Hydrogen production from formic acid catalyzed by NHC–Cu complexes

• Orlando Santoro and
• Catherine S. J. Cazin

Beilstein J. Org. Chem. 2026, 22, 620–627, doi:10.3762/bjoc.22.48

• equimolar mixture of H2 and CO2. The efficiency of the catalysis showed to be strongly dependent on the nature of the amine. Keywords: copper N-heterocyclic carbene; formic acid dehydrogenation; hydrogen storage; metal hydride; silanes; Introduction The discovery and utilization of alternative and

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

• -Naphthaldehyde (1s) and salicylaldehyde (1t) were hydrogenated quantitatively, and analytically pure products were isolated by simple evaporation of the collected fraction eluted from the flow reactor (Table 2, entries 19 and 20). Heterocyclic aldehydes 1u and 1v were also applicable, while the conversion of 1v

Melifoliox B, a novel phloroglucin derivative isolated from Melicope barbigera (Rutaceae) and synthesis of new oxidation products from melifoliones A and B

• Horst Weber,
• Kim-Thao Tran-Cong,
• Bernhard Mayer,
• Guido J. Reiss,
• Iryna S. Konovalova,
• Marc S. Appelhans,
• Kenneth R. Wood and
• Claus M. Passreiter

Beilstein J. Org. Chem. 2026, 22, 535–546, doi:10.3762/bjoc.22.39

• contraction of the acetyl phenol to a furanone ring, forming the derivatives 11 and 12, whose structures were confirmed by X-ray analysis. A hypothetical mechanism for the oxidative ring contraction is proposed. 11 and 12 are the first representatives of new heterocyclic ring systems that have not previously

• been described in the literature. Keywords: Melicope barbigera; Melifoliones A and B; new heterocyclic ring systems; new natural compounds; para-quinols; phenol oxidation; Introduction The genus Melicope is a member of the Rutaceae (Citrus family) and contains more than 200 species distributed in the

• and 14 seems also to be possible [19] (Scheme 5). Compounds 11 and 12 are the first representatives of two new heterocyclic ring systems consisting of two pyran rings, one cyclohexane and one furan ring. Conclusion Finally, it remains to be noted that it was not possible to prepare the quinols 3 and 4

Modern synthetic pathways towards eribulin and its subunits

• Sebastian Dominik Graf

Beilstein J. Org. Chem. 2026, 22, 495–526, doi:10.3762/bjoc.22.37

• C1–C13 fragment 11 with C14–C35 fragment 12 [66][67][68]. Despite these great advances, still, the research on improving synthetic efficiency, reducing production costs, omitting toxic chemicals, as well as on new pathways towards 1`s 4 heterocyclic precursor fragments is rigorously ongoing [69][70

• also considerable amounts of 183`s epimer were formed (2:1 dr). Oxidation with DDQ removed the Bn-moiety (184) and triggered ketalization towards 185. Eventual mesylation formed key fragment 186 in 95% yield. For the assembly of both heterocyclic subunits of 186, Nicholas etherification and radical

• field of the synthesis of 1. This is especially observable for the synthesis of the 4 heterocyclic key fragments or intermediates obtained during the Eisai process. Here, the major progresses can be registered in terms of enhancing the sustainability of pathways through the removal of metal catalysts

Recent advances in the stereoselective synthesis of distal biaxially chiral molecules

• Fanxing Zhou,
• Chen Zhang,
• Lingyu Sun,
• Yiyun Fang,
• Siming Zheng,
• Lina Hu,
• Mengyang Shen,
• Zhen Zhao,
• Wei Xu,
• Yunqiang Sun and
• Zi-Qiang Rong

Beilstein J. Org. Chem. 2026, 22, 461–479, doi:10.3762/bjoc.22.34

• yields, indicating potential utility in chiral fluorescent materials. In addition, Du’s group reported an N-heterocyclic carbene (NHC)-catalyzed (3 + 3) cycloaddition of 2,6-disubstituted alkyne esters 38 with 6-aminouracils 39, affording distal biaxial uracil frameworks with both C–C and C–N chiral axes

