Oxetanes: formation, reactivity and total syntheses of natural products

• Peter Gabko,
• Martin Kalník and
• Maroš Bella

Beilstein J. Org. Chem. 2025, 21, 1324–1373, doi:10.3762/bjoc.21.101

• of oxetanes from epoxides using sulphur-stabilised carbanions such as dimethyloxosulphonium methilide (105) or S-methyl-S-(sodiomethyl)-N-(4-tolylsulphonyl)sulphoximine (106) (Scheme 26) [71][72]. Because these reagents are also known to induce epoxidation when reacted with a ketone or aldehyde

gem-Difluorovinyl and trifluorovinyl Michael acceptors in the synthesis of α,β-unsaturated fluorinated and nonfluorinated amides

• Monika Bilska-Markowska,
• Marcin Kaźmierczak,
• Wojciech Jankowski and
• Marcin Hoffmann

Beilstein J. Org. Chem. 2024, 20, 2946–2953, doi:10.3762/bjoc.20.247

• blocks [26]. Despite the known instability of trifluoromethylated carbanions [27], their catalytic application has yielded valuable products [28][29][30]. gem-Difluoroalkenes and trifluoroalkenes are excellent acceptors in the Michael addition reactions. There are also known examples of the use of gem

A review of recent advances in electrochemical and photoelectrochemical late-stage functionalization classified by anodic oxidation, cathodic reduction, and paired electrolysis

• Nian Li,
• Ruzal Sitdikov,
• Ajit Prabhakar Kale,
• Joost Steverlynck,
• Bo Li and
• Magnus Rueping

Beilstein J. Org. Chem. 2024, 20, 2500–2566, doi:10.3762/bjoc.20.214

Ligand effects, solvent cooperation, and large kinetic solvent deuterium isotope effects in gold(I)-catalyzed intramolecular alkene hydroamination

• Ruichen Lan,
• Brock Yager,
• Yoonsun Jee,
• Cynthia S. Day and
• Amanda C. Jones

Beilstein J. Org. Chem. 2024, 20, 479–496, doi:10.3762/bjoc.20.43

• 23–27) [53], thus rates do not correlate with N–H acidity either (the least acidic urea is the most active). Interaction of gold(I) with the two functional group types (carbonyl versus sulfonamide) is predicted to differ in a key aspect. Lithiated carbanions alpha to carbonyl functional groups are O

Synthetic study toward tridachiapyrone B

• Morgan Cormier,
• Florian Hernvann and
• Michaël De Paolis

Beilstein J. Org. Chem. 2022, 18, 1741–1748, doi:10.3762/bjoc.18.183

• carbanions of 1,3-dithiane [27], allyl [27], and methyldienylbenzene groups [31] to compound 2 were demonstrated, this result amounts to the first grafting of an aromatic nucleophile to the motif. The construction of the vicinal quaternary carbon of 6b was next investigated by methylation of the highly

Development of N-F fluorinating agents and their fluorinations: Historical perspective

• Teruo Umemoto,
• Yuhao Yang and
• Gerald B. Hammond

Beilstein J. Org. Chem. 2021, 17, 1752–1813, doi:10.3762/bjoc.17.123

• cleavage reactions with F2. This method, using the dilute F2, was inefficient for their production due to long reaction times. N-Fluoro-N-alkyl-p-toluenesulfonamides 4-1b,c,f proved to be efficient fluorinating agents in the fluorination of carbanions (Scheme 7). The yields of reactions with sodium

• malonates and Grignard reagents were largely improved to up to 81% and 50%, respectively. The carbanions of aromatics, ketones, nitroalkanes, amides, etc. could also be reasonably well fluorinated and this study showed great progress. However, although these fluorinating agents were stable and easy-to

• -handle, their fluorinating power was low. They could fluorinate only reactive carbanions, but not aromatics, olefins, vinyl acetates, trimethylsilyl or alkyl enol ethers, and so on. Soon after (1986), Schwartz and co-worker reported the stereospecific synthesis of alkenyl fluorides with N-fluoro-N-tert

Methodologies for the synthesis of quaternary carbon centers via hydroalkylation of unactivated olefins: twenty years of advances

