagent) that favor the formation of the kinetic product 32.3 (Figure 32). Then, a quite similar sequence (the order was different) can be applied to

Unravelling a trichloroacetic acid-catalyzed cascade access to benzo[f]chromeno[2,3-h]quinoxalinoporphyrins

• Chandra Sekhar Tekuri,
• Pargat Singh and
• Mahendra Nath

Beilstein J. Org. Chem. 2023, 19, 1216–1224, doi:10.3762/bjoc.19.89

• ). However, the reaction in the presence of comparatively strong trifluoroacetic acid (TFA) afforded an inseparable mixture of products under the same conditions (Table 1, entry 6). Hence, trichloroacetic acid was found to be an efficient acidic catalyst for the formation of the targeted porphyrin 3 in good

• -diamino-5,10,15,20-tetra(p-tolyl)porphyrin (1) with 2-hydroxynaphthalene-1,4-dione, dimedone and benzaldehyde in the presence of different acidic catalysts such as p-toluenesulfonic acid (PTSA), La(OTf)3, ʟ-ascorbic acid, p-dodecylbenzenesulfonic acid (DBSA), trichloroacetic acid (TCA) and trifluoroacetic

• acid (TFA) in CHCl3 for 3 hours at 65 °C under one-pot operation (Table 1, entries 1–6). Surprisingly, the reaction did not proceed when La(OTf)3 and ʟ-ascorbic acid were used as acidic catalysts (Table 1, entries 2 and 3). In contrast, the use of Brønsted acidic catalysts such as DBSA and PTSA

Selective and scalable oxygenation of heteroatoms using the elements of nature: air, water, and light

• Damiano Diprima,
• Hannes Gemoets,
• Stefano Bonciolini and
• Koen Van Aken

Beilstein J. Org. Chem. 2023, 19, 1146–1154, doi:10.3762/bjoc.19.82

• acids, an increase in reaction rate was observed. For example, when adding 1 equiv trifluoroacetic acid, a full conversion was achieved in 40 minutes instead of 60 minutes. Contrarily, the addition of a strong base substantially slowed down the reaction rate, e.g., the addition of 1 equiv NaOH resulted

Photoredox catalysis harvesting multiple photon or electrochemical energies

• Mattia Lepori,
• Simon Schmid and
• Joshua P. Barham

Beilstein J. Org. Chem. 2023, 19, 1055–1145, doi:10.3762/bjoc.19.81

Intermediates and shunt products of massiliachelin biosynthesis in Massilia sp. NR 4-1

• Till Steinmetz,
• Blaise Kimbadi Lombe and
• Markus Nett

Beilstein J. Org. Chem. 2023, 19, 909–917, doi:10.3762/bjoc.19.69

• , Macherey-Nagel) and a gradient of acetonitrile in water supplemented with 0.1% (v/v) trifluoroacetic acid. The gradient conditions were as follows: from 20% acetonitrile to 90% in 30 minutes and kept at 90% for 10 minutes. The flow rate was set to 5 mL/min. The elution of compounds was monitored with a

Eschenmoser coupling reactions starting from primary thioamides. When do they work and when not?

• Lukáš Marek,
• Jiří Váňa,
• Jan Svoboda and
• Jiří Hanusek

Beilstein J. Org. Chem. 2023, 19, 808–819, doi:10.3762/bjoc.19.61

• phosphite does not give 8a-Me at all. The combined yield of 8a and 8a-Me can be increased when trifluoroacetic acid is added (Table 1, entry 9). Its role probably involves an acid-catalyzed elimination of a water molecule from 7a or 7a-Me. On the other hand, the addition of a stronger base (triethylamine

CuAAC-inspired synthesis of 1,2,3-triazole-bridged porphyrin conjugates: an overview

• Dileep Kumar Singh

Beilstein J. Org. Chem. 2023, 19, 349–379, doi:10.3762/bjoc.19.29

• catalyst at room temperature. In addition, the free-base porphyrin-carborane conjugate 76b was successfully obtained after the treatment of 76a with trifluoroacetic acid in СН2Сl2. The research group of Ravikanth [42] prepared the triazole-bridged porphyrin-BODIPY conjugates 78 and 80 via CuAAC reaction in