Design, synthesis and biological evaluation of 2,5-diaryloxazolo[4,5-d]pyrimidin-7-ylamines as selective cytotoxic agents against HeLa cells

• Maryna V. Kachaeva,
• Agnieszka B. Olejniczak,
• Marta Denel-Bobrowska,
• Victor V. Zhirnov,
• Yevheniia S. Velihina,
• Stepan G. Pilyo and
• Volodymyr S. Brovarets

Beilstein J. Org. Chem. 2026, 22, 390–398, doi:10.3762/bjoc.22.27

• Maryna V. Kachaeva Agnieszka B. Olejniczak Marta Denel-Bobrowska Victor V. Zhirnov Yevheniia S. Velihina Stepan G. Pilyo Volodymyr S. Brovarets Department of Chemistry of Bioactive Nitrogen-Containing Heterocyclic Bases, V.P. Kukhar Institute of Bioorganic Chemistry and Petrochemistry, National

• oxazolopyrimidine derivatives may demonstrate selective cytotoxicity against cancer cell lines like HeLa, HepG2, A549, and central nervous system (CNS) tumor models [1][2][3]. The introduction of heterocyclic molecules with different amino groups as hydrogen-bond donors (and sometimes acceptors via lone electron

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

• equivalents of LiHMDS, N-alkyl- and N-arylanilides were efficiently cleaved to afford the corresponding amides 64 and 162–165 in high yields. A broad range of N,N-dialkylamides, cyclic amides, and heterocyclic amides were also compatible, all delivering amide products 3, 4, and 166–172 in good to excellent

Synthesis of tricyclic fused pyrrolidine nitroxides from 2-alkynylpyrrolidine-1-oxyls

• Mark M. Gulman,
• Yuliya F. Polienko,
• Sofia Yu. Trakhininа,
• Yuri V. Gatilov,
• Tatyana V. Rybalova,
• Sergey A. Dobrynin and
• Igor A. Kirilyuk

Beilstein J. Org. Chem. 2026, 22, 344–351, doi:10.3762/bjoc.22.22

• -2-ethynylpyrrolidine-1-oxyls with nucleophilic agents can lead to the formation of condensed systems involving the substituent at position 3 of the pyrrolidine ring [16]. Alkynes are broadly used in the synthesis of various heterocyclic compounds, and participation of neighboring functional groups

Spirobarbiturates with a pyrrolizidine moiety: synthesis, structure and biological evaluation

• Arthur A. Puzyrkov,
• Andrew S. Drachuk,
• Ekaterina A. Popova,
• Alexander V. Stepakov and
• Vitali M. Boitsov

Beilstein J. Org. Chem. 2026, 22, 274–288, doi:10.3762/bjoc.22.20

• system of two condensed pyrrolidine rings sharing a common nitrogen atom. This heterocyclic system occurs naturally in numerous plant-derived alkaloids [27][28][29][30]. Notably, most pyrrolizidine alkaloids exhibit severe hepatotoxicity, genotoxicity and cause neurological disorders in humans and

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

• , affording the corresponding sulfinimidate esters 3j’ and 3k’ in excellent yields. Notably, a pyrazine-2-carboxamide-derived sulfenamide also underwent efficient transformation to 3l’, further highlighting the method’s functional group compatibility and applicability to heterocyclic systems. We further

Symmetrical D–π–A–π–D indanone dyes: a new design for nonlinear optics and cyanide detection

• Ergin Keleş,
• Alberto Barsella,
• Nurgül Seferoğlu,
• Zeynel Seferoğlu and
• Burcu Aydıner

