Electrochemical reduction of unsaturated carbon–carbon bonds via 3d transition-metal catalysis

• Geon Kang,
• Minki Jeon,
• Pooja Kumari Jat,
• Cheoljae Kim and
• Isaac Choi

Beilstein J. Org. Chem. 2026, 22, 955–981, doi:10.3762/bjoc.22.75

• previously established in Baran’s study (Scheme 6A) [103]. Redox-sensitive functionalities such as esters, ketones, epoxides, nitriles, and arylboronic esters remained intact, and both electron-rich and electron-poor arenes were fully compatible with the reaction conditions (Scheme 6B). Importantly, this

Synthesis of sterically shielded piperidine nitroxides via acid-catalyzed heterocyclization of β-aminoketone derivatives with ketones

• Mark M. Gulman,
• Yurii I. Glazachev and
• Sergey A. Dobrynin

Beilstein J. Org. Chem. 2026, 22, 948–954, doi:10.3762/bjoc.22.74

• in materials science and structural biology. The new heterocyclization strategy implies the construction of a 2,2,6-trisubstituted piperidine scaffold from β-aminoketone acetals and dialkyl ketones under acid catalysis. The resulting amines were oxidized to the corresponding ketonitrones and

• of sterically hindered piperidine nitroxyl radicals. Six-membered cyclic nitrones – 2,2,6-trialkyl-substituted 2,3,4,5-tetrahydropyridine-1-oxides were prepared via the acid-catalyzed reaction of 2-(2-aminoalkyl)-2-methyl-1,3-dioxolanes with ketones in analogy to literature procedures [25][26][27][28

• formation, and hydrazinolysis (Scheme 1). The target 2-(2-aminoalkyl)-1,3-dioxolanes 4a,b were obtained in pure form after vacuum distillation. Conversion of α,β-unsaturated ketones 1a,b to aminodioxolanes 4a,b proceeded in 49% and 69% overall yield, respectively. In the 1H NMR spectrum of 4a

Recent advances in copper-catalyzed direct hydroamination of alkenes with (hetero)aromatic amines

• Hyejeong Lee and
• Yunmi Lee

Beilstein J. Org. Chem. 2026, 22, 925–947, doi:10.3762/bjoc.22.73

• saturated ketones (Scheme 8, conditions C) [45]. In this system, copper initially promoted oxidative dehydrogenation of ketone substrate 18 to generate an α,β-unsaturated intermediate 19 in situ via the radical-based pathway. The resulting enone 19 was subsequently activated through coordination to the

• copper center, facilitating nucleophilic addition of nitrogen sources to form β-amino ketones 20. Although the initial desaturation step involved radical intermediates, the subsequent C–N bond formation proceeded via Lewis acid activation of the conjugated olefin. Therefore, copper played a dual role by

• -catalyzed cascade reaction for the synthesis of N-alkyl 2-arylindoles 32 from readily available 2-arylethynylanilines 29 and saturated ketones 30 under oxidizing conditions (Scheme 10) [48]. The transformation involved a sequential dehydrogenation, aza-Michael addition, and intramolecular annulation

Cascade transformation of 2-(diazoacetyl)-2H-azirines to 2-aroyl-3-hydroxy-1H-pyrroles via condensation with aromatic aldehydes

• Timur O. Zanakhov,
• Ekaterina E. Galenko,
• Mikhail S. Novikov and
• Alexander F. Khlebnikov

Beilstein J. Org. Chem. 2026, 22, 897–904, doi:10.3762/bjoc.22.70

• ][18], and heterocyclic hybrids [11][19]. However, the diversity of known azirinyl-substituted diazo compounds is currently limited to diazo ketones [11][12][13][15], 2-(diazoacetyl)-2H-azirines, α-diazo-β-ketoesters [14][16][17][18][19], and alkyl 2-diazo-3-oxo-3-(2H-azirin-2-yl)propanoates

Knoevenagel condensation of 4,5- and 1,8-diazafluorenes

• Darya S. Cheshkina,
• Christina S. Becker,
• Alina A. Sonina and
• Maxim S. Kazantsev

