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Search for "mechanisms" in Full Text gives 682 result(s) in Beilstein Journal of Organic Chemistry. Showing first 200.
Photochemical reduction of acylimidazolium salts
- Michael Jakob,
- Nick Bechler,
- Hassan Abdelwahab,
- Fabian Weber,
- Janos Wasternack,
- Leonardo Kleebauer,
- Jan P. Götze and
- Matthew N. Hopkinson
Beilstein J. Org. Chem. 2025, 21, 1973–1983, doi:10.3762/bjoc.21.153
- offer many synthetic advantages while the wide availability of chiral NHCs can also allow for high levels of enantioselectivity. As effective enamine and active ester derivatives, Breslow and acylazolium intermediates A and B typically react via classical two-electron polar mechanisms, however, recent
- an O-benzoylated intermediate species also being obtained under some conditions. Supported by TD-DFT studies, plausible reaction mechanisms for both processes were proposed. Moreover, further investigations employing silicon-containing additives allowed for an increase in the reduction yield beyond
Graphical Abstract
Figure 1: (a) Combining N-heterocyclic carbene (NHC) organocatalysis with photoredox catalysis for radical–ra...
Figure 2: Initial test reaction employing [Ir(dF(CF3)ppy)2(dtbpy)]PF6 as a photocatalyst in the presence of D...
Scheme 1: Plausible mechanism for the photocatalytic reduction of benzoylimidazolium salt 1 with DIPEA. [PC] ...
Scheme 2: Plausible mechanism for the photocatalyst-free reduction of benzoylimidazolium salt 1 into O-benzoy...
Figure 3: Reduction of 2-benzoylimidazolium triflate (1) under photocatalyst-free conditions monitored over 4...
Scheme 3: (a) Reduction of 2-benzoylimidazolium triflate (1) under photocatalyst-free conditions with DIPEA a...
Chiral phosphoric acid-catalyzed asymmetric synthesis of helically chiral, planarly chiral and inherently chiral molecules
- Wei Liu and
- Xiaoyu Yang
Beilstein J. Org. Chem. 2025, 21, 1864–1889, doi:10.3762/bjoc.21.145
- reaction mechanisms and applications of the chiral products for selected examples. Review Helical chirality Helicenes are a group of rigid polycyclic aromatic compounds composed of ortho-fused aromatic (hetero)cyclic rings, with their helically twisted conformation enforced by steric hindrance between
Graphical Abstract
Figure 1: General structure of CPAs and selected CPAs with various chiral scaffolds.
Figure 2: Representative elements of molecular chirality.
Scheme 1: CPA-catalyzed asymmetric synthesis of azahelicenes via Fischer indole synthesis.
Scheme 2: CPA-catalyzed asymmetric synthesis of azahelicenes via sequential Povarov reaction and oxidative ar...
Scheme 3: CPA-catalyzed asymmetric synthesis of azahelicenes via sequential Povarov reaction involving 3-viny...
Scheme 4: CPA-catalyzed asymmetric synthesis of heterohelicenes via sequential Povarov reaction involving 2-v...
Scheme 5: Diverse enantioselective synthesis of hetero[7]helicenes via a CPA-catalyzed double annulation stra...
Scheme 6: CPA-catalyzed asymmetric synthesis of indolohelicenoids through enantioselective cycloaddition and ...
Scheme 7: Kinetic resolution of helical polycyclic phenols via CPA-catalyzed enantioselective aminative dearo...
Scheme 8: Kinetic resolution of azahelicenes via CPA-catalyzed transfer hydrogenation.
Scheme 9: Asymmetric synthesis of planarly chiral macrocycles via CPA-catalyzed electrophilic aromatic aminat...
Scheme 10: Enantioselective synthesis of planarly chiral macrocycles via CPA-catalyzed macrocyclization.
Scheme 11: (Dynamic) kinetic resolution of planarly chiral paracyclophanes via CPA-catalyzed asymmetric reduct...
Scheme 12: Kinetic resolution of macrocyclic paracyclophanes through CPA/Bi-catalyzed asymmetric allylation.
Scheme 13: Enantioselective synthesis of planarly chiral macrocycles via CPA-catalyzed coupling of carboxylic ...
Scheme 14: Kinetic resolution of substituted amido[2.2]paracyclophanes via CPA-catalyzed asymmetric electrophi...
Scheme 15: Enantioselective synthesis of inherently chiral calix[4]arenes via sequential CPA-catalyzed Povarov...
Scheme 16: Asymmetric synthesis of inherently chiral calix[4]arenes via CPA-catalyzed aminative desymmetrizati...
Scheme 17: Asymmetric synthesis of chiral heterocalix[4]arenes via CPA-catalyzed intramolecular SNAr reaction.
Scheme 18: Enantioselective synthesis of inherently chiral DDDs via CPA-catalyzed cyclocondensation.
Scheme 19: Asymmetric synthesis of saddle-shaped inherently chiral 9,10-dihydrotribenzoazocines via CPA-cataly...
Scheme 20: Enantioselective synthesis of inherently chiral saddle-shaped dibenzo[b,f][1,5]diazocines via CPA-c...
Scheme 21: Enantioselective synthesis of inherent chiral 7-membered tribenzocycloheptene oximes via CPA-cataly...
Systematic pore lipophilization to enhance the efficiency of an amine-based MOF catalyst in the solvent-free Knoevenagel reaction
- Pricilla Matseketsa,
- Margret Kumbirayi Ruwimbo Pagare and
- Tendai Gadzikwa
Beilstein J. Org. Chem. 2025, 21, 1854–1863, doi:10.3762/bjoc.21.144
- ×20 magnification. Right: ratios of BMN:HPMM products for each catalyst. Probable mechanisms for the Knoevenegel condensation reaction between benzaldehyde and malononitrile catalyzed by a MOF-immobilized amine to form benzylidenemalononitrile (BMN). A) Mechanism in which the amine catalyst first
Graphical Abstract
Figure 1: Schematic representation of the modulation of MOF pore environments. A) de novo synthesis of severa...
Figure 2: A) Schematic representation of the reaction of KSU-1 with aliphatic isocyanates and the estimated c...
Scheme 1: Probable mechanisms for the Knoevenegel condensation reaction between benzaldehyde and malononitril...
Figure 3: A) Schematic representation of the reaction between benzaldehyde and malononitrile to form benzylid...
Figure 4: Graphical representation of the Knoevenagel catalysis results. A) Comparison of the reaction in tol...
Figure 5: Left: comparison of BMN and HPMM protons in 1H NMR spectra. Note that the peaks corresponding to HP...
Photoswitches beyond azobenzene: a beginner’s guide
- Michela Marcon,
- Christoph Haag and
- Burkhard König
Beilstein J. Org. Chem. 2025, 21, 1808–1853, doi:10.3762/bjoc.21.143
- explain the important terminology and discuss the synthesis, switching mechanisms, and properties of seven interesting photoswitch classes, namely azoheteroarenes, diazocines, indigoid photoswitches, arylhydrazones, diarylethenes, fulgides, and spiropyrans. Keywords: photoswitches; photoswitch properties
- ; synthesis of photoswitches; switching mechanisms; tutorial review; Introduction Photophysical properties and switching mechanism Key learning points Switching mechanisms and the change in properties. Overview of the major classes of photoswitches beyond azobenzenes. Main synthetic pathways for their
- absence of light. Apart from some special cases where more competing mechanisms are operating [5], the thermal isomerisation typically is a first-order decay: Where I is the monitored signal at the time t, I0 the initial signal, and k the kinetic constant. Once k is known, the thermal half-life t1/2 can
Graphical Abstract
Figure 1: Energy diagram of a two-state photoswitch. Figure 1 was redrawn from [2].
Figure 2: Example of the absorption spectra of the isomers of a photoswitch with most efficient irradiation w...
Scheme 1: Photoswitch classes described in this review.
Figure 3: Azoheteroarenes.
Scheme 2: E–Z Isomerisation (top) and mechanisms of thermal Z–E isomerisation (bottom).
Scheme 3: Rotation mechanism favoured by the electron displacement in push–pull systems. Selected examples of...
Figure 4: A) T-shaped and twisted Z-isomers determine the thermal stability and the Z–E-PSS (selected example...
Figure 5: Effect of di-ortho-substitution on thermal half-life and PSS.
Figure 6: Selected thermal lifetimes of azoindoles in different solvents and concentrations. aConcentration o...
Figure 7: Aryliminopyrazoles: N-pyrazoles (top) and N-phenyl (bottom).
Scheme 4: Synthesis of symmetrical heteroarenes through oxidation (A), reduction (B), and the Bayer–Mills rea...
Scheme 5: Synthesis of diazonium salt (A); different strategies of azo-coupling: with a nucleophilic ring (B)...
Scheme 6: Synthesis of arylazothiazoles 25 (A) and heteroaryltriazoles 28 (B).
Scheme 7: Synthesis of heteroarylimines 31a,b [36-38].
Figure 8: Push–pull non-ionic azo dye developed by Velasco and co-workers [45].
Scheme 8: Azopyridine reported by Herges and co-workers [46].
Scheme 9: Photoinduced phase transitioning azobispyrazoles [47].
Figure 9: Diazocines.
Scheme 10: Isomers, conformers and enantiomers of diazocine.
Scheme 11: Partial overlap of the ππ* band with electron-donating substituents and effect on the PSS. Scheme 11 was ada...
Figure 10: Main properties of diazocines with different bridges. aMeasured in n-hexane [56]. bMeasured in THF. cMe...
Scheme 12: Synthesis of symmetric diazocines.
Scheme 13: Synthesis of asymmetric diazocines.
Scheme 14: Synthesis of O- and S-heterodiazocines.
Scheme 15: Synthesis of N-heterodiazocines.
Scheme 16: Puromycin diazocine photoswitch [60].
Figure 11: Indigoids.
Figure 12: The main representatives of the indigoid photoswitch class.
Scheme 17: Deactivation process that prevents Z-isomerisation of indigo.
Figure 13: Stable Z-indigo derivative synthesised by Wyman and Zenhäusern [67].
Figure 14: Selected examples of indigos with aliphatic and aromatic substituents [68]. Dashed box: proposed π–π in...
Scheme 18: Resonance structures of indigo and thioindigo involving the phenyl ring.
Scheme 19: Possible deactivation mechanism for 4,4'-dihydroxythioindigo [76].
Scheme 20: Effect of different heteroaryl rings on the stability and the photophysical properties of hemiindig...
