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

• , entry 6), but TfOH gave the product 2a in 72% yield (Table 1, entry 7). As for the solvent, CH3CN slightly afforded 2a, although N,N-dimethylformamide (DMF) and dimethyl sulfoxide (DMSO) were not suitable for the reactions (Table 1, entries 8–10). A fluorine source, such as Bu4NF or BF3·Et2O, instead of

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

• partially azidated poly(vinyl chloride) (PVA-N3) was prepared by stirring poly(vinyl chloride) and NaN3 in DMF at room temperature overnight. Measurements NMR spectra were recorded using a JEOL mode Al300 (300 MHz) at room temperature. Deuterated chloroform was used as the solvent unless otherwise stated

Multicomponent syntheses of pyrazoles via (3 + 2)-cyclocondensation and (3 + 2)-cycloaddition key steps

• Ignaz Betcke,
• Alissa C. Götzinger,
• Maryna M. Kornet and
• Thomas J. J. Müller

Beilstein J. Org. Chem. 2024, 20, 2024–2077, doi:10.3762/bjoc.20.178

• the corresponding pyrazolone derivatives, thereby providing access to both bis(pyrazolyl) and bis(pyrazolonyl)methanes. Enaminones 81 can be generated as intermediates by condensation of 1,3-dicarbonyl compounds and DMF-dimethylacetal (DMFDMA, 79). The reaction is catalyzed by the solvent 2,2,2

Allostreptopyrroles A–E, β-alkylpyrrole derivatives from an actinomycete Allostreptomyces sp. RD068384

• Marwa Elsbaey,
• Naoya Oku,
• Mohamed S. A. Abdel-Mottaleb and
• Yasuhiro Igarashi

Beilstein J. Org. Chem. 2024, 20, 1981–1987, doi:10.3762/bjoc.20.174

• , 332.1832; found, 332.1838. Methylation of 1 Allostreptopyrrole A (1, 2.0 mg, 0.007 mmol) and K2CO3 (4.4 mg, 0.032 mmol) were stirred in dry DMF (0.5 mL) at 50 °C for 10 min. Methyl iodide (19 μL, 0.32 mmol) was added and the mixture was stirred at this temperature for 12 h [29]. Reaction completion was

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

• ) [101][102]. Our group attempted to use (E/Z)-1,2-difluoroethylene in a Heck reaction [78]. The experiments were performed using 4-iodotoluene or methyl 4-iodobenzoate in DMF, Pd(OAc)2 as a catalyst, and Et3N as a base (Scheme 25). The reactions were carried out in a stainless steel autoclave at 120 °C

Regioselective alkylation of a versatile indazole: Electrophile scope and mechanistic insights from density functional theory calculations

• Pengcheng Lu,
• Luis Juarez,
• Paul A. Wiget,
• Weihe Zhang,
• Krishnan Raman and
• Pravin L. Kotian

Beilstein J. Org. Chem. 2024, 20, 1940–1954, doi:10.3762/bjoc.20.170

• -substituted indazole analogs in 44% and 40% yields, respectively, by treating compound 6 with methyl iodide and potassium carbonate in dimethylformamide (DMF) at room temperature for 17 h [40]. Other works have shown poor selectivity when 6 and other isomers similar to 6 were reacted with isopropyl iodide and

• Scheme 1 compound 6 was treated with isopropyl iodide (7) in DMF in the presence of sodium hydride to provide products 8 and 9 in 38% and 46% yields, respectively. The structures of both compounds were unambiguously assigned using X-ray crystallography and 1H and nuclear Overhauser effect (NOE) NMR

• S1 in Supporting Information File 1. Stoichiometric manipulation of 12 to 6 in DMF at 90 °C provided the N1-substituted product P1 in 52–60% yields. The yields of P1 formation were largely unaffected in DMF with temperatures ranging from room temperature to 110 °C. Varying the equivalents of Cs2CO3

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

• conducted under remarkably mild conditions. Results and Discussion The initial step of our method involved the N-alkylation of DPP 1 with pentafluorobenzyl bromide (Scheme 1). Although a similar reaction had been previously reported for other DPP derivatives, the experimental conditions used (DMF, K2CO3

