Facile preparation of fluorine-containing 2,3-epoxypropanoates and their epoxy ring-opening reactions with various nucleophiles

• Yutaro Miyashita,
• Sae Someya,
• Tomoko Kawasaki-Takasuka,
• Tomohiro Agou and
• Takashi Yamazaki

Beilstein J. Org. Chem. 2024, 20, 2421–2433, doi:10.3762/bjoc.20.206

• 49.4 (q, J = 2.5 Hz), 52.7 (q, J = 42.2 Hz), 68.0, 121.4 (q, J = 276.0 Hz), 128.5, 128.7, 128.8, 134.3, 165.6; 19F NMR (282.65 MHz, CDCl3) δ −75.12 (d, J = 4.5 Hz); IR (neat) ν: 3944, 3689, 3054, 2987, 2685, 2306, 1756, 1456, 1422, 1382, 1341, 1265, 1169, 1089, 988, 929, 896, 664 cm−1; Anal. calcd for

• = 34.1 Hz), 122.5 (q, J = 282.9 Hz), 128.61, 128.63, 128.8, 134.0, 165.1, 165.6, 167.4; 19F NMR (282.65 MHz, CDCl3) δ −75.84 (d, J = 6.8 Hz); IR (neat) ν: 2987, 1813, 1742, 1457, 1389, 1321,1218, 1182, 1128, 1023, 972, 755 cm−1; HRMS–FAB+ (m/z): [M + H]+ calcd for C16H16F3O6, 361.0893; found, 361.0911

• , 1H), 3.49 (d, J = 4.2 Hz, 1H), 4.43–4.56 (m, 1H); 13C NMR (75.45 MHz, CDCl3) δ 14.0, 15.0, 22.6, 23.4, 29.26, 29.28, 29.4, 29.5, 31.8, 41.8 (q, J = 1.2 Hz), 43.7, 66.4 (q, J = 32.2 Hz), 124.7 (q, J = 281.1 Hz), 208.9; 19F NMR (282.65 MHz, CDCl3) δ −80.79 (d, J = 7.1 Hz); IR (neat) ν: 3408, 2958, 2927

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

• to be a good reagent for the gem-difluorination of alkynes, reported by Hammond and Xu (Figure 1, reaction 3) [37]. HF/DMPU is easy to handle under experimental conditions. In addition, they recently reported the utilization of a combination of KHSO4·13HF and DMPU·12HF under neat conditions for the

The Groebke–Blackburn–Bienaymé reaction in its maturity: innovation and improvements since its 21st birthday (2019–2023)

• Cristina Martini,
• Muhammad Idham Darussalam Mardjan and
• Andrea Basso

Beilstein J. Org. Chem. 2024, 20, 1839–1879, doi:10.3762/bjoc.20.162

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

• preliminary electrochemical examples [93][101]. Middleton and co-workers described an alternating polarity approach for the fluorination of simple toluene derivatives in neat pyridine·HF (Figure 42) [102][103]. Poor conductivity necessitated the use of this waveform type. The benzylic fluorination was

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

• = 17.2 Hz, 1H), 2.99 (d, J = 17.2 Hz, 1H), 1.45 (s, 9H); 13C NMR (75 MHz, CDCl3, 298 K, δ/ppm) 198.1, 167.4, 152.3, 136.4, 133.3, 128.4, 126.5, 125.6, 84.6, 70.6, 38.6, 28.0; IR (neat, FT-ATR, 298 K, ν̃/cm−1): 2984, 2928, 2853, 2110, 1747, 1736, 1718, 1604, 1589, 1548, 1466, 1431, 1397, 1372, 1353, 1326

• , 1H), 7.48 (t, J = 7.5 Hz, 1H), 4.11 (d, J = 17.9 Hz, 1H), 3.99 (d, J = 17.9 Hz, 1H), 1.49 (s, 9H); 13C NMR (126 MHz, CDCl3, 298 K, δ/ppm) 188.4, 162.0, 150.1, 137.0, 132.9, 129.1, 126.5, 126.2, 96.7, 86.1, 37.5, 27.8; IR (neat, FT-ATR, 298 K, ν̃/cm−1): 2984, 2930, 2878, 2854, 1748, 1719, 1656, 1604

