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Search for "carbene" in Full Text gives 326 result(s) in Beilstein Journal of Organic Chemistry. Showing first 200.

High-pressure activation for the solvent- and catalyst-free syntheses of heterocycles, pharmaceuticals and esters

  • Kelsey Plasse,
  • Valerie Wright,
  • Guoshu Xie,
  • R. Bernadett Vlocskó,
  • Alexander Lazarev and
  • Béla Török

Beilstein J. Org. Chem. 2025, 21, 1374–1387, doi:10.3762/bjoc.21.102

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  • imidazole-based N-heterocyclic carbene (NHC)–CuCl complexes [40]. However, their synthesis is often tainted by the use of toxic reagents and solvents. In addition, when o-phenylenediamine reacts with ketones, the common catalytic methods yield benzodiazepine products [41]. In our case the reaction of o
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Published 02 Jul 2025

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

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  • 2016 complemented by a few older works that were deemed powerful and relevant for illustrating a given reaction mode. Chapter 1 covers strategies for the oxetane ring formation including substitutions, cycloadditions, ring-size manipulations and carbene insertions. Chapter 2 details chemical
  • enantioselectivities. In 2018, Scheidt and colleagues disclosed the first N-heterocyclic carbene (NHC)-catalysed [2 + 2] annulation between trifluoromethyl ketones and γ-substituted allenoates (Scheme 25a) [68]. The resulting 2-alkylideneoxetane products 95 were generally obtained in >90% yields and good
  • still runs smoothly, if the aryl is substituted for cyclohexyl. The proposed mechanism, supported by control experiments, deuterium exchange studies and energy calculations, consists of the following steps: conjugate addition of the carbene to the allenoate, regioselective addition of the resulting
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Published 27 Jun 2025

Recent advances in oxidative radical difunctionalization of N-arylacrylamides enabled by carbon radical reagents

  • Jiangfei Chen,
  • Yi-Lin Qu,
  • Ming Yuan,
  • Xiang-Mei Wu,
  • Heng-Pei Jiang,
  • Ying Fu and
  • Shengrong Guo

Beilstein J. Org. Chem. 2025, 21, 1207–1271, doi:10.3762/bjoc.21.98

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  • for constructing quaternary carbon centers in oxindoles via an N-heterocyclic carbene (NHC)-catalyzed intermolecular Heck-type alkyl radical addition and annulation reaction (Scheme 47) [28]. The reaction proceeds through a redox-neutral mechanism, where the NHC catalyst serves a dual role as both a
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Published 24 Jun 2025

Recent advances in synthetic approaches for bioactive cinnamic acid derivatives

  • Betty A. Kustiana,
  • Galuh Widiyarti and
  • Teni Ernawati

Beilstein J. Org. Chem. 2025, 21, 1031–1086, doi:10.3762/bjoc.21.85

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  • construction, alkyne hydrogenation, ylide and carbene reaction, metathesis, E/Z isomerization, and other methods, including Cα and Cβ functionalizations. Preparing various functional group-tethered aromatic groups can be achieved by directly installing an aromatic group via cross-coupling reactions and other
  • (2022) investigated the visible-light-mediated amidation of cinnamic acid (7) by using ethyl 2-diazoacetate and acetonitrile to give its corresponding amide 103 in excellent yield (Scheme 32) [29]. The reactive free carbene 104 was released upon light exposure of the diazo ester leading to the nitrilium
  • -workers (2019) reported an enantioselective esterification via oxidative N-heterocyclic carbene (NHC)-catalyzed phthalaldehyde activation to form azolium ester intermediate 147 to give the chiral phthalidyl ester 146 with excellent enantiomeric ratio (Scheme 45B) [85]. Additionally, the reaction capacity
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Published 28 May 2025

Recent total synthesis of natural products leveraging a strategy of enamide cyclization

  • Chun-Yu Mi,
  • Jia-Yuan Zhai and
  • Xiao-Ming Zhang

Beilstein J. Org. Chem. 2025, 21, 999–1009, doi:10.3762/bjoc.21.81

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  • was utilized to transform enamine 18 and propargyl ester 19 into 1-azaspiro[4.4]nonane 20 with high diastereoselectivity. Notably, the combination of an N-heterocyclic carbene gold catalyst and a silver salt AgSbF6 was found to be essential in guaranteeing the reactivity of the alkyne partner
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Published 22 May 2025