• performed in dry DMF at room temperature, in the presence of a base (K2CO3 or Cs2CO3). Room temperature was chosen due to the observed rapid degradation of the starting material at elevated temperatures. The work described herein allowed us to assess the potential of DPP 2 as a novel platform for obtaining

• excellent nucleophiles and generally react under mild conditions, resulting in the substitution of the 4-F atom of the pentafluorophenyl groups. In this case, reactions with thiols were performed in dry DMF and K2CO3 was used as the base. Three different thiols were tested: pyridine-4-thiol, pyridine-2

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

• diaryldihydrophenazine was increased (10%). Thus, protonation completely suppressed the intramolecular cyclization route. Heterocyclic salts S1–S3 were obtained as amorphous solids, soluble in polar solvents (acetonitrile, DMF, acetone) and chlorinated hydrocarbons (CHCl3, CH2Cl2). The structure of new N

• in line with the green chemistry requirements [24]. To test the assumption, the preparative oxidation of amine A1 was performed in the potentiostatic mode at 1.6 V (vs Ag/AgCl, KCl(sat.)) in a two-compartment cell in DMF; sodium tosylate was used as a supporting electrolyte. After a charge

• conditions of the potentiostatic electrolysis were the following: a two-compartment cell, a glassy carbon (GC) anode, DMF, the potential increased from 1.0 V to 1.4 V vs Ag/AgCl, KCl(sat.)), 2 F per mol of amine electricity passed, sodium tosylate (0.1 M) as a supporting electrolyte, and 2 equiv of 2.6

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

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

• was significantly enhanced when refluxing in DMF with a catalytic amount of AlCl3 compared to the reaction in clear DMF (Table 1, entries 7–9). Other Lewis acids were not as effective, except for a combination of DMSO/TMSOTf (Table 1, entry 4). The application of AcOH/PPA for the synthesis of 5

• heating conditions (CH). Syntheses were performed in DMSO, DMSO/AlCl3, DMF/AlCl3 and AcOH/H2SO4 at 110 °C (Table 1, entries 5, 6, 9, and 12). Under these conditions, the reaction time was significantly reduced to 1 hour from the usual 15 hours, however, the yields stayed in the range of 30%, and the

• derivatives 2i–k, we changed the solvent to DMF/AlCl3, which increased the yields to 41–45%. However, the 7-methoxy derivative 2l with o-methyl substituent in the aldehyde moiety precipitated in DMSO after two days of reaction time. Interestingly, we observed only traces of another possible regioisomer 2m

Syntheses and medicinal chemistry of spiro heterocyclic steroids

• Laura L. Romero-Hernández,
• Ana Isabel Ahuja-Casarín,
• Penélope Merino-Montiel,
• Sara Montiel-Smith,
• José Luis Vega-Báez and
• Jesús Sandoval-Ramírez

Beilstein J. Org. Chem. 2024, 20, 1713–1745, doi:10.3762/bjoc.20.152

Chemo-enzymatic total synthesis: current approaches toward the integration of chemical and enzymatic transformations

• Ryo Tanifuji and
• Hiroki Oguri

Beilstein J. Org. Chem. 2024, 20, 1693–1712, doi:10.3762/bjoc.20.151

• experimental results, Gulder and co-workers devised a strategy to control the dimerization modes by adjusting the polarity of the organic co-solvent to establish the divergent synthesis of dimeric scaffolds. Indeed, with 20% DMF in the SorbC-catalyzed enzymatic oxidative dearomatization, the Michael addition

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

• . Secondary and tertiary substrates worked well under the reaction conditions, whereas primary positions afforded low yields (14). No additive was required to achieve the desired selectivity, but in some cases the addition of small amounts of iron salt [FeCl4][FeCl2(dmf)3] improved yields. In 2022, Pieber and

Electrophotochemical metal-catalyzed synthesis of alkylnitriles from simple aliphatic carboxylic acids

• Yukang Wang,
• Yan Yao and
• Niankai Fu

Beilstein J. Org. Chem. 2024, 20, 1497–1503, doi:10.3762/bjoc.20.133

• -known to be highly susceptible to electroplating on the cathode and thus require the use of ligands to avoid detrimental cathode deposition during electrolysis (Table 1, entry 3). In addition, we discovered that the additional use of DMF as co-solvent is beneficial to the reaction efficiency–reactions

