Three-component reactions of conjugated dienes, CH acids and formaldehyde under diffusion mixing conditions

• Dmitry E. Shybanov,
• Maxim E. Kukushkin,
• Eugene V. Babaev,
• Nikolai V. Zyk and
• Elena K. Beloglazkina

Beilstein J. Org. Chem. 2025, 21, 262–269, doi:10.3762/bjoc.21.18

• participation. Interaction of diketone 1 with formaldehyde under the diffusion mixing conditions. Products of three-component reactions of methylene derivatives, formaldehyde and various dienes. Proposed mechanism for the formation of compounds 8 and 9 in the presence of ʟ-proline. Interconversion of

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

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

• = number of quadricyclylethynyl units. Triplet-sensitized photoisomerization of norbornadiene 1o to quadricyclane 2o. Photochemical and physicochemical parameters of the norbornadiene–quadricyclane interconversion of 1h–l,n in cyclohexane. Supporting Information Supporting Information File 8: Experimental

Synthesis and antimycotic activity of new derivatives of imidazo[1,2-a]pyrimidines

• Dmitriy Yu. Vandyshev,
• Daria A. Mangusheva,
• Khidmet S. Shikhaliev,
• Kirill A. Scherbakov,
• Oleg N. Burov,
• Alexander D. Zagrebaev,
• Tatiana N. Khmelevskaya,
• Alexey S. Trenin and
• Fedor I. Zubkov

Beilstein J. Org. Chem. 2024, 20, 2806–2817, doi:10.3762/bjoc.20.236

• interconversion into each other. A peculiarity of the reaction with N-phenylithaconimide (3a) is that the formation of intermediates 8a and 9a is an endothermic process (paths B1 and B2, correspondingly, Scheme 5). However, the formation of the final product from the starting reagents (∆G = −1.88 kcal/mol) as

Computational design for enantioselective CO₂ capture: asymmetric frustrated Lewis pairs in epoxide transformations

• Maxime Ferrer,
• Iñigo Iribarren,
• Tim Renningholtz,
• Ibon Alkorta and
• Cristina Trujillo

Beilstein J. Org. Chem. 2024, 20, 2668–2681, doi:10.3762/bjoc.20.224

• favourable process. During the study, it will be observed that several transition states (TSs) can lead to the same product. As there is no possible interconversion between the reactant states, the different reactions will be considered independent, and it will be necessary to use an effective rate constant

Negishi-coupling-enabled synthesis of α-heteroaryl-α-amino acid building blocks for DNA-encoded chemical library applications

• Matteo Gasparetto,
• Balázs Fődi and
• Gellért Sipos

Beilstein J. Org. Chem. 2024, 20, 1922–1932, doi:10.3762/bjoc.20.168

• , no reaction was observed with indazoles and furans using the first two conditions, requiring the formation of the ketoesters 4j and 4r first, followed by the functional group interconversion (FGI) with NH2OH·HCl (Scheme 6, blue and green sections). The Riley oxidation of the furanyl derivative 2j

Novel oxidative routes to N-arylpyridoindazolium salts

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

Beilstein J. Org. Chem. 2024, 20, 1906–1913, doi:10.3762/bjoc.20.166

• . Voltammetry studies of the electrochemical behavior of the novel pyridoindazolium salts and the starting diarylamines were performed confirming a possibility for their reversible redox interconversion. Results and Discussion Chemical oxidation Three previously reported ortho-pyridine-substituted diarylamines

• testing confirmed that oxidation of the pyridyl-containing amines results in the intramolecular heterocyclization yielding pyridoindazolium salts. The reduction of N-arylpyridoindazoliums in the presence of a source of protons restores the starting diarylamines. Redox-interconversion between diarylamines

• structures demonstrating the electron density distribution in pyridoindazolium salts. Redox-interconversion between diarylamines A1–A3 and N-arylpyridoindazoliums S1–S3. Electrochemical approach to pyridoindazolium salts. Peak potential values for the reduction of salts S1–S3 (, V) and oxidation of the

