Development and mechanistic studies of calcium–BINOL phosphate-catalyzed hydrocyanation of hydrazones

• Carola Tortora,
• Christian A. Fischer,
• Sascha Kohlbauer,
• Alexandru Zamfir,
• Gerd M. Ballmann,
• Jürgen Pahl,
• Sjoerd Harder and
• Svetlana B. Tsogoeva

Beilstein J. Org. Chem. 2025, 21, 755–765, doi:10.3762/bjoc.21.59

• -hydrazones, respectively. A thermodynamic control of the reaction outcome (i.e., especially enantioselectivity) would require the possibility to approach an equilibrium between 9 and 10 (seeing the reversibility of step 9 → 10), in which case the relative energies of stereoisomeric forms of 10 determine the

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

• are reacted in the presence of the catalyst A [25]. This can be explained by considering the principle of microscopic reversibility. In the reversible process, the catalyst forms the same enamine intermediate preferentially formed in the Michael reaction. This means that the adduct anti-(3R,4S)-1

• to enamine E, which epimerizes at C-4 and, after hydrolysis, provides the adduct syn-(3R,4R)-1 with an initial er of 4:96. This diastereoselective epimerization phenomenon promoted by an organocatalyst has not been previously described. The study emphasizes the reversibility of some organocatalyzed

Reactivity of hypervalent iodine(III) reagents bearing a benzylamine with sulfenate salts

• Beatriz Dedeiras,
• Catarina S. Caldeira,
• José C. Cunha,
• Clara S. B. Gomes and
• M. Manuel B. Marques

Beilstein J. Org. Chem. 2024, 20, 3281–3289, doi:10.3762/bjoc.20.272

• is more favorable at higher temperatures [4]. Due to the reversibility of the retro-Michael addition, an experiment was carried out using an excess of tert-butyl 3-(p-tolylsulfinyl)propanoate (4a) leading to an increase in the yield of the corresponding sulfonamide 5aa by 38% (Table 1, entry 6). A

The charge transport properties of dicyanomethylene-functionalised violanthrone derivatives

• Sondos A. J. Almahmoud,
• Joseph Cameron,
• Dylan Wilkinson,
• Michele Cariello,
• Claire Wilson,
• Alan A. Wiles,
• Peter J. Skabara and
• Graeme Cooke

Beilstein J. Org. Chem. 2024, 20, 2921–2930, doi:10.3762/bjoc.20.244

• reversible oxidation waves as shown from the CV data (Figure 6 and Table 1). This reversibility is crucial for the regeneration of dyes following redox processes. The compounds display ionisation energies (IEs) of −5.38 eV, −5.34 eV, and −5.40 eV for 3a, 3b, and 3c, respectively, with electron affinities

Investigation of a bimetallic terbium(III)/copper(II) chemosensor for the detection of aqueous hydrogen sulfide

• Parvathy Mini,
• Michael R. Grace,
• Genevieve H. Dennison and
• Kellie L. Tuck

Beilstein J. Org. Chem. 2024, 20, 2818–2826, doi:10.3762/bjoc.20.237

• an antenna chromophore and a receptor for Cu2+ ions; the Cu2+ complex was shown to be a chemosensor for the detection of aqueous hydrogen sulfide. The chemosensor exhibited significant reversibility over multiple cycles, observed with the sequential addition of Na2S followed by Cu2+ ions. The limit

• addition of 3.0 equivalents of HS−(aq) ions. The calculated theoretical LoD was 0.63 μM (20 ppb), which is comparable to that observed with the europium(III) analogue (1.1 μM, 36 ppb) [16]). The chemosensor exhibited significant reversibility over multiple cycles involving the addition and subsequent

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

• reversibility and photostability in organic solvent (Figure S1a and S1b, Supporting Information File 1). The photoisomerization between O-DA11 and C-DA11, upon irradiation with 625 nm red light and thermal back reaction in the dark, could be repeated for over five cycles, with only 5% absorbance decreases per

• cycle (Figure S1a and S1b, Supporting Information File 1). In contrast, the previously studied reversibility of the photoswitching of DA10 had revealed 10% absorbance decreases per cycle [37], indicating a mild improvement to the fatigue resistance of DA11. To further investigate the photostability and

• reversibility of the other compounds, DAn with shorter alkyl linkers were also examined in THF solvent by UV–vis absorption spectroscopy, where they showed photochemical properties similar to those of DA11 (Figure 1a and Figure 1b). THF solutions of DA7 and DA6 showed a strong absorption band at 470–685 nm

Novel route to enhance the thermo-optical performance of bicyclic diene photoswitches for solar thermal batteries