Figure 15: Thermal half-lives of red-shifted hemithioindigos in toluene [79]. aMeasured in toluene-d8.
Scheme 21: Structures of pyrrole [81] and imidazole hemithioindigo [64].
Figure 16: Examples of fully substituted double bond hemithioindigo (left), oxidised hemithioindigos (centre),...
Scheme 22: Structure of iminothioindoxyl 72 (top) and acylated phenyliminoindolinone photoswitch 73 (bottom). ...
Scheme 23: (top) Transition states of iminothioindoxyl 72. The planar transition state is associated with a lo...
Scheme 24: Baeyer–Drewsen synthesis of indigo (top) and N-functionalisation strategies (bottom).
Scheme 25: Synthesis of hemiindigo.
Scheme 26: Synthesis of hemithioindigo and iminothioindoxyl.
Scheme 27: Synthesis of double-bond-substituted hemithioindigos.
Scheme 28: Synthesis of phenyliminoindolinone.
Scheme 29: Hemithioindigo molecular motor [85].
Figure 17: Arylhydrazones.
Scheme 30: Switching of arylhydrazones. Note: The definitions of stator and rotor are arbitrary.
Scheme 31: Photo- and acidochromism of pyridine-based phenylhydrazones.
Scheme 32: A) E–Z thermal inversion of a thermally stable push–pull hydrazone [109]. B) Rotation mechanism favoured...
Scheme 33: Effect of planarisation on the half-life.
Scheme 34: The longest thermally stable hydrazone switches reported so far (left). Modulation of thermal half-...
Figure 18: Dependency of t1/2 on concentration and hypothesised aggregation-induced isomerisation.
Figure 19: Structure–property relationship of acylhydrazones.
Scheme 35: Synthesis of arylhydrazones.
Scheme 36: Synthesis of acylhydrazones.
Scheme 37: Photoswitchable fluorophore by Aprahamian et al. [115].
Scheme 38: The four-state photoswitch synthesised by the Cigáň group [116].
Figure 20: Diarylethenes.
Scheme 39: Isomerisation and oxidation pathway of E-stilbene to phenanthrene.
Scheme 40: Strategies adapted to avoid E–Z isomerisation and oxidation.
Scheme 41: Molecular orbitals and mechanism of electrocyclisation for a 6π system.
Figure 21: Aromatic stabilisation energy correlated with the thermal stability of the diarylethenes [127,129].
Figure 22: Half-lives of diarylethenes with increasing electron-withdrawing groups [128,129].
Scheme 42: Photochemical degradation pathway promoted by electron-donating groups [130].
Figure 23: The diarylethenes studied by Hanazawa et al. [134]. Increased rigidity leads to bathochromic shift.
Scheme 43: The dithienylethene synthesised by Nakatani's group [135].
Scheme 44: Synthesis of perfluoroalkylated diarylethenes.
Scheme 45: Synthesis of 139 and 142 via McMurry coupling.
Scheme 46: Synthesis of symmetrical derivatives 145 via Suzuki–Miyaura coupling.
Scheme 47: Synthesis of acyclic 148, malonic anhydride 149, and maleimide derivatives 154.
Figure 24: Gramicidin S (top left) and two of the modified diarylethene derivatives: first generation (bottom ...
Scheme 48: Pyridoxal 5'-phosphate and its reaction with an amino acid (top). The analogous dithienylethene der...
Figure 25: Fulgides.
Scheme 49: The three isomers of fulgides.
Scheme 50: Thermal and photochemical side products of unsubstituted fulgide [150].
Figure 26: Maximum absorption λc of the closed isomer compared with the nature of the aromatic ring and the su...
Scheme 51: Possible rearrangement of the excited state of 5-dimethylaminoindolylfulgide [153].
Figure 27: Quantum yields of ring closure (ΦE→C) and E–Z isomerisation (ΦE→Z) correlated with the increasing s...
Scheme 52: Active (Eα) and inactive (Eβ) conformers (left) and the bicyclic sterically blocked fulgide 169 (ri...
Scheme 53: Quantum yield of ring-opening (ΦC→E) and E–Z isomerisation (ΦE→Z) for different substitution patter...
Scheme 54: Stobbe condensation pathway for the synthesis of fulgides 179, fulgimides 181 and fulgenates 178.
Scheme 55: Alternative synthesis of fulgides through Pd-catalysed carbonylation.
Scheme 56: Optimised synthesis of fulgimides [166].
Scheme 57: Photoswitchable FRET with a fulgimide photoswitch [167].
Scheme 58: Three-state fulgimide strategy by Slanina's group.
Figure 28: Spiropyrans.
Scheme 59: Photochemical (left) and thermal (right) ring-opening mechanisms for an exemplary spiropyran with a...
Figure 29: Eight possible isomers of the open merocyanine according to the E/Z configurations of the bonds hig...
Scheme 60: pH-Controlled photoisomerisation between the closed spiropyran 191-SP and the open E-merocyanine 19...
Scheme 61: Behaviour of spiropyran in water buffer according to Andréasson and co-workers [180]. 192-SP in an aqueo...
Scheme 62: (left box) Proposed mechanism of basic hydrolysis of MC [184]. (right box) Introduction of electron-dona...
Scheme 63: Photochemical interconversion of naphthopyran 194 (top) and spirooxazine 195 (bottom) photoswitches...
Scheme 64: Synthesis of spiropyrans and spirooxazines 198 and the dicondensation by-product 199.
Scheme 65: Alternative synthesis of spiropyrans and spirooxazines with indolenylium salt 200.
Scheme 66: Synthesis of 4’-substituted spiropyrans 203 by condensation of an acylated methylene indoline 201 w...
Scheme 67: Synthesis of spironaphthopyrans 210 by acid-catalysed condensation of naphthols and diarylpropargyl...
Scheme 68: Photoswitchable surface wettability [194].
Figure 30: Some guiding principles for the choice of the most suitable photoswitch. Note that this guide is ve...
Fe-catalyzed efficient synthesis of 2,4- and 4-substituted quinolines via C(sp2)–C(sp2) bond scission of styrenes
- Prafull A. Jagtap,
- Manish M. Petkar,
- Vaishnavi R. Sawant and
- Bhalchandra M. Bhanage
Beilstein J. Org. Chem. 2025, 21, 1799–1807, doi:10.3762/bjoc.21.142
- [18]. Due to its wide range of applications, several methods for synthesizing substituted quinoline derivatives have been developed in recent decades, based on mechanisms such as Conrad–Limpach–Knorr [19], Friedländer [20], Doebner−Miller [21], Pfitzinger [22], Skraup [23], Povarov [24], and Combes
Graphical Abstract
Figure 1: Representative examples of bioactive quinolines.
Scheme 1: C(sp2)–C(sp2) bond-cleavage strategies for quinoline synthesis.
Scheme 2: Substrate scope of various arylamines and styrenes.
Scheme 3: Scale-up studies for the synthesis of antifungal agents.
Scheme 4: Mechanistic investigations.
Scheme 5: Plausible reaction mechanism.
Research progress on calixarene/pillararene-based controlled drug release systems
- Liu-Huan Yi,
- Jian Qin,
- Si-Ran Lu,
- Liu-Pan Yang,
- Li-Li Wang and
- Huan Yao
Beilstein J. Org. Chem. 2025, 21, 1757–1785, doi:10.3762/bjoc.21.139
- categorizes supramolecular chemistry-based drug-controlled release systems into the following three mechanisms: (1) Drugs are identified and combined with supramolecular hosts through host–guest interactions [23][24][25][26][27][28]. By adjusting the conditions surrounding the guest molecules, such as changes
- mechanisms that will be detailed in this article, researchers have made progress in the transport of amino acids and molecular peptides across membranes using macrocycles in recent years [35][36][37]. These works have paved the way for the potential application of remote-controlled membrane transport
- , enzymatic activity, hypoxia-triggered, and multi-responsive triggers. This article, based on the mechanisms of host–guest recognition, multifunctional assembly, and supramolecular nano-valves, provides several representative examples of CAs and PAs in the field of drug-controlled release. Finally, the
Graphical Abstract
Figure 1: Schematic diagram of drug-controlled release mechanisms based on aromatic macrocycles.
Figure 2: Chemical structure of a) calix[n]arene (m = 1,3,5), and b) pillar[n]arene (m = 1,2,3).
Figure 3: Changes in pH conditions cause the release of drugs from CA8 host–guest complexes [101]. Figure 3 was adapted wi...
Figure 4: The illustration of the pH-mediated 1:1 complex formation between the host and guest molecules in a...
Figure 5: Illustration of the pH-responsive self-assembly of mannose-modified CA4 into micelles and the subse...
Figure 6: Illustration of the assembly of supramolecular prodrug nanoparticles from WP6 and DOX-derived prodr...
Figure 7: Illustration of the formation of supramolecular vesicles and their pH-dependent drug release [93]. Figure 7 was...
Figure 8: Schematic illustration of the application of the multifunctional nanoplatform CyCA@POPD in combined...
Figure 9: Illustration of the photolysis of an amphiphilic assembly via CA-induced aggregation [114]. Figure 9 was reprint...
Figure 10: Schematic illustration of drug release controlled by the photo-responsive macroscopic switch based ...
Figure 11: Schematic illustration of the formation process of Azo-SMX and its photoisomerization reaction unde...
Figure 12: Schematic illustration of the enzyme-responsive behavior of supramolecular polymers [95]. Figure 12 was used wit...
Figure 13: Schematic illustration of the amphiphilic assembly of SC4A and its enzyme-responsive applications [119]. ...
Figure 14: Stimuli-responsive nanovalves based on MSNs and choline-SC4A[2]pseudorotaxanes, MSN-C1 with ester-l...
Figure 15: A schematic diagram showing the construction of a supramolecular system by host–guest interaction b...
Figure 16: A schematic diagram showing the formation of the host–guest complex DOX@Biotin-SAC4A by biotin modi...
Figure 17: A schematic diagram showing the self-assembly of CA4 into a hypoxia-responsive peptide hydrogel, wh...
Figure 18: Schematic illustration of the formation process of Lip@GluAC4A and the release of Lip under hypoxic...
Figure 19: Schematic illustration of the construction of a supramolecular vesicle based on the host–guest comp...
Figure 20: Schematic illustration of WP6 self-assembly at pH > 7, and the stimulus-responsive drug release beh...
Figure 21: Schematic illustration of the formation of supramolecular vesicles based on the WP5⊃G super-amphiph...