A fiber-optic spectroscopic setup for isomerization quantum yield determination

• Anouk Volker,
• Jorn D. Steen and
• Stefano Crespi

Beilstein J. Org. Chem. 2024, 20, 1684–1692, doi:10.3762/bjoc.20.150

• ]. Among the different switches known in the literature, azobenzene is a textbook example of a photoswitch operating via a double bond isomerization mechanism, with the first reports of its trans-to-cis interconversion under direct sunlight dating back to the work of Hartley in 1937 [2]. Over the decades

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

• energy between both states indicates the importance of the spontaneous interconversion of both species, which is observed only in the presence of two equivalents of the Lewis acid. After the addition of 2-naphthol, the chlorine atom is introduced barrier-free into the phenolic ring, producing the

Regio- and stereochemical stability induced by anomeric and gauche effects in difluorinated pyrrolidines

• Ana Flávia Candida Silva,
• Francisco A. Martins and
• Matheus P. Freitas

Beilstein J. Org. Chem. 2024, 20, 1572–1579, doi:10.3762/bjoc.20.140

• envelope of cyclopentane, with an NH unit occupying either a pseudoaxial or pseudoequatorial position (Figure 1a). When a hydrogen atom of the pyrrolidine at C-3 is replaced with fluorine, a conformational interconversion can occur within the cis- and trans-isomers, as illustrated in Figure 1b. The

• were degenerate (i.e., 10/11 and 14/15), reducing the number of distinct structures to 22. However, due to the considerable flexibility of the five-membered ring and the low barrier for pyramidal interconversion of the N–H moiety, some inputs converged to the same isomer post-geometry optimization

(Bio)isosteres of ortho- and meta-substituted benzenes

• H. Erik Diepers and
• Johannes C. L. Walker

Beilstein J. Org. Chem. 2024, 20, 859–890, doi:10.3762/bjoc.20.78

• 166) [64]. In addition to their synthesis of cubane 166, Coote and co-workers also reported a number of bifunctional 1,3-cubanes accessible through functional group interconversion from acid ester cubane 167 (Scheme 17D) [64]. Reduction to the alcohol (to 179) and iodination (to 180) of the carboxylic

Tandem Hock and Friedel–Crafts reactions allowing an expedient synthesis of a cyclolignan-type scaffold

• Viktoria A. Ikonnikova,
• Cristina Cheibas,
• Oscar Gayraud,
• Alexandra E. Bosnidou,
• Nicolas Casaretto,
• Gilles Frison and
• Bastien Nay

Beilstein J. Org. Chem. 2024, 20, 162–169, doi:10.3762/bjoc.20.15

• alternative mechanism, we envisionned a possible interconversion of 7 and 7’ through a [1,5]-sigmatropic rearrangement resulting in a hydrogen and cation shift towards 7’ (Scheme 4). To test this hypothesis, this rearrangement was computed at the DFT level. A cyclic transition state (TS) was found between

Tying a knot between crown ethers and porphyrins

• Maksym Matviyishyn and
• Bartosz Szyszko

Beilstein J. Org. Chem. 2023, 19, 1630–1650, doi:10.3762/bjoc.19.120

• to a dimer 37 was achieved using N,N-dimethylformamide, dimethyl sulfoxide, or acetonitrile. Interestingly, the dissolution of compound 37 in CHCl3, MeOH, or EtOH resulted in the interconversion to 36 within 1–2 days, as evidenced by 1H NMR spectroscopy. The Ravikanth group has developed an

Unraveling the role of prenyl side-chain interactions in stabilizing the secondary carbocation in the biosynthesis of variexenol B

• Moe Nakano,
• Rintaro Gemma and
• Hajime Sato

Beilstein J. Org. Chem. 2023, 19, 1503–1510, doi:10.3762/bjoc.19.107

• presence of the cation–π interaction, the cation is delocalized, resulting in a decrease in cationicity at C10 and a corresponding increase in cationicity at C15. Note that the interconversion of TS_2a-3a to TS_2b-3b requires a significant conformational change, such as a 180 degree rotation of the iPr

Organic thermally activated delayed fluorescence material with strained benzoguanidine donor

• Alexander C. Brannan,
• Elvie F. P. Beaumont,
• Nguyen Le Phuoc,
• George F. S. Whitehead,
• Mikko Linnolahti and
• Alexander S. Romanov

