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Search for "heating" in Full Text gives 1078 result(s) in Beilstein Journal of Organic Chemistry. Showing first 200.
Synthesis of the tetracyclic skeleton of Aspidosperma alkaloids via PET-initiated cationic radical-derived interrupted [2 + 2]/retro-Mannich reaction
- Ru-Dong Liu,
- Jian-Yu Long,
- Zhi-Lin Song,
- Zhen Yang and
- Zhong-Chao Zhang
Beilstein J. Org. Chem. 2025, 21, 2470–2478, doi:10.3762/bjoc.21.189
- photoredox catalysis) processes [8][9][10]. Cyclobutenone (A) is a versatile C4 synthon [11] – its [2 + 2] photocyclization yields B, featuring a strained bicyclo[2.2.0]hexane unit [12], which can fragment to form C (Figure 1a) [13][14]. However, competitive C1–C4 bond cleavage under irradiation or heating
Graphical Abstract
Figure 1: Synthetic plan. a) General model of cyclobutenone bond cleavage; b) our previously reported method;...
Scheme 1: Substrate scope.
Figure 2: Computational study. a) Energy profiles from IN1 to IN3 and spin density of TS2 (isovalue = 0.004),...
Transformation of the cyclohexane ring to the cyclopentane fragment of biologically active compounds
- Natalya Akhmetdinova,
- Ilgiz Biktagirov and
- Liliya Kh. Faizullina
Beilstein J. Org. Chem. 2025, 21, 2416–2446, doi:10.3762/bjoc.21.185
- 30% and a selectivity of 70% at −100 °C (Scheme 21). 2.3 Wolff rearrangement The Wolff rearrangement is the transformation of α-diazoketones into acids or their derivatives through heating, catalysis, or UV irradiation in the presence of water, alcohols, ammonia, amines, etc. The Wolff rearrangement
- intermediate. The Wolff rearrangement was carried out by heating 132 in collidine and BnOH to obtain trans-hydrindane 133 as a single diastereomer with a yield of 73% (Scheme 23). In the work of Ding et al. [68], an elegant synthesis of (−)-pavidolide B (134) was described using the Wolff rearrangement. In
- the perhydrindanic structure. In contrast, the use of Al-H-Na-Lar pillared clay [90] as a heterogeneous catalyst and heating in 2-nitropropane at 100 °C induced angular methyl migration with formation of the halimanic bicyclic system 203 [90]. The acid-induced rearrangement of the drimanic epoxide 201
Graphical Abstract
Scheme 1: Ozonolysis–cyclization sequence in the synthesis of echinopine A (3).
Scheme 2: Ozonolysis–cyclization sequence in the synthesis of taiwaniaquinoids 7–12.
Figure 1: Iridoid skeleton.
Scheme 3: Ozonolysis–cyclization sequence in the synthesis of compounds 17a,b, 18 and 19 with iridoid topolog...
Scheme 4: Oxidation–aldol condensation sequence in the synthesis of compounds 21 and 23 with iridoid topology....
Scheme 5: Oxidation–aldol condensation sequence in the synthesis of compounds 29 and 30 with iridoid topology....
Scheme 6: Method for ring contraction in the absence of a double bond in a six-membered ring of triterpenoids....
Scheme 7: Oxidation–Dieckmann cyclization sequence in the synthesis of a new nortriterpenoid 39.
Scheme 8: Oxidation–Dieckmann cyclization sequence in the synthesis of 18,19-di-nor-cholesterol (40).
Scheme 9: Oxidation–cyclization sequence in the synthesis of 3-ethyl-substituted betulinic acid derivatives 49...
Scheme 10: Benzilic acid-type rearrangement in the synthesis of 4β-acetoxyprobotryane-9β,15α-diol (52).
Scheme 11: Benzilic acid-type rearrangement in the synthesis of (−)-taiwaniaquinone H (11).
Scheme 12: Benzilic acid-type rearrangement in the synthesis of dactylicapnosines A (63) and B (64).
Scheme 13: Aza-benzilic acid-type rearrangement in the synthesis of (+)-stephadiamine (71).