Figure 22: Schematic illustrations of the host–guest recognition of QAP5⊃SXD, the formation of the nanoparticl...
Figure 23: Schematic illustration of the activation of T-SRNs by acid, alkali, or Zn2+ stimuli to regulate the...
Figure 24: Illustration of the triggered release of BH from CP[5]A@MSNs-Q NPs in response to a drop in pH or a...
Figure 25: Illustration of the supramolecular amphiphiles TPENCn@1 (n = 6 and 12) self-assembling with disulfi...
Continuous-flow-enabled intensification in nitration processes: a review of technological developments and practical applications over the past decade
- Feng Zhou,
- Chuansong Duanmu,
- Yanxing Li,
- Jin Li,
- Haiqing Xu,
- Pan Wang and
- Kai Zhu
Beilstein J. Org. Chem. 2025, 21, 1678–1699, doi:10.3762/bjoc.21.132
- nitration compounds while inherently mitigating process hazards through intrinsic safety mechanisms. It is critical to clarify that although continuous-flow nitration processes have been extensively documented for a long time, the flow-chemistry technology discussed here primarily addresses small and
- advancements in flow-chemistry applications for nitration processes, this work establishes a practical framework to guide researchers in developing continuous-flow nitration systems. The analysis facilitates rapid understanding of fundamental principles and operational mechanisms governing continuous nitration
- aliphatic counterparts) due to their predictable electrophilic substitution mechanisms and relatively mild reaction conditions, which enable superior controllability and regioselectivity. Unlike aromatic nitrations that predominantly follow ionic mechanisms, aliphatic systems governed by free radical
Graphical Abstract
Figure 1: Three key dimensions of a complete nitration process.
Figure 2: A typical continuous-flow nitration reaction system.
Figure 3: Corrosion characteristics of common wetted materials used in continuous-flow nitration system. Note...
Figure 4: Analysis of the literature on continuous-flow nitration reaction over the past decade.
Scheme 1: Model reaction for the homogeneous nitration by nitric acid/mixed acid.
Figure 5: Safety assessment criteria for nitration reactions. Notes: apressure-independent; bno hazards arisi...
Figure 6: Guide for the investigation of continuous-flow nitration processes.
Structural analysis of stereoselective galactose pyruvylation toward the synthesis of bacterial capsular polysaccharides
- Tsun-Yi Chiang,
- Mei-Huei Lin,
- Chun-Wei Chang,
- Jinq-Chyi Lee and
- Cheng-Chung Wang
Beilstein J. Org. Chem. 2025, 21, 1671–1677, doi:10.3762/bjoc.21.131
- reaction mechanisms. Through this project, we aimed to explore the practical applications of PS A1 while simultaneously enhancing our understanding of synthetic chemistry. This endeavor reflects our commitment to advancing chemical knowledge and contributing to ongoing research in the field. Next, in-depth
Graphical Abstract
Figure 1: Pyruvylated galactose on bacterial polysaccharides PS A1 (1), 1.15 EPS (2) and Rhizobium leguminosa...
Figure 2: (a) Oak Ridge Thermal Ellipsoid Plot view of the X-ray crystal structure of pyruvylated galactose 6...
Scheme 1: Synthesis of trisaccharide precursor 14.
Transition-state aromaticity and its relationship with reactivity in pericyclic reactions
- Israel Fernández
Beilstein J. Org. Chem. 2025, 21, 1613–1626, doi:10.3762/bjoc.21.125
- ) of the butadiene + ethylene reaction proceeds with a lower barrier (up to 7 kcal/mol) than the corresponding stepwise pathway leading to a diradical intermediate (Scheme 1a) [19][20]. Similar preferences for concerted pathways over stepwise mechanisms were also found for dipolar cycloadditions and
- concerted mechanisms has not been considered. For instance, very little is known about the influence of TS-aromaticity (if any) on the barrier heights of catalyzed pericyclic reactions and related transformations. Our group has been focused on this aspect in recent years by exploring the interplay between
Graphical Abstract
Scheme 1: (a) Diels–Alder cycloaddition reaction between butadiene and ethylene. (b) Gold(I)-catalyzed propar...
Figure 1: Transition states computed for the Diels–Alder cycloaddition reaction between isoprene and methyl a...
Figure 2: Comparative activation strain analyses (a) and energy decomposition analysis (b) of the Diels–Alder...
Figure 3: (a) Evolution of the NICS(3, +1) values along a z-axis perpendicular to the molecular plane of the ...
Figure 4: Comparative activation strain analyses (a) and energy decomposition analysis (b) of the carbonyl–en...
Figure 5: AICD (a) and EDDB (b) plots for the transition state involved in the DGRT between ethene and ethane....
Figure 6: Comparative activation strain analyses (a) and energy decomposition analysis (b) of the DGRT betwee...
Scheme 2: Representative cycloisomerization reaction of 1,3-hexadien-5-yne.
Figure 7: AICD plots of the transition states associated with the Hopf cyclization reactions involving cis-he...
Figure 8: Comparative activation strain analyses of the Hopf cyclization involving ene–ene–ynes E=CH–CH=CH–C≡...
Scheme 3: 1,3-Dipolar cycloaddition reactions between t-BuN3 and cyaphide complexes.
Figure 9: Evolution of the NICS(3, +1) values along a z-axis perpendicular to the molecular plane of the TSs ...
Figure 10: Comparative activation strain analyses (a) and energy decomposition analysis (b) of the 1,3-dipolar...
3-Aryl-2H-azirines as annulation reagents in the Ni(II)-catalyzed synthesis of 1H-benzo[4,5]thieno[3,2-b]pyrroles
- Julia I. Pavlenko,
- Pavel A. Sakharov,
- Anastasiya V. Agafonova,
- Derenik A. Isadzhanyan,
- Alexander F. Khlebnikov and
- Mikhail S. Novikov
Beilstein J. Org. Chem. 2025, 21, 1595–1602, doi:10.3762/bjoc.21.123
- mechanisms of the formation of azirindine 16 under Ni(II)- and Cu(I)-catalysis. Oxidative dimerization of non-aromatic cyclic enols has been previously observed in their reactions with 3-arylazirines catalyzed by Cu(I) and Cu(II) complexes and was attributed to the recombination of intermediate free radicals
Graphical Abstract
Scheme 1: Synthesis of fused pyrroles and azoles by [3 + 2] annulation reactions of azirines.
Scheme 2: Synthesis of benzo[4,5]thieno[3,2-b]pyrroles 3.
Scheme 3: Plausible mechanism for the formation of compounds 3.
Scheme 4: Post-modifications of 1H-benzo[4,5]thieno[3,2-b]pyrrole (3b).
Scheme 5: Synthesis of pyrrolo[3,2-b]indole 10.
Scheme 6: IPrCuCl-catalyzed reactions of indoles 9b,c with azirine 2a.
Scheme 7: Ni(II)- and Cu(I)-catalyzed reactions of indole 15 with azirine 2a.
Azobenzene protonation as a tool for temperature sensing
- Antti Siiskonen,
- Sami Vesamäki and
- Arri Priimagi
Beilstein J. Org. Chem. 2025, 21, 1528–1534, doi:10.3762/bjoc.21.115
- -dichloroethane and highlight its potential for temperature sensing applications. Density functional theory calculations were performed to support our findings and to investigate the mechanisms of azobenzene–acid interactions, aiming to guide the design of azobenzene-based temperature sensors in future research
Graphical Abstract
Figure 1: A) Protonation reaction scheme of azobenzene (1), 4-methoxyazobenzene (2), and 4,4'-dimethoxyazoben...
Figure 2: A) The effect of temperature on the degree of protonation of compound 3 (40 μM at 25 °C) in DCE wit...
Figure 3: The geometry-optimized structure of 3H+MSA−MSA.
Wittig reaction of cyclobisbiphenylenecarbonyl
- Taito Moribe,
- Junichiro Hirano,
- Hideaki Takano,
- Hiroshi Shinokubo and
- Norihito Fukui
Beilstein J. Org. Chem. 2025, 21, 1454–1461, doi:10.3762/bjoc.21.107
- group (Figure S20, Supporting Information File 1), which will be due to the disrupted nucleophilic attack to the carbonyl group by the intramolecular steric repulsion toward the Bürgi–Dunitz angle. However, alternative mechanisms initiated by a conventional oxaphosphetane formation cannot not yet be
Graphical Abstract
Figure 1: Synthesis and structures of CBBC 1.
Scheme 1: Wittig reactions of CBBC 1.
Figure 2: X-ray crystal structures of (a) 3, (b) 4, and (c) 5 with thermal ellipsoids at 50% probability; all...
Figure 3: VT 1H NMR spectra of 5 in CD2Cl2 at (a) 298 K, (b) 243 K, and (c) 203 K. Blue circle and red triang...
Figure 4: Simulated dynamics of bis-olefin 5 at the B3LYP/6-31G(d) level of theory. The description for the c...
Figure 5: (a) UV–vis absorption (solid lines) and emission (dashed lines) spectra of 1 (black), 3 (blue), and ...
Scheme 2: Conversion of mono-olefin 3 to internally functionalized DBC derivative 6.
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
- have also been reported. The following sub-chapters will describe the recently developed systems, including possible mechanisms and potential applications, if appropriate. 3.1.1 Intramolecular ring-opening reactions: In 2016, Bull and colleagues developed a mild approach towards 2,3-dihydrobenzofurans
Graphical Abstract
Figure 1: Bond lengths and bond angles in oxetane at 140 K [2].
Figure 2: Analogy of 3-substituted oxetanes to carbonyl and gem-dimethyl groups [12].
Figure 3: Use of oxetanes in drug design – selected examples.
Figure 4: Examples of oxetane-containing natural products.
Scheme 1: Synthetic strategies towards construction of the oxetane ring.
Scheme 2: Overview of intramolecular Williamson etherification and competing Grob fragmentation.
Scheme 3: Synthesis of spiro-oxetanes via 1,4-C–H insertion and Williamson etherification.
Scheme 4: Use of phenyl vinyl selenone in the synthesis of spirooxindole oxetanes.
Scheme 5: Synthesis of bicyclic 3,5-anhydrofuranoses via double epoxide opening/etherification.
Scheme 6: Preparation of spirooxetanes by cycloisomerisation via MHAT/RPC.
Scheme 7: Oxetane synthesis via alcohol C–H functionalisation.
Scheme 8: Access to oxetanes 38 from α-acetyloxy iodides.