Beilstein J. Org. Chem. 2023, 19, 1289–1298, doi:10.3762/bjoc.19.95

• Supporting Information File 1 for NMR). In DMSO-d6 solution, 4BGIPN isomers do not show interconversion even upon warming to 120 °C, resulting in a similar set of signals. Excellent fit between HRMS and elemental analysis further supports the formation of the isomeric mixture of 4BGIPN as evidenced by the

• benzonitrile acceptor core. We found that the material is formed as a mixture of the rotational isomers that do not experience interconversion upon heating the 4BGIPN solution in DMSO to 120 °C. Two rotational isomers were successfully crystallized to show different up and down orientations of the

The effect of dark states on the intersystem crossing and thermally activated delayed fluorescence of naphthalimide-phenothiazine dyads

• Liyuan Cao,
• Xi Liu,
• Xue Zhang,
• Jianzhang Zhao,
• Fabiao Yu and
• Yan Wan

Beilstein J. Org. Chem. 2023, 19, 1028–1046, doi:10.3762/bjoc.19.79

• -separated states 1CS and 3CS of these emitters are believed to undergo nonefficient slow interconversion, thus the poor rISC will not lead to efficient TADF. Later, a three-state model was proposed, i.e., the 1CS, 3CS, and a locally excited (3LE) state should be involved in the TADF process. The rISC is

Germacrene B – a central intermediate in sesquiterpene biosynthesis

• Houchao Xu and
• Jeroen S. Dickschat

Beilstein J. Org. Chem. 2023, 19, 186–203, doi:10.3762/bjoc.19.18

• the 13C NMR spectrum [26] indicates that the interconversion between these conformers is a fast process at room temperature. This is in contrast to the findings for germacrene A (2) and hedycaryol (3) that show strong line broadening in the NMR spectra and multiple sets of peaks for different

• Sharpless epoxidation of its derivative 15-hydroxygermacrene (17) showed that this material was racemic, indicating a rapid interconversion between the enantiomers of 17. Consequently, also the enantiomers of 1 may undergo a fast interconversion [52]. The 1H and 13C NMR data of 1 have been reported [26

Combining the best of both worlds: radical-based divergent total synthesis

• Kyriaki Gennaiou,
• Antonios Kelesidis,
• Maria Kourgiantaki and
• Alexandros L. Zografos

Beilstein J. Org. Chem. 2023, 19, 1–26, doi:10.3762/bjoc.19.1

• allowed the delivery of trans-decalin 85 in a gram-scale quantity. Birch reduction of the electron-rich aromatic ring, followed by propargylic addition and functional group interconversion (FGI) provided dienyne 86. Compound 86, under the previously developed radical reductive cyclization for 1,6-dienyne

Synthesis of bis-spirocyclic derivatives of 3-azabicyclo[3.1.0]hexane via cyclopropene cycloadditions to the stable azomethine ylide derived from Ruhemann's purple

• Alexander S. Filatov,
• Olesya V. Khoroshilova,
• Anna G. Larina,
• Vitali M. Boitsov and
• Alexander V. Stepakov

Beilstein J. Org. Chem. 2022, 18, 769–780, doi:10.3762/bjoc.18.77

• and TS-4'-exo associate with nitrogen invertomers 4'-endo and 4'-exo of cycloadduct 4', respectively. Next, we determined the Gibbs energy of activation for nitrogen inversion in cycloadducts 4 and 4' to figure out if the invertomers undergo rapid interconversion. Having carried out full geometry

• -exo = 2.1 kcal/mol, ΔG‡4'-exo->4'-endo = 0.2 kcal/mol, and ΔG‡4'-endo->4'-exo = 3.8 kcal/mol). Since rapid interconversion takes place, it does not matter via which transition state (ΤS-4-endo or ΤS-4-exo) cycloadduct 4 is formed. The same pattern is consistent with cycloadduct 4'. It should be

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

• identified in two consecutive catalytic cycles. As a result, an astounding switchable catalytic system could be based on information processing (Figure 22). The following example of switchable catalysis involves the interconversion of the closed dimeric parallelogram [Cu2(104)2]2+ and the bishomoleptic