Scheme 14: α-Ketol rearrangement in the synthesis of saffloneoside (73).
Scheme 15: Conversion of (−)-preaustinoid A (80) to (−)-preaustinoid B (81) via α-ketol rearrangement.
Scheme 16: α-Ketol rearrangement in the synthesis of 2,8-oxymethano-bridged diquinane 90.
Scheme 17: Oxidative ring contraction during the synthesis of (+)-cuparene (91) and (+)-tochuinylacetate (92).
Scheme 18: Semipinacol rearrangement in the synthesis of diterpenoids 97–100.
Scheme 19: Co-catalyzed homoallyl-type rearrangement in the syntheses of meroterpenes 106–109.
Scheme 20: Ring contraction reaction promoted by TTN·3H2O and HTIB in the synthesis of indanes.
Scheme 21: Rearrangement involving a hypervalent iodine compound in the synthesis of derivative 120.
Scheme 22: Wolff rearrangement in the synthesis of taiwaniaquinones A (7), F (8), taiwaniaquinols B (10), D (1...
Scheme 23: Wolff rearrangement in the synthesis of cheloviolene C (128), seconorrisolide B (129), and seconorr...
Scheme 24: Wolff rearrangement in the synthesis of (−)-pavidolide B (134).
Scheme 25: Wolff rearrangement in the synthesis of presilphiperfolan-8-ol (141).
Scheme 26: Photochemical rearrangement in the synthesis of cyclopentane derivatives 147a,b.
Scheme 27: Synthesis of cyclopentane derivatives 147a and 151.
Scheme 28: Photochemical rearrangement in the synthesis of cyclopentane derivative 153.
Scheme 29: Photochemical rearrangement in the synthesis of tricyclic ketones 155, 156.
Scheme 30: Photochemical rearrangement in the synthesis of cis/trans salts 160.
Figure 2: Scope of the photoinduced carboborative ring contraction of steroids. Reaction conditions: steroid ...
Scheme 31: Photoinduced carboborative ring contraction in the synthesis of artalbic acid (180).
Scheme 32: Synthetic versatility of the photoinduced carboborative ring contraction.
Scheme 33: Methods of disclosure of epoxide 189.
Scheme 34: Methods of disclosure of epoxide 190.
Scheme 35: Rearrangement of α,β-epoxy ketone 197.
Scheme 36: Acid-induced rearrangement in the synthesis of perhydrindane ketones 202 and 205.
Scheme 37: Rearrangement of epoxyketone 208 in the synthesis of huperzine Q (206).
Scheme 38: Rearrangement of epoxide 212 under the action of Grignard reagent.
Scheme 39: Semipinacol rearrangement of epoxide 220 in the synthesis of (−)-citrinadin A (217) and (+)-citrina...
Scheme 40: Semipinacol rearrangement of epoxide 225 in the synthesis of hamigeran G (223).
Scheme 41: Semipinacol rearrangement of epoxide 231 in the synthesis of (−)-spirochensilide A (228).
Scheme 42: Wagner–Meerwein rearrangement in the synthesis of compound 234 with iridoid topology.
Scheme 43: Wagner–Meerwein rearrangement in the synthesis of compound 238 with iridoid topology.
Scheme 44: Wagner–Meerwein rearrangement in the synthesis of compound 241 with iridoid topology.
Scheme 45: Wagner–Meerwein rearrangement in the synthesis of lupane derivatives 245, 246, 248, and 249.
Scheme 46: Wagner–Meerwein rearrangement in the synthesis of weisaconitine D (252) and cardiopetaline (255).
Scheme 47: Wagner–Meerwein rearrangement in the synthesis of cardiopetaline (255).
The high potential of methyl laurate as a recyclable competitor to conventional toxic solvents in [3 + 2] cycloaddition reactions
- Ayhan Yıldırım and
- Mustafa Göker
Beilstein J. Org. Chem. 2025, 21, 2389–2415, doi:10.3762/bjoc.21.184
- laurate can be readily purified by vacuum distillation at the end of the reaction and safely reused. The synthesis of the corresponding cycloaddition products 3a–u was achieved by heating equimolar amounts of nitrone and maleimide in methyl laurate at 80 °C for the times indicated in Table 4. The
Graphical Abstract
Figure 1: Versatile compounds via cycloaddition reactions.