Scheme 9: The kilogram-scale synthesis of oxetane intermediate 41.
Scheme 10: Overview of the intramolecular opening of 3-membered rings.
Scheme 11: Synthesis of 4,7-dioxatricyclo[3.2.1.03,6]octane skeletons.
Scheme 12: Silicon-directed electrophilic cyclisation of homoallylic alcohols.
Scheme 13: Hydrosilylation–iodocyclisation of homopropargylic alcohols.
Scheme 14: Cu-catalysed intramolecular O-vinylation of γ-bromohomoallylic alcohols.
Scheme 15: Cu-catalysed intramolecular cross-coupling of hydroxyvinylstannanes.
Scheme 16: Isomerisation of oxiranyl ethers containing weakly carbanion-stabilising groups.
Scheme 17: Cyclisation of diethyl haloalkoxymalonates.
Scheme 18: Synthesis of oxetanes through a 1,5-HAT/radical recombination sequence.
Scheme 19: General approach to oxetanes via [2 + 2] cycloadditions.
Scheme 20: Synthesis of tricyclic 4:4:4 oxetanes through a photochemical triple cascade reaction.
Scheme 21: Iridium-catalysed Paternò–Büchi reaction between α-ketoesters and simple alkenes.
Scheme 22: Three-step synthesis of spirocyclic oxetanes 83 via Paternò–Büchi reaction, nucleophilic ring openi...
Scheme 23: Enantioselective Paternò–Büchi reaction catalysed by a chiral iridium photocatalyst.
Scheme 24: Synthesis of polysubstituted oxetanes 92 via Cu(II)-mediated formal [2 + 2] cycloadditions.
Scheme 25: Synthesis of alkylideneoxetanes via NHC- and DBU-mediated formal [2 + 2] cycloadditions.
Scheme 26: Use of sulphur-stabilised carbanions in ring expansions.
Scheme 27: Synthesis of α,α-difluoro(arylthio)methyl oxetanes.
Scheme 28: Ring expansion in an industrial synthesis of PF-06878031.
Scheme 29: Ring contraction of triflated 2-hydroxy-γ-lactones.
Scheme 30: Ring contraction in an industrial synthesis of PF-06878031.
Scheme 31: Photochemical ring contraction of 2,5-dihydrofurans by aryldiazoacetic acid esters.
Scheme 32: Synthesis of 3-oxetanones via O-H insertion of carbenes.
Scheme 33: Synthesis of phosphonate oxetanones via gold-mediated alkyne oxidation/O–H insertion.
Scheme 34: Syntheses and common derivatisations of 3-oxetanone.
Scheme 35: SN1 substitution of 3-aryloxetan-3-ols by thiols and alcohols.
Scheme 36: Fe–Ni dual-catalytic olefin hydroarylation towards 3-alkyl-3-(hetero)aryloxetanes.
Scheme 37: Synthesis of 3-aryloxetan-3-carboxylic acids.
Scheme 38: Decarboxylative alkylation of 3-aryloxetan-3-carboxylic acids.
Scheme 39: Synthesis of 3-amino-3-aryloxetanes via photoredox/nickel cross-coupling catalysis.
Scheme 40: Intermolecular cross-selective [2 + 2] photocycloaddition towards spirooxetanes.
Scheme 41: Synthesis of 3-aryl-3-aminooxetanes via defluorosulphonylative coupling.
Scheme 42: Two-step synthesis of amide bioisosteres via benzotriazolyl Mannich adducts 170.
Scheme 43: Functionalisation of oxetanyl trichloroacetimidates 172.
Scheme 44: Synthesis of oxetane-amino esters 176.
Scheme 45: Tandem Friedel–Crafts alkylation/intramolecular ring opening of 3-aryloxetan-3-ols.
Scheme 46: Synthesis of polysubstituted furans and pyrroles.
Scheme 47: Synthesis of oxazolines and bisoxazolines.
Scheme 48: Tandem, one-pot syntheses of various polycyclic heterocycles.
Scheme 49: Synthesis of 1,2-dihydroquinolines via skeletal reorganisation of oxetanes.
Scheme 50: Synthesis of benzoindolines and 2,3-dihydrobenzofurans and their derivatisations.
Scheme 51: Synthesis of polysubstituted 1,4-dioxanes.
Scheme 52: Preparation of various lactones via ring opening of oxetane-carboxylic acids 219.
Scheme 53: Tsuji-Trost allylation/ring opening of 3-aminooxetanes.
Scheme 54: Arylative skeletal rearrangement of 3-vinyloxetan-3-ols to 2,5-dihydrofurans.
Scheme 55: Reductive opening of oxetanes using catalytic Mg–H species.
Scheme 56: Opening of oxetanes by silyl ketene acetals.
Scheme 57: Rhodium-catalysed hydroacylation of oxetanes.
Scheme 58: Generation of radicals from oxetanes mediated by a vitamin B12-derived cobalt catalyst.
Scheme 59: Reductive opening of oxetanes by B–Si frustrated Lewis pairs.
Scheme 60: Zirconocene-mediated reductive opening of oxetanes.
Scheme 61: Enantioselective syntheses of small and medium-size rings using chiral phosphoric acids.
Scheme 62: Asymmetric synthesis of 2,3-dihydrobenzo[b]oxepines catalysed by a chiral scandium complex.
Scheme 63: Enantioselective synthesis of 1,3-bromohydrins under a chiral squaramide catalysis.
Scheme 64: Enantioselective opening of 2-aryl-2-ethynyloxetanes by anilines.
Scheme 65: Ru-catalysed insertion of diazocarbonyls into oxetanes.
Scheme 66: Ring expansion of oxetanes by stabilised carbenes generated under blue light irradiation.
Scheme 67: Expansion of oxetanes via nickel-catalysed insertion of alkynyltrifluoroborates.
Scheme 68: Nickel-catalysed expansion of oxetanes into ε-caprolactones.
Scheme 69: Expansion of oxetanes via cobalt-catalysed carbonyl insertion.
Scheme 70: Gold-catalysed intramolecular 1,1-carboalkoxylation of oxetane-ynamides.
Scheme 71: Expansion of oxetanes by stabilised sulphoxonium ylides.
Scheme 72: Cu-catalysed ring expansion of 2-vinyloxetanes by diazoesters.
Scheme 73: Total synthesis of (+)-oxetin.
Scheme 74: Total synthesis of racemic oxetanocin A.
Scheme 75: Total synthesis of (−)-merrilactone A.
Scheme 76: Total synthesis of (+)-dictyoxetane.
Scheme 77: Total synthesis of ent-dichrocephone B.
Scheme 78: Total synthesis of (−)-mitrephorone A.
Scheme 79: Total synthesis of (−)-taxol.
Recent advances in amidyl radical-mediated photocatalytic direct intermolecular hydrogen atom transfer
- Hao-Sen Wang,
- Lin Li,
- Xin Chen,
- Jian-Li Wu,
- Kai Sun,
- Xiao-Lan Chen,
- Ling-Bo Qu and
- Bing Yu
Beilstein J. Org. Chem. 2025, 21, 1306–1323, doi:10.3762/bjoc.21.100
- the research of direct functionalization via HAT processes and the development of green chemistry in photocatalysis, this review will focus on the generation of amidyl radicals and reaction mechanisms and highlight the photocatalyzed reaction characteristics. This review aims to provide researchers
Graphical Abstract
Figure 1: (a) BDE of C–H. (b) Direct functionalization of C–H catalyzed by transition-metal. (c) Direct funct...
Figure 2: (a) Amidyl radical-enabled hydrogen atom transfer. (b) Substituent effects to amidyl radical proper...
Figure 3: Representative photocatalysts discussed in this review.
Scheme 1: Alkylation of C(sp3)–H catalyzed by amidyl radical under visible light.
Scheme 2: Direct heteroarylation of C(sp3)–H catalyzed by amidyl radical under visible light.
Scheme 3: Alkylation of C(sp3)–H catalyzed by amidyl radical and metal-free photocatalyst under visible light....
Scheme 4: Alkylation of C(sp3)–H, Si–H, and Ge–H catalyzed by amidyl radical under visible light.
Scheme 5: Direct heteroarylation of C(sp3)–H catalyzed by synergistic promotion of amidyl radical and photoca...
Scheme 6: Direct B–H functionalization of icosahedral carboranes catalyzed by amidyl radical under visible li...
Scheme 7: Nucleophilic amination of C(sp3)–H enabled by amidyl radical under visible light.
Scheme 8: Direct heteroarylation of C(sp3)–H and C(sp3)–H without the presence of strong bases, acids, or oxi...
Scheme 9: Xanthylation of C(sp3)–H addressed by amidyl radical under visible light.
Scheme 10: Xanthylation of C(sp3)–H in polyolefins addressed by amidyl radical under visible light.
Scheme 11: Site-selective C(sp3)–H bromination implemented by amidyl radical under visible light.
Scheme 12: Site-selective chlorination of C(sp3)–H in natural products implemented by amidyl radical under vis...
Scheme 13: Alkylation of C(sp3)–H catalyzed by amidyl radical photocatalyst under visible light.
Recent advances and future challenges in the bottom-up synthesis of azulene-embedded nanographenes
- Bartłomiej Pigulski
Beilstein J. Org. Chem. 2025, 21, 1272–1305, doi:10.3762/bjoc.21.99
- ]. Instead, products of a skeletal arrangement of one azulene moiety 121 and two azulene moieties 122 were isolated in low yields (1% and 4%, respectively). Plausible mechanisms of such a cyclopenta[ef]heptalene to phenanthrene rearrangement were proposed by the authors and involve the arenium ion pathway or
Graphical Abstract
Figure 1: a) Stone–Wales (red) and azulene (blue) defects in graphene; b) azulene and its selected resonance ...
Figure 2: Examples of azulene-embedded 2D allotropic forms of carbon: a) phagraphene and b) TPH-graphene.
Scheme 1: Synthesis of non-alternant isomers of pyrene (2 and 6) using dehydrogenation.
Scheme 2: Synthesis of non-alternant isomer 9 of benzo[a]pyrene and 14 of benzo[a]perylene using dehydrogenat...
Scheme 3: Synthesis of azulene-embedded isomers of benzo[a]pyrene (18 and 22) inspired by Ziegler–Hafner azul...
Figure 3: General strategies leading to azulene-embedded nanographenes: a) construction of azulene moiety in ...