Beilstein J. Org. Chem. 2026, 22, 131–142, doi:10.3762/bjoc.22.6

• cyanide and the chemosensor is determined by a 1H NMR study and explained by DFT calculations. Keywords: chemosensor; DFT calculations; donor–π–acceptor–π–donor based organic dyes; indan-2-one; NLO; Introduction Over the past decades, the functional heterocyclic push–pull dyes have attracted significant

Highly electrophilic, gem- and spiro-activated trichloromethylnitrocyclopropanes: synthesis and structure

• Ilia A. Pilipenko,
• Mikhail V. Grigoriev,
• Olga Yu. Ozerova,
• Igor A. Litvinov,
• Darya V. Spiridonova,
• Aleksander V. Vasilyev and
• Sergey V. Makarenko

Beilstein J. Org. Chem. 2026, 22, 123–130, doi:10.3762/bjoc.22.5

• cyanoacetate, ethyl cyanoacetate, benzoylacetonitrile), carbocyclic (1,3-indanedione), and heterocyclic (Meldrum’s acid, dimethylbarbituric acid, 3-methyl-1-phenyl-5-pyrazolone) CH-acids – allows the synthesis of both monocyclic and spirocyclic 1SR,2RS vic-trichloromethylnitrocyclopropanes under mild

Total synthesis of natural products based on hydrogenation of aromatic rings

• Haoxiang Wu and
• Xiangbing Qi

Beilstein J. Org. Chem. 2026, 22, 88–122, doi:10.3762/bjoc.22.4

• highlights representative examples that illustrate recent synthetic advances [35][36]. Hydrogenation of monocyclic aromatic rings Hydrogenation of heterocyclic aromatic rings: Despite the widespread application of six-membered aromatic heterocycles in various fields of organic chemistry, reports on their

• catalyst to achieve the hydrogenation of the nitrogen heterocyclic moiety in quinoline, that yielded the target product in near-quantitative amounts [51]. In 2021, the research groups of Sun [52] and Zhang [53] reported the use of iridium or manganese as catalysts to convert quinoline derivatives into

• new stereocenters, producing architecturally complex 6–5 fused ring systems. The key points lie in the utility of a chiral homogeneous ruthenium-N-heterocyclic carbene complex, as well as an in-situ activated rhodium catalyst. In 2022, Bach and co-workers reported a modular approach for the highly

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

• , generated via borocupration of terminal alkynes, underwent allylic substitutions to furnish Bpin-substituted alkenyl chlorides in high enantioselectivity (Scheme 65B) [204]. Key to the transformation was the use of a sulfonate-substituted N-heterocyclic carbene ligand, introduced as its imidazolium salt

Sustainable electrochemical synthesis of aliphatic nitro-NNO-azoxy compounds employing ammonium dinitramide and their in vitro evaluation as potential nitric oxide donors and fungicides

• Alexander S. Budnikov,
• Nikita E. Leonov,
• Michael S. Klenov,
• Andrey A. Kulikov,
• Igor B. Krylov,
• Timofey A. Kudryashev,
• Aleksandr M. Churakov,
• Alexander O. Terent’ev and
• Vladimir A. Tartakovsky

Beilstein J. Org. Chem. 2025, 21, 2739–2754, doi:10.3762/bjoc.21.211

• particular interest for the regioselective synthesis of azoxy compounds [5][71][72]. Unique and understudied representatives of the latter are nitro-NNO-azoxy compounds [R–N(O)=N–NO2], first synthesized at ZIOC RAS [73][74][75]. Nowadays, aromatic and heterocyclic compounds of this class have been studied in

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

• , respectively. The introduction of cycloketones has resulted in the same types of heterocyclic systems, yet they are now carboannelated, which are synthetic analogues of alkaloids [26]. Moreover, it has been shown that acetaldehyde is capable of reacting in a similar manner with ethyl trifluoroacetoacetate and

• ]. In general, the developed approach allows pyridone derivatives to be generated in various environments of condensed carbo- and heterocyclic structures. Among the synthesized pyridone derivatives we have found analgesic [20][26], antibacterial [20] and antifungal [20] agents, which show practical

