Beyond symmetric self-assembly and effective molarity: unlocking functional enzyme mimics with robust organic cages

• Keith G. Andrews

Beilstein J. Org. Chem. 2025, 21, 421–443, doi:10.3762/bjoc.21.30

• formation possible in metal–ligand bonding provides chemists with a shortcut to access 3D scaffolds. When well-designed linkers and metals are combined, discrete cages emerge as the thermodynamic product (Figure 5A) [22][142][143][144]. Typically, rigid linkers are required to enforce geometry, although a

• constriction (ground-state destabilization) are also possible [140][168][169][170]. The metals can sometimes participate in redox catalysis [171], and may be stabilized by the cage structure [160][172][173][174]. The organic part of the MOC has also been levied as a hydrogen-bond donor to activate an

• cavity, for instance by constriction (organization) [36][180][181]. Likewise, the cationic cages of Fujita [151][154][160][170][172][182][183][184][185][186][187][188][189] can stabilize anionic species [184]. The work of Lusby [166][190][191][192][193][194][195][196] is notable for using the metals in

Unraveling aromaticity: the dual worlds of pyrazole, pyrazoline, and 3D carborane

• Zahra Noori,
• Miquel Solà,
• Clara Viñas,
• Francesc Teixidor and
• Jordi Poater

Beilstein J. Org. Chem. 2025, 21, 412–420, doi:10.3762/bjoc.21.29

• their broader use. With this in mind, Lee and colleagues have recently developed an efficient synthetic method for producing o-carborane-fused pyrazoles as a novel scaffold, without using transition metals. Their approach involves reacting B(4)-acylmethyl and B(3,5)-diacylmethyl o-carborane with 2-azido

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

• advantageous for large-scale applications, offering enhanced safety and operational simplicity. Traditionally, research in this field has focused on metal-based photocatalysts, particularly those based on transition metals like ruthenium and osmium due to their intrinsic photophysical properties. However, with

• diverse catalyst types and applications. The first section is dedicated to metal-based photocatalysts. Complexes involving metals such as osmium and ruthenium, have dominated red-light photoredox catalysis because of their ability to absorb low-energy photons and sustain redox cycles via stable excited

• organic photocatalysts. Unlike metal-based systems, organic photocatalysts such as phthalocyanins, squaraines and cyanins, offer effective electron and energy transfer under red-light irradiation without relying on transition metals. This shift towards organic catalysts opens new possibilities for

Dioxazolones as electrophilic amide sources in copper-catalyzed and -mediated transformations

• Seungmin Lee,
• Minsuk Kim,
• Hyewon Han and
• Jongwoo Son

Beilstein J. Org. Chem. 2025, 21, 200–216, doi:10.3762/bjoc.21.12

• widely used as N-acylamide sources in amidation processes of challenging substrates, typically employing precious transition metals. However, these catalytic systems often present several challenges associated with cost, toxicity, stability, and recyclability. Among the 3d transition metals, copper

Recent advances in electrochemical copper catalysis for modern organic synthesis

• Yemin Kim and
• Won Jun Jang

Beilstein J. Org. Chem. 2025, 21, 155–178, doi:10.3762/bjoc.21.9

• –heteroatom (C–X, where X = N, O, or halogens) bonds in organic synthesis. Copper was one of the first transition metals employed in cross-coupling to form C–C and C–X bonds [1][2]. In 1901, Ullmann reported the first cross-coupling reaction for the formation of biaryl compounds in the presence of

• ], however, no comprehensive review focusing on Cu-catalyzed electrochemistry has been reported to date. Copper catalysts are potential candidates for pharmaceutical applications owing to their abundance, low cost, and lower toxicity compared with noble transition metals such as palladium [39]. In terms of

Cu(OTf)₂-catalyzed multicomponent reactions

• Sara Colombo,
• Camilla Loro,
• Egle M. Beccalli,
• Gianluigi Broggini and
• Marta Papis

Beilstein J. Org. Chem. 2025, 21, 122–145, doi:10.3762/bjoc.21.7

• ; heteropolycycles; multicomponent reactions; one-pot reaction; Introduction Copper has gained a relevant role in organic synthesis as an alternative to precious metals due to its low toxicity, ease of handling, high catalytic activity, and cost-effectiveness [1][2]. In recent years, Cu(OTf)2 has significantly

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

• -catalyst containing transition metals but are purely of organocatalytic nature. In these experiments, the chiral phosphoric acid C28 catalyzed the reaction of aminopyrroles 101 and 1,4-diketones 102. Under the optimized reaction conditions, the yields were good to excellent, and high levels of

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

• the reaction with nucleophiles (Scheme 1). Two approaches to the preparation of diacyl chlorides 2 without using noble metals have also been developed. Results and Discussion 5-Сhloroisoxazole-4-carbonyl chlorides 1, required for the preparation of 2H-azirine-2,2-dicarboxylic acids and their

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

• well as transition and rare-earth metals [32][33]. There are many comprehensive reviews covering these two areas along with the connection of these ligands to supramolecular and medicinal chemistry [34][35][36]. In addition, calix[4]pyrroles, due to the presence of four accessible inner NHs and well