Scheme 4: Synthesis of biradical PAHs possessing significant biradical character using oxidation of partially...
Scheme 5: Synthesis of dicyclohepta[ijkl,uvwx]rubicene (29) and its further modifications.
Scheme 6: Synthesis of warped PAHs with one embedded azulene subunit using Scholl-type oxidation.
Scheme 7: Synthesis of warped PAHs with two embedded azulene subunits using Scholl oxidation.
Scheme 8: Synthesis of azulene-embedded PAHs using [3 + 2] annulation accompanied by ring expansion.
Scheme 9: Synthesis of azulene-embedded isomers of linear acenes using [3 + 2] annulation accompanied by ring...
Scheme 10: Synthesis of azulene-embedded PAHs using intramolecular C–H arylation.
Scheme 11: Synthesis of azulene-embedded isomers of acenes using intramolecular C–H arylation.
Scheme 12: Synthesis of azulene-embedded PAHs using intramolecular condensations.
Scheme 13: Synthesis of azulene-embedded PAH 89 using palladium-catalysed [5 + 2] annulation.
Scheme 14: Synthesis of azulene-embedded PAHs using oxidation of substituents around the azulene core.
Scheme 15: Synthesis of azulene-embedded PAHs using the oxidation of reactive positions 1 and 3 of azulene sub...
Scheme 16: Synthesis of azulene-embedded PAHs using intramolecular C–H arylation.
Scheme 17: Synthesis of an azulene-embedded isomer of terylenebisimide using tandem Suzuki coupling and C–H ar...
Scheme 18: Synthesis of azulene embedded PAHs using a bismuth-catalyzed cyclization of alkenes.
Scheme 19: Synthesis of azulene-embedded nanographenes using intramolecular cyclization of alkynes.
Scheme 20: Synthesis of azulene-embedded graphene nanoribbons and azulene-embedded helicenes using annulation ...
Scheme 21: Synthesis of azulene-fused acenes.
Scheme 22: Synthesis of non-alternant isomer of perylene 172 using Yamamoto-type homocoupling.
Scheme 23: Synthesis of N- and BN-nanographenes with embedded azulene unit(s).
Scheme 24: On-surface synthesis of azulene-embedded nanographenes from benzenoid precursors via dehydrogenatio...
Scheme 25: On-surface synthesis of azulene-embedded nanographenes from benzenoid precursors.
Scheme 26: On-surface synthesis of azulene-embedded nanoribbons.
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
- substrate scope and excellent functional-group tolerance (62a–f). Based on the experimental results, two possible mechanisms were proposed for this transformation, as illustrated in Scheme 30. In the first mechanism, an alkyl radical A is generated in the presence of PdCl2(MeCN)2 and Ag2CO3, and then
Graphical Abstract
Scheme 1: DTBP-mediated oxidative alkylarylation of activated alkenes.
Scheme 2: Iron-catalyzed oxidative 1,2-alkylarylation.
Scheme 3: Possible mechanism for the iron-catalyzed oxidative 1,2-alkylation of activated alkenes.
Scheme 4: A metal-free strategy for synthesizing 3,3-disubstituted oxindoles.
Scheme 5: Iminoxyl radical-promoted cascade oxyalkylation/alkylarylation of alkenes.
Scheme 6: Proposed mechanism for the iminoxyl radical-promoted cascade oxyalkylation/alkylarylation of alkene...
Scheme 7: Bicyclization of 1,n-enynes with alkyl nitriles.
Scheme 8: Possible reaction mechanism for the bicyclization of 1,n-enynes with alkyl nitriles.
Scheme 9: Radical cyclization of N-arylacrylamides with isocyanides.
Scheme 10: Plausible mechanism for the radical cyclization of N-arylacrylamides with isocyanides.
Scheme 11: Electrochemical dehydrogenative cyclization of 1,3-dicarbonyl compounds.
Scheme 12: Plausible mechanism for the dehydrogenative cyclization of 1,3-dicarbonyl compounds.
Scheme 13: Photocatalyzed cyclization of N-arylacrylamide and N,N-dimethylaniline.
Scheme 14: Proposed mechanism for the photocatalyzed cyclization of N-arylacrylamides and N,N-dimethylanilines....
Scheme 15: Electrochemical monofluoroalkylation cyclization of N-arylacrylamides with dimethyl 2-fluoromalonat...
Scheme 16: Proposed mechanism for the electrochemical radical cyclization of N-arylacrylamides with dimethyl 2...
Scheme 17: Photoelectrocatalytic carbocyclization of unactivated alkenes using simple malonates.
Scheme 18: Plausible mechanism for the photoelectrocatalytic carbocyclization of unactivated alkenes with simp...
Scheme 19: Bromide-catalyzed electrochemical trifluoromethylation/cyclization of N-arylacrylamides.
Scheme 20: Proposed mechanism for the electrochemical trifluoromethylation/cyclization of N-arylacrylamides.
Scheme 21: Visible light-mediated trifluoromethylarylation of N-arylacrylamides.
Scheme 22: Plausible reaction mechanism for the visible light-mediated trifluoromethylarylation of N-arylacryl...
Scheme 23: Electrochemical difluoroethylation cyclization of N-arylacrylamides with sodium difluoroethylsulfin...
Scheme 24: Electrochemical difluoroethylation cyclization of N-methyacryloyl-N-alkylbenzamides with sodium dif...
Scheme 25: Photoredox-catalyzed radical aryldifluoromethylation of N-arylacrylamides with S-(difluoromethyl)su...
Scheme 26: Proposed mechanism for the photoredox-catalyzed radical aryldifluoromethylation of N-arylacrylamide...
Scheme 27: Visible-light-induced domino difluoroalkylation/cyclization of N-cyanamide alkenes.
Scheme 28: Proposed mechanism of photoredox-catalyzed radical domino difluoroalkylation/cyclization of N-cyana...
Scheme 29: Palladium-catalyzed oxidative difunctionalization of alkenes.
Scheme 30: Two possible mechanisms of palladium-catalyzed oxidative difunctionalization.
Scheme 31: Silver-catalyzed oxidative 1,2-alkyletherification of unactivated alkenes with α-bromoalkylcarbonyl...
Scheme 32: Photochemical radical cascade cyclization of dienes.
Scheme 33: Proposed mechanism for the photochemical radical cascade 6-endo cyclization of dienes with α-carbon...
Scheme 34: Photocatalyzed radical coupling/cyclization of N-arylacrylamides and.
Scheme 35: Photocatalyzed radical-type couplings/cyclization of N-arylacrylamides with sulfoxonium ylides.
Scheme 36: Possible mechanism of visible-light-induced radical-type couplings/cyclization of N-arylacrylamides...
Scheme 37: Visible-light-promoted difluoroalkylated oxindoles systhesis via EDA complexes.
Scheme 38: Possible mechanism for the visible-light-promoted radical cyclization of N-arylacrylamides with bro...
Scheme 39: A dicumyl peroxide-initiated radical cascade reaction of N-arylacrylamide with DCM.
Scheme 40: Possible mechanism of radical cyclization of N-arylacrylamides with DCM.
Scheme 41: An AIBN-mediated radical cascade reaction of N-arylacrylamides with perfluoroalkyl iodides.
Scheme 42: Possible mechanism for the reaction with perfluoroalkyl iodides.
Scheme 43: Photoinduced palladium-catalyzed radical annulation of N-arylacrylamides with alkyl halides.
Scheme 44: Radical alkylation/cyclization of N-Alkyl-N-methacryloylbenzamides with alkyl halides.
Scheme 45: Possible mechanism for the alkylation/cyclization with unactivated alkyl chlorides.
Scheme 46: Visible-light-driven palladium-catalyzed radical cascade cyclization of N-arylacrylamides with unac...
Scheme 47: NHC-catalyzed radical cascade cyclization of N-arylacrylamides with alkyl bromides.
Scheme 48: Possible mechanism of NHC-catalyzed radical cascade cyclization.
Scheme 49: Electrochemically mediated radical cyclization reaction of N-arylacrylamides with freon-type methan...
Scheme 50: Proposed mechanistic pathway of electrochemically induced radical cyclization reaction.
Scheme 51: Redox-neutral photoinduced radical cascade cylization of N-arylacrylamides with unactivated alkyl c...
Scheme 52: Proposed mechanistic hypothesis of redox-neutral radical cascade cyclization.
Scheme 53: Thiol-mediated photochemical radical cascade cylization of N-arylacrylamides with aryl halides.
Scheme 54: Proposed possible mechanism of thiol-mediated photochemical radical cascade cyclization.
Scheme 55: Visible-light-induced radical cascade bromocyclization of N-arylacrylamides with NBS.
Scheme 56: Possible mechanism of visible-light-induced radical cascade cyclization.
Scheme 57: Decarboxylation/radical C–H functionalization by visible-light photoredox catalysis.
Scheme 58: Plausible mechanism of visible-light photoredox-catalyzed radical cascade cyclization.
Scheme 59: Visible-light-promoted tandem radical cyclization of N-arylacrylamides with N-(acyloxy)phthalimides....
Scheme 60: Plausible mechanism for the tandem radical cyclization reaction.
Scheme 61: Visible-light-induced aerobic radical cascade alkylation/cyclization of N-arylacrylamides with alde...
Scheme 62: Plausible mechanism for the aerobic radical alkylarylation of electron-deficient amides.
Scheme 63: Oxidative decarbonylative [3 + 2]/[5 + 2] annulation of N-arylacrylamide with vinyl acids.
Scheme 64: Plausible mechanism for the decarboxylative (3 + 2)/(5 + 2) annulation between N-arylacrylamides an...
Scheme 65: Rhenium-catalyzed alkylarylation of alkenes with PhI(O2CR)2.
Scheme 66: Plausible mechanism for the rhenium-catalyzed decarboxylative annulation of N-arylacrylamides with ...
Scheme 67: Visible-light-induced one-pot tandem reaction of N-arylacrylamides.
Scheme 68: Plausible mechanism for the visible-light-initiated tandem synthesis of difluoromethylated oxindole...
Scheme 69: Copper-catalyzed redox-neutral cyanoalkylarylation of activated alkenes with cyclobutanone oxime es...
Scheme 70: Plausible mechanism for the copper-catalyzed cyanoalkylarylation of activated alkenes.
Scheme 71: Photoinduced alkyl/aryl radical cascade for the synthesis of quaternary CF3-attached oxindoles.
Scheme 72: Plausible photoinduced electron-transfer (PET) mechanism.