Beilstein J. Org. Chem. 2026, 22, 803–812, doi:10.3762/bjoc.22.62

• with ketones resulted in unique di(pyridin-2-yl)methylene)-9H-diazafluorenes being electron-deficient ligands and functional materials. Keywords: acidic conditions; diazafluorene; diazafluorenylidene; Knoevenagel condensation; protonation; Introduction Diazafluorenylidene derivatives were reported to

• corresponding ketones complicating the synthetic protocol. Therefore, the Knoevenagel condensation seemed to be an alternative and preferable approach. Previously reported syntheses of diazafluorenylidenes employed diazafluorenones as the carbonyl component which are reacted with an active methylene moiety like

• 1,8-diazafluorene (2) was performed using a TiCl4/pyridine system. However, the reaction yield was very low (11%) [15]. The latter approach was also used [22] for the condensation of 4,5-diazafluorene with ketones being especially challenging due to sterical issues. Moreover, this approach requires

Synthesis of heterocycles based on azomethine ylides from α-amino acids (or amines) and carbonyl compounds

• Ekaterina V. Berezhnaya,
• Alexander I. Ponyaev,
• Vitali M. Boitsov and
• Alexander V. Stepakov

Beilstein J. Org. Chem. 2026, 22, 705–741, doi:10.3762/bjoc.22.55

• heating were used. Notably, this process can proceed solvent-free at 140 °C, which is suitable for less reactive substrates. Various exo-cyclic alkenes obtained from cyclic (hetero)aliphatic ketones such as cyclobutanone, azetidinone, thienone, as well as endo-(hetero)cyclic alkenes containing oxygen

• formyl steroid 112 and sarcosine 99 (Scheme 41) [86]. The synthesis yielded N-methyl-2-substituted pyrrolidino[3,4:1,2][60]fullerenes (2R/2S)-113 as a mixture of two diastereomers. Azomethine ylides based on cyclic ketones Azomethine ylides from ninhydrin. In [87][88][89][90], four-component one-pot

Continuous-flow carbonyl hydrogenation under subatmospheric to atmospheric hydrogen pressure enabled by robust heterogeneous Pt–Fe catalysts

• Hiroyuki Miyamura,
• Ryosuke Kajiyama,
• Shun-ya Onozawa,
• Yoshihiro Kon and
• Shū Kobayashi

Beilstein J. Org. Chem. 2026, 22, 575–582, doi:10.3762/bjoc.22.43

• , including ketones and aldehydes, to alcohols is a fundamental and important reaction in organic synthesis. One of the most ideal methods is catalytic hydrogenation, however, the hydrogenation of ketones generally requires harsh reaction conditions, such as high temperature and high pressure. We developed a

• bimetallic Pt–Fe nanoparticle catalyst immobilized on a composite support of dimethylpolysilane and alumina. Both ketones and aldehydes, including highly bulky and sterically hindered substrates, were smoothly hydrogenated using the newly developed catalysts under continuous-flow conditions at room

• : bimetallic nanostructure; carbonyl reduction; continuous-flow reaction; heterogeneous catalyst; subatmospheric hydrogen; Introduction The reduction of carbonyl compounds, ketones and aldehydes to alcohols is a fundamental and important reaction in organic synthesis that can provide valuable chemicals such

Recent advances in the cleavage of non-activated amides

• Eun-Sol Choi and
• Hyo-Jun Lee

Beilstein J. Org. Chem. 2026, 22, 352–369, doi:10.3762/bjoc.22.23

• , furnishing the corresponding hindered amides and anilides 203–205 in high yields. Likewise, esters 206 and 207 and ketones 208 were efficiently obtained by treating the acyl fluoride intermediates 194 with alcohols as O-nucleophiles and thiophene as a C-nucleophile, respectively. Mechanistic studies support

• the presence of secondary or tertiary amides to generate the corresponding acyl fluoride intermediate. Subsequent in-situ amidation with 2-methylbenzylamine furnished diamide products 211 and 212 in 48% and 62% yields, respectively. Amido esters and amido ketones were likewise converted to the

Ring contraction and ring expansion reactions in terpenoid biosynthesis and their application to total synthesis