Towards an asymmetric β-selective addition of azlactones to allenoates

• Behzad Nasiri,
• Ghaffar Pasdar,
• Paul Zebrowski,
• Katharina Röser,
• David Naderer and
• Mario Waser

Beilstein J. Org. Chem. 2024, 20, 1504–1509, doi:10.3762/bjoc.20.134

• ), 3.52–3.16 (m, 4H), 1.15 (t, J = 7.1 Hz, 3H); 13C NMR (75 MHz, CDCl3, 298.0 K) δ/ppm = 177.4, 171.0, 160.3, 139.1, 133.8, 132.6, 130.5, 128.6, 128.0, 127.8, 127.3, 125.6, 118.1, 75.9, 60.9, 44.9, 39.3, 13.9; IR (neat): 3080, 3070, 2917, 1815, 1732, 1656, 1480, 1175, 1093, 1059, 1030, 974, 893, 694 cm−1

Synthesis of 2-benzyl N-substituted anilines via imine condensation–isoaromatization of (E)-2-arylidene-3-cyclohexenones and primary amines

• Lu Li,
• Na Li,
• Xiao-Tian Mo,
• Ming-Wei Yuan,
• Lin Jiang and
• Ming-Long Yuan

Beilstein J. Org. Chem. 2024, 20, 1468–1475, doi:10.3762/bjoc.20.130

• ). However, carrying out the reaction under neat conditions rendered to dramatically dropped yield (Table 1, entry 9). It indicates that the involvement of conventional organic solvents into the reaction system seems to be critical for target transformation. Though the exact reason is not apparent now, we

Manganese-catalyzed C–C and C–N bond formation with alcohols via borrowing hydrogen or hydrogen auto-transfer

• Mohd Farhan Ansari,
• Atul Kumar Maurya,
• Abhishek Kumar and
• Saravanakumar Elangovan

Beilstein J. Org. Chem. 2024, 20, 1111–1166, doi:10.3762/bjoc.20.98

• regeneration of the active catalyst Mn23-a (Scheme 61). Later, Srimani and co-workers studied the C-3 alkylation of indoles with various primary and secondary alcohols using Mn24 (5 mol %) and KOH (0.6 equiv) under neat conditions for 36 h at 130 °C (Scheme 62) [90]. The same cationic complex was used for the

• (Scheme 75). In 2022, Srimani and co-workers showed the synthesis of C3-functionalized indoles by coupling of (2-aminophenyl)ethanol with various alcohols, including aliphatic alcohols, using Mn24 (8 mol %) and KOH (1 equiv) under neat conditions for 36 h at 130 °C and afforded yields up to 78% (Scheme 76

Light on the sustainable preparation of aryl-cored dibromides

• Fabrizio Roncaglia,
• Alberto Ughetti,
• Nicola Porcelli,
• Biagio Anderlini,
• Andrea Severini and
• Luca Rigamonti

Beilstein J. Org. Chem. 2024, 20, 1076–1087, doi:10.3762/bjoc.20.95

• anhydrous HBr. A notable increase in selectivity towards 3b was suddenly observed (Table 2, entry 8). However, this method led to the undesired, uncontrolled generation of Br2 when neat H2SO4 was mixed with NaBr. This issue was addressed through an alternative reagent introduction scheme, where NaBr was

Advancements in hydrochlorination of alkenes

• Daniel S. Müller

Beilstein J. Org. Chem. 2024, 20, 787–814, doi:10.3762/bjoc.20.72

• , HCl gas was bubbled through neat alkene 1 for several hours, as depicted in Scheme 3A [35]. This example highlights an intriguing regioselectivity that might have been challenging to predict through a simple analysis of the stability of the corresponding cations. Alternatively, the HCl gas was bubbled

• dependence. Brown also explored the influence of solvents (Figure 4). While reactions conducted in neat α-methylstyrene (11) or dichloromethane showed identical kinetics, the reaction was delayed when pentane was employed as a solvent. The method of bubbling HCl gas through neat alkenes or solutions of