• using acetonitrile as the solvent frequently led to the observation of Cu deposition at cathode (Table 1, entry 4). We reasoned that DMF could coordinate to the copper center, acting as a ligand to prevent copper from cathode reduction. Constant current electrolysis is also applicable to the reaction

• yields are of isolated products. Unless otherwise noted, reaction conditions were as follows: 0.2 mmol acids, 0.4 mmol TMSCN, CeCl3 (10 mol %), Cu(OTf)2/BPhen (5/6 mol %), 0.05 mmol BTMG, 0.2 mmol TBABF4, 0.5 mmol TFE, 3.5 mL of CH3CN, 0.5 mL of DMF, carbon felt as the anode, Pt as the cathode, under N2

Photoswitchable glycoligands targeting Pseudomonas aeruginosa LecA

• Yu Fan,
• Ahmed El Rhaz,
• Stéphane Maisonneuve,
• Emilie Gillon,
• Maha Fatthalla,
• Franck Le Bideau,
• Guillaume Laurent,
• Samir Messaoudi,
• Anne Imberty and
• Juan Xie

Beilstein J. Org. Chem. 2024, 20, 1486–1496, doi:10.3762/bjoc.20.132

• binding of one isomer only. Experimental General experimental details. Commercially available solvents and reagents were used without further purification. Reactions carried out under anhydrous conditions are performed under argon in glassware previously dried in an oven. DMF and THF were previously dried

• (1.0 equiv) in anhydrous DMF (≈3.5 mL per mmol) was added K2CO3 (2.0–4 equiv) and BocNHCH2CH2Br (1.5–4 equiv), then stirred overnight at 60 °C. After the reaction was completed (TLC monitoring), the mixture was evaporated to dryness under reduced pressure. The residue was dissolved in EtOAc

• crystalline complexes. The protein is represented by orange ribbon, His53 by lines, and calcium by green sphere. Synthesis of photoswitchable LecA inhibitors. Reagents and conditions: (i) DMC, Et3N, H2O, −10 °C to rt, 8 h, 50% for 7, 40% for 10; (ii) BrCH2CH2NHBoc, K2CO3, DMF, 60 °C, 15 h, 91% for 8, 80% for

Selectfluor and alcohol-mediated synthesis of bicyclic oxyfluorination compounds by Wagner–Meerwein rearrangement

• Ziya Dağalan,
• Muhammed Hanifi Çelikoğlu,
• Saffet Çelik,
• Ramazan Koçak and
• Bilal Nişancı

Beilstein J. Org. Chem. 2024, 20, 1462–1467, doi:10.3762/bjoc.20.129

• that there was a 12% conversion with CH3CN and a 10% conversion with nitromethane, while no conversion occurred with the other solvents including, CH2Cl2, EtOAc, 1,4-dioxane and DMF (Table 1, entries 1–6). To see the effect of reactant ratios on yields, when reactants were gradually increased at room

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

• , solvent screening showed that toluene was the most appropriate solvent, while the reaction led to a much lower yield when DMF, MeOH, MeCN, or DCM were used as solvents (Table 1, entries 13–17). On the basis of the above experimental results, the optimized conditions for the thiocyanation of the model

Generation of alkyl and acyl radicals by visible-light photoredox catalysis: direct activation of C–O bonds in organic transformations

• Mithu Roy,
• Bitan Sardar,
• Itu Mallick and
• Dipankar Srimani

Beilstein J. Org. Chem. 2024, 20, 1348–1375, doi:10.3762/bjoc.20.119

• in DMF solvent and requires ca. 18 h to finish upon irradiation with blue LEDs. The catecholboronic esters produced at first are transesterified into pinacol borane by addition of pinacol and triethylamine. The reaction proved to be useful for a wide variety of substrates, such as borneol, menthol

• DMF with the help of photoexcited Ir(ppy)3. The suggested mechanism begins with the formation of photoexcited *[Ir(III)], which promotes SET to oxalate and generates an oxalate radical anion and [Ir(IV)]. The fragmentation of the oxalate radical anion produces an alkyl radical. The radical