• Thiago S. Silva and
• Fernando Coelho

Beilstein J. Org. Chem. 2021, 17, 1565–1590, doi:10.3762/bjoc.17.112

• hampered the development of more general catalytic hydrofunctionalization methodologies until Widenhoefer’s work in 2001 [25]. Based on previous works that had demonstrated the addition of stabilized carbanions [26][27] and enol silyl ethers [28] to olefins under stoichiometric Pd catalysis, the authors

Fritsch–Buttenberg–Wiechell rearrangement of magnesium alkylidene carbenoids leading to the formation of alkynes

• Tsutomu Kimura,
• Koto Sekiguchi,
• Akane Ando and
• Aki Imafuji

Beilstein J. Org. Chem. 2021, 17, 1352–1359, doi:10.3762/bjoc.17.94

• rearrangement because the trend of migratory aptitude (aryl, alkynyl >> alkyl) follows the trend of the stability of carbanions [21][22]. The trans-relationship between the chloro group and the migrating substituent appears to be of importance for a successful 1,2-rearrangement [8]. Given the difference in

[2 + 1] Cycloaddition reactions of fullerene C₆₀ based on diazo compounds

• Yuliya N. Biglova

Beilstein J. Org. Chem. 2021, 17, 630–670, doi:10.3762/bjoc.17.55

• synthetic organic chemists as it allows to obtain methanofullerenes, fullerenoaziridines, or fullerenooxyranes. These reactions can involve, for example, the addition of stabilized carbanions, carbenes, and nitrenes and can involve various reaction mechanisms. While in the early years of intense research on

• processes, among which reactions leading to methanofullerenes are widely used. Two main synthetic methods for the production of methanofullerenes can be distinguished (Scheme 1): nucleophilic cyclopropanation with stabilized carbanions that occurs by the addition–cleavage mechanism – the Bingel reaction (I

• addition of diazo compounds to C60 have appeared in recent years. Though the reaction has to be performed with heating, the yield of a functionalized C60 is much higher than in the nucleophilic cyclopropanation with stabilized carbanions. This variant for synthesizing methanofullerenes is also attractive

CF₃-substituted carbocations: underexploited intermediates with great potential in modern synthetic chemistry

• Anthony J. Fernandes,
• Armen Panossian,
• Bastien Michelet,
• Agnès Martin-Mingot,
• Frédéric R. Leroux and
• Sébastien Thibaudeau

Beilstein J. Org. Chem. 2021, 17, 343–378, doi:10.3762/bjoc.17.32

The preparation and properties of 1,1-difluorocyclopropane derivatives

• Kymbat S. Adekenova,
• Peter B. Wyatt and
• Sergazy M. Adekenov

Beilstein J. Org. Chem. 2021, 17, 245–272, doi:10.3762/bjoc.17.25

• - or dibromomethyl carbanions. The so-obtained carbanions form lipophilic ion pairs with the catalyst cation and move into the organic phase, where they react with dibromodifluoromethane. Consequently, carbon tetrabromide (or bromoform) and the ion pair CBrF2−N+Bu4 are formed. The ion pair decomposes

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

• carbanions or alcoholates was also attempted but the starting bromide E-1d degraded under these conditions. Finally, this expeditious synthesis of tetrasubstituted fluoroalkenes by sequential ring-opening and nucleophilic substitution reactions was applied to test the robustness of a selective preparation of

Recent synthesis of thietanes

• Jiaxi Xu

Beilstein J. Org. Chem. 2020, 16, 1357–1410, doi:10.3762/bjoc.16.116

Allylic cross-coupling using aromatic aldehydes as α-alkoxyalkyl anions

• Akihiro Yuasa,
• Kazunori Nagao and
• Hirohisa Ohmiya

Beilstein J. Org. Chem. 2020, 16, 185–189, doi:10.3762/bjoc.16.21

• -catalyzed allylic substitution. Keywords: aldehyde; copper; copper catalysis; cross-coupling; palladium; synthetic method; Introduction α-Alkoxy-substituted carbanions (α-alkoxyalkyl anions) are useful C(sp3) nucleophiles for the construction of alcohol units found in a majority of pharmaceuticals