• alkenes remains a commonly employed approach, yielding high yields for styrene derivatives (Scheme 4) [41][42][43]. The example by Theato is remarkable (Scheme 4A), who used HCl (gas) bubbled into neat alkene 13 for 5 hours, and obtained a relatively high yield of the monohydrochlorinated product 14 after

Isolation and structure determination of a new analog of polycavernosides from marine Okeania sp. cyanobacterium

• Kairi Umeda,
• Naoaki Kurisawa,
• Ghulam Jeelani,
• Tomoyoshi Nozaki,
• Kiyotake Suenaga and
• Arihiro Iwasaki

Beilstein J. Org. Chem. 2024, 20, 645–652, doi:10.3762/bjoc.20.57

• , MeOH); UV (MeOH) λmax, nm (log ε): 281 (2.27), 270 (2.96), 260 (2.40); ECD (100 μg/mL; MeOH), λmax, nm (Δε): 226 (−0.31), 274 (−0.76), 282 (−0.96); IR (neat): 3443, 2965, 2925, 2896, 1646, 1457, 1086 cm−1; HRESIMS (m/z): [M + Na]+ calcd for C44H66O15Na+, 857.4294; found, 857.4294. In vitro

Green and sustainable approaches for the Friedel–Crafts reaction between aldehydes and indoles

• Periklis X. Kolagkis,
• Eirini M. Galathri and
• Christoforos G. Kokotos

Beilstein J. Org. Chem. 2024, 20, 379–426, doi:10.3762/bjoc.20.36

Synthesis of π-conjugated polycyclic compounds by late-stage extrusion of chalcogen fragments

• Aissam Okba,
• Pablo Simón Marqués,
• Kyohei Matsuo,
• Naoki Aratani,
• Hiroko Yamada,
• Gwénaël Rapenne and
• Claire Kammerer

Beilstein J. Org. Chem. 2024, 20, 287–305, doi:10.3762/bjoc.20.30

• temperature under neat conditions [73][74][75][76][77]. In order to promote light-induced ring contraction of 1,2-dithiin scaffolds, Furukuwa et al. explored the reactivity of precursors bearing one sulfur atom in a higher oxidation state [78]. In their synthesis of dibenzo[1,4]dithiapentalene 46, the 1,2

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

• glycosyl donor) was added under argon followed by neat TfOH (2 μL, 0.02 mmol) to give a persistent iodine color as described previously [36]. The reaction mixture was stirred under argon at −40 °C until complete consumption of the starting thioglycoside (TLC monitoring, Rf 0.68 (1), Rf 0.57 (2), benzene

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

• , amphiphiles PA-OCH3 and PA-OH were synthesized by reacting prePA under neat conditions with 1-(2-bromoethoxy)-2-(2-methoxyethoxy)ethane (67% yield over 2 steps after ion-exchange) and 2-[2-(2-chloroethoxy)ethoxy]ethanol (42% yield), respectively (Figure 2b). Imidazole-functionalized amphiphile PA-Im was

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

• 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

• base and the base–BF3 adduct, we should obtain an approximate current yield. Our first choice was N,N-diisopropylethylamine (DIPEA), as the DIPEA-BF3 adduct is reported in the literature and fully characterized by NMR in CDCl3 [113]. To be consistent with literature data, the BF4− peak in neat BMIm-BF4

• anolyte and the mixture was kept under stirring at room temperature for 30 min. Then, the neat anolyte was analysed by NMR (19F and 13C). The 19F NMR spectrum showed a new peak at −148.7 ppm and, to our great astonishment, we found only one set of signals in the 13C NMR spectrum (55.0, 42.8, 17.4, 16.0

Aromatic systems with two and three pyridine-2,6-dicarbazolyl-3,5-dicarbonitrile fragments as electron-transporting organic semiconductors exhibiting long-lived emissions

• Karolis Leitonas,
• Brigita Vigante,
• Dmytro Volyniuk,
• Audrius Bucinskas,
• Pavels Dimitrijevs,
• Sindija Lapcinska,
• Pavel Arsenyan and
• Juozas Vidas Grazulevicius