Tailored charge-neutral self-assembled L₂Zn₂ container for taming oxalate

• David Ocklenburg and
• David Van Craen

Beilstein J. Org. Chem. 2024, 20, 3007–3015, doi:10.3762/bjoc.20.250

• coordinating or which can act as good chelating ligands [65]. The latter holds true for oxalate as shortest dicarboxylate anion which likely forms complexes with all sorts of metals [66][67]. In fact, oxalate’s ideal ligand character is one reason for the aforementioned diseases and this property poses a fatal

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

Recent advances in transition-metal-free arylation reactions involving hypervalent iodine salts

• Ritu Mamgain,
• Kokila Sakthivel and
• Fateh V. Singh

Beilstein J. Org. Chem. 2024, 20, 2891–2920, doi:10.3762/bjoc.20.243

• or without the use of transition metals [44]. Thus, they address both the financial and environmental challenges associated with organic synthesis by acting as environmentally benign substitutes for costly organometallic catalysts and heavy-metal-based oxidants. Diaryl iodide salts consist of two

• significant as it circumvents the use of costly and hazardous metals and ligands which are commercially not available. In order to obtain a variety of synthetically desirable tetrasubstituted α-aryl-α-fluoroacetoacetamides 7, Zaheer et al. disclosed a straightforward, metal-free technique for the α-arylation

• group of the iodonium salt was also investigated. A potential radical-mediated mechanism was evaluated. Under mild conditions, a base-promoted arylation of general sulfinates 86 without the need for transition metals was introduced using diaryliodonium salts 16 as an aryl source (Scheme 35). Inspired by

C–C Coupling in sterically demanding porphyrin environments

• Liam Cribbin,
• Brendan Twamley,
• Nicolae Buga,
• John E. O’ Brien,
• Raphael Bühler,
• Roland A. Fischer and
• Mathias O. Senge

Beilstein J. Org. Chem. 2024, 20, 2784–2798, doi:10.3762/bjoc.20.234

• from the Ni(II)...Ni(II) vector approximately perpendicular to the metals through the c-axis. Upon co-crystallization of borylated porphyrin 46 and bis(pinacolato)diboron, the accommodation of bis(pinacolato)diboron in the void of the lattice was observed (Figure 4). The crystal packing of this

Transition-metal-free decarbonylation–oxidation of 3-arylbenzofuran-2(3H)-ones: access to 2-hydroxybenzophenones

• Bhaskar B. Dhotare,
• Seema V. Kanojia,
• Chahna K. Sakhiya,
• Amey Wadawale and
• Dibakar Goswami

Beilstein J. Org. Chem. 2024, 20, 2655–2667, doi:10.3762/bjoc.20.223

• rearrangement of 2-aryloxybenzaldehydes yielded 2-hydroxybenzophenone [12]. Pd-catalyzed o-hydroxylation of benzophenones gave moderate yield of the title compound, and Br-substituted substrates were found to be not compatible with this method [13]. Various metals (Rh, Cu, Ir etc.) were applied to catalyze the

• oxidative coupling of salicylaldehyde with arylboronic acids to successfully produce 2-hydroxybenzophenones [14]. Recently, a Ni-catalyzed decarbonylation–oxidation of 3-arylbenzofuran-2(3H)-ones emerged as an innovative route to access 2-hydroxybenzophenones [2]. The use of transition metals poses

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

• industrial settings. An anodic oxidation is frequently employed for C–H functionalization, which can simplify late-stage functionalization strategies. Additionally, many of these synthetic methods do not require precious metals, enhancing their appeal in terms of sustainability and cost-effectiveness

Facile preparation of fluorine-containing 2,3-epoxypropanoates and their epoxy ring-opening reactions with various nucleophiles

• Yutaro Miyashita,
• Sae Someya,
• Tomoko Kawasaki-Takasuka,
• Tomohiro Agou and
• Takashi Yamazaki

Beilstein J. Org. Chem. 2024, 20, 2421–2433, doi:10.3762/bjoc.20.206

• intramolecular interaction between fluorine and metals would also facilitate the smooth progress of these reactions. Such high potential of 1a allowed us to apply it to nucleophilic epoxidation because the resultant epoxyester 2a is recognized as an intriguing building block (Scheme 1). Another expectation to 2a

Electrochemical allylations in a deep eutectic solvent

• Sophia Taylor and
• Scott T. Handy

Beilstein J. Org. Chem. 2024, 20, 2217–2224, doi:10.3762/bjoc.20.189

• spectroscopy to determine that the deposited metal was tin, with traces of other metals consistent with the purity of the initial tin source. The tin recovery was 99% of the theoretical. To explore recycling of this recovered tin, 1 mmol was used in a 0.5 mmol scale allylation of anisaldehyde under the

