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

• poor light penetration, side reactions, and scalability related to traditional blue-light-driven metallophotoredox reactions. By switching from blue light (460 nm) to red light (660 nm) and osmium complex [Os(phen)3]2+ instead of an iridium complex, the authors have been able to significantly enhance

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

• possible to exclude its action also as Lewis acid. Confirming this dual activity, it should be noted that copper triflate can rarely be replaced by other copper salts or complexes to obtain the same results. In general, catalyst switching does not work with copper triflate, thus supporting its unique

Emerging trends in the optimization of organic synthesis through high-throughput tools and machine learning

• Pablo Quijano Velasco,
• Kedar Hippalgaonkar and
• Balamurugan Ramalingam

Beilstein J. Org. Chem. 2025, 21, 10–38, doi:10.3762/bjoc.21.3

• multistep reactions into parallel processes. Individually accessible reactors are arranged around a central switching station that enables the delivery of independent reaction mixtures or reagents. Each reactor loop functions as an independent unit to carry out thermal or photochemical reactions under

Direct trifluoroethylation of carbonyl sulfoxonium ylides using hypervalent iodine compounds

• Radell Echemendía,
• Carlee A. Montgomery,
• Fabio Cuzzucoli,
• Antonio C. B. Burtoloso and
• Graham K. Murphy

Beilstein J. Org. Chem. 2024, 20, 3182–3190, doi:10.3762/bjoc.20.263

• % yield, however, the related benzyl derived ylides gave 3i and 3j in 73% and 61% yields, respectively. Phenyl esters performed well with this methodology (3k,l), but switching to anilide-derived ylides were consistently poorer performing. The N-phenyl ylide derivative reacted to produce 3m in only 50

Extension of the π-system of monoaryl-substituted norbornadienes with acetylene bridges: influence on the photochemical conversion and storage of light energy

• Robin Schulte,
• Dustin Schade,
• Thomas Paululat,
• Till J. B. Zähringer,
• Christoph Kerzig and
• Heiko Ihmels

Beilstein J. Org. Chem. 2024, 20, 3061–3068, doi:10.3762/bjoc.20.254

• that the triplet energy of 1i is significantly lower than 2.4 eV and even triplet sensitizers with lower triplet energies than that of [Ru(phen)3](PF6)2 could be employed for this reaction, which might even allow red light-driven switching. In addition to these kinetic studies, the photoisomerization

4,6-Diaryl-5,5-difluoro-1,3-dioxanes as chiral dopants for liquid crystal compositions

• Maurice Médebielle,
• Peer Kirsch,
• Jérémy Merad,
• Carolina von Essen,
• Clemens Kühn and
• Andreas Ruhl

Beilstein J. Org. Chem. 2024, 20, 2940–2945, doi:10.3762/bjoc.20.246

• of double twist cylinders [10][11]. A prototype of a polymer-stabilized Blue Phase LCD with ultra-fast switching times has been presented in 2008 by Samsung [12]. Another class of materials including high HTP chiral dopants are cholesteric films prepared by the polymerization of reactive mesogens

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

• product were obtained. However, the yield of products 52 could be improved up to 66% by using iodonium salt 51 having the TMP group substituted with anisyl (Scheme 21) [72]. Switching the base in the arylation process can influence the chemoselectivity of the reaction as was reported by Onomura and group

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

• the starting material porphyrin 13 being left unreacted. On switching the substrate from boronic acid to the boronic acid ester and opting for the weaker base Cs2CO3 instead of K3PO4, a significant difference in reactivity was observed with a 72% yield accomplished in the synthesis of porphyrin 29

• (Table 1, entry 9), bearing a methoxycarbonyl electron-withdrawing group utilizing boronic acid pinacol ester 18b. Following on from these results porphyrin 30 was synthesized in an 8% yield, when switching to weaker base Cs2CO3 using pinacol ester 16b (Table 1, entry 6). Switching the base to a weaker