• Akanksha Ashok Sangolkar,
• Rama Krishna Kadiyam and
• Ravinder Pawar

Beilstein J. Org. Chem. 2024, 20, 1053–1068, doi:10.3762/bjoc.20.93

• the most versatile solvent to exhibit the best photoswitching behaviour which is beneficial for real-life energy storage applications. Additionally, the stability and reversibility of the photoswitching system with elongated unsaturated bridges have also been assessed. By means of the studied

• aromatic ring via a kinetically controlled retro-Diels–Alder pathway [31]. However, the reversibility of the photoswitching cycle is a prerequisite for a closed MOST system. Recent studies have demonstrated that structural modifications in the basic BBD skeleton can alter the intrinsic properties of a

• solvents on the photoswitching properties has also been investigated for a real-life MOST application. The stability and the reversibility of the photoswitches have also been verified to attain a closed cyclic photoswitching process for practical MOST system. Results and Discussion As can be seen from

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

• system and enable dynamic ligand formation due to the reversibility of the hydrazone bond formation [40]. More recently, Vives and co-workers have developed a family of terpyridine-based tweezers bearing metal–salphen complexes as functional units (Figure 9). Using metal complexes as arms brings

• ligands. The reversibility of the opening/closing process was achieved in situ by the addition and removal of CO yielding one of the first examples of allosteric regulation in artificial systems. Dissymmetric molecular tweezers are also accessible with high selectivity using two different hemilabile

Enabling artificial photosynthesis systems with molecular recycling: A review of photo- and electrochemical methods for regenerating organic sacrificial electron donors

• Grace A. Lowe

Beilstein J. Org. Chem. 2023, 19, 1198–1215, doi:10.3762/bjoc.19.88

• considered: solubility in the chosen solvent, absorption spectrum, oxidation potential, and the reversibility of the sacrificial donor oxidation. As the sacrificial donor is a reactant in the photoreduction reaction of carbon dioxide, it needs to be highly soluble in the solvent used. It also needs to have a

Synthesis of tetrahydrofuro[3,2-c]pyridines via Pictet–Spengler reaction

• Elena Y. Mendogralo and
• Maxim G. Uchuskin

Beilstein J. Org. Chem. 2023, 19, 991–997, doi:10.3762/bjoc.19.74

• . The reversibility of the acid hydrolysis is quite typical for furans and is more pronounced for di- and polysubstituted furans, due to the higher stability of the latter [49][50][51]. 3-(2-Oxopropyl)piperidin-4-one 5a could be involved into the Paal–Knorr pyrrole synthesis in a one-pot manner. Thus

A new oxidatively stable ligand for the chiral functionalization of amino acids in Ni(II)–Schiff base complexes

• Alena V. Dmitrieva,
• Oleg A. Levitskiy,
• Yuri K. Grishin and
• Tatiana V. Magdesieva

Beilstein J. Org. Chem. 2023, 19, 566–574, doi:10.3762/bjoc.19.41

• ]. Meanwhile, an important difference is the reversibility of the oxidation observed at low potential scan rates (100 mV/s) for the complexes (GlyNi)L7 and (ΔAlaNi)L7 (see Figure 4), in contrast to their t-Bu-free analogs. The similarity of the potential values for the complexes derived from L1 and L7 allows

• reversibility can be reached at scan rates above 20 V/s allowing the E1/2 estimation. Similarly to previously studied complex (ΔAlaNi)L1 [36], electron transfer to (ΔAlaNi)L7 is mainly ligand centered. The DFT-estimated LUMO is formed as an overlap of the π antibonding orbitals of the dehydroalanine and imine

Recommendations for performing measurements of apparent equilibrium constants of enzyme-catalyzed reactions and for reporting the results of these measurements

• Robert N. Goldberg,
• Robert T. Giessmann,
• Peter J. Halling,
• Carsten Kettner and
• Hans V. Westerhoff

Beilstein J. Org. Chem. 2023, 19, 303–316, doi:10.3762/bjoc.19.26

Ionic multiresonant thermally activated delayed fluorescence emitters for light emitting electrochemical cells

• Merve Karaman,
• Abhishek Kumar Gupta,
• Subeesh Madayanad Suresh,
• Tomas Matulaitis,
• Lorenzo Mardegan,
• Daniel Tordera,
• Henk J. Bolink,
• Sen Wu,
• Stuart Warriner,
• Ifor D. Samuel and
• Eli Zysman-Colman

Beilstein J. Org. Chem. 2022, 18, 1311–1321, doi:10.3762/bjoc.18.136

• -butylammonium hexafluorophosphate as the supporting electrolyte (Figure 3a and Table S2 in Supporting Information File 1). The oxidation and reduction of both emitters showed good reversibility, which is beneficial for better performance in LEEC devices [31]. The oxidation potentials, Eox, determined from the