Scheme 73: Photoinduced cerium-mediated decarboxylative alkylation cascade cyclization.
Scheme 74: Plausible reaction mechanism for the decarboxylative radical-cascade alkylation/cyclization.
Scheme 75: Metal-free oxidative tandem coupling of activated alkenes.
Scheme 76: Control experiments and possible mechanism for 1,2-carbonylarylation of alkenes with carbonyl C(sp2...
Scheme 77: Silver-catalyzed acyl-arylation of activated alkenes with α-oxocarboxylic acids.
Scheme 78: Proposed mechanism for the decarboxylative acylarylation of acrylamides.
Scheme 79: Visible-light-mediated tandem acylarylation of olefines with carboxylic acids.
Scheme 80: Proposed mechanism for the radical cascade cyclization with acyl radical via visible-light photored...
Scheme 81: Erythrosine B-catalyzed visible-light photoredox arylation-cyclization of N-arylacrylamides with ar...
Scheme 82: Electrochemical cobalt-catalyzed radical cyclization of N-arylacrylamides with arylhydrazines or po...
Scheme 83: Proposed mechanism of radical cascade cyclization via electrochemical cobalt catalysis.
Scheme 84: Copper-catalyzed oxidative tandem carbamoylation/cyclization of N-arylacrylamides with hydrazinecar...
Scheme 85: Proposed reaction mechanism for the radical cascade cyclization by copper catalysis.
Scheme 86: Visible-light-driven radical cascade cyclization reaction of N-arylacrylamides with α-keto acids.
Scheme 87: Proposed mechanism of visible-light-driven cascade cyclization reaction.
Scheme 88: Peroxide-induced radical carbonylation of N-(2-methylallyl)benzamides with methyl formate.
Scheme 89: Proposed cyclization mechanism of peroxide-induced radical carbonylation with N-(2-methylallyl)benz...
Scheme 90: Persulfate promoted carbamoylation of N-arylacrylamides and N-arylcinnamamides.
Scheme 91: Proposed mechanism for the persulfate promoted radical cascade cyclization reaction of N-arylacryla...
Scheme 92: Photocatalyzed carboacylation with N-arylpropiolamides/N-alkyl acrylamides.
Scheme 93: Plausible mechanism for the photoinduced carboacylation of N-arylpropiolamides/N-alkyl acrylamides.
Scheme 94: Electrochemical Fe-catalyzed radical cyclization with N-arylacrylamides.
Scheme 95: Plausible mechanism for the electrochemical Fe-catalysed radical cyclization of N-phenylacrylamide.
Scheme 96: Substrate scope of the selective functionalization of various α-ketoalkylsilyl peroxides with metha...
Scheme 97: Proposed reaction mechanism for the Fe-catalyzed reaction of alkylsilyl peroxides with methacrylami...
Scheme 98: EDA-complex mediated C(sp2)–C(sp3) cross-coupling of TTs and N-methyl-N-phenylmethacrylamides.
Scheme 99: Proposed mechanism for the synthesis of oxindoles via EDA complex.
Enhancing chemical synthesis planning: automated quantum mechanics-based regioselectivity prediction for C–H activation with directing groups
- Julius Seumer,
- Nicolai Ree and
- Jan H. Jensen
Beilstein J. Org. Chem. 2025, 21, 1171–1182, doi:10.3762/bjoc.21.94
- metallation deprotonation mechanisms mediated by common catalysts like Pd(OAc)2. Our methodology not only identifies potential activation sites but also addresses the limitations of existing models by including a broader range of directing groups and reaction conditions while maintaining moderate
- chemistry’s structural variability. Cao et al. [14] developed an automated workflow that predicts the regioselectivity of C–H activations using extensive DFT calculations on a HPC cluster using up to 600 nodes, each containing 16 Intel Xeon E5-2670 cores. They considered two possible reaction mechanisms, an
Graphical Abstract
Figure 1: Overview of the predictive workflow: For the shown substrate on the left, three unique activation s...
Figure 2: Example of the output from running the SMARTS pattern approach introduced by Tomberg et al. [9] with t...
Figure 3: An example where our algorithm found a more specific SMARTS pattern match than highlighted in Tombe...
Figure 4: An example highlighting the difficulties in prioritizing the SMARTS patterns. All three patterns ma...
Figure 5: Example of a combination of C–H bond and DG that is discarded because of the angle constraint on th...
Figure 6: Example of combinations of C–H bonds and DGs that are considered identical because of symmetry of t...
Figure 7: Example of combinations of C–H bonds and DGs that are considered identical because of symmetry of t...
Figure 8: Example of combinations of C–H bonds and DGs that are considered identical because of resonance str...
Figure 9: A: Distribution of correct (green) and wrong (red) predictions for molecules with two to five poten...
Figure 10: Molecules with five potential reaction sites that are predicted wrong by the QM workflow. The exper...
Figure 11: Predictions of reaction sites within a 1 kcal·mol−1 threshold for ten molecules are marked with a b...
Figure 12: Substrate with six potential unique reaction sites for C–H functionalization. The experimentally de...
A multicomponent reaction-initiated synthesis of imidazopyridine-fused isoquinolinones
- Ashutosh Nath,
- John Mark Awad and
- Wei Zhang
Beilstein J. Org. Chem. 2025, 21, 1161–1169, doi:10.3762/bjoc.21.92
- thiophene to reduce the diene's reactivity or altering the electrophilicity of the dienophile. Based on the computational analysis of the transition states, reaction mechanisms for the IMDA and the dehydration re-aromatization process are proposed in Scheme 5. In the IMDA reaction for the preparation of
- preparation of imidazo[1,2-a]pyridines 6. Substrate scope for IMDA and dehydrative aromatization in making 8. Reaction conditions: 6 and AlCl3 (10 mol %) in 1,2-dichlorobenzene at 180 °C for 4 h. Using thiophene-2-carbaldehyde for the synthesis of 8t. Proposed mechanisms for IMDA reaction and dehydration re
Graphical Abstract
Figure 1: Bioactive compounds bearing imidazopyridine (red) and isoquinolinone-kind (blue) rings.
Scheme 1: GBB-initiated synthesis of imidazopyridine-fused isoquinolinones.
Scheme 2: GBB reaction and N-acylation for the preparation of imidazo[1,2-a]pyridines 6.
Scheme 3: Substrate scope for IMDA and dehydrative aromatization in making 8. Reaction conditions: 6 and AlCl3...
Figure 2: Transition state analysis of IMDA reactions for 6a, 6j, 6h and 6r.
Figure 3: Relative energy diagram for the synthesis of 8a from 6a.
Scheme 4: Using thiophene-2-carbaldehyde for the synthesis of 8t.
Scheme 5: Proposed mechanisms for IMDA reaction and dehydration re-aromatization.
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
- these derivatives, this study aims to offer direct synthetic guidance and important insights into the rational design of novel cinnamate molecules with promising potential as future drug candidates. The reaction mechanisms will be discussed briefly. 2 Carboxyl group functionalization 2.1 O/N-acylations
Graphical Abstract
Figure 1: Biologically active cinnamic acid derivatives.
Scheme 1: General synthetic strategies for cinnamic acid derivatizations.
Scheme 2: Cinnamic acid coupling via isobutyl anhydride formation.
Scheme 3: Amidation reaction via O/N-pivaloyl activation.
Scheme 4: Cinnamic acid amidation using TCCA/PPh3 reagent.
Scheme 5: Cinnamic acid amidation using triazine-based reagents.
Scheme 6: Cinnamic acid amidation using continuous flow mechanochemistry.
Scheme 7: Cinnamic acid amidation using COMU as coupling reagent.
Scheme 8: Cinnamic acid amidation using allenone coupling reagent.
Scheme 9: Cinnamic acid amidation using 4-acetamidophenyl triflimide as reagent.
Scheme 10: Cinnamic acid amidation using methyltrimethoxysilane (MTM).
Scheme 11: Cinnamic acid amidation utilizing amine–borane reagent.
Scheme 12: Cinnamic acid amidation using TCCA/PPh3 reagent.
Scheme 13: Cinnamic acid amidation using PPh3/I2 reagent.
Scheme 14: Cinnamic acid amidation using PCl3 reagent.
Scheme 15: Cinnamic acid amidation utilizing pentafluoropyridine (PFP) as reagent.
Scheme 16: Cinnamic acid amidation using hypervalent iodine(III).
Scheme 17: Mechanochemical amidation using 1,1,2,2-tetrafluoroethyl-N,N-dimethylamine (TFEDMA) reagent.
Scheme 18: Methyl ester preparation using tris(2,4,6-trimethoxyphenyl)phosphine (TMPP).
Scheme 19: N-Trifluoromethyl amide preparation using isothiocyanate and AgF.
Scheme 20: POCl3-mediated amide coupling of carboxylic acid and DMF.
Scheme 21: O-Alkylation of cinnamic acid using alkylating agents.
Scheme 22: Glycoside preparation via Mitsunobu reaction.
Scheme 23: O/N-Acylation via rearrangement reactions.
Scheme 24: Amidation reactions using sulfur-based alkylating agents.
Scheme 25: Amidation reaction catalyzed by Pd0 via C–N cleavage.
Scheme 26: Amidation reaction catalyzed by CuCl/PPh3.
Scheme 27: Cu(II) triflate-catalyzed N-difluoroethylimide synthesis.
Scheme 28: Cu/Selectfluor-catalyzed transamidation reaction.
Scheme 29: CuO–CaCO3-catalyzed amidation reaction.
Scheme 30: Ni-catalyzed reductive amidation.
Scheme 31: Lewis acidic transition-metal-catalyzed O/N-acylations.
Scheme 32: Visible-light-promoted amidation of cinnamic acid.
Scheme 33: Sunlight/LED-promoted amidation of cinnamic acid.
Scheme 34: Organophotocatalyst-promoted N–O cleavage of Weinreb amides to synthesize primary amides.
Scheme 35: Cinnamamide synthesis through [Ir] photocatalyst-promoted C–N-bond cleavage of tertiary amines.
Scheme 36: Blue LED-promoted FeCl3-catalyzed reductive transamidation.
Scheme 37: FPyr/TCT-catalyzed amidation of cinnamic acid derivative 121.
Scheme 38: Cs2CO3/DMAP-mediated esterification.
Scheme 39: HBTM organocatalyzed atroposelective N-acylation.
Scheme 40: BH3-catalyzed N-acylation reactions.
Scheme 41: Borane-catalyzed N-acylation reactions.