Scheme 1: Molecular structures of parent compounds 1a–f, 2a–d and cycloadducts 3a–u.
Figure 2: a) Radar view of the physical properties of methyl laurate. b) Oral toxicity values of methyl laura...
Figure 3: The oral toxicity values of all the solvents utilized in the present study obtained with ProTox 3.0....
Figure 4: Ecological, environmental risk assessments, pesticide similarity and biodegradability assessments o...
Figure 5: Ecological, environmental risk assessments, pesticide similarity and biodegradability assessments o...
Figure 6: Ecological, environmental risk assessments, pesticide similarity and biodegradability assessments o...
Figure 7: Various toxicity parameters of methyl laurate and a series of other solvents calculated by ADMETLab...
Figure 8: a) Visualization of the localization of conventional organic and bio-based solvents in the Hansen s...
Figure 9: Vapour pressures of the solvents used (values retrieved from the Chemeo molecular database).
Scheme 2: Endo and exo stereoisomeric approaches of nitrone 1a and maleimide 2a in [3 + 2] cycloaddition reac...
Figure 10: Signals of protons used in the calculation of the diastereomeric ratios (cis/trans) of cycloadditio...
Figure 11: Results of studies on the recovery of solvents used in the reaction.
Figure 12: Simplified scheme describing the reaction monitoring and solvent recovery.
Figure 13: a) The superimposed spectra of C,N-diphenylnitrone and N-phenylmaleimide. b) The spectrum of methyl...
An Fe(II)-catalyzed synthesis of spiro[indoline-3,2'-pyrrolidine] derivatives
- Elizaveta V. Gradova,
- Nikita A. Ozhegov,
- Roman O. Shcherbakov,
- Alexander G. Tkachenko,
- Larisa Y. Nesterova,
- Elena Y. Mendogralo and
- Maxim G. Uchuskin
Beilstein J. Org. Chem. 2025, 21, 2383–2388, doi:10.3762/bjoc.21.183
- under heating furnished chiral spiroindolylpyrroles in excellent yields and enantioselectivity (Scheme 1, path d) [11]. Moreover, a copper-catalyzed reaction of oxindole-derived alkenes with acetophenone O-acetyl oxime has also been employed to construct the spiroindolylpyrrole scaffold (Scheme 1, path
Graphical Abstract
Figure 1: Natural and synthetic bioactive spiro[indoline-3,2'-pyrrolidine] derivatives.
Scheme 1: Previous approaches and our work.
Scheme 2: The reaction of 2-arylindoles 1 with α,β-unsaturated ketones 2. aIsolated yield of the 5 mmol scale...
Scheme 3: The scope of the Fe-catalyzed spirocyclization. aIsolated yield of the 4.2 mmol scale experiment.
Scheme 4: The proposed mechanism of product 4 formation.
Rotaxanes with integrated photoswitches: design principles, functional behavior, and emerging applications
- Jullyane Emi Matsushima,
- Khushbu,
- Zuliah Abdulsalam,
- Udyogi Navodya Kulathilaka Conthagamage and
- Víctor García-López
Beilstein J. Org. Chem. 2025, 21, 2345–2366, doi:10.3762/bjoc.21.179
- , temperature, and acid–base stimuli. Additionally, this spiropyran-based rotaxane showed pronounced photochromic and fluorescent behavior in both powder and solid film under alternating UV/sunlight and visible light/heating conditions, highlighting its suitability for dynamic optical systems and anti
- is suppressed, and the macrocycle becomes effectively immobilized. The process is reversible upon heating. Later, Tron and co-workers synthesized a [2]rotaxane containing a barbiturate moiety in the axle, which serves as a template for a reversible clipping approach [84]. The macrocycle precursor is
Graphical Abstract
Figure 1: Schematic of common rotaxanes (left) and depiction of the macrocycle shuttling (right).
Figure 2: Structure of some common photoswitches integrated into rotaxanes.