Polymer and small molecule mechanochemistry: closer than ever

• José G. Hernández

Beilstein J. Org. Chem. 2022, 18, 1225–1235, doi:10.3762/bjoc.18.128

• organocatalytic units embedded in polymers for catalysis in small molecule systems have been discussed [15][19][20]. Moreover, the ability of force to deform the reaction energy landscape and modulate the reversibility of the reactions within proteins has been demonstrated. For example, mechanical force was used

Synthesis, optical and electrochemical properties of (D–π)₂-type and (D–π)₂Ph-type fluorescent dyes

• Kosuke Takemura,
• Kazuki Ohira,
• Taiki Higashino,
• Keiichi Imato and
• Yousuke Ooyama

Beilstein J. Org. Chem. 2022, 18, 1047–1054, doi:10.3762/bjoc.18.106

• rates (50, 100, 200, 400, 600 and 1000 mV s−1) and reversibility of the oxidation process by repeated potential cycling (20 cycles). For both OTK-2 and OTT-2, the Epaox remained steady at different scan rates while the anodic peak current (Ipa) increased with the increase in scan rate. The Ipa showed a

• negligible change during 20 cycles at a scan rate of 100 mV s−1, indicating diffusion control and good reversibility of the oxidation process (Figures S2b,c and S3b,c, Supporting Information File 1). The highest occupied molecular orbital (HOMO) energy level versus vacuum level was estimated from the E1/2ox

Introducing a new 7-ring fused diindenone-dithieno[3,2-b:2',3'-d]thiophene unit as a promising component for organic semiconductor materials

• Valentin H. K. Fell,
• Joseph Cameron,
• Alexander L. Kanibolotsky,
• Eman J. Hussien and
• Peter J. Skabara

Beilstein J. Org. Chem. 2022, 18, 944–955, doi:10.3762/bjoc.18.94

• more negative. This can be attributed to the presence of the electron-withdrawing keto groups [3][20]. In contrast to compounds 2–4, which showed poor reversibility for oxidation and reduction, EtH-T-DI-DTT shows excellent electrochemical stability. Two sequential reversible oxidations can be seen in

Heteroleptic metallosupramolecular aggregates/complexation for supramolecular catalysis

• Prodip Howlader and
• Michael Schmittel

Beilstein J. Org. Chem. 2022, 18, 597–630, doi:10.3762/bjoc.18.62

• 98 reacted with the copper(I) ions to afford [Cu2(98)2]2+ representing again a reservoir for a rotator. Based on the stoichiometry of the above equation, two equiv of copper(I) ions were liberated. Since the released free copper(I) ions generated problems with reversibility of the transformation, 1

• [133]. In order to test the reversibility, both switches were toggled by adding and removing the iron(II) ions over 2.5 cycles demonstrating that ON/OFF catalysis was reversible and reproducible. Interestingly, the nanoswitches [Cu2(130)]2+ and [Cu2(131)]2+ (1:1) could be selectively addressed in the

In-depth characterization of self-healing polymers based on π–π interactions

• Josefine Meurer,
• Julian Hniopek,
• Johannes Ahner,
• Michael Schmitt,
• Jürgen Popp,
• Stefan Zechel,
• Kalina Peneva and
• Martin D. Hager

Beilstein J. Org. Chem. 2021, 17, 2496–2504, doi:10.3762/bjoc.17.166

• compared to other self-healing supramolecular polymers, e.g., metallopolymers [25]. Supramolecular polymers feature certain temperature ranges, in which the noncovalent bond is activated. The degree of reversibility can be determined by the supramolecular bond lifetime [26]. For example, a study regarding

Constrained thermoresponsive polymers – new insights into fundamentals and applications

• Patricia Flemming,
• Alexander S. Münch,
• Andreas Fery and
• Petra Uhlmann

Beilstein J. Org. Chem. 2021, 17, 2123–2163, doi:10.3762/bjoc.17.138

• complex interplay of attractive interactions enables fine-tuning of the phase transition temperature itself, as well as the sharpness, switching amplitude and reversibility of the transition for a desired application [6][50][51]. Today there are several excellent reviews offering synthetic guidelines for

Annulation of a 1,3-dithiole ring to a sterically hindered o-quinone core. Novel ditopic redox-active ligands

• Sergey V. Norkov,
• Anton V. Cherkasov,
• Andrey S. Shavyrin,
• Maxim V. Arsenyev,
• Viacheslav A. Kuropatov and
• Vladimir K. Cherkasov

Beilstein J. Org. Chem. 2021, 17, 273–282, doi:10.3762/bjoc.17.26

•  2. The high extent of enolization of 1,3-diketones results in lower nucleophilicity of the active methylene function. This fact enhances the reversibility of the dithiocarboxylation of sodium acetylacetonate. It is known that dithiocarboxylates and gem-dithiolates can lose CS2 resulting in active