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

• available drugs [1]. These structures exhibit unique properties that influence pharmacokinetic and pharmacodynamic parameters, including lipophilicity, polarity, hydrogen-bonding capacity, and toxicological profiles [2][3][4]. Among them, five-membered multi-heterocyclic (FMMH) rings are privileged

• heterocyclic aldehydes such as furfural (3v), thiophene (3w) and indole (3x) carboxaldehydes. Application of the optimized EDA-catalyzed Knoevenagel conditions to thiazolidine-2,4-dione (2b) afforded the expected product 4a in moderate yield (Supporting Information File 1, Table S1). Adding excess thiazolidine

• condensation reactions involving rhodanine derivatives (26 examples). In addition, it requires a lower catalyst loading (10 mol %) and eliminates the need for further purification steps. EDDA has also been employed in reactions for the synthesis of heterocyclic compounds such as tetrahydroquinolines [67

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

• chemistry. In particular, dual catalysis combining N-heterocyclic carbenes (NHCs) with organophotocatalysts (e.g., 4CzIPN, eosin Y, rhodamine, 3DPAFIPN, Mes-Acr-Me+ClO4−) has emerged as a powerful photocatalytic strategy for efficiently constructing a wide variety of carbonyl compounds via radical cross

• , particularly the synergistic combination of N-heterocyclic carbenes (NHCs) with organic photocatalysts, has opened new avenues in molecular construction, particularly for the novel, practical preparation of carbonyl group-containing compounds [13][14][15][16]. These ubiquitous ketone, ester, and amide

• functional groups are found in various drugs, natural products, and optoelectronic materials. In the last three decades, N-heterocyclic carbenes (NHCs) have been renowned as versatile organocatalysts, including thiazolium, imidazolium, and triazolium moieties. NHCs are extensively used in many catalytic

Rapid access to the core of malayamycin A by intramolecular dipolar cycloaddition

• Yilin Liu,
• Yuchen Yang,
• Chen Yang,
• Sha-Hua Huang,
• Jian Jin and
• Ran Hong

Beilstein J. Org. Chem. 2025, 21, 2542–2547, doi:10.3762/bjoc.21.196

• stereochemistry of substituents, as well as the heterocyclic anomeric unit. Uncertainty regarding the mode of action, along with inadequate synthetic approaches toward a lead compound, remains elusive. The well-established synthetic route reported by Hanessian and co-workers began with ᴅ-ribonolactone which bears

Palladium-catalyzed regioselective C1-selective nitration of carbazoles

• Vikash Kumar,
• Jyothis Dharaniyedath,
• Aiswarya T P,
• Sk Ariyan,
• Chitrothu Venkatesh and
• Parthasarathy Gandeepan

Beilstein J. Org. Chem. 2025, 21, 2479–2488, doi:10.3762/bjoc.21.190

• are ubiquitous and privileged heterocyclic scaffolds in various functional organic materials and naturally occurring products. Although extensive efforts have focused on developing synthetic strategies toward carbazole derivatives, direct regioselective functionalization of the carbazole core remains

• ; palladium; Introduction Carbazole represents an important heterocyclic scaffold that is broadly present in many natural products, biologically active motifs, as well as optoelectronic and functional materials [1][2][3][4][5][6][7][8]. By virtue of its substantial application in various fields, significant

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

• useful strategic transformations for the construction of carbocyclic and heterocyclic cyclopentanes. Six-membered carbocycles are convenient starting compounds for the synthesis of cyclopentanoids due to their widespread occurrence in nature and their synthetic availability. Undoubtedly, the development

The high potential of methyl laurate as a recyclable competitor to conventional toxic solvents in [3 + 2] cycloaddition reactions