• [48], switching catalyst to Pd(PPh)3, and base to Na2CO3 (Table 1, entry 16) gave no product. Ultimately, an increased catalyst loading of 25 mol % per C–Br bond gave the desired porphyrin in a 16% yield when using Cs2CO3 as base. The synthesis of other heterocycle-appended dodecasubstituted

Asymmetric organocatalytic synthesis of chiral homoallylic amines

• Nikolay S. Kondratyev and
• Andrei V. Malkov

Beilstein J. Org. Chem. 2024, 20, 2349–2377, doi:10.3762/bjoc.20.201

• almost exclusively produced anti-homoallylamine 7, with (E)-6 being slightly more efficient. This was explained by the reaction switching from the chair-like TS in (E)-crotylation to the boat-like TS in (Z)-crotylation. The developed methodology was successfully applied for the total synthesis of

Stereoselective mechanochemical synthesis of thiomalonate Michael adducts via iminium catalysis by chiral primary amines

• Michał Błauciak,
• Dominika Andrzejczyk,
• Błażej Dziuk and
• Rafał Kowalczyk

Beilstein J. Org. Chem. 2024, 20, 2313–2322, doi:10.3762/bjoc.20.198

• enhancing the reactivity of a relatively inert acceptor does not necessarily lead to increased reaction rates, involves the use of more reactive nucleophiles. In this context, varying the stabilization energy of carboxylic acid derivatives by switching from oxoesters to thioesters is the significant

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

• product, although in this case, reduction of the nitro group to an amino group was observed and the resulting 4-aminobenzaldehyde is likely too electron-rich to undergo allylation. The use of other halides was also explored (Table 3). Switching to allyl chloride (Table 3, entry 2) did result in partial

Understanding X-ray-induced isomerisation in photoswitchable surfactant assemblies

• Beatrice E. Jones,
• Camille Blayo,
• Jake L. Greenfield,
• Matthew J. Fuchter,
• Nathan Cowieson and
• Rachel C. Evans

Beilstein J. Org. Chem. 2024, 20, 2005–2015, doi:10.3762/bjoc.20.176

• , respectively, with comparable dimensions to those in H2O (Tables S1 and S3, Supporting Information File 1). However, there is a large difference in the interactions between AAPTAB micelles on switching solvents, which can be seen as a decrease in the interaction hump in the SAXS pattern at Q ≈ 0.045 Å−1

• isomers. It is thought that this is due to X-ray-induced radiolysis of water, which produces many primary species, including H+ ions, that are known to catalyse the Z–E isomerisation reaction. By switching the H2O solvent to D2O, we observed that the increased viscosity and reduced acidification acted to

Supramolecular assemblies of amphiphilic donor–acceptor Stenhouse adducts as macroscopic soft scaffolds

• Ka-Lung Hung,
• Leong-Hung Cheung,
• Yikun Ren,
• Ming-Hin Chau,
• Yan-Yi Lam,
• Takashi Kajitani and
• Franco King-Chi Leung

Beilstein J. Org. Chem. 2024, 20, 1590–1603, doi:10.3762/bjoc.20.142

• design of the reported DAs, we designed and synthesized a series of DAs featuring a second-generation DASA switching motif and different chain lengths of the alkyl linker (i.e., DAn) that connects the DASA indoline motif with the hydrophilic part (i.e., the carboxylic acid motif, Scheme 1). The alkyl

• compared to the THF (Figure 1a). The thermal back reaction in the resulting aqueous solution was further studied, showing no reverse switching to O-DA11 upon storage in the dark at 20 °C (Figure S2, Supporting Information File 1). It has previously been observed that the cyclized-isomers of common DASAs

Synthesis and optical properties of bis- and tris-alkynyl-2-trifluoromethylquinolines

• Stefan Jopp,
• Franziska Spruner von Mertz,
• Peter Ehlers,
• Alexander Villinger and
• Peter Langer