• methylene compound salts [17]. Due to the reversibility of dithiocarboxylation, the reaction mixture contains some amount of sodium acetylacetonate, which can attack the chlorine atom at the backbone of 2 to give the substitution product (Scheme 2). According to the reported data, the quinone-methide form

Multiswitchable photoacid–hydroxyflavylium–polyelectrolyte nano-assemblies

• Alexander Zika and
• Franziska Gröhn

Beilstein J. Org. Chem. 2021, 17, 166–185, doi:10.3762/bjoc.17.17

• are reversible. Quantitatively, comparing the absorbance of Flavy before and after completion of the different cycles shows that close to 75% of Flavy revert back (data given in Table 1). Likely the reason for the incomplete reversibility is a photoprotective effect which hinders the open form Cc to

• state C the size of the assemblies decreases to RH = 161 nm. At the same time, the structure changes back to a sphere (Figure 5c). To make a statement on the reversibility, it is necessary to compare this state of cycle I with the second state of cycle II. Cycle II shows a decrease in size from RH = 192

• DLS and again show the reversibility of both cycles. As reported for other systems, the structures in AFM are substantially smaller than in DLS due to the shrinking upon drying in the AFM sample preparation [40][60][83][84][85]. Further, the ζ-potential was determined to understand the changes in the

Using multiple self-sorting for switching functions in discrete multicomponent systems

• Amit Ghosh and
• Michael Schmittel

Beilstein J. Org. Chem. 2020, 16, 2831–2853, doi:10.3762/bjoc.16.233

• reversibility was achieved by the addition of the rhodium porphyrin 19 that reversed the system reviving the state SelfSORT-I. Since both self-sorted states exhibited a distinct fluorescence due to the changes at the zinc porphyrin sites, luminescence was used for the selective detection of DABCO in a mixture

• transformation 32 + 33 → 34 was observed, because the copper(I) is deeply embedded in [Cu(30)]+. This double self-sorting showed a full reversibility upon the addition and removal of zinc(II) ions along with ON/OFF catalytic behavior and reproducible yields of the product 34 (36%) in two subsequent cycles. An

• catalytic behavior showed a full reversibility up to three cycles and provided 45%, 43%, and 41% yield, respectively, in subsequent cycles. The small decrease of the yield over three release/capture cycles was explained by a minor degradation of silver(I), a phenomenon equally seen in the emission channel

Dirhamnolipid ester – formation of reverse wormlike micelles in a binary (primerless) system

• David Liese,
• Hans Henning Wenk,
• Xin Lu,
• Jochen Kleinen and
• Gebhard Haberhauer

Beilstein J. Org. Chem. 2020, 16, 2820–2830, doi:10.3762/bjoc.16.232

• Information File 1) shows the thermal reversibility of the gel formation process. The phase transition temperature can be obtained from the temperature sweeps and is defined as the temperature where the dynamic moduli intercept. In an alternative representation, the phase transition temperature can also be

• demonstrate the thermal reversibility of the gelation process. There are peak maxima at the heating and cooling phases that can be assigned to the formation of the gel structure and its decomposition. For the heating phase, a maximum was found at 45 °C, the endothermic melting process of the sample. In the

Anion exchange resins in phosphate form as versatile carriers for the reactions catalyzed by nucleoside phosphorylases

• Julia N. Artsemyeva,
• Ekaterina A. Remeeva,
• Tatiana N. Buravskaya,
• Irina D. Konstantinova,
• Roman S. Esipov,
• Anatoly I. Miroshnikov,
• Natalia M. Litvinko and
• Igor A. Mikhailopulo

Beilstein J. Org. Chem. 2020, 16, 2607–2622, doi:10.3762/bjoc.16.212

• problems associated with the reversibility of enzymatic phosphorolysis/synthesis reactions, along with the solubility of heterocyclic bases and accessibility of PF-1Pis. Despite all this, in a number of cases these problems have been successfully solved and, as a result, the desired base and/or sugar

Thermodynamic and electrochemical study of tailor-made crown ethers for redox-switchable (pseudo)rotaxanes

• Henrik Hupatz,
• Marius Gaedke,
• Hendrik V. Schröder,
• Julia Beerhues,
• Arto Valkonen,
• Fabian Klautzsch,
• Sebastian Müller,
• Felix Witte,
• Kari Rissanen,
• Biprajit Sarkar and
• Christoph A. Schalley

Beilstein J. Org. Chem. 2020, 16, 2576–2588, doi:10.3762/bjoc.16.209

• ), which can be explained by diffusion and comproportionation of the dianion, as it was observed earlier for other NDI2− species [59]. Applying more positive potentials gradually converts the spectra back to the initial forms, which confirms the reversibility of the reduction processes. Overall, the