• 115 reclaims the proton back (Figure 25, top). As a result, State-II may be afforded under dissipative conditions. A surprising facet of this State-I/State-II interconversion (Figure 24) [112] was the finding that the protonated DABCO (60-H+) was a rather efficient base catalyst for a Knoevenagel

• -I/State-II interconversion in the presence of 116 and 117 was triggered by addition of the fuel acid. The traces in Figure 26 show the amount of Knoevenagel addition product 118 within two subsequent pulses of the fuel. In summary, the examples listed in this subchapter shed some light on the

Menadione: a platform and a target to valuable compounds synthesis

• Acácio S. de Souza,
• Ruan Carlos B. Ribeiro,
• Dora C. S. Costa,
• Fernanda P. Pauli,
• David R. Pinho,
• Matheus G. de Moraes,
• Fernando de C. da Silva,
• Luana da S. M. Forezi and
• Vitor F. Ferreira

Beilstein J. Org. Chem. 2022, 18, 381–419, doi:10.3762/bjoc.18.43

• ][38]. In the presence of oxygen, the reduced species is oxidized back to the quinone, thus completing the cycle. In case of naphthoquinones such as menadione, the quinone–semiquinone or quinone–hydroquinone interconversion generates reactive oxygen species (ROS), such as superoxide anion (O2

Iridium-catalyzed hydroacylation reactions of C1-substituted oxabenzonorbornadienes with salicylaldehyde: an experimental and computational study

• Angel Ho,
• Austin Pounder,
• Krish Valluru,
• Leanne D. Chen and
• William Tam

Beilstein J. Org. Chem. 2022, 18, 251–261, doi:10.3762/bjoc.18.30

• the art and science of selective molecular engineering [1]. To date, organic synthesis has largely been governed by the interconversion of pre-existing functional groups through the use of more traditional transition-metal-catalyzed cross-coupling reactions [2][3][4][5]. Although these reactions have

Peptide stapling by late-stage Suzuki–Miyaura cross-coupling

• Hendrik Gruß,
• Rebecca C. Feiner,
• Ridhiwan Mseya,
• David C. Schröder,
• Michał Jewgiński,
• Kristian M. Müller,
• Rafał Latajka,
• Antoine Marion and
• Norbert Sewald

Beilstein J. Org. Chem. 2022, 18, 1–12, doi:10.3762/bjoc.18.1

• diastereomers, i.e. cis/trans isomers or conformers with a high interconversion barrier. For complestatin-based macrocyclic peptides, the existence of biaryl atropisomers caused by the indole of tryptophan has been reported [82]. Recently, the occurrence of isomers was also observed in our group for SMC

• 1:44 at 300 K, with an interconversion barrier of 18.7 kcal mol−1 [83]. The experimental P5.1/P5.2 ratio is nearly 1:3, suggesting an energy difference of only 0.9 kcal mol−1 in favour of P5.2. Strain in the macrocycle might be responsible for such slight decrease in the relative energy between the

• hopeless to expect catching energy differences as small as that between P5.1/P5.2 by molecular modelling. Instead, we discuss qualitatively the conformational properties of the macrocycle in the two diastereomers of P5 to determine if conformers may exist with high interconversion barriers, and suggest an

Synthetic strategies toward 1,3-oxathiolane nucleoside analogues

• Umesh P. Aher,
• Dhananjai Srivastava,
• Girij P. Singh and
• Jayashree B. S

Beilstein J. Org. Chem. 2021, 17, 2680–2715, doi:10.3762/bjoc.17.182

• at C-2 but advantageous for the crystallization process. A number of bases was also evaluated by this research group: pyridine gave only a small amount of interconversion, whereas TEA caused rapid interconversion. Furthermore, it was discovered that instant interconversion and crystallization of 56a

α-Ketol and α-iminol rearrangements in synthetic organic and biosynthetic reactions

• Scott Benz and
• Andrew S. Murkin

Beilstein J. Org. Chem. 2021, 17, 2570–2584, doi:10.3762/bjoc.17.172

• interconversion of natural products prekinamycin (76) and isoprekinamycin (77) and chemical models of their proposed α-ketol intermediates. a) The natural products are believed to interconvert biologically by a reversible sequence of hydration–rearrangement–dehydration. b) α-Ketol rearrangement of 80, an analogue