1,2-Difluoroethylene (HFO-1132): synthesis and chemistry

• Liubov V. Sokolenko,
• Taras M. Sokolenko and
• Yurii L. Yagupolskii

Beilstein J. Org. Chem. 2024, 20, 1955–1966, doi:10.3762/bjoc.20.171

• catalyst (Pd, Pd, Pt, Rh, Ru, Ir, Ni/Cu, Ag, Au, Zn, Cr, Co, Scheme 5) [62][63]. Further, 1,2-Dichloroethylene was reacted with hydrogen fluoride in the presence of metal fluorides or transition metals (Cr, Al, Co, Mn, Ni, Fe) to form 1,2-difluoroethylene (Scheme 6) [56][58]. In patents [59][60], an exotic

Oxidation of benzylic alcohols to carbonyls using N-heterocyclic stabilized λ³-iodanes

• Thomas J. Kuczmera,
• Pim Puylaert and
• Boris J. Nachtsheim

Beilstein J. Org. Chem. 2024, 20, 1677–1683, doi:10.3762/bjoc.20.149

• easily overoxidized to carboxylic acids. Over the past decades a variety of methods have been developed, utilizing toxic heavy metals such as pyridinium dichromate (PDC) [3][4][5] or manganese dioxide (Figure 1) [6][7]. Molecular oxygen [8] and peroxides [9][10] can also be used as inexpensive terminal

Divergent role of PIDA and PIFA in the AlX₃ (X = Cl, Br) halogenation of 2-naphthol: a mechanistic study

• Kevin A. Juárez-Ornelas,
• Manuel Solís-Hernández,
• Pedro Navarro-Santos,
• J. Oscar C. Jiménez-Halla and
• César R. Solorio-Alvarado

Beilstein J. Org. Chem. 2024, 20, 1580–1589, doi:10.3762/bjoc.20.141

• reactivity [9] usually associated with transition metals [10][11]. Iodine(III) compounds have been used for the formation of different bond types, such as C–C [12][13], C–O [14][15], C–N [16], C–S [17], C–CN [18], C–F [19][20][21], C–I [22][23], C–NO2 [24][25] and, in the context of this work, C–X (X = Cl

Rapid construction of tricyclic tetrahydrocyclopenta[4,5]pyrrolo[2,3-b]pyridine via isocyanide-based multicomponent reaction

• Xiu-Yu Chen,
• Ying Han,
• Jing Sun and
• Chao-Guo Yan

Beilstein J. Org. Chem. 2024, 20, 1436–1443, doi:10.3762/bjoc.20.126

• carbon atom of isocyanide has both a lone electron pair and empty orbitals, so it has outstanding electrophilic and nucleophilic reactivity. At the same time, isocyanide also has good coordination ability to coordinate with metals to form diverse metal complexes [1][2][3]. Therefore, isocyanides have

Diameter-selective extraction of single-walled carbon nanotubes by interlocking with Cu-tethered square nanobrackets

• Guoqing Cheng and
• Naoki Komatsu

Beilstein J. Org. Chem. 2024, 20, 1298–1307, doi:10.3762/bjoc.20.113

• can calculate larger system (>500 atoms) containing transition metals more precisely [16][17]. Result and Discussion Synthesis of Cu-tethered square nanobrackets 1b A pyrene-based nanobracket 4b was synthesized via a one-pot Suzuki coupling followed by the formation of dipyrrin from the dialdehyde 3

Oxidative hydrolysis of aliphatic bromoalkenes: scope study and reactivity insights

• Amol P. Jadhav and
• Claude Y. Legault

Beilstein J. Org. Chem. 2024, 20, 1286–1291, doi:10.3762/bjoc.20.111

• metals, inspired by Nature's metalloproteins. However, using toxic and expensive metals is not always practical, making alternative oxidative methodologies more appealing. Enter hypervalent iodine reagents – a leading metal-free choice for oxidation reactions. These robust and low-toxicity reagents have

Mechanistic investigations of polyaza[7]helicene in photoredox and energy transfer catalysis

• Johannes Rocker,
• Till J. B. Zähringer,
• Matthias Schmitz,
• Till Opatz and
• Christoph Kerzig

Beilstein J. Org. Chem. 2024, 20, 1236–1245, doi:10.3762/bjoc.20.106

• recent years was pioneered by the introduction of photocatalysts (PC) based on metals such as Ru and Ir [1][2][3][4][5][6]. However, due to the high cost and limited availability of precious metals, organic photocatalysts have become a focal point of academic and industrial research [7][8][9][10][11][12

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

• achieving both selective dehydrogenation and hydrogenation is highly important. A typical BH process is demonstrated in Scheme 1. Several precious transition-metal catalysts have been used successfully in this area, including iridium, rhodium, ruthenium, and osmium [4]. However, these noble metals are toxic

• , expensive, and limited in availability. Hence, replacing them with the first row of transition metals would increase the sustainability and profitability of this procedure [13]. Indeed, many 3d-metal-based homogeneous catalysts have been documented for BH reactions [14][15] since these metals are

• considerably inexpensive, eco-friendly and more abundant in the Earth’s crust. According to this viewpoint, manganese is biocompatible and less expensive than noble metals. Also, it is the third most abundant transition metal, behind titanium and iron. After the independent pioneering works of Beller [16] and