Beilstein J. Org. Chem. 2024, 20, 1246–1255, doi:10.3762/bjoc.20.107

• 2.5 mol % or switching to more simple Pd(PPh3)4 still achieved quantitative yields. Less catalyst led to a reduced yield (Table 1). Consequently, we chose 2.5 mol % Pd(PPh3)4 for all further reactions. As a next step, we analysed the scope of our methodology (Scheme 2). The optimized conditions allow

Kinetically stabilized 1,3-diarylisobenzofurans and the possibility of preparing large, persistent isoacenofurans with unusually small HOMO–LUMO gaps

• Qian Liu and
• Glen P. Miller

Beilstein J. Org. Chem. 2024, 20, 1099–1110, doi:10.3762/bjoc.20.97

• switching the dienophile from DMAD to acrylonitrile. Once again, compounds 3 and 23 were unreactive, even after 184 hours of reaction time with a 13,500-fold excess of acrylonitrile. The reaction between 3 and a large excess of DMAD (116 equivalents) in boiling toluene (111 °C) was also studied by 1H NMR

Enantioselective synthesis of β-aryl-γ-lactam derivatives via Heck–Matsuda desymmetrization of N-protected 2,5-dihydro-1H-pyrroles

• Arnaldo G. de Oliveira Jr.,
• Martí F. Wang,
• Rafaela C. Carmona,
• Danilo M. Lustosa,
• Sergei A. Gorbatov and
• Carlos R. D. Correia

Beilstein J. Org. Chem. 2024, 20, 940–949, doi:10.3762/bjoc.20.84

•  1). However, neither one of these new ligands performed better than L1 (see Table 1 below). In an attempt to enhance the protocol performance, we also evaluated the palladium source as indicated in Table 1. Switching Pd(TFA)2 by Pd(OAc)2 led to a minor increase in the yield, but without any changes

Advancements in hydrochlorination of alkenes

• Daniel S. Müller

Beilstein J. Org. Chem. 2024, 20, 787–814, doi:10.3762/bjoc.20.72

• ) could be prevented when switching to BCl3 (10 mol %). Interestingly, toluene (94), which is generated as a byproduct of the Grob fragmentation, must react more sluggishly with the generated cationic intermediates compared to chloride, as no alkylations of toluene were reported. In 2017, the Snyder group

SOMOphilic alkyne vs radical-polar crossover approaches: The full story of the azido-alkynylation of alkenes

• Julien Borrel and
• Jerome Waser

Beilstein J. Org. Chem. 2024, 20, 701–713, doi:10.3762/bjoc.20.64

• discovery and development of the synthesis of homopropargylic azides by the azido-alkynylation of alkenes. Initially, a strategy involving SOMOphilic alkynes was adopted, but only resulted in a 29% yield of the desired product. By switching to a radical-polar crossover approach and after optimization, a

• reagents as SOMOphilic alkynes but this only afforded a 29% yield of the desired product. After switching to a radical-polar crossover approach the yield could be significantly improved. Key to the reaction optimization was the reduction of the temperature to −20 °C and the addition of BF3·Et2O. A large

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

• reactions. Electrochemical stimuli, while generating no waste when employing electrodes, may face limitations due to the electroactive window of the solvent and require the incorporation of redox-active switching units, which can impose constraints on design and functionality. It is worth noting that the

• proximity, either by direct interaction or via a small intercalating molecule. Therefore, switchable molecular tweezers can be considered a prototype of a mechanical molecular device capable of allosteric regulation and dual control through switching and guest binding. While the primary application of

• mainly driven by intramolecular hydrogen bonds. The methoxyphenyl-pyridine-methoxyphenyl moiety, developed by Petitjean et al. [19], demonstrates conformational switching upon the addition of acid in aqueous media (Figure 2). The neutral tweezers adopt a "U"-shaped conformation with both arms pointing in

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

• concentrations of 1a, solutions became turbid as the substrate became less soluble, thus limiting the range of concentrations that could be used for relative rate plots. Switching to carbamate 1b alleviated the solubility problem, but the significantly slower reactions required switching to a more reactive