• Nicolas Kratena,
• Nicolas Heinzig and
• Peter Gärtner

Beilstein J. Org. Chem. 2026, 22, 289–343, doi:10.3762/bjoc.22.21

Arene activation via π-bond localization: concepts and opportunities

• Paul Meiners,
• Julian J. Melder and
• Tobias Morack

Beilstein J. Org. Chem. 2026, 22, 257–273, doi:10.3762/bjoc.22.19

• (Figure 6C), so suitable aromatic ligands are limited to those lacking strongly π-acidic functional groups, e.g., alkenes, alkynes, aldehydes, certain ketones, and nitriles. Lewis-basic heteroarenes, such as pyridines or imidazoles, tend to coordinate via nitrogen instead, disfavoring η2-binding (Figure

A mild and atom-efficient four-component cascade strategy for the construction of biologically relevant 4-hydroxyquinolin-2(1H)-one derivatives

• Dmitrii A. Grishin,
• Kseniia I. Sharkovskaia,
• Ilya G. Kolmakov,
• Daria A. Ipatova,
• Rostislav A. Petrov,
• Nikolai D. Dagaev,
• Dmitry A. Skvortsov,
• Maria G. Khrenova,
• Valeriy V. Andreychev,
• Sergei A. Evteev,
• Yan A. Ivanenkov,
• Roman L. Antipin,
• Olga А. Dontsova and
• Elena K. Beloglazkina

Beilstein J. Org. Chem. 2026, 22, 244–256, doi:10.3762/bjoc.22.18

• approach involves the 1,4-Michael addition of the ambident anion derived from 6-halo-4-hydroxyquinolin-2-one to suitably activated unsaturated compounds. Considering the target structures (Figure 2), suitable Michael acceptors include α,β-unsaturated esters, aldehydes, methyl ketones, arylidene malonates

• desired 1,4-addition adduct was not detected (Scheme 4A). Michael adducts formed with α,β-unsaturated methyl ketones (e.g., compound 5). However, the subsequent haloform reaction failed to produce the target acid, yielding only trace amounts of a complex, difficult-to-separate mixture (Scheme 4B). Also

Base-promoted deacylation of 2-acetyl-2,5-dihydrothiophenes and their oxygen-mediated hydroxylation

• Vladimir G. Ilkin,
• Margarita Likhacheva,
• Igor V. Trushkov,
• Tetyana V. Beryozkina,
• Vera S. Berseneva,
• Vladimir T. Abaev,
• Wim Dehaen and
• Vasiliy A. Bakulev

Beilstein J. Org. Chem. 2026, 22, 192–204, doi:10.3762/bjoc.22.13

• oxidation of ketones includes C‒C-bond cleavage, and carboxylic acids are predominantly formed. This can be achieved by the treatment of acyclic ketones with hypohalites [13], in the nitroarene-catalyzed oxidation with oxygen under basic conditions [14] or by the use of hypervalent iodine compounds (Scheme

•  1A) [15][16]. Oxidative rearrangements of carbonyl compounds are based on Dakin [17] and Baeyer–Villiger reactions [18] and their modifications. Cyclic and acyclic ketones were oxidized to afford lactones and esters, accordingly, involving catalytic reactions with hydrogen peroxide [19][20][21][22

• ], oxygen [23][24] or with m-CPBA (Scheme 1B) [25][26] or non-catalytic transformations [27]. The few known oxidative transformations of o- or p-hydroxy-substituted aromatic ketones, that in most cases lead to phenols, involve the use of hydrogen peroxide as an oxygen source (Scheme 1C) [20][25][26

Circumventing Mukaiyama oxidation: selective S–O bond formation via sulfenamide–alcohol coupling

• Guoling Huang,
• Huarui Zhu,
• Shuting Zhou,
• Wanlin Zheng,
• Fangpeng Liang,
• Zhibo Zhao,
• Yifei Chen and
• Xunbo Lu

Beilstein J. Org. Chem. 2026, 22, 158–166, doi:10.3762/bjoc.22.9

• , such transformations remain synthetically challenging. This is primarily due to the well-known Mukaiyama-type oxidation, wherein sulfenamides serve as redox catalysts for NBS- or NCS-mediated oxidations of alcohols to aldehydes or ketones (Scheme 1b, top) [38][39][40][41][42]. Under such oxidative