Figure 3: Rotaxane with an acridane photoswitch on the axle modulates the translation of a CBQT4+ macrocycle ...
Figure 4: Hydrogel composed of [2]rotaxanes featuring a central azobenzene in the axle and a cyclodextrin mac...
Figure 5: Dendrimer composed of [2]rotaxane with an azobenzene photoswitch functioning as a macroscopic actua...
Figure 6: (a) Structure of the [2]rotaxane and (b) mechanism for K+ cations transport across lipid bilayers. Figure 6...
Figure 7: Dithienylethene-based [2]rotaxane used in writing patterning applications: (a) rotaxane with open d...
Figure 8: Dithienylethene-based [1]rotaxane shuttling motion triggered by pH changes (top). Dithienylethene p...
Figure 9: Depiction of a fumaramide-based [2]rotaxane photoswitching cycle and deposition on glass and mica s...
Figure 10: Hydrazone-based rotaxane controls helical pitch in a liquid crystal. Figure 10 was adapted from [73] (© 2024 S. ...
Figure 11: (a) Light- and pH-responsive Förster resonance energy transfer observed on a spiropyran-based [2]ro...
Figure 12: Photoresponsive bending of artificial muscle with [c2]daisy chain reported by Harada and collaborat...
Figure 13: Light-responsive shuttling motion of [2]rotaxane based on a stiff-stilbene photoswitch. Figure 13 was reprod...
Figure 14: Azobenzene-based rotaxane modulating lipid bilayers upon photoisomerization. Figure 14 was adapted from [23] (© ...
Figure 15: Depiction of fluorescence quenching processes upon external stimuli of a dithienylethene-based [2]r...
Figure 16: Diagrammatic illustration of rotaxane 1-H-SP depicting interconversions between the four isomeric s...
Figure 17: Representation of [2]rotaxane chloride binding modulated by photoisomerization of a stiff-stilbene. ...
Insoluble methylene-bridged glycoluril dimers as sequestrants for dyes
- Suvenika Perera,
- Peter Y. Zavalij and
- Lyle Isaacs
Beilstein J. Org. Chem. 2025, 21, 2302–2314, doi:10.3762/bjoc.21.176
- . Before use, samples of H2, G2W1–G2W4 were repeatedly washed with water to remove TFA (monitored by 19F NMR) and activated by grinding and heating overnight at 90 °C under high vacuum. Experimentally, we incubated equimolar amounts (7.2 μmol) of each host with aqueous solutions of each dye (240 μM, 1 mL
Graphical Abstract
Figure 1: Chemical structures of selected hosts used as the basis for sequestrants.
Scheme 1: a) Synthesis of triphenylene-derived aromatic walls W1 and W2, and b) structure of commercially ava...
Scheme 2: Synthesis of methylene-bridged glycoluril dimers G2W1–G2W4. Conditions: a) TFA: Ac2O, 95 °C, 3.5 h (...
Figure 2: Chemical structures of dyes used in this study.
Figure 3: 1H NMR spectra recorded (400 MHz, DMSO-d6, rt) for: a) G2W1, b) G2W2, c) G2W3, d) G2W4.
Figure 4: Plot of removal efficiency of dyes from water after incubating with equimolar amounts (7.2 μmol) of ...
Figure 5: Cross-eyed stereoview of: a) one molecule of G2W3 in the crystal, and b) the packing of G2W3 in the...
Figure 6: Cross-eyed stereoview of: a) a molecule of G2W1 in the crystal, b) the packing of G2W1 along the xz...
Figure 7: a) Plot of removal efficiency of methylene blue (240 μM, 1 mL) from water after incubating with dif...
Figure 8: Plot of the removal efficiency versus methylene blue concentration (70, 90, 120, 180, 240, 300, 100...
Figure 9: a) Plot of removal efficiency of methylene blue (240 μM, 1 mL) from water as a function of time aft...