• subsequently undergoes addition to B2cat2 (19) to produce the boryl radical 41. Here, the choice of solvent is also important. The interaction between DMF and the boryl radical 41 assists B–B bond scission to furnish the target borylated products and an intermediate 43, which is oxidized by [Ir(IV

Synthesis of 1,2,3-triazoles containing an allomaltol moiety from substituted pyrano[2,3-d]isoxazolones via base-promoted Boulton–Katritzky rearrangement

• Constantine V. Milyutin,
• Andrey N. Komogortsev and
• Boris V. Lichitsky

Beilstein J. Org. Chem. 2024, 20, 1334–1340, doi:10.3762/bjoc.20.117

• in the presence of K2CO3 in DMF allowed us to prepare 3-methoxypyran-4-one derivative 7 (Scheme 9). Conclusion In summary, we investigated the reaction of substituted pyrano[2,3-d]isoxazolones with diverse hydrazines. We have demonstrated that initially the studied process leads to appropriate

Domino reactions of chromones with activated carbonyl compounds

• Peter Langer

Beilstein J. Org. Chem. 2024, 20, 1256–1269, doi:10.3762/bjoc.20.108

• (10%). Synthesis of 33. Conditions: i, DBU (1.3 equiv), THF, 20 °C, 12 h. Synthesis of 35a–x. Conditions: i, DBU (1.3 equiv), 1,4-dioxane, 20 °C, 12 h. Synthesis of 36a–f. Conditions: i, 1) DBU (1.3 equiv), 1,4-dioxane, 20 °C, 12 h; 2) I2 (2 equiv), DBU (3 equiv), MeCN or DMF. Synthesis of 37a,b

• . Conditions: i, 1) DBU (1.3 equiv), 1,4-dioxane, 20 °C, 12 h; 2) I2 (2 equiv), DBU (3 equiv), MeCN or DMF. Then aqueous work-up at the air. Synthesis of 39a–i. Conditions: i, method A: DBU (1.3 equiv), 1,4-dioxane, 20 °C; method B: K2CO3 (4 equiv), DMF, 20 °C. Synthesis of 40. Conditions: i, piperidine, MeOH

The Ugi4CR as effective tool to access promising anticancer isatin-based α-acetamide carboxamide oxindole hybrids

• Carolina S. Marques,
• Aday González-Bakker and
• José M. Padrón

Beilstein J. Org. Chem. 2024, 20, 1213–1220, doi:10.3762/bjoc.20.104

• into the scaffold. Benzyl azide (6), obtained using a previously reported procedure [27], was used in the CuAAC reaction. The α-acetamide carboxamide 1,2,3-triazole oxindole hybrid 7 was easily obtained in 61% yield using Cu(OAc)2 as catalyst, ascorbic acid, DMF as solvent, and microwave reaction

Introduction of peripheral nitrogen atoms to cyclo-meta-phenylenes

• Koki Ikemoto and
• Hiroyuki Isobe

Beilstein J. Org. Chem. 2024, 20, 1207–1212, doi:10.3762/bjoc.20.103

• Cs2CO3 (48.9 g, 150 mmol) in 3.0 L of DMF was stirred at 110 °C for 24 h. After the addition of H2O (2.5 L) and CHCl3 (3.0 L), the precipitate was removed by filtration. The organic layer was separated, dried over Na2SO4, and concentrated in vacuo. To eliminate the soluble by-products, the crude material

Mild and efficient synthesis and base-promoted rearrangement of novel isoxazolo[4,5-b]pyridines

• Vladislav V. Nikol’skiy,
• Mikhail E. Minyaev,
• Maxim A. Bastrakov and
• Alexey M. Starosotnikov

Beilstein J. Org. Chem. 2024, 20, 1069–1075, doi:10.3762/bjoc.20.94

• method, however, the cyclization occurred under drastic conditions (NaH, DMF, 130 °C) as it was reported in patent literature [23]. We assumed that a similar synthetic route (nitrosation/SNAr) would be applicable for the synthesis of isoxazolo[4,5-b]pyridine derivatives bearing other EWG in position 3