Advances in Zr-mediated radical transformations and applications to total synthesis

• Hiroshige Ogawa and
• Hugh Nakamura

Beilstein J. Org. Chem. 2026, 22, 71–87, doi:10.3762/bjoc.22.3

• conditions, delivering the desired ketones 12 in good yields. The reaction also tolerated a wide range of protecting groups, including esters, carbamates, and silyl ethers, without degradation (10f–k). Neopentyl iodide 10l and secondary alkyl iodide 10m were also competent substrates, although tertiary alkyl

• hydrogen atom from 1,4-cyclohexadiene, affording the hydrogenated product 36. The reaction proved broadly applicable to a wide range of alkyl chlorides. For example, primary alkyl chlorides bearing functional groups such as amides (34b), esters (34c), ketones (34d), and phosphoesters (34e) underwent smooth

• issue, the authors first examined a model system. When β-alkoxythioesters (S)-52 were coupled with chiral alkyl iodides (S)-53 and (R)-53 under the developed conditions, the desired β-alkoxy ketones 54 were obtained in good yields without epimerization, affording optically pure products. These results

Synthesis and applications of alkenyl chlorides (vinyl chlorides): a review

• Daniel S. Müller

Beilstein J. Org. Chem. 2026, 22, 1–63, doi:10.3762/bjoc.22.1

• prepared in 1868 by Charles Friedel – best known for the Friedel–Crafts reaction – via the reaction of ketones with phosphorus pentachloride, these compounds have steadily gained attention over the decades. In recent years, their distinct reactivity and potential in organic synthesis have been increasingly

• Synthesis of Acetylenes” [29] which discusses the preparation of alkenyl chlorides via ketone chlorination using PCl5 (Figure 3A). The synthesis of β-chlorovinyl ketones was later reviewed by Poland and Benson in 1966 (Figure 3B) [30]. More recently, Morandi and co-workers summarized transition-metal

• -catalyzed additions of alkynes to acyl chlorides to access β-chlorovinyl ketones (2024) [31]. A review by Sharma and Singh covers comprehensively the synthesis and application of β-halovinyl aldehydes [32]. It should be noted that the synthesis of β-chloroalkenes substituted with an electron-withdrawing

Competitive cyclization of ethyl trifluoroacetoacetate and methyl ketones with 1,3-diamino-2-propanol into hydrogenated oxazolo- and pyrimido-condensed pyridones

• Svetlana O. Kushch,
• Marina V. Goryaeva,
• Yanina V. Burgart,
• Marina A. Ezhikova,
• Mikhail I. Kodess,
• Pavel A. Slepukhin,
• Alexandrina S. Volobueva,
• Vladimir V. Zarubaev and
• Victor I. Saloutin

Beilstein J. Org. Chem. 2025, 21, 2716–2729, doi:10.3762/bjoc.21.209

• -trifluoroacetoacetate and methyl ketones enables the synthesis to be carried out for octahydropyrido[1,2-a]pyrimidin-6-ones and hexahydrooxazolo[3,2-a]pyridin-5-ones, the preferential formation of which depends on the substituent in the methyl ketone component. Dual acid–base catalysis of the reactions with alkyl

• methyl ketones increases the regioselectivity in the synthesis of octahydropyrido[1,2-a]pyrimidinones. The cyclization with acetophenone is characterized by the regiospecific generation of these bicycles. The presence of three chiral centers in the synthesized bicycles, depending on the alkyl substituent

• , causes the formation of two to four diastereomers, the structure of which has been determined with 1H, 19F, 13C, 2D 1H-13C HSQC/HMBC, 1H-1H COSY/NOESY NMR and X-ray diffraction analysis. Keywords: condensed pyridones; 1,3-diamino-2-propanol; ethyl 4,4,4-trifluoroacetoacetate; methyl ketones; three

Mechanistic insights into hydroxy(tosyloxy)iodobenzene-mediated ditosyloxylation of chalcones: a DFT study

• Jai Parkash,
• Sangeeta Saini,
• Vaishali Saini,
• Omkar Bains and
• Raj Kamal

Beilstein J. Org. Chem. 2025, 21, 2703–2715, doi:10.3762/bjoc.21.208

• of the hydroxy(tosyloxy)iodobenzene (HTIB)-mediated conversion of chalcones (α,β-unsaturated carbonyl compounds) to ditosyloxy ketones is investigated. Here, at β-carbon of the chalcone, an aryl group with a para-substituent is present. Our study focuses on investigating the effect of different