Scheme 42: Catalytic N-acylation reactions via H/F bonding activation.
Scheme 43: Brønsted base-catalyzed synthesis of cinnamic acid esters.
Scheme 44: DABCO/Fe3O4-catalyzed N-methyl amidation of cinnamic acid 122.
Scheme 45: Catalytic oxidation reactions of acylating agents.
Scheme 46: Preparation of cinnamamide-substituted benzocyclooctene using I(I)/I(III) catalysis.
Scheme 47: Pd-colloids-catalyzed oxidative esterification of cinnamyl alcohol.
Scheme 48: Graphene-supported Pd/Au alloy-catalyzed oxidative esterification via hemiacetal intermediate.
Scheme 49: Au-supported on A) carbon nanotubes (CNT) and B) on porous boron nitride (pBN) as catalyst for the ...
Scheme 50: Cr-based catalyzed oxidative esterification of cinnamyl alcohols with H2O2 as the oxidant.
Scheme 51: Co-based catalysts used for oxidative esterification of cinnamyl alcohol.
Scheme 52: Iron (A) and copper (B)-catalyzed oxidative esterification of cinnamaldehyde.
Scheme 53: NiHPMA-catalyzed oxidative esterification of cinnamaldehyde.
Scheme 54: Synthesis of cinammic acid esters through NHC-catalyzed oxidative esterification via intermolecular...
Scheme 55: Redox-active NHC-catalyzed esterification via intramolecular oxidation.
Scheme 56: Electrochemical conversion of cinnamaldehyde to methyl cinnamate.
Scheme 57: Bu4NI/TBHP-catalyzed synthesis of bisamides from cinnamalaldehyde N-tosylhydrazone.
Scheme 58: Zn/NC-950-catalyzed oxidative esterification of ketone 182.
Scheme 59: Ru-catalyzed oxidative carboxylation of terminal alkenes.
Scheme 60: Direct carboxylation of alkenes using CO2.
Scheme 61: Carboxylation of alkenylboronic acid/ester.
Scheme 62: Carboxylation of gem-difluoroalkenes with CO2.
Scheme 63: Photoredox-catalyzed carboxylation of difluoroalkenes.
Scheme 64: Ru-catalyzed carboxylation of alkenyl halide.
Scheme 65: Carboxylation of alkenyl halides under flow conditions.
Scheme 66: Cinnamic acid ester syntheses through carboxylation of alkenyl sulfides/sulfones.
Scheme 67: Cinnamic acid derivatives synthesis through a Ag-catalyzed decarboxylative cross-coupling proceedin...
Scheme 68: Pd-catalyzed alkyne hydrocarbonylation.
Scheme 69: Fe-catalyzed alkyne hydrocarbonylation.
Scheme 70: Alkyne hydrocarboxylation using CO2.
Scheme 71: Alkyne hydrocarboxylation using HCO2H as CO surrogate.
Scheme 72: Co/AlMe3-catalyzed alkyne hydrocarboxylation using DMF.
Scheme 73: Au-catalyzed oxidation of Au–allenylidenes.
Scheme 74: Pd-catalyzed C–C-bond activation of cyclopropenones to synthesize unsaturated esters and amides.
Scheme 75: Ag-catalyzed C–C-bond activation of diphenylcyclopropenone.
Scheme 76: Cu-catalyzed C–C bond activation of diphenylcyclopropenone.
Scheme 77: PPh3-catalyzed C–C-bond activation of diphenylcyclopropenone.
Scheme 78: Catalyst-free C–C-bond activation of diphenylcyclopropenone.
Scheme 79: Cu-catalyzed dioxolane cleavage.
Scheme 80: Multicomponent coupling reactions.
Scheme 81: Pd-catalyzed partial hydrogenation of electrophilic alkynes.
Scheme 82: Nickel and cobalt as earth-abundant transition metals used as catalysts for the partial hydrogenati...
Scheme 83: Metal-free-catalyzed partial hydrogenation of conjugated alkynes.
Scheme 84: Horner–Wadsworth–Emmons reaction between triethyl 2-fluoro-2-phosphonoacetate and aldehydes with ei...
Scheme 85: Preparation of E/Z-cinnamates using thiouronium ylides.
Scheme 86: Transition-metal-catalyzed ylide reactions.
Scheme 87: Redox-driven ylide reactions.
Scheme 88: Noble transition-metal-catalyzed olefination via carbenoid species.
Scheme 89: TrBF4-catalyzed olefination via carbene species.
Scheme 90: Grubbs catalyst (cat 7)/photocatalyst-mediated metathesis reactions.
Scheme 91: Elemental I2-catalyzed carbonyl-olefin metathesis.
Scheme 92: Cu-photocatalyzed E-to-Z isomerization of cinnamic acid derivatives.
Scheme 93: Ni-catalyzed E-to-Z isomerization.
Scheme 94: Dehydration of β-hydroxy esters via an E1cB mechanism to access (E)-cinnamic acid esters.
Scheme 95: Domino ring-opening reaction induced by a base.
Scheme 96: Dehydroamination of α-aminoester derivatives.
Scheme 97: Accessing methyl cinnamate (44) via metal-free deamination or decarboxylation.
Scheme 98: The core–shell magnetic nanosupport-catalyzed condensation reaction.
Scheme 99: Accessing cinnamic acid derivatives from acetic acid esters/amides through α-olefination.
Scheme 100: Accessing cinnamic acid derivatives via acceptorless α,β-dehydrogenation.
Scheme 101: Cu-catalyzed formal [3 + 2] cycloaddition.
Scheme 102: Pd-catalyzed C–C bond formation via 1,4-Pd-shift.
Scheme 103: NHC-catalyzed Rauhut–Currier reactions.
Scheme 104: Heck-type reaction for Cα arylation.
Scheme 105: Cu-catalyzed trifluoromethylation of cinnamamide.
Scheme 106: Ru-catalyzed alkenylation of arenes using directing groups.
Scheme 107: Earth-abundant transition-metal-catalyzed hydroarylation of α,β-alkynyl ester 374.
Scheme 108: Precious transition-metal-catalyzed β-arylation of cinnamic acid amide/ester.
Scheme 109: Pd-catalyzed β-amination of cinnamamide.
Scheme 110: S8-mediated β-amination of methyl cinnamate (44).
Scheme 111: Pd-catalyzed cross-coupling reaction of alkynyl esters with phenylsilanes.
Scheme 112: Pd-catalyzed β-cyanation of alkynyl amide/ester.
Scheme 113: Au-catalyzed β-amination of alkynyl ester 374.
Scheme 114: Metal-free-catalyzed Cβ-functionalizations of alkynyl esters.
Scheme 115: Heck-type reactions.
Scheme 116: Mizoroki–Heck coupling reactions using unconventional functionalized arenes.
Scheme 117: Functional group-directed Mizoroki–Heck coupling reactions.
Scheme 118: Pd nanoparticles-catalyzed Mizoroki–Heck coupling reactions.
Scheme 119: Catellani-type reactions to access methyl cinnamate with multifunctionalized arene.
Scheme 120: Multicomponent coupling reactions.
Scheme 121: Single atom Pt-catalyzed Heck coupling reaction.
Scheme 122: Earth-abundant transition metal-catalyzed Heck coupling reactions.
Scheme 123: Polymer-coated earth-abundant transition metals-catalyzed Heck coupling reactions.
Scheme 124: Earth-abundant transition-metal-based nanoparticles as catalysts for Heck coupling reactions.
Scheme 125: CN- and Si-based directing groups to access o-selective cinnamic acid derivatives.
Scheme 126: Amide-based directing group to access o-selective cinnamic acid derivatives.
Scheme 127: Carbonyl-based directing group to access o-selective cinnamic acid derivatives.
Scheme 128: Stereoselective preparation of atropisomers via o-selective C(sp2)–H functionalization.
Scheme 129: meta-Selective C(sp2)–H functionalization using directing group-tethered arenes.
Scheme 130: para-Selective C(sp2)–H functionalization using directing group-tethered arenes.
Scheme 131: Non-directed C(sp2)–H functionalization via electrooxidative Fujiwara–Moritani reaction.
Scheme 132: Interconversion of functional groups attached to cinnamic acid.
Scheme 133: meta-Selective C(sp2)–H functionalization of cinnamate ester.
Scheme 134: C(sp2)–F arylation using Grignard reagents.
Scheme 135: Truce–Smiles rearrangement of N-aryl metacrylamides.
Scheme 136: Phosphine-catalyzed cyclization of γ-vinyl allenoate with enamino esters.
On the photoluminescence in triarylmethyl-centered mono-, di-, and multiradicals
- Daniel Straub,
- Markus Gross,
- Mona E. Arnold,
- Julia Zolg and
- Alexander J. C. Kuehne
Beilstein J. Org. Chem. 2025, 21, 964–998, doi:10.3762/bjoc.21.80
- , there are no reports on substantial photoluminescence, nor are there concepts to increase the ϕ in such systems, despite the many examples of highly emissive donor-substituted PTM- and TTM-based mono-radicals. In this overview, we will focus on reviewing the different hypotheses for the mechanisms
- mechanisms and reasons behind the fluorescence color and the fluorescence quantum yield and derive structure–optical property relationships. We will provide the reader with an overview of the perspectives and challenges of open-shell light-emitting radicals and discuss what to do to solve the remaining
Graphical Abstract
Figure 1: a) Tris(trichlorophenyl)methyl (TTM) radical and related trityl radicals, b) HDMO, SOMO, LUMO orbit...
Figure 2: Mixed halide tri- and perhalogenated triphenylmethyl radicals: a) Molecular structures of homo- and...
Figure 3: Pyridine-functionalized triarylmethyl radicals. a) Chemical structures of X2PyBTM, Py2MTM, and Au-F2...
Figure 4: Pyridine-functionalized triarylmethyl radicals. a) Molecular structure of Mes2F2PyBTM, and b) its f...
Figure 5: Carbazole functionalized triarylmethyl radical. a) Chemical structure of Cz-BTM and b) its energy d...
Figure 6: Donor-functionalized triphenylmethyl radicals. Molecular structures of TTM-Cz, DTM-Cz, TTM-3PCz, PT...
Figure 7: Tuning of the donor strength. Functionalization with electron-donating and electron-withdrawing gro...
Figure 8: Tuning of the donor strength, by varying the Cz-derived donor (1–36) on a TTM radical fragment. a) ...
