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

• 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

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

• 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

• amidine base catalysis (Scheme 25b) [69]. Although this methodology employs equimolar catalyst loadings, the products 100 are obtained with complete diastereoselectivity and mostly in moderate to good yields. As for the mechanism, it is assumed to be analogous to the NHC-variant. Four years later, Somappa

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

• 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

• single-electron reductant and an organocatalyst. The optimized conditions involve using an NHC precursor, cesium carbonate as the base, and 1,4-dioxane as the solvent at 110 °C, yielding structurally diverse oxindoles 88 with satisfactory efficiency. The substrate scope was systematically investigated

• bromide, and secondary alkyl bromides failed to yield the desired products, suggesting limitations in radical generation efficiency for certain substrates. A plausible mechanism, as shown in Scheme 48, involves the NHC catalyst donating a single electron to the α-bromo substrate, generating an NHC radical

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

• -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

• reactions, have also been explored, thus boosting sustainability value. For instance, Wang and co-workers (2019) synthesized benzyl cinnamate (166) from cinnamaldehyde (162) catalyzed by an NHC catalyst (cat 4) in the presence of the low-cost oxidant CCl3CN. The reaction involves formation of acyl azolium

• intermediate 168 formed through hydride transfer from 167 (Scheme 54A) [95]. Similarly, Huang and co-workers (2020) employed the same NHC catalyst but used ambient air as the external oxidant for acyl azolium intermediate formation (Scheme 54B) [96]. On the other hand, Ohshima and co-workers (2020) directly

Regioselective formal hydrocyanation of allenes: synthesis of β,γ-unsaturated nitriles with α-all-carbon quaternary centers

• Seeun Lim,
• Teresa Kim and
• Yunmi Lee

Beilstein J. Org. Chem. 2025, 21, 800–806, doi:10.3762/bjoc.21.63

• 98% yield. Ortho-bromoaryl-substituted nitrile 3m also underwent tandem amidation and copper-catalyzed cyclization, efficiently producing lactam 9 in a 98% yield. Scheme 7 illustrates a plausible reaction mechanism based on previous studies [34]. The process begins with the formation of NHC–copper

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

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

• 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

• -catalyzed enantioselective allylic substitution of styrenes utilizing Cu–Bpin species [51]. Through implementation of a chiral NHC–Cu complex with B2(pin)2, they achieved the highly selective formation of homoallylic boronic esters with excellent enantioselectivities (up to 98% ee). This methodology

• reaction, catalyzed by a sulfonate-containing chiral NHC–Cu complex, proceeded with excellent chemo-, regio- (SN2'-), diastereo-, and enantioselectivity to afford homoallylic boronates 36. The resulting organoboron compounds could be oxidized to secondary homoallylic alcohols, providing an alternative to

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

• 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

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

• to NHC-catalyzed reactions. The major part is devoted to chiral Brønsted acid catalysis as it seems so far the most widely used activation principle for the generation of axially chiral compounds. Hydrogen-bond-donating catalysts and various other activation modes complete the discussion of recent

• 24. NHC-catalyzed atroposelective reactions Organocatalysis with N-heterocyclic carbenes (NHC) became one of the main types of covalent activation strategies, which grew into a very diverse area, allowing the synthesis of a wide array of interesting structures. Also, in atroposelective synthesis, NHC

• -catalysis recently led to an array of intriguing transformations. Axially chiral styrenes 26 were assembled via the NHC-catalyzed reaction of propargylic aldehydes 25, sulfinic acids, and phenols [28]. The crucial step of this transformation is the 1,4-addition of the sulfinic anion to the triple bond of

Synthesis of acenaphthylene-fused heteroarenes and polyoxygenated benzo[j]fluoranthenes via a Pd-catalyzed Suzuki–Miyaura/C–H arylation cascade

• Merve Yence,
• Dilgam Ahmadli,
• Damla Surmeli,
• Umut Mert Karacaoğlu,
• Sujit Pal and
• Yunus Emre Türkmen

Beilstein J. Org. Chem. 2024, 20, 3290–3298, doi:10.3762/bjoc.20.273

• from certain plant species (Figure 1) [12]. The acenaphthylene-fused thiophene-based heteroarene 3 is another heterocyclic fluoranthene analogue, which was used as an organic semiconductor in transistors [13]. The synthesis and coordination complexes of the acenaphthylene-fused N-heterocyclic (NHC

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

• 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

• 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

Catalysing (organo-)catalysis: Trends in the application of machine learning to enantioselective organocatalysis

• Stefan P. Schmid,
• Leon Schlosser,
• Frank Glorius and
• Kjell Jorner

Beilstein J. Org. Chem. 2024, 20, 2280–2304, doi:10.3762/bjoc.20.196

• , Corminboeuf and co-workers reported OSCAR, a computational repository of 4,000 organocatalyst structures mined from the literature and Cambridge Structural Database (CSD) [31]. In addition, the authors utilised the combinatorial nature of organocatalysts to create data bases comprising more than 8,000 NHC

Deuterated reagents in multicomponent reactions to afford deuterium-labeled products