[1,3]/[1,4]-Sulfur atom migration in β-hydroxyalkylphosphine sulfides

• Katarzyna Włodarczyk,
• Piotr Borowski and
• Marek Stankevič

Beilstein J. Org. Chem. 2020, 16, 88–105, doi:10.3762/bjoc.16.11

• ketophosphonates from vinylphosphates [53]. [1,4]-Rearrangements include that of o-phosphorus-substituted benzyl carbanions [34], phosphorus group migration in O-phosphorylated 1,4-benzodiazepines [54], or phosphoryl group carbon-to-oxygen transfer [55]. The common feature of every rearrangement presented above is

Transition-metal-free [3 + 3] annulation of indol-2-ylmethyl carbanions to nitroarenes. A novel synthesis of indolo[3,2-b]quinolines (quindolines)

• Michał Nowacki and
• Krzysztof Wojciechowski

Beilstein J. Org. Chem. 2018, 14, 194–202, doi:10.3762/bjoc.14.14

• Michal Nowacki Krzysztof Wojciechowski Institute of Organic Chemistry, Polish Academy of Sciences, Kasprzaka 44/52, 01-224 Warsaw, Poland 10.3762/bjoc.14.14 Abstract Indol-2-ylmethyl carbanions stabilized by alkoxycarbonyl, cyano or benzenesulfonyl groups react with nitroarenes to form σH-adducts

• , which in the presence of base (triethylamine or DBU) and trimethylchlorosilane transform into indolo[3,2-b]quinoline derivatives in moderate to good yields. Keywords: carbanions; cyclization; heterocycles; nitroarenes; nucleophilic substitution; silylation; Introduction The indolo[3,2-b]quinoline

• pharmaceutical applications [19]. During our studies on the reactions of nitroarenes with nucleophiles [20][21][22][23], particularly carbanions, we were interested in a direct transformation of the formed σH-adducts into heterocyclic systems – indoles [21][23] and quinolines [21][22]. Quinolines were formed

CF₃SO₂X (X = Na, Cl) as reagents for trifluoromethylation, trifluoromethylsulfenyl-, -sulfinyl- and -sulfonylation and chlorination. Part 2: Use of CF₃SO₂Cl

• Hélène Chachignon,
• Hélène Guyon and
• Dominique Cahard

Beilstein J. Org. Chem. 2017, 13, 2800–2818, doi:10.3762/bjoc.13.273

• of chlorination of carbanions was calculated to be more than 105 higher than that of the sulfonylation of methanol. However, forty years later, Shainyan and Danilevich reported that the process might not be that selective in regard to mono- versus dichlorination of compounds carrying two acidic

A novel application of 2-silylated 1,3-dithiolanes for the synthesis of aryl/hetaryl-substituted ethenes and dibenzofulvenes

• Grzegorz Mlostoń,
• Paulina Pipiak,
• Róża Hamera-Fałdyga and
• Heinz Heimgartner

Beilstein J. Org. Chem. 2017, 13, 1900–1906, doi:10.3762/bjoc.13.185

• intermediate carbanions with water led to the corresponding 1,3-dithiolanes 15a and 15b, and no [3 + 2]-cycloreversion of the heterocyclic ring was observed (Scheme 5). As mentioned before, 1,3-dithiolane 13c has been reported as a convenient source of a reactive carbanion, which subsequently was trapped with

• observed. These experiments demonstrate that the 4,5-unsubstituted 1,3-dithiolane carbanions generated under mild conditions through desilylation of the appropriate precursors 13 do not require an electron-withdrawing substituent for their stabilization [29]. The preparation of 1,3-dithianes and 1,3

• -dithiolanes, as well as the generation of the corresponding carbanions are widely applied in the umpolung chemistry [27][28] and in the chemistry of protective groups [29][30], but tetrasubstituted ethenes have never been prepared by using this approach. Conclusion The presented study showed that 2

Synthesis of benzothiophene and indole derivatives through metal-free propargyl–allene rearrangement and allyl migration