Recent advances in controllable/divergent synthesis

  • Jilei Cao,
  • Leiyang Bai and
  • Xuefeng Jiang

Beilstein J. Org. Chem. 2025, 21, 890–914, doi:10.3762/bjoc.21.73

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  • , Koenigs, and co-workers demonstrated solvent-controlled bifurcation in the light-driven reactivity of cyclic diazo imides 41 with thiols 42, unveiling two mechanistically distinct pathways (Scheme 11) [40]. In dichloromethane (DCM), the reaction proceeds via a carbene intermediate, enabling cascade C(sp2
  • )–H functionalization/thiolation to deliver indane-fused pyrrolidines 43 in excellent yields (up to 92%). Strikingly, switching the solvent to acetonitrile completely suppresses carbene formation under identical conditions, redirecting the pathway toward an unconventional diazo reduction wherein aryl
  • thiols act as stoichiometric reductants. Mechanistic insights, elucidated through control experiments and DFT calculations, revealed that photoexcitation of diazo imide 41 triggers nitrogen extrusion (ΔG‡ = +10.0 kcal·mol−1), generating the triplet carbene intermediate Int-45. In DCM, this species
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Published 07 May 2025

Origami with small molecules: exploiting the C–F bond as a conformational tool

  • Patrick Ryan,
  • Ramsha Iftikhar and
  • Luke Hunter

Beilstein J. Org. Chem. 2025, 21, 680–716, doi:10.3762/bjoc.21.54

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Published 02 Apr 2025

Recent advances in allylation of chiral secondary alkylcopper species

  • Minjae Kim,
  • Gwanggyun Kim,
  • Doyoon Kim,
  • Jun Hee Lee and
  • Seung Hwan Cho

Beilstein J. Org. Chem. 2025, 21, 639–658, doi:10.3762/bjoc.21.51

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  • their exploration of phosphoramidite ligands with various organometallic nucleophiles [24][25]. The field was further advanced by the research group of Hoveyda, who made substantial contributions by introducing bidentate N-heterocyclic carbene (NHC)-based chiral ligands, achieving high selectivity with
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Published 20 Mar 2025

Photocatalyzed elaboration of antibody-based bioconjugates

  • Marine Le Stum,
  • Eugénie Romero and
  • Gary A. Molander

Beilstein J. Org. Chem. 2025, 21, 616–629, doi:10.3762/bjoc.21.49

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  • researchers identified high-affinity binding sites for the ligand within the Fc domain. This structural analysis allowed precise determination of amino acid residue positions and orientations. Upon photoirradiation, the pLeu within the pFcBP generated a carbene from the diazirine moiety. This transformation
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Published 18 Mar 2025

Organocatalytic kinetic resolution of 1,5-dicarbonyl compounds through a retro-Michael reaction

  • James Guevara-Pulido,
  • Fernando González-Pérez,
  • José M. Andrés and
  • Rafael Pedrosa

Beilstein J. Org. Chem. 2025, 21, 473–482, doi:10.3762/bjoc.21.34

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  • processes with low catalyst loading. It involves the kinetic resolution of alcohols, amines, and esters using chiral phosphoric acids [6][7][8][9][10][11][12][13] and sulfoximines with enals using chiral N-heterocyclic carbene (NHC) catalysts [14]. Additionally, these processes have been conducted using
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Published 03 Mar 2025

Red light excitation: illuminating photocatalysis in a new spectrum

  • Lucas Fortier,
  • Corentin Lefebvre and
  • Norbert Hoffmann

Beilstein J. Org. Chem. 2025, 21, 296–326, doi:10.3762/bjoc.21.22

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  • acetone, allowing the pre-activation of the ruthenium complex with the successive release of an N-heterocyclic carbene ligand and a chlorine atom, which are replaced by two acetone molecules to form compound 2. Simultaneously, excitation of the osmium(II) complex in the red region (660 nm) decreases its
  • catalysis for carbene transfer reactions and radical-based functionalizations [41]. In another study by Derksen et al., thiaporphyrins were introduced as highly effective catalysts for red-light-mediated photoreductive dehalogenation [42]. These thiophene-modified porphyrins exhibit excellent absorption
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Published 07 Feb 2025

Recent advances in organocatalytic atroposelective reactions

  • Henrich Szabados and
  • Radovan Šebesta

Beilstein J. Org. Chem. 2025, 21, 55–121, doi:10.3762/bjoc.21.6

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  • organocatalytic reactions are discussed according to the dominant catalyst activation mode. For covalent organocatalysis, the typical enamine and iminium modes are presented, followed by N-heterocyclic carbene-catalyzed reactions. The bulk of the review is devoted to non-covalent activation, where chiral Brønsted
  • axially chiral N-aryl succinimides 54. The tentative mechanism comprises the formation of the Breslow intermediate Int-31 from the catalyst carbene and aldehyde 52, which then adds to the electron-deficient double bond of maleimide giving rise to Int-32 (Scheme 17). Chi and co-workers developed an
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Published 09 Jan 2025