• opposite effect is observed [60]. Ligand effects. Early studies identified two key strategies for improving alkene hydroamination, switching from an electron-withdrawing catalyst (Ph3PAuCl/AgOTf) to an electron-donating catalyst (IPrAuCl/AgOTf (IPr = 1,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidene), or by

Photochromic derivatives of indigo: historical overview of development, challenges and applications

• Gökhan Kaplan,
• Zeynel Seferoğlu and
• Daria V. Berdnikova

Beilstein J. Org. Chem. 2024, 20, 228–242, doi:10.3762/bjoc.20.23

• substituents in the isatin ring showed pronounced negative photochromism upon irradiation with red light (625−650 nm). Supramolecular complexation with Schreiner’s thiourea organocatalyst (STC) allowed to reach better conversion with the isomeric ratio in PSS increased from 46% to 84%. The backward switching

• appealing due to the possibility of performing the switching within the biooptical transparency window (650–900 nm) [87]. Additionally, significant structural differences (180° flip) between the E- and Z-isomers of the compounds provide a prerequisite of light-controllable geometry control in biomolecular

• assemblies as well as precise switching of the biological activity of the photoswitchable derivative. Along these lines, in 2023, Leung and co-workers prepared amphiphilic indigo-based photoswitches and incorporated them into vesicles [88]. Irradiation of the vesicles with red light resulted in the E–Z

Optimizations of lipid II synthesis: an essential glycolipid precursor in bacterial cell wall synthesis and a validated antibiotic target

• Milandip Karak,
• Cian R. Cloonan,
• Brad R. Baker,
• Rachel V. K. Cochrane and
• Stephen A. Cochrane

Beilstein J. Org. Chem. 2024, 20, 220–227, doi:10.3762/bjoc.20.22

• reaction (Table 1, entries 6, 8, and 9). A slight improvement in the yield of 3a was observed when switching from TMSOTf to TfOH as the activator (Table 1, entry 5 vs entry 10). However, substituting TMSOTf with BF3·OEt2 did not yield any target product 3a (Table 1, entry 3 vs entry 12). In our

Chiral phosphoric acid-catalyzed transfer hydrogenation of 3,3-difluoro-3H-indoles

• Yumei Wang,
• Guangzhu Wang,
• Yanping Zhu and
• Kaiwu Dong

Beilstein J. Org. Chem. 2024, 20, 205–211, doi:10.3762/bjoc.20.20

• steric hinderance of Hantzsch ester raised (Table 2, entries 1–3) and switching from ethyl to tert-butyl esters the desired product was obtained in excellent yield and enantioselectivity (Table 2, entry 3). Subsequently, we investigated the effect of the amounts of HE-t-Bu and chiral phosphoric acid on

Metal-catalyzed coupling/carbonylative cyclizations for accessing dibenzodiazepinones: an expedient route to clozapine and other drugs

• Amina Moutayakine and
• Anthony J. Burke

Beilstein J. Org. Chem. 2024, 20, 193–204, doi:10.3762/bjoc.20.19

• , did not provide any improvement of the reaction outcome as only traces of the intermediate 3a were obtained (entry 3, Table 1). Switching to DBU as the base under these conditions, gave intermediate 3a in 35% yield (entry 4, Table 1). In fact, DBU was previously shown by Wannberg and Larhed to be an

Synthesis of the 3’-O-sulfated TF antigen with a TEG-N₃ linker for glycodendrimersomes preparation to study lectin binding

• Mark Reihill,
• Hanyue Ma,
• Dennis Bengtsson and
• Stefan Oscarson

Beilstein J. Org. Chem. 2024, 20, 173–180, doi:10.3762/bjoc.20.17

• in formation of a homogenous solution, but still no conversion to the sulfated product, even when the temperature was raised to 80 °C [28][29]. Switching the sulfating reagent to SO3·Py or performing the reaction at 150 °C in a microwave did not improve the outcome [30][31]. Since there was no