• nature of para-substituents on the reaction mechanism. The substituents considered in the study include -OCH3, -SCH3, -Cl and -NO2 groups. For these chalcones, different possible pathways at various steps during the reaction are investigated leading to formation of α,β-ditosyloxy ketones and β,β

• -ditosyloxy ketones. It is found that the mechanism for the formation of α,β-ditosyloxy ketone involves only electrophilic addition of HTIB, and the mechanism is the same for all studied chalcones, irrespective of whether an electron-donating or electron-withdrawing substituent is present on the aryl ring

Synthesis of new tetra- and pentacyclic, methylenedioxy- and ethylenedioxy-substituted derivatives of the dibenzo[c,f][1,2]thiazepine ring system

• Gábor Berecz,
• András Dancsó,
• Mária Tóthné Lauritz,
• Loránd Kiss,
• Gyula Simig and
• Balázs Volk

Beilstein J. Org. Chem. 2025, 21, 2645–2656, doi:10.3762/bjoc.21.205

• substitution reactions of benzo-1,3-dioxoles and benzo-1,4-dioxanes [20]. Reduction of ketones 6 and 7 with NaBH4 gave alcohols 16 and 17, which were chlorinated with SOCl2 to result in compounds 18 and 19. Treatment of the latter with the appropriate amines gave amino derivatives 20a, 20c–e, and 21a, 21c–p

Thiazolidinones: novel insights from microwave synthesis, computational studies, and potentially bioactive hybrids

• Luan A. Martinho,
• Victor H. J. G. Praciano,
• Guilherme D. R. Matos,
• Claudia C. Gatto and
• Carlos Kleber Z. Andrade

Beilstein J. Org. Chem. 2025, 21, 2618–2636, doi:10.3762/bjoc.21.203

• isobutyraldehyde could be obtained. Other aliphatic aldehydes, such as phenylacetaldehyde, isovaleraldehyde, and heptanal, yielded only self-condensation products. A similar issue was observed with certain ketones, such as cyrene, cyclohexanone, 1,3-dichloroacetone, and acetophenone, since the condensation

• a catalyst in AcOH under microwave (μw) heating for the synthesis of 5-arylidene derivatives of rhodanine or thiazolidine-2,4-dione. Despite some minor limitations, such as the use of some ketones and aliphatic aldehydes, this convenient methodology is broad in scope (49 products were obtained

Visible-light-driven NHC and organophotoredox dual catalysis for the synthesis of carbonyl compounds

• Vasudevan Dhayalan

Beilstein J. Org. Chem. 2025, 21, 2584–2603, doi:10.3762/bjoc.21.200

• of single-electron NHC catalysis by incorporating oxidatively generated aryloxymethyl radicals A as a key intermediate. A variety of γ-aryloxy ketones 12 were successfully prepared in the presence of NHC (15 mol %), photocatalyst (2 mol %), using 467 nm LED and a combination of alkene 11, amide 9

• is the reduction of acylazolium C to generate a stable benzylic radical D is formed, and this extends the lifetime of the radical, allowing for radical–radical coupling reaction to afford the desired γ-aryloxy ketones 12 in good yields. The utility of this sustainable method was further demonstrated

• silylboronates 13. This photochemical method operates via catalytic activation of the silylboronate 13 in the presence of NHC (10 mol %) and 4CZIPN (1 mol %) with Rb2CO3 (10 mol %) as a base in CH3CN at rt for 20 h. The approach affords highly functionalized β-silylated aryl ketones 14 in moderate to good yields

Ex-situ generation of gaseous nitriles in two-chamber glassware for facile haloacetimidate synthesis

• Nikolai B. Akselvoll,
• Jonas T. Larsen and
• Christian M. Pedersen

Beilstein J. Org. Chem. 2025, 21, 2465–2469, doi:10.3762/bjoc.21.188

• of various trifluoromethyl-containing aza-heterocycles, such as pyridines [2], pyridinones and pyrimidinones [3], tetrazoles [4], tetrazapentalenes [5] and uracil [6]. In addition, it has also been used for the synthesis of fluoro-substituted ketones [7] and substituted trifluoroacetamides via the