• Jinzhong Yao,
• Yajie Xie,
• Lianpeng Zhang,
• Yujin Li and
• Hongwei Zhou

Beilstein J. Org. Chem. 2017, 13, 1866–1870, doi:10.3762/bjoc.13.181

• heterocycles are not well-documented [30][31]. Recently, our group explored the utilization of β-sulfonium carbanions for the preparation of thiophene derivatives [19]. Alkynes were treated with acyl chloride under Sonogashira reaction conditions and the expected β-sulfonium carbanions were obtained in a one

Et₃B-mediated and palladium-catalyzed direct allylation of β-dicarbonyl compounds with Morita–Baylis–Hillman alcohols

• Ahlem Abidi,
• Yosra Oueslati and
• Farhat Rezgui

Beilstein J. Org. Chem. 2016, 12, 2402–2409, doi:10.3762/bjoc.12.234

• selected the acyclic alcohol 1b to react with stabilized carbanions derived from the β-keto esters 2e–f and β-diketones 2g–i in anhydrous THF using 1 equiv of NaH and 2 equiv of Et3B. Under these conditions, all these reactions worked well in refluxing THF, affording in 2 h the corresponding monoallylation

From N-vinylpyrrolidone anions to modified paraffin-like oligomers via double alkylation with 1,8-dibromooctane: access to covalent networks and oligomeric amines for dye attachment

• Daniela Obels,
• Melanie Lievenbrück and
• Helmut Ritter

Beilstein J. Org. Chem. 2016, 12, 1395–1400, doi:10.3762/bjoc.12.133

• ) can be mono or di-deprotonated in α-position to the carbonyl group by the use of the strong and sterically demanding base lithium diisopropylamide [14][34][35]. As mentioned above, the resulting carbanions do not attack the electron-rich N-vinyl double bond. Accordingly, by using 1,8-dibromooctane as

Investigation of the role of stereoelectronic effects in the conformation of piperidones by NMR spectroscopy and X-ray diffraction

• Cesar Garcias-Morales,
• David Ortegón-Reyna and
• Armando Ariza-Castolo

Beilstein J. Org. Chem. 2015, 11, 1973–1984, doi:10.3762/bjoc.11.213

• carbanions [13][14], carbocations [15][16][17][18], and free radicals [19][20][21] which has been explained by negative (nX→σ*C–Y) or positive hyperconjugation (σC–Y→π* or p). Hyperconjugation is commonly described as the interaction between electronic orbitals where one filled orbital (donor) interacts with

Synthesis of γ-hydroxypropyl P-chirogenic (±)-phosphorus oxide derivatives by regioselective ring-opening of oxaphospholane 2-oxide precursors

• Iris Binyamin,
• Shoval Meidan-Shani and
• Nissan Ashkenazi

Beilstein J. Org. Chem. 2015, 11, 1332–1339, doi:10.3762/bjoc.11.143

• commonly result in the formation of a pentavalent P-center which can no longer be exploited as a nucleophile. Therefore, this type of reaction can be used for the introduction of only one alkyl ligand. (B) Electrophilic P(V) compounds which can undergo a nucleophilic attack by various carbanions to form

Superoxide chemistry revisited: synthesis of tetrachloro-substituted methylenenortricyclenes

• Basavaraj M. Budanur and
• Faiz Ahmed Khan

Beilstein J. Org. Chem. 2014, 10, 2531–2538, doi:10.3762/bjoc.10.264

• norcamphor using o-amino acetophenone hydrochloride. Ladenberger and co-worker [27] observed the rearrangement of a lithiated-tetrachloronorbornyl intermediate to a tricyclene derivative in a study about stability of vinyl carbanions. Li and co-workers [28][29] have synthesized aryl/benzyl substituted

Electrocarboxylation: towards sustainable and efficient synthesis of valuable carboxylic acids

• Roman Matthessen,
• Jan Fransaer,
• Koen Binnemans and
• Dirk E. De Vos

Beilstein J. Org. Chem. 2014, 10, 2484–2500, doi:10.3762/bjoc.10.260

• . Oxidation of chloride, which itself originates in the CCl4 reactant, likely results in partial chlorination of the acetonitrile solvent, releasing protons which in turn cause the formation of chloroform by attacking the cathodically formed carbanions [143]. An undivided electrosynthesis setup with stable