Thiadiazino-indole, thiadiazino-carbazole and benzothiadiazino-carbazole dioxides: synthesis, physicochemical and early ADME characterization of representatives of new tri-, tetra- and pentacyclic ring systems and their intermediates
- Gyöngyvér Pusztai,
- László Poszávácz,
- Anna Vincze,
- András Marton,
- Ahmed Qasim Abdulhussein,
- Judit Halász,
- András Dancsó,
- Gyula Simig,
- György Tibor Balogh and
- Balázs Volk
Beilstein J. Org. Chem. 2025, 21, 2220–2233, doi:10.3762/bjoc.21.169
- were previously used for the synthesis of 7-nitroindole derivatives: heating in polyphosphoric acid (PPA) at 80 °C [24][25]. However, our attempt was not successful. Experiments with zinc chloride, the most commonly used Lewis acid catalyst in Fischer indole syntheses, also failed under various
- performed using the method described in the literature [18], i.e., by heating compounds 5a,b with ketones 6a–e in the presence of bismuth nitrate pentahydrate catalyst and PPA in methanol at 110 °C in a closed vial (Scheme 1, method B). In the synthesis of asymmetric hydrazones 7a,c,f,h, the major product
Graphical Abstract
Figure 1: Phthalazinones 1, benzothiadiazine dioxides 2, and thiadiazinoindole dioxides 3.
Scheme 1: Synthesis of tri- and tetracyclic thiadiazinoindole dioxides 3.
Figure 2: 1H NMR and selective 1D NOESY (with the excitation of NH) spectra of (E)-7h.
Figure 3: 1H NMR and selective 1D NOESY (with the excitation of NH) spectra of (Z)-7h.
Scheme 2: Synthesis of pentacyclic compounds 10.
Figure 4: X-ray structures of compounds 3d (A), 7d (B), (Z)-7h (C), and (E)-9a (D).
Figure 5: The capacity factor (logk) vs calculated partition coefficients (clogP) by ACD Labs/Percepta [36]); the...
Synthesis of triazolo- and tetrazolo-fused 1,4-benzodiazepines via one-pot Ugi–azide and Cu-free click reactions
- Xiaoming Ma,
- Zijie Gao,
- Jiawei Niu,
- Wentao Shao,
- Shenghu Yan,
- Sai Zhang and
- Wei Zhang
Beilstein J. Org. Chem. 2025, 21, 2202–2210, doi:10.3762/bjoc.21.167
- ), tert-butyl isocyanide (3a), and TMSN3 (4) in 2 mL of MeOH. After heating the reaction mixture at 40 °C for 12 h, the solvent was removed and changed to 2 mL of MeCN followed by heating at 130 °C for 2 h (Scheme 3A). However, no desired product was detected in the reaction mixture. The functional groups
Graphical Abstract
Figure 1: Some bioactive molecules bearing triazole, tetrazole, and 1,4-benzodiazepin rings.
Scheme 1: Ugi–azide reaction for the synthesis of 1,5-DS-T-containing heterocycles.
Scheme 2: Proposed Ugi–azide-initiated synthesis of polyheterocyclic scaffolds 7 and 8.
Scheme 3: 4-CR vs stepwise Ugi–azide reactions for the synthesis of 7a.
Scheme 4: Synthesis of benzodiazepines 7a–k. Reaction conditions: 1) 0.2 mmol each of 2-azidobenzaldehyde (1a...
Scheme 5: Synthesis of polycyclic compound 8a.
Scheme 6: Synthesis of product analogs 8. Reaction conditions: 1) 0.2 mmol each of 2-azidobenzaldehyde (1a) a...
Scheme 7: Control reactions to trap the Ugi–azide adduct.
Figure 2: 1H NMR spectra of compounds 6a (red) and 8a (blue).
Scheme 8: Gram-scale one-pot synthesis of 8a.
C2 to C6 biobased carbonyl platforms for fine chemistry
- Jingjing Jiang,
- Muhammad Noman Haider Tariq,
- Florence Popowycz,
- Yanlong Gu and
- Yves Queneau
Beilstein J. Org. Chem. 2025, 21, 2103–2172, doi:10.3762/bjoc.21.165
Graphical Abstract
Figure 1: C2–C6 biobased carbonyl building blocks.