Transformation of the cyclohexane ring to the cyclopentane fragment of biologically active compounds

• Natalya Akhmetdinova,
• Ilgiz Biktagirov and
• Liliya Kh. Faizullina

Beilstein J. Org. Chem. 2025, 21, 2416–2446, doi:10.3762/bjoc.21.185

• [52] achieved high regioselectivity and stereospecific construction of contiguous all-carbon quaternary centers through an oxidative ring contraction of cyclic α-formyl ketones by the action of H2O2. This reaction is easy to perform, environmentally friendly, and does not require expensive catalysts

• ], the mechanism and factors controlling the selectivity of the oxidative ring contraction in cyclic α-formyl ketones under the action of H2O2 were studied in detail. Due to their complex architecture and diverse biological activities, including antiviral, antitumor, antimalarial, and antifungal activity

• products 147a and 148a. The authors of [74] believe that methyl ketones 148a,b were obtained as a result of breaking the C4–C5 bond, and cyclopentanes 147a,b were formed from methyl ketones through intramolecular aldol condensation. Treatment of keto ester 148a with NaH led to a complex mixture, from which

An Fe(II)-catalyzed synthesis of spiro[indoline-3,2'-pyrrolidine] derivatives

• Elizaveta V. Gradova,
• Nikita A. Ozhegov,
• Roman O. Shcherbakov,
• Alexander G. Tkachenko,
• Larisa Y. Nesterova,
• Elena Y. Mendogralo and
• Maxim G. Uchuskin

Beilstein J. Org. Chem. 2025, 21, 2383–2388, doi:10.3762/bjoc.21.183

• -arylindoles with α,β-unsaturated ketones, followed by Fe(II)-catalyzed spirocyclization of readily accessible oxime acetates. The method exhibits a broad substrate scope and good functional group tolerance. The synthesized spirocyclic compounds showed no significant antimicrobial activity. Keywords: α,β

• yield substituted spiropyrrolidines (Scheme 1, path b) [9]. Additionally, an organocatalytic, enantioselective Michael addition/cyclization sequence of 3-aminooxindole Schiff bases with terminal vinyl ketones, catalyzed by a cinchona-derived base, has been reported to afford chiral spiroindolylpyrroles

• -one derivatives bearing an indolyl moiety. For this purpose, the reaction of 2-arylindoles 1 with α,β-unsaturated ketones 2 was employed, affording the corresponding indolylalkanones 3 (Scheme 2) [19][20][21]. A combination of trimethylsilyl chloride and acetonitrile served as a mild promoter for the

Recent advances in Norrish–Yang cyclization and dicarbonyl photoredox reactions for natural product synthesis

• Peng-Xi Luo,
• Jin-Xuan Yang,
• Shao-Min Fu and
• Bo Liu

Beilstein J. Org. Chem. 2025, 21, 2315–2333, doi:10.3762/bjoc.21.177

• synthesis of natural products but also establish a solid foundation for subsequent pharmaceutical investigations. Keywords: dicarbonyls; natural product; Norrish–Yang cyclization; photoredox; total synthesis; Introduction In the 1930s, Norrish documented the photodecomposition of aldehydes and ketones [1

Halogenated butyrolactones from the biomass-derived synthon levoglucosenone

• Johannes Puschnig,
• Martyn Jevric and
• Ben W. Greatrex

Beilstein J. Org. Chem. 2025, 21, 2297–2301, doi:10.3762/bjoc.21.175

• in 22% yield. Fluorination of α,β-unsaturated ketones is a more challenging transformation than the halogenation reactions presented in Scheme 1 [33]. The previous reports of enamines as suitable substrates led us to prepare and examine enamine 15, which was generated from 5 with 3.0 equivalents of

• low, the synthesis of 7c via this method represents a substantial improvement on previous approaches to this material [24]. The Baeyer–Villiger oxidation of 7c was uneventful and the fluorinated alkene 17 was isolated in 50% yield. The α-trifluoromethylation of ketones and aldehydes can be performed