• Ayhan Yıldırım and
• Mustafa Göker

Beilstein J. Org. Chem. 2025, 21, 2389–2415, doi:10.3762/bjoc.21.184

• context of these strategies, it would be judicious to consider cycloaddition reactions of the [3 + 2] type, a field in which Smith and Huisgen are recognized as pioneers [24][25]. In the field of heterocyclic chemistry, the [3 + 2] type of cycloaddition reaction is a widely employed method for the

• formation of the five-membered isoxazolidine ring motif, which displays a range of biologically active properties [26][27][28][29][30]. It is notable that the fused pyrrolo-isoxazolidines represent a particularly versatile class of heterocyclic compounds and intermediates, which have been demonstrated to

• -based nitrone with some maleimides via a mechanochemical route in a solvent-free medium [67][68]. The development of environmentally friendly green methodologies for the preparation of heterocyclic compounds via such cycloaddition reactions is a significant and ongoing research area that should not be

Enantioselective radical chemistry: a bright future ahead

• Anna C. Renner,
• Sagar S. Thorat,
• Hariharaputhiran Subramanian and
• Mukund P. Sibi

Beilstein J. Org. Chem. 2025, 21, 2283–2296, doi:10.3762/bjoc.21.174

• ], ion pairs [15], N-heterocyclic carbene (NHC) catalysts [16][17][18], or thiols [19][20][21] are not covered here but can also be effective for achieving high levels of enantioselectivity in radical reactions. Lewis acid-catalyzed radical reactions In the context of enantioselective radical reactions

Pathway economy in cyclization of 1,n-enynes

• Hezhen Han,
• Wenjie Mao,
• Bin Lin,
• Maosheng Cheng,
• Lu Yang and
• Yongxiang Liu

Beilstein J. Org. Chem. 2025, 21, 2260–2282, doi:10.3762/bjoc.21.173

• heterocyclic scaffolds, which established a versatile platform for synthesizing structurally diverse indoline frameworks. Ligand-controlled cyclization of 1,n-enynes The core function of catalyst ligands lies in their ability to precisely modulate catalyst performance through electronic and steric effects. The

• cyclization, yielding a six-membered ring product 72 (Scheme 15, path b). This observed selectivity arose from differential stabilization of transition states by ligands, thereby enabling the Au(I)-catalyzed cyclization to directly access bioactive heterocyclic frameworks commonly encountered in natural

• intermediate 76 to drive hydrolysis. This methodology tolerates structurally diverse 1,7-enyne esters and generates defined cis-1,2,3,6-tetrahydropyridine scaffolds, which serve as synthetic intermediates for complex natural products and pharmacologically relevant heterocyclic frameworks. In 2016, Jiang group

Synthesis of triazolo- and tetrazolo-fused 1,4-benzodiazepines via one-pot Ugi–azide and Cu-free click reactions

• Xiaoming Ma,
• Zijie Gao,
• Jiawei Niu,
• Wentao Shao,
• Shenghu Yan,
• Sai Zhang and
• Wei Zhang

Beilstein J. Org. Chem. 2025, 21, 2202–2210, doi:10.3762/bjoc.21.167

• piperazinone ring. Keywords: benzodiazepine; click reaction; multicomponent reaction; one-pot; piperazinone; polycyclic; triazole; tetrazole; Ugi–azide reaction; Introduction Triazole, tetrazole, and benzodiazepine are privileged heterocyclic rings commonly found in drug molecules and functional materials [1

• heterocyclic scaffolds to obtain biologically interesting compounds (Scheme 1) [35][36][37][38][39][40][41]. The development of methods for the synthesis of triazole, tetrazole, piperazinone, and 1,4-benzodiazepine motifs are attractive from both synthetic and medicinal chemistry considerations [42][43][44][45

• , the Ugi–azide adducts could undergo lactamization and lead to the formation of highly condensed 1,4-benzodiazepines 8 fused with triazole, tetrazole, and piperazinone rings. This is a new example of combining MCR and post-condensation modification as a one-pot synthesis to access novel heterocyclic