Beilstein J. Org. Chem. 2023, 19, 1867–1880, doi:10.3762/bjoc.19.139

• . Since the freedom of movements (vibrations and rotations) of parts of REF are prevented in the solid state, the PL spectra of the films of compounds 6–9 were practically in the same spectral region (Figure 2d). It should be noted that the PL spectra of the neat films exhibit low-intensity high-energy

• . Similarly, the strongest TADF intensity was obtained for the neat films of compound 9 and of compound 9 molecularly dispersed in the host 1,3-bis(N-carbazolyl)benzene (mCP; Figure 3c,d and Figure S3a in Supporting Information File 1). Low-energy absorption bands of molecular mixtures of compounds 6–9 and

• (ΔEST) between the lowest singlet and triplet states (Figure 4d and Figure S7 in Supporting Information File 1). A ΔEST value of 0.24 eV was obtained for compound 9. The highest photoluminescence quantum yield (PLQY) of 17.1% was obtained for the dilute toluene solution of compound 8 (Table 1). The neat

Synthetic approach to 2-alkyl-4-quinolones and 2-alkyl-4-quinolone-3-carboxamides based on common β-keto amide precursors

• Yordanka Mollova-Sapundzhieva,
• Plamen Angelov,
• Danail Georgiev and
• Pavel Yanev

Beilstein J. Org. Chem. 2023, 19, 1804–1810, doi:10.3762/bjoc.19.132

• additional decarbamoylative step (Scheme 2). The decarbamoylation of compounds 3a–d was carried out by heating at 60 °C in neat H3PO4 for 90 minutes [62] and gave the corresponding β-enaminoketones 6a–d in good yields (Table 2). The NMR spectra of compounds 6 in DMSO-d6 in all cases indicated a mixture of Z

Synthesis of 7-azabicyclo[4.3.1]decane ring systems from tricarbonyl(tropone)iron via intramolecular Heck reactions

• Aaron H. Shoemaker,
• Elizabeth A. Foker,
• Elena P. Uttaro,
• Sarah K. Beitel and
• Daniel R. Griffith

Beilstein J. Org. Chem. 2023, 19, 1615–1619, doi:10.3762/bjoc.19.118

• substrates. a) Substrate 7, reagents and conditions: 1) neat (5 equiv 5), 24 h; 2) Boc2O, NaHCO3, EtOH, ultrasound, 1 h, 88% (2 steps); 3) AcOH, hν (360 nm), 6 h, 74%. b) Substrate 9, reagents and conditions: 1) 11 (2 equiv), EtOAc, 23 °C, 1 h; 2) Boc2O, NaHCO3, EtOH, ultrasound, 23 °C, 1 h, 68% (2 steps); 3

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

• , white neat solid, tR = 85 min). The LC–MS analysis of other fractions suggested the presence of very low amounts of compounds and these fractions were not further investigated. Series C (1.2 g) eluted with CH2Cl2/MeOH 97.5:2.5 (v/v) was divided into three portions of 400 mg each. Every portion was

• oil, tR = 8 min), 9 (1.3 mg, yellow oil, tR = 14 min), 3 (2.76 mg, white neat solid, tR = 16 min), and 1 (0.79 mg, yellow oil, tR = 22 min), respectively. Series E (294 mg) was further purified to yield compounds 5 (0.95 mg, white amorphous powder, tR = 35.20 min), 17 (6.1 mg, white amorphous powder

• , tR = 11.21 min), and 7 (1.45 mg, yellow neat solid, tR = 15.00 min), 4 (2.45 mg, white amorphous powder, tR = 22.00 min), respectively. Successive purifications of series F (898 mg) over normal (CH2CH2/MeOH 92:8, Nucleosil 120 OH Diol column) and reversed-phase preparative HLPC (Gilson, PLC 2020

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

• was found that enones 2 were transformed into the corresponding 3-trichloromethylindan-1-ones 3 upon heating in neat TfOH at 80 °C for 2–10 h (Scheme 5). Under the same reaction conditions, hydroxy ketones 1 were cyclized into indanones 3 as well (Scheme 6). The structure of compound 3a was confirmed