Non-covalent organocatalyzed enantioselective cyclization reactions of α,β-unsaturated imines

  • Sergio Torres-Oya and
  • Mercedes Zurro

Beilstein J. Org. Chem. 2024, 20, 3221–3255, doi:10.3762/bjoc.20.268

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  • -workers reported a dihydroquinine-derived squaramide-catalyzed (3 + 2) cycloaddition reaction of isocyanoacetates 26 and saccharin-derived 1-azadienes 14 [32]. In this work, the azadiene works as a C2 synthon, while the isocyanoacetate, bearing a protected carboxylic acid and a carbene-like divalent
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Published 10 Dec 2024

Synthesis of 2H-azirine-2,2-dicarboxylic acids and their derivatives

  • Anastasiya V. Agafonova,
  • Mikhail S. Novikov and
  • Alexander F. Khlebnikov

Beilstein J. Org. Chem. 2024, 20, 3191–3197, doi:10.3762/bjoc.20.264

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  • situation. Dibenzyl ester 11c was prepared using traditional activation of carboxylic acid 6a, although the yield was only 23%. A higher yield of the branched ester 11d (86%, as a mixture of diastereomers) was obtained by carbene insertion, generated by blue LED irradiation of methyl 2-diazo-2-phenylacetate
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Published 05 Dec 2024

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

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  • and a photosensitizer, facilitating photoinduced electron transfer (PET) to form the active cation radical B, and intersystem crossing (ISC) for energy transfer to generate the triplet carbene C. Radical B then reacted with biradical C, producing the new radical D, which accepted an electron from the
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Published 27 Nov 2024

Advances in radical peroxidation with hydroperoxides

  • Oleg V. Bityukov,
  • Pavel Yu. Serdyuchenko,
  • Andrey S. Kirillov,
  • Gennady I. Nikishin,
  • Vera A. Vil’ and
  • Alexander O. Terent’ev

Beilstein J. Org. Chem. 2024, 20, 2959–3006, doi:10.3762/bjoc.20.249

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Published 18 Nov 2024

Structure and thermal stability of phosphorus-iodonium ylids

  • Andrew Greener,
  • Stephen P. Argent,
  • Coby J. Clarke and
  • Miriam L. O’Duill

Beilstein J. Org. Chem. 2024, 20, 2931–2939, doi:10.3762/bjoc.20.245

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  • )triphenylphosphonium salt 6 and (iodomethyl)triphenyl-phosphonium salt 7. Homolytic or heterolytic scission of the I–C(ylid) bond with loss of ArI (path a) would result in a carbene, though it is unclear how this would transform to compound 6. Alternatively, scission of the I–C(Ar) bond with loss of benzyne (path b
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Published 14 Nov 2024

Mechanochemical difluoromethylations of ketones

  • Jinbo Ke,
  • Pit van Bonn and
  • Carsten Bolm

Beilstein J. Org. Chem. 2024, 20, 2799–2805, doi:10.3762/bjoc.20.235

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  • -depleting sulfur dioxide as side products [46][47]. Later, Ichikawa and co-workers established the release of difluorocarbene from TFDA with catalytic amounts of an N-heterocyclic carbene and a base (Scheme 1C) [29][48][49]. In these reactions, difluoromethyl enol ethers were obtained, which were
  • reaction time of 60 min, both reducing and increasing the amount of 2 (from initially used 2.0 equiv to 1.5 equiv and 3.0 equiv, respectively) reduced the yield of 3a by about 10% (Table 1, entries 3–5). Probably, with less carbene precursor the amount of generated difluorocarbene was insufficient, and
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Published 04 Nov 2024

5th International Symposium on Synthesis and Catalysis (ISySyCat2023)

  • Anthony J. Burke and
  • Elisabete P. Carreiro

Beilstein J. Org. Chem. 2024, 20, 2704–2707, doi:10.3762/bjoc.20.227

Graphical Abstract
  • carbene (NHC) framework from polysubstituted aminoimidazo[5,1-b]oxazol-6-ium salts, which demonstrated strong catalytic activity in gold-catalyzed alkyne hydration and arylative cyclization reactions [14]. The synthesis of this new carbene involved the use of a novel nitrenoid reagent that was
  • successfully synthesized on a gram scale through a three-step reaction sequence. The process began with 2,6-diisopropylphenylamine, which underwent alkylation, formylation, and substitution reactions. The carbene synthesis was then achieved via a two-step process involving ynamide annulation, followed by
  • imidazolium ring formation. The resulting carbene was metalated at the C2 position with Au(I), Cu(I), and Ir(I), obtaining an L-shaped NHC ligand scaffold. Līpiņš et al. introduced a new method for synthesizing 4-azido-6,7-dimethoxy-2-alkyl/arylsulfonylquinazolines, which are key intermediates in the
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Published 28 Oct 2024