• with DMF-DMA afforded enamines 6 which, upon nitrosation, were converted into oximes 7a–c in moderate yields (Scheme 3). When compounds 7 were treated with K2CO3 3-hydroxypyridine-2-carbonitriles 8 were obtained as sole products (Scheme 4). Apparently, a cyclization of oximes 7 to 3-formylisoxazolo[4,5

• mixture was treated with K2CO3 in DMF at 60 °C, compound 13a was isolated in 92% yield (from 7a) (Table 1, entry 1). Such rearrangement has been reported previously for the benzo[d]isoxazole series [30], however, it has not been observed for isoxazolo[4,5-b]pyridine derivatives. It was found that the

Structure–property relationships in dicyanopyrazinoquinoxalines and their hydrogen-bonding-capable dihydropyrazinoquinoxalinedione derivatives

• Tural N. Akhmedov,
• Ajeet Kumar,
• Daken J. Starkenburg,
• Kyle J. Chesney,
• Khalil A. Abboud,
• Novruz G. Akhmedov,
• Jiangeng Xue and
• Ronald K. Castellano

Beilstein J. Org. Chem. 2024, 20, 1037–1052, doi:10.3762/bjoc.20.92

• reactions (over 10-gram scale) using diaminomaleonitrile (15) as a starting material in accordance with the procedure in the literature (Scheme 1) [27]. The first step is the acylation with oxalyl chloride to yield 14 followed by a reaction with SOCl2 in the presence of cat. DMF to obtain dichloropyrazine

• 12 under standard boiling acetic acid conditions, as reported in Scheme 1. The crude product could be collected via vacuum filtration, followed by additional purification via recrystallization from boiling DMF to afford golden crystals of 4a in moderate yields. In order to access 5a and 6a, a

• modified procedure from the literature was implemented [28]. To synthesize 6a, the condensation was performed with 9,10-phenanthrenequinone, building block 12 in the presence of glacial CH3COOH, trifluoracetic acid, and 1,4-dioxane at reflux. Then, recrystallization from DMF and sublimation under ambient

Novel analogues of a nonnucleoside SARS-CoV-2 RdRp inhibitor as potential antivirotics

• Luca Julianna Tóth,
• Kateřina Krejčová,
• Milan Dejmek,
• Eva Žilecká,
• Blanka Klepetářová,
• Lenka Poštová Slavětínská,
• Evžen Bouřa and
• Radim Nencka

Beilstein J. Org. Chem. 2024, 20, 1029–1036, doi:10.3762/bjoc.20.91

• , DCM, rt, overnight, b) BnBr, NaH, DMF, 0 °C to rt, 1 h, c) (R = Et) diethyl carbonate, LiHMDS, THF, −78 to 0 °C, 1 h, d) (R = allyl) allyl chloroformate, LiHMDS, THF, −78 to 0 °C, 1 h, e) POCl3, DMF, 90 °C, 30 min, f) (BnCO)2O, 100 °C, 1.5 h, g) methanesulfonic acid, DCM, 0 °C to rt, 4 h, h) CyOH

• , PPh3, DIAD, 1,4-dioxane, 50 °C, overnight, i) (R = Et) NaOH, H2O, EtOH, 75 °C, 3 h, j) (R = allyl) Et3SiH, PPh3, Pd(OAc)2, ACN, rt, k) H–ʟ-Tyr–OMe, HOBt, EDCI, TEA, DCM, DMF, rt, 12 h, l) LiOH⋅H2O, H2O, 1,4-dioxane, rt, 45 min. Cy = cyclohexyl. Synthetic pathway to pyridone derivatives 3a–c of HeE1

• -2Tyr (1). Reagents and conditions: a) MeI, K2CO3, DMF, rt, 2.5 h, b) LiOH⋅H2O, H2O, 1,4-dioxane, rt, 15 min, c) H–ʟ-Tyr–OMe, HOBt, EDCI, TEA, DCM, DMF, rt, 12 h, d) ArB(OH)2, Pd(dppf)Cl2⋅CH2Cl2, Cs2CO3, DMF, H2O, 80 °C, overnight. Synthetic pathway to thiazolopyridone derivatives 4a,b of HeE1-2Tyr (1