• Brønsted and Lewis acids were also tested for this cyclization. Thus, enones 2a and 2e were not transformed into the corresponding indanones 3 in neat sulfuric acid (H2SO4) at room temperature for 3 days. That is in accord with literature data [19], where H2SO4 was used for dehydration of hydroxy ketones 1

Clauson–Kaas pyrrole synthesis using diverse catalysts: a transition from conventional to greener approach

• Dileep Kumar Singh and
• Rajesh Kumar

Beilstein J. Org. Chem. 2023, 19, 928–955, doi:10.3762/bjoc.19.71

• of the catalyst for up to nine consecutive runs without loss of catalytic activity. Recently, Rohit et al. [86] described a modified Clauson–Kaas synthesis of N-substituted pyrrole with up to 89% yields by microwave irradiation at 120 °C in neat conditions by reacting amines 66 with 2,5-DMTHF (2) in

• derivatives 77 in good to excellent yields using a microwave-assisted and bismuth nitrate Bi(NO3)3∙5H2O-catalyzed reaction between various amines 76 and 2,5-dimethoxytetrahydrofuran (2) in neat, H2O or THF (Scheme 37). This approach provides different pyrrole derivatives without the use of sensitive or

• , H2O, neat), reaction times (10–22 minutes), and amount of oxone were investigated in order to stabilize the best reaction conditions. Among these, CH3CN as the best solvent system, 0.09 g of oxone, and a temperature of 110 ± 10 °C were chosen as optimized reaction conditions and used for the synthesis

A fluorescent probe for detection of Hg²⁺ ions constructed by tetramethyl cucurbit[6]uril and 1,2-bis(4-pyridyl)ethene

• Xiaoqian Chen,
• Naqin Yang,
• Yue Ma,
• Xinan Yang and
• Peihua Ma

Beilstein J. Org. Chem. 2023, 19, 864–872, doi:10.3762/bjoc.19.63

• 6.5) of probe G@TMeQ[6] (3.0 × 10−5 mol·L−1) to Hg2+ ions; (b) detection limit of probe G@TMeQ[6] to Hg2+ ions. (A) Titration 1H NMR spectra (400 MHz) obtained for TMeQ[6] with (a) 0.00, (b) 0.50, (c) 1.00 and (d) 1.20 equiv of G and (e) neat TMeQ[6] (5.0 × 10−4 mol·L−1); (B) titration 1H NMR spectra

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

• . Elemental analyses were performed on a Flash 2000 Organic Elemental Analyser (Thermofisher). For samples containing chlorine, mercurimetric titration was used. IR spectra were recorded on a Nicolet iS50 equipped with an ATR diamond crystal (neat solid samples). Flash chromatography was performed using a

Cassane diterpenoids with α-glucosidase inhibitory activity from the fruits of Pterolobium macropterum

• Sarot Cheenpracha,
• Ratchanaporn Chokchaisiri,
• Lucksagoon Ganranoo,
• Sareeya Bureekaew,
• Thunwadee Limtharakul and
• Surat Laphookhieo

Beilstein J. Org. Chem. 2023, 19, 658–665, doi:10.3762/bjoc.19.47

• silica gel CC eluting with 100% CH2Cl2 afforded compound 2 (6.9 mg). 14β-Hydroxycassa-11(12),13(15)-dien-12,16-olide (1): amorphous, white powder; −22 (c 0.01, MeOH); UV (MeOH) λmax (log ε) 283 (4.20) nm; ECD (0.001, MeOH) λmax (Δε) 241 (+11.5), 271 (−10.4), 297 (+2.5) nm; IR (neat) νmax 3429, 2926

• ) 243 (+21.1), 330 (−4.70) nm; IR (neat) νmax: 2973, 1724, 1660, 1508, 1733 cm−1; 1H NMR (500 MHz, CDCl3) and 13C NMR (125 MHz, CDCl3) spectra, see Table 1; HRESI–TOF–MS m/z: 733.4305 [M + H]+ (calcd for C44H61O9, 733.4310). α-Glucosidase inhibitory assay α-Glucosidase inhibitory activity was performed