Efficacy of radical reactions of isocyanides with heteroatom radicals in organic synthesis

  • Akiya Ogawa and
  • Yuki Yamamoto

Beilstein J. Org. Chem. 2024, 20, 2114–2128, doi:10.3762/bjoc.20.182

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  • phenanthridines via silver-catalyzed radical sulfonylation–cyclization of 2-isocyanobiphenyls (Scheme 25) [98]. Wang et al. reported a radical borylative cyclization of 2-isocyanobiaryls with N-heterocyclic carbene borane (Scheme 26) [99]. The boryl radical generated via hydrogen abstraction in the presence of di
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Published 26 Aug 2024

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

Graphical Abstract
  • -Methylene spirolactones at C-3 11a and 11b derived from dihydrocholesterol and stanolone were also obtained in 41% and 52% yields, respectively (dr > 20:1) (Scheme 3). More recently, a functionalized spiro-β-lactone was obtained via a metal-free procedure involving photoinduced carbene C–H insertion in a
  • diazo precursor. To achieve this, cholesterol was first esterificated using 2-(4-methoxyphenyl)acetic acid and DCC. The resulting arylacetic ester 12 was then reacted with 4-acetamidobenzenesulfonyl azide (p-ABSA) and DBU in anhydrous acetonitrile to yield the diazo compound 13 in 22% yield. The carbene
  • C–H insertion to produce the spiro-β-lactone was accomplished by simply exposing the diazo derivative to 440 nm blue LEDs (Kessil lamp) at 50 °C, that favored the formation of a singlet carbene that reacted selectively by insertion into the C(3)–H bond. Spiro-lactones 14 were obtained in 80% yield
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Published 24 Jul 2024

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

Graphical Abstract
  • fractionated cell cultures of M. alba with 49 was followed by irradiation with 365 nm light to generate reactive carbene from diazirine. This sequence allowed the formation of covalent bonds between the synthetic probe and binding proteins. The resulting mixture was subjected to a copper-catalyzed click
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Published 23 Jul 2024

Synthetic applications of the Cannizzaro reaction

  • Bhaskar Chatterjee,
  • Dhananjoy Mondal and
  • Smritilekha Bera

Beilstein J. Org. Chem. 2024, 20, 1376–1395, doi:10.3762/bjoc.20.120

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  • reaction. AlCl3-mediated Cannizzaro disproportionation of aldehydes. Ru–N-heterocyclic carbene catalyzed dehydrogenative synthesis of carboxylic acids. Intramolecular desymmetrization of tetraethylene glycol. Desymmetrization of oligoethylene glycol dialdehydes. Intramolecular Cannizzaro reaction of calix
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Published 19 Jun 2024

Two-fold addition reaction of silylene to C60: structural and electronic properties of a bis-adduct

  • Masahiro Kako,
  • Masato Kai,
  • Masanori Yasui,
  • Michio Yamada,
  • Yutaka Maeda and
  • Takeshi Akasaka

Beilstein J. Org. Chem. 2024, 20, 1179–1188, doi:10.3762/bjoc.20.100

Graphical Abstract
  • 305-8577, Japan 10.3762/bjoc.20.100 Abstract The addition reaction of C60 with silylene 1, a silicon analog of carbene, yielded the corresponding bis-adduct 3. The structure of 3 was determined by single-crystal X-ray structure analysis, representing the first example of a crystal structure of a
  • silicon analog of carbene, were described as providing silirane (silacyclopropane)-type 6,6-mono-adducts Dip2SiC60 (2, Scheme 1) and Dip2SiC70 [15][16]. Furthermore, bis-adducts (Dip2Si)2C60 and (Dip2Si)2C70 were obtained as byproducts, but no details of these bis-adducts have been clarified [15][16]. The
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Published 22 May 2024

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

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  • mechanism suggested that dearomatization–aromatization pathways operated for the dehydrogenation of the alcohol and C–C bond formations. After the successful attempt of bidentate N-heterocyclic carbene-manganese complex-catalyzed N-alkylation of amines with alcohols at room temperature [41], Liu and Ke's
  • ]. Under optimized conditions (2 mol % Mn(CO)5Br, 10 mol % t-BuOK, t-AmOH, argon atmosphere), various quinoline derivatives were successfully synthesized with this protocol (Scheme 71). In 2019, Liu et al. used a bis-N-heterocyclic carbene-supported manganese complex for quinoline synthesis by coupling
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Published 21 May 2024
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