Scheme 1: Proposed (2 + 2) route to glycolaldehyde and glycolic acid from erythritol by Cu/AC catalyst (AC = ...
Scheme 2: Reductive amination of GCA.
Scheme 3: N-Formylation of secondary amines by reaction with GCA.
Scheme 4: Synthesis and conversion of hydroxy acetals to cyclic acetals.
Scheme 5: Synthesis of 3-(indol-3-yl)-2,3-dihydrofurans via three-component reaction of glycolaldehyde, indol...
Scheme 6: BiCl3-catalyzed synthesis of benzo[a]carbazoles from 2-arylindoles and α-bromoacetaldehyde ethylene...
Scheme 7: Cu/NCNSs-based conversion of glycerol to glycolic acid and other short biobased acids.
Scheme 8: E. coli-based biotransformation of C1 source molecules (CH4, CO2 and CO) towards C2 glycolic acid.
Scheme 9: N-Formylation of amines with C2 (a) or C3 (b) biomass-based feedstocks.
Scheme 10: Methods for the formation of propanoic acid (PA) from lactic acid (LA).
Scheme 11: Co-polymerization of biobased lactic acid and glycolic acid via a bicatalytic process.
Scheme 12: Oxidation of α-hydroxy acids by tetrachloroaurate(III) in acetic acid–sodium acetate buffer medium.
Figure 2: Selective catalytic pathways for the conversion of lactic acid (LA).
Scheme 13: Synthesis of 1,3-PDO via cross-aldol reaction between formaldehyde and acetaldehyde to 3-hydroxypro...
Scheme 14: Hydrothermal conversion of 1,3-dihydroxy-2-propane and 2,3-dihydroxypropanal to methylglyoxal.
Scheme 15: FLS-catalyzed formose reaction to synthesize GA and DHA.
Scheme 16: GCA and DHA oxidation products of glycerol and isomerization of GCA to DHA under flow conditions us...
Scheme 17: Acid-catalyzed reactions of DHA with alcohols.
Scheme 18: Synthesis of dihydroxyacetone phosphate from dihydroxyacetone.
Scheme 19: Bifunctional acid–base catalyst DHA conversion into lactic acid via pyruvaldehyde or fructose forma...
Scheme 20: Catalytic one-pot synthesis of GA and co-synthesis of formamides and formates from DHA.
Scheme 21: (a) Synthesis of furan derivatives and (b) synthesis of thiophene derivative by cascade [3 + 2] ann...
Scheme 22: Brønsted acidic ionic liquid catalyzed synthesis of benzo[a]carbazole from renewable acetol and 2-p...
Scheme 23: Asymmetric hydrogenation of α-hydroxy ketones to 1,2-diols.
Scheme 24: Synthesis of novel 6-(substituted benzylidene)-2-methylthiazolo [2,3-b]oxazol-5(6H)-one from 1-hydr...
Scheme 25: ʟ-Proline-catalyzed synthesis of anti-diols from hydroxyacetone and aldehydes.
Scheme 26: C–C-bond-formation reactions of a biomass-based feedstock aromatic aldehyde (C5) and hydroxyacetone...
Scheme 27: Ethanol upgrading to C4 bulk chemicals via the thiamine (VB1)-catalyzed acetoin condensation.
Scheme 28: One-pot sequential chemoenzymatic synthesis of 2-aminobutane-1,4-diol and 1,2,4-butanetriol via 1,4...
Scheme 29: Synthesis of 1,4-dihydroxybutan-2-one by microbial transformation.
Scheme 30: Conversion of polyols by [neocuproine)Pd(OAc)]2(OTf)2] to α-hydroxy ketones.
Scheme 31: Chemoselective oxidation of alcohols with chiral palladium-based catalyst 2.
Scheme 32: Electrochemical transformation of furfural to 5-hydroxy-2(5H)-furanone (HFO).
Scheme 33: Selective hydrodeoxygenation of HFO and oxidation to γ-butyrolactone (GBL).
Scheme 34: Photosensitized oxygenation of furan towards HFO via ozonide intermediates.
Scheme 35: Conversion of furfural to HFO and MAN by using mesoporous carbon nitride (SGCN) as photocatalyst.
Scheme 36: Synthesis of HFO from furan derivatives.
Scheme 37: Photooxidation of furfural to 5-hydroxy-2(5H)-furanone (HFO).
Scheme 38: Synthesis of Friedel–Crafts indole adduct from HFO.
Scheme 39: Conversion of HFO to α,γ-substituted chiral γ-lactones.
Scheme 40: Tautomeric transformation of HFO to formylacrylic acid.
Scheme 41: Hydrolysis of HFO to succinic acid in aqueous solution.
Scheme 42: Substitution and condensation reactions of 5-hydroxy-2(5H)-furanone (HFO).
Scheme 43: (a) Conversion of HFO towards valuable C4 chemicals and (b) anodic oxidation of 5-hydroxy-2(5H)-fur...
Figure 3: Conversion of HFO towards other natural and synthetic substances.
Scheme 44: Conversion of furfural to maleic anhydride (reaction a: VOx/Al2O3; reaction b: VPO).
Scheme 45: Conversion of furfural into succinic acid.
Scheme 46: Electro‑, photo‑, and biocatalysis for one-pot selective conversions of furfural into C4 chemicals.
Scheme 47: Production route of furfural from hemicellulose.
Scheme 48: Mechanism for xylose dehydration to furfural through a choline xyloside intermediate.
Scheme 49: Conversion of furfural to furfuryl alcohol and its derivatives.
Scheme 50: Conversion of furfural to furfuryl alcohol and 3-(2-furyl)acrolein.
Scheme 51: The aerobic oxidative condensation of biomass-derived furfural and linear alcohols.
Scheme 52: The single-step synthesis of 2-pentanone from furfural.
Scheme 53: Electrocatalytic coupling reaction of furfural and levulinic acid.
Scheme 54: Conversion of furfural to m-xylylenediamine.
Scheme 55: Conversion of furfural to tetrahydrofuran-derived amines.
Scheme 56: Formation of trans-4,5-diamino-cyclopent-2-enones from furfural.
Scheme 57: Production of pyrrole and proline from furfural.
Scheme 58: Synthesis of 1‑(trifluoromethyl)-8-oxabicyclo[3.2.1]oct-3-en-2-ones from furfural.
Scheme 59: Conversion of furfural to furfural-derived diacids.
Scheme 60: A telescope protocol derived from furfural and glycerol.
Scheme 61: A tandem cyclization of furfural and 5,5-dimethyl-1,3-cyclohexanedione.
Scheme 62: A Ugi four-component reaction to construct furfural-based polyamides.
Scheme 63: One-pot synthesis of γ-acyloxy-Cy7 from furfural.
Scheme 64: Dimerization–Piancatelli sequence toward humins precursors from furfural.
Scheme 65: Conversion of furfural to CPN.
Scheme 66: Synthesis of jet fuels range cycloalkanes from CPN and lignin-derived vanillin.
Scheme 67: Solar-energy-driven synthesis of high-density biofuels from CPN.
Scheme 68: Reductive amination of CPN to cyclopentylamine.
Scheme 69: Asymmetric hydrogenation of C=O bonds of exocyclic α,β-unsaturated cyclopentanones.
Scheme 70: Preparation of levulinic acid via the C5 route (route a) or C6 route (routes b1 and b2).
Scheme 71: Mechanism of the rehydration of HMF to levulinic acid and formic acid.
Scheme 72: Important levulinic acid-derived chemicals.
Scheme 73: Direct conversion of levulinic acid to pentanoic acid.
Scheme 74: Catalytic aerobic oxidation of levulinic acid to citramalic acid.
Scheme 75: Conversion of levulinic acid to 1,4-pentanediol (a) see ref. [236]; b) see ref. [237]; c) see ref. [238]; d) see r...
Scheme 76: Selective production of 2-butanol through hydrogenolysis of levulinic acid.
Scheme 77: General reaction pathways proposed for the formation of 5MPs from levulinic acid.
Scheme 78: Selective reductive amination of levulinic acid to N-substituted pyrroles.
Scheme 79: Reductive amination of levulinic acid to chiral pyrrolidinone.
Scheme 80: Reductive amination of levulinic acid to non-natural chiral γ-amino acid.
Scheme 81: Nitrogen-containing chemicals derived from levulinic acid.
Scheme 82: Preparation of GVL from levulinic acid by dehydration and hydrogenation.
Scheme 83: Ruthenium-catalyzed levulinic acid to chiral γ-valerolactone.
Scheme 84: Catalytic asymmetric hydrogenation of levulinic acid to chiral GVL.
Scheme 85: Three steps synthesis of ε-caprolactam from GVL.
Scheme 86: Multistep synthesis of nylon 6,6 from GVL.
Scheme 87: Preparation of MeGVL by α-alkylation of GVL.
Scheme 88: Ring-opening polymerization of five-membered lactones.
Scheme 89: Synthesis of GVL-based ionic liquids.
Scheme 90: Preparation of butene isomers from GVL under Lewis acid conditions.
Scheme 91: Construction of C5–C12 fuels from GVL over nano-HZSM-5 catalysts.
Scheme 92: Preparation of alkyl valerate from GVL via ring opening/reduction/esterification sequence.
Scheme 93: Construction of 4-acyloxypentanoic acids from GVL.
Scheme 94: Synthesis of 1,4-pentanediol (PDO) from GVL.
Scheme 95: Construction of novel cyclic hemiketal platforms via self-Claisen condensation of GVL.
Scheme 96: Copper-catalyzed lactamization of GVL.
Figure 4: Main scaffolds obtained from HMF.
Scheme 97: Biginelli reactions towards HMF-containing dihydropyrimidinones.
Scheme 98: Hantzsch dihydropyridine synthesis involving HMF.
Scheme 99: The Kabachnik–Fields reaction involving HMF.
Scheme 100: Construction of oxazolidinone from HMF.
Scheme 101: Construction of rhodamine-furan hybrids from HMF.
Scheme 102: A Groebke–Blackburn–Bienaymé reaction involving HMF.
Scheme 103: HMF-containing benzodiazepines by [4 + 2 + 1] cycloadditions.
Scheme 104: Synthesis of fluorinated analogues of α-aryl ketones.
Scheme 105: Synthesis of HMF derived disubstituted γ-butyrolactone.
Scheme 106: Functionalized aromatics from furfural and HMF.
Scheme 107: Diels–Alder adducts from HMF or furfural with N-methylmaleimide.
Scheme 108: Pathway of the one-pot conversion of HMF into phthalic anhydride.
Scheme 109: Photocatalyzed preparation of humins (L-H) from HMF mixed with spoiled HMF residues (LMW-H) and fur...
Scheme 110: Asymmetric dipolar cycloadditions on HMF.
Scheme 111: Dipolar cycloadditions of HMF based nitrones to 3,4- and 3,5-substituted isoxazolidines.
Scheme 112: Production of δ-lactone-fused cyclopenten-2-ones from HMF.
Scheme 113: Aza-Piancatelli access to aza-spirocycles from HMF-derived intermediates.
Scheme 114: Cross-condensation of furfural, acetone and HMF into C13, C14 and C15 products.
Scheme 115: Base-catalyzed aldol condensation/dehydration sequences from HMF.
Scheme 116: Condensation of HMF and active methylene nitrile.
Scheme 117: MBH reactions involving HMF.
Scheme 118: Synthesis of HMF-derived ionic liquids.
Scheme 119: Reductive amination/enzymatic acylation sequence towards HMF-based surfactants.
Scheme 120: The formation of 5-chloromethylfurfural (CMF).
Scheme 121: Conversion of CMF to HMF, levulinic acid, and alkyl levulinates.
Scheme 122: Conversion of CMF to CMFCC and FDCC.
Scheme 123: Conversion of CMF to BHMF.
Scheme 124: Conversion of CMF to DMF.
Scheme 125: CMF chlorine atom substitutions toward HMF ethers and esters.
Scheme 126: Introduction of carbon nucleophiles in CMF.
Scheme 127: NHC-catalyzed remote enantioselective