Figure 9: Three-state model and Marcus theory: q is the charge transfer coordinate and G the free energy. Gro...
Figure 10: Dendronized carbazole donors on TTM radicals. a) Molecular structures of G3TTM and G4TTM. b) Photol...
Figure 11: Electronic extension of the Cz donor. a) Molecular structures and optoelectronic properties of TTM-...
Figure 12: Kekulé diradicals: a) hexadeca- and perchlorinated Thiele (TTH, PTH), Chichibabin (TTM-TTM, PTM-PTM...
Figure 13: Non-Kekulé diradicals: perchlorinated Schlenk–Brauns radical (m-PTH), meta-coupled TTM radicals in ...
Figure 14: UV–vis absorption and photoluminescence spectra of a) TTH in solvents of different polarity, b) dir...
Figure 15: Molecular structures of m-4BTH (meta-butylated Thiele hydrocarbon), m-4TTH (meta-trichlorinated Thi...
Figure 16: a) Polystyrene-based TTM-Cz polymer. b) Molecular structure of radical particles with backbone thro...
Figure 17: Molecular structures of polyradicals. a) Molecular structures of p-TBr6Cl3M-F8, p-TBr6Cl3M-acF8 and ...
Figure 18: Structures of coordination and metal-organic frameworks. a) Carboxylic acid functionalized monomers...
Figure 19: Structures of coordination and metal-organic frameworks. a) Molecular structures of monomers TTMDI, ...
Figure 20: Molecular structures of covalent organic frameworks m-TPM-Ph-COF, m-PTM-Ph-COF, p-TPH-COF, p-PTH-COF...
Figure 21: Molecular structures of covalent organic frameworks PTMAc-COF, oxTAMAc-COF, TOTAc-COF, PTMTAz-COF, p...
Study of tribenzo[b,d,f]azepine as donor in D–A photocatalysts
- Katy Medrano-Uribe,
- Jorge Humbrías-Martín and
- Luca Dell’Amico
Beilstein J. Org. Chem. 2025, 21, 935–944, doi:10.3762/bjoc.21.76
- results are comparable to those obtained by the same author using the well-established PCs 1 and 3 (Table 3, entries 6 and 7) Next, we wanted to analyze the use of the PCs in reductive quenching mechanisms. For this purpose, we selected the Giese-type addition between the N-Cbz-Pro (12, Eox = 0.95 V vs
Graphical Abstract
Figure 1: D–A–D organic PCs previously reported and our new D–A bimodal organic PCs.
Figure 2: Selected frontier MOs and relative calculated energies of D–A photocatalysts (4a,5a–e, and 6a). Abs...
Figure 3: Comparison of the ground state redox potential of the acceptor moieties (4–6), the donor moieties (a...
Recent advances in controllable/divergent synthesis
- Jilei Cao,
- Leiyang Bai and
- Xuefeng Jiang
Beilstein J. Org. Chem. 2025, 21, 890–914, doi:10.3762/bjoc.21.73
- literatures focusing on key regulatory factors for product divergent formation, in which controlling chemical selectivity primarily relies on ligands, metal catalysts, solvents, time, temperature, acids/bases, and subtle modifications of substrates. To gain a deeper understanding of the mechanisms underlying
- reaction activity and selectivity differentiation, the review provides a systematic analysis of the mechanisms of critical steps through specific case studies. It is hoped that the controllable/divergent synthesis concept will spark the interest of practitioners and aficionados to delve deeper into the
- substrates, both dicarbonylation and monocarbonylation processes occurred simultaneously with Cu(OAc)2, favoring the dicarbonylation process. In contrast, using CuBr(Me2S) the monocarbonylation process was favored. Possible reaction mechanisms: First, CO coordinates with copper salts to form (carbonyl)copper
Graphical Abstract
Scheme 1: Ligand-controlled regiodivergent C1 insertion into arynes [19].
Scheme 2: Ligand effect in homogenous gold catalysis enabling regiodivergent π-bond-activated cyclization [20].
Scheme 3: Ligand-controlled palladium(II)-catalyzed regiodivergent carbonylation of alkynes [21].
Scheme 4: Catalyst-controlled annulations of strained cyclic allenes with π-allyl palladium complexes and pro...
Scheme 5: Ring expansion of benzosilacyclobutenes with alkynes [23].
Scheme 6: Photoinduced regiodivergent and enantioselective cross-coupling [24].
Scheme 7: Catalyst-controlled regiodivergent and enantioselective formal hydroamination of N,N-disubstituted ...
Scheme 8: Catalyst-tuned regio- and enantioselective C(sp3)–C(sp3) coupling [31].
Scheme 9: Catalyst-controlled annulations of bicyclo[1.1.0]butanes with vinyl azides [32].
Scheme 10: Solvent-driven reversible macrocycle-to-macrocycle interconversion [39].
Scheme 11: Unexpected solvent-dependent reactivity of cyclic diazo imides and mechanism [40].
Scheme 12: Palladium-catalyzed annulation of prochiral N-arylphosphonamides with aromatic iodides [41].
Scheme 13: Time-dependent enantiodivergent synthesis [42].
Scheme 14: Time-controlled palladium-catalyzed divergent synthesis of silacycles via C–H activation [43].
Scheme 15: Proposed mechanism for the time-controlled palladium-catalyzed divergent synthesis of silacycles [43].
Scheme 16: Metal-free temperature-controlled regiodivergent borylative cyclizations of enynes [45].
Scheme 17: Nickel-catalyzed switchable site-selective alkene hydroalkylation by temperature regulation [46].
Scheme 18: Copper-catalyzed decarboxylative amination/hydroamination sequence [48].
Scheme 19: Proposed mechanism of copper-catalyzed decarboxylative amination/hydroamination sequence [48].
Scheme 20: Enantioselective chemodivergent three-component radical tandem reactions [49].
Scheme 21: Substrate-controlled synthesis of indoles and 3H-indoles [52].
Scheme 22: Controlled mono- and double methylene insertions into nitrogen–boron bonds [53].
Scheme 23: Copper-catalyzed substrate-controlled carbonylative synthesis of α-keto amides and amides [54].
Scheme 24: Divergent sulfur(VI) fluoride exchange linkage of sulfonimidoyl fluorides and alkynes [55].
Scheme 25: Modular and divergent syntheses of protoberberine and protonitidine alkaloids [56].
Unraveling cooperative interactions between complexed ions in dual-host strategy for cesium salt separation
- Zhihua Liu,
- Ya-Zhi Chen,
- Ji Wang,
- Qingling Nie,
- Wei Zhao and
- Biao Wu
Beilstein J. Org. Chem. 2025, 21, 845–853, doi:10.3762/bjoc.21.68
- carbonyl (C=O) groups, as well as direct ion-pairing interactions between 18-crown-6-complexed Cs+ and hexaurea-bound PO43−. Single-crystal structural analysis corroborates these interactions, shedding light on the underlying mechanisms and providing valuable guidance for the rational design of advanced
Graphical Abstract
Figure 1: (a) Schematic illustration of the dual-host strategy for ion pair extraction via solid–liquid metho...
Figure 2: Single crystal structure of complexed Cs2SO4 with 18-crown-6 and tripodal receptor L (CCDC: 2411573...
Figure 3: Stacked 1H NMR spectra of (a) free anion receptor L and its complexes with one equivalent of (b) Cs2...
Figure 4: Single crystal structure of complexed Cs2CO3 (CCDC: 2411574) with 18-crown-6 and tripodal receptor L...
Figure 5: (a) Single crystal structure of complexed Cs3PO4 with 18-crown-6 and tripodal receptor (CCDC: 24115...
Substituent effects in N-acetylated phenylazopyrazole photoswitches
- Radek Tovtik,
- Dennis Marzin,
- Pia Weigel,
- Stefano Crespi and
- Nadja A. Simeth
Beilstein J. Org. Chem. 2025, 21, 830–838, doi:10.3762/bjoc.21.66
- . For example, for NH-PAP-CF3 we observed that the ΦE→Z has a value of 25%, for NMe-PAP-CF3 27%, while for NAc-PAP-CF3 we observed an increase of ΦE→Z to 69%. Thermal half-lifes The metastable Z isomers can be converted back to the thermodynamically favored E form by thermal means. Four mechanisms were
- NAc-PAP-H and -Me), even surpassing the effects of methylation. Hammett analysis showed that the thermal population of the triplet state seem to be preferred as the thermal relaxation mechanisms of the back isomerization. EWGs and EDGs accelerated the relaxation dynamics compared to NAc-PAP-H
Graphical Abstract
Scheme 1: Reaction pathway for synthesizing NH-substituted, methylated-, and acetylated arylazopyrazoles. Con...
Figure 1: UV–vis absorption spectra of selected NAc-PAP derivatives in CH3CN. The strong π→π* can be observed...
Figure 2: A) Time-resolved UV–vis absorption spectra of NAc-PAP-CN upon 365 nm irradiation (12.5 µM in CH3CN,...
Figure 3: Hammett plot of NAc-PAP derivatives.
Figure 4: Eyring plots for NAc-PAP-CN and NAc-PAP-OMe.
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
Graphical Abstract
Figure 1: Fundamental characteristics of the C–F bond.
Figure 2: Incorporation of fluorine at the end of an alkyl chain.
Figure 3: Incorporation of fluorine into the middle of a linear alkyl chain.
Figure 4: Incorporation of fluorine across much, or all, of a linear alkyl chain.
Figure 5: Incorporation of fluorine into cycloalkanes.
Figure 6: Conformational effects of introducing fluorine into an ether (geminal to oxygen).
Figure 7: Conformational effects of introducing fluorine into an ether (vicinal to oxygen).
Figure 8: Effects of introducing fluorine into alcohols (and their derivatives).
Figure 9: Controlling the ring pucker of sugars through fluorination.
Figure 10: Controlling bond rotations outside the sugar ring through fluorination.
Figure 11: Effects of incorporating fluorine into amines.
Figure 12: Effects of incorporating fluorine into amine derivatives, such as amides and sulfonamides.
Figure 13: Effects of incorporating fluorine into organocatalysts.
Figure 14: Effects of incorporating fluorine into carbonyl compounds, focusing on the “carbon side.”
Figure 15: Fluoroproline-containing peptides and proteins.
Figure 16: Further examples of fluorinated linear peptides (besides fluoroprolines). For clarity, sidechains a...
Figure 17: Fluorinated cyclic peptides.
Figure 18: Fluorine-derived conformational control in sulfur-containing compounds.