• -base tetracationic triazolium salt 156 in quantitative yield. Also, a free-base dyad 158c was obtained in 95% yield by the demetallation of zinc porphyrin 158a with trifluoroacetic acid in a CHCl3/MeOH mixture. These synthesized conjugates showed great affinity for major biological carriers like

Solid-phase total synthesis and structural confirmation of antimicrobial longicatenamide A

• Takumi Matsumoto,
• Takefumi Kuranaga,
• Yuto Taniguchi,
• Weicheng Wang and
• Hideaki Kakeya

Beilstein J. Org. Chem. 2022, 18, 1560–1566, doi:10.3762/bjoc.18.166

• )-protected ᴅ-serine 12 (Scheme 2). Treatment of the olefin 15 with trifluoroacetic acid (TFA) cleaved the Boc protecting group and the acetonide to deliver unsaturated amino alcohol 16. The amino group in 16 was protected by the fluorenylmethyloxycarbonyl (Fmoc) protecting group for solid-phase peptide

1,4,6,10-Tetraazaadamantanes (TAADs) with N-amino groups: synthesis and formation of boron chelates and host–guest complexes

• Artem N. Semakin,
• Ivan S. Golovanov,
• Yulia V. Nelyubina and
• Alexey Yu. Sukhorukov

Beilstein J. Org. Chem. 2022, 18, 1424–1434, doi:10.3762/bjoc.18.148

• , treatment of adamantanes 4a and 4b with excess hydrazine (100–200 equiv) upon heating did not lead to any conversion. Also attempts to deprotect Boc-derivatives 4c, 4e, 6a, and 8a with trifluoroacetic acid or hydrochloric acid (in water or dioxane) were not successful and led to complex mixtures of products

Thermally activated delayed fluorescence (TADF) emitters: sensing and boosting spin-flipping by aggregation

• Ashish Kumar Mazumdar,
• Gyana Prakash Nanda,
• Nisha Yadav,
• Upasana Deori,
• Upasha Acharyya,
• Bahadur Sk and
• Pachaiyappan Rajamalli

Beilstein J. Org. Chem. 2022, 18, 1177–1187, doi:10.3762/bjoc.18.122

• sensitive to acidic protons. Hence, the exposure to acid and base vapors using trifluoroacetic acid (TFA) and triethylamine (TEA) led to solid-phase fluorescence switching with fatigue resistance. The current study demonstrates the role of the donor strength and size in tuning ΔEST in the aggregated state

• fluorescence responses upon exposure to acidic and basic fumes on neat film (Figure 6a and Figure 6c). The intense green emission of the BPy-pTC film turned dark upon exposure to trifluoroacetic acid (TFA) vapor for 4 s (Figure 6a). The green fluorescence reappeared after neutralization with triethylamine (TEA

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

• , trifluoroacetic acid (TFA, 1 equiv) as a proton source for the cathodic reduction, and iPr2NEt (1 equiv) as a base for the formation of N-acyliminium ions of DMA at the anode was carried out under constant current conditions (20 mA/cm2) with 3 F/mol of electricity at 0 °C. It was found that 66% of 1 remained

Electroreductive coupling of 2-acylbenzoates with α,β-unsaturated carbonyl compounds: density functional theory study on product selectivity

• Naoki Kise and
• Toshihiko Sakurai

Beilstein J. Org. Chem. 2022, 18, 956–962, doi:10.3762/bjoc.18.95

• -dihydronaphthalene-1,4-diones (Scheme 1) [5]. In addition, we disclosed that the electroreduction of phthalimides with α,β-unsaturated carbonyl compounds under the same conditions and subsequent treatment with trifluoroacetic acid (TFA) produced 3- and 2-substituted 4-aminonaphthalen-1-ols (Scheme 2) [6]. In this

Synthetic strategies for the preparation of γ-phostams: 1,2-azaphospholidine 2-oxides and 1,2-azaphospholine 2-oxides

• Jiaxi Xu

Beilstein J. Org. Chem. 2022, 18, 889–915, doi:10.3762/bjoc.18.90

• -methylphenol (DTBMP)), trifluoroacetic acid (TFA), and 4-methylbenzenesulfonic acid (TsOH) as the proton donors. The results indicated that the less bulky methanol, more bulky DTBMP, more sterically hindered and acidic TsOH show certain regio- and stereoselectivities, which also depended upon the steric