• Kevin Schofield,
• Shayna Maddern,
• Yueteng Zhang,
• Grace E. Mastin,
• Rachel Knight,
• Wei Wang,
• James Galligan and
• Christopher Hulme

Beilstein J. Org. Chem. 2024, 20, 2270–2279, doi:10.3762/bjoc.20.195

• reagents in MCRs and determination of discrepancies in deuterium retention with MCRs has yet to be explored, although one would expect scrambling to be limited. Thus, we began by gathering highly deuterated aldehydes (>95% D) prepared via NHC catalysis [13] and developed a route to deuterated [D2]-benzylic

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

• metallaphotoredox catalysis (Scheme 19). Therein, alcohols were activated by the use of NHC salts. This activation facilitated the construction of C–C bonds when combined with aryl halide coupling partners. A diverse array of alcohols and various medicinally important aryl and heteroaryl halides reacted well in

• this protocol. Under basic conditions, the mechanism involves the condensation of a benzoxazolium salt 80, creating NHC–alcohol adduct 81. The [Ir(III)] photocatalyst is excited when exposed to blue light, leading to the formation of a long-lived triplet-excited-state *[Ir(III)] complex. This excited

• -state *[Ir(III)] complex can effectively oxidize the nitrogen atom of activated NHC–alcohol adduct 66 via SET. The resulting nitrogen radical cation intermediate 67 weakens the adjacent C–H bond, making it more acidic and susceptible to deprotonation by a suitable base, ultimately yielding an α-amino

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

•  10). However, sulfonamides with electron-withdrawing groups attached to the aromatic ring (e.g., 4-NO2, 4-CN) were found incompatible with the conditions. Ke and co-workers described an exciting example of a phosphine-free Mn(I)-NHC catalyst for the N-alkylation of amines with alcohols at room

• temperature [41]. The coupling of several aromatic amines with aliphatic and benzylic alcohols was studied with bis-NHC-manganese complex (Mn6). A catalyst loading of 1.5 mol % in the presence of t-BuOK (1 equiv) at room temperature produced the corresponding N-alkylated amines with 40–93% yield (Scheme 11

A laterally-fused N-heterocyclic carbene framework from polysubstituted aminoimidazo[5,1-b]oxazol-6-ium salts

• Andrew D. Gillie,
• Matthew G. Wakeling,
• Bethan L. Greene,
• Louise Male and
• Paul W. Davies

Beilstein J. Org. Chem. 2024, 20, 621–627, doi:10.3762/bjoc.20.54

• -step ynamide annulation and imidazolium ring-formation sequence. Metalation with Au(I), Cu(I) and Ir(I) at the C2 position provides an L-shaped NHC ligand scaffold that has been validated in gold-catalysed alkyne hydration and arylative cyclisation reactions. Keywords: annulation; carbene; gold

• ; imidazolium; NHC; Introduction Imidazolium-derived nucleophilic heterocyclic carbenes (NHCs) have had a sustained impact across the fields of organometallic and main group chemistry, transition-metal catalysis, materials synthesis and organocatalysis [1]. Laterally annellated polycyclic NHCs offer a useful

• particularly underinvestigated [2][18][19]. In this work we report the preparation of a new L-shaped NHC motif, the 3-aminoimidazo[5,1-b]oxazol-5-ylidene A (shortened hereafter to AImOx), which fuses two π-rich rings and positions a sulfonamide group alongside the metal centre (Figure 1b). We envisaged that

Switchable molecular tweezers: design and applications

• Pablo Msellem,
• Maksym Dekthiarenko,
• Nihal Hadj Seyd and
• Guillaume Vives

Beilstein J. Org. Chem. 2024, 20, 504–539, doi:10.3762/bjoc.20.45

• such Pt(II) dissymmetric tweezers could be controlled as aryl thioethers are more labile than alkyl thioethers. The addition of Cl− thus first breaks the Pt–SAr bond. Platinum-based dissymmetric tweezers were also synthetized using NHC thioether ligands that are more stable than the phosphine thioether

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

• have been masked by the high temperatures and long reaction times of early reports. For example, Widenhoefer engaged carbamates and amides in dioxane at temperatures >80 °C [12][13]. Later work showed that ureas could be engaged at room temperature when a NHC–gold catalyst system was used, outpacing

Mechanisms for radical reactions initiating from N-hydroxyphthalimide esters

• Carlos R. Azpilcueta-Nicolas and
• Jean-Philip Lumb

Beilstein J. Org. Chem. 2024, 20, 346–378, doi:10.3762/bjoc.20.35

• carbene (NHC)-catalyzed radical relay, and (iv) mechanisms under electrochemical activation. By discussing selected literature examples, we illustrate how the activation mode of NHPI esters, and the reactivity of the resulting radical species, can vary depending upon the choice of catalytic or

• , accompanied by the formation of cyano-B(pin) 142. Importantly, in the absence of ZnCl2, intermediate 140 could be detected by HRMS and 11B NMR, highlighting the pivotal role of ZnCl2 in promoting rearomatization. N-Heterocyclic carbene (NHC) catalysis In 2019, Nagao and Ohmiya reported the decarboxylative

• coupling of NHPI esters with aldehydes enabled by NHC catalysis [106]. The reaction proceeds with the catalyst NHC-1 at 60 °C and gives rise to ketones (Scheme 30A). The proposed mechanism begins with the reaction of benzaldehyde (143) and the NHC-catalyst 144 to form the neutral Breslow intermediate 145

1-Butyl-3-methylimidazolium tetrafluoroborate as suitable solvent for BF₃: the case of alkyne hydration. Chemistry vs electrochemistry

• Marta David,
• Elisa Galli,
• Richard C. D. Brown,
• Marta Feroci,
• Fabrizio Vetica and
• Martina Bortolami

Beilstein J. Org. Chem. 2023, 19, 1966–1981, doi:10.3762/bjoc.19.147

• carried out in an undivided cell (see Supporting Information File 1, Figure S1d). In this last case, in fact, the NHC-BF3 adduct is formed between anodically electrogenerated BF3 and cathodically electrogenerated NHC [103]. Evaluation of the current efficiency in the electrogeneration of BF3 in BMIm-BF4

• presence of the NHC derived from the IL deprotonation. Conclusion In conclusion, in this work we demonstrated the possibility to carry out the hydration of alkynes in imidazolium ILs, as alternative solvents until now still little explored for this reaction, employing the Lewis acid BF3 as catalyst. The

Recent advancements in iodide/phosphine-mediated photoredox radical reactions

• Tinglan Liu,
• Yu Zhou,
• Junhong Tang and
• Chengming Wang

Beilstein J. Org. Chem. 2023, 19, 1785–1803, doi:10.3762/bjoc.19.131

• NHC catalyst acted as a stabilizer for the EDA complex and generates a radical species, which was confirmed by further computational studies. Monofluoromethylation The monofluoromethyl (CH2F) group, which is commonly found in a lot of agrochemicals, pharmaceuticals, and materials, serves as a powerful

Active-metal template clipping synthesis of novel [2]rotaxanes

• Cătălin C. Anghel,
• Teodor A. Cucuiet,
• Niculina D. Hădade and
• Ion Grosu

Beilstein J. Org. Chem. 2023, 19, 1776–1784, doi:10.3762/bjoc.19.130

• . Our results proved that the CuAAC reaction catalyzed by copper(I) N-heterocyclic carbenes can be successfully used in the synthesis of [2]rotaxanes. This, combined with the fast and simple assembly of [CuCl(SIMes)] [45][46] could lead to the development of a Cu(I) NHC click chemistry in the field of

Unprecedented synthesis of a 14-membered hexaazamacrocycle

• Anastasia A. Fesenko and
• Anatoly D. Shutalev

Beilstein J. Org. Chem. 2023, 19, 1728–1740, doi:10.3762/bjoc.19.126

• (KBr, cm−1) ν: 3313 (s), 3113 (br s), 1705 (s), 1624 (s), 1573 (s), 1521 (m), 1304 (m), 1249 (s), 1155 (m), 872 (s), 761 (m); 1H NMR (600.13 MHz, DMSO-d6, 30 °C) δ 9.68 (br s, 1Н, NHC=O), ≈9.50 (very br s, 1Н, C=NH, signal partly overlaps with the signal of the NHC=O proton), 8.24 (br s, 1Н, H-6), 8.06

Application of N-heterocyclic carbene–Cu(I) complexes as catalysts in organic synthesis: a review

• Nosheen Beig,
• Varsha Goyal and
• Raj K. Bansal

Beilstein J. Org. Chem. 2023, 19, 1408–1442, doi:10.3762/bjoc.19.102

• the metal to the π* orbital of the NHC. Over the last two decades, NHC–metal complexes have been extensively used as efficient catalysts in different types of organic reactions. Of these, NHC–Cu(I) complexes found prominence for various reasons, such as ease of preparation, possibility of structural

• diversity, low cost, and versatile applications. This article overviews applications of NHC–Cu(I) complexes as catalysts in organic synthesis over the last 12 years, which include hydrosilylation reactions, conjugate addition, [3 + 2] cycloaddition, A3 reaction, boration and hydroboration, N–H and C(sp2)–H

• carboxylation, C(sp2)–H alkenylation and allylation, C(sp2)–H arylation, C(sp2)–H amidation, and C(sp2)–H thiolation. Preceding the section of applications, a brief description of the structure of NHCs, nature of NHC–metal bond, and methods of preparation of NHC–Cu complexes is provided. Keywords: conjugate

Visible-light-induced nickel-catalyzed α-hydroxytrifluoroethylation of alkyl carboxylic acids: Access to trifluoromethyl alkyl acyloins

• Feng Chen,
• Xiu-Hua Xu,
• Zeng-Hao Chen,
• Yue Chen and
• Feng-Ling Qing

Beilstein J. Org. Chem. 2023, 19, 1372–1378, doi:10.3762/bjoc.19.98

• acyloins (Scheme 1a). Anand’s group [25] demonstrated that a NHC-catalyzed selective acyloin condensation between aromatic aldehydes and trifluoroacetaldehyde ethyl hemiacetal afforded the analogous products (Scheme 1b). In comparison, the synthesis of trifluoromethyl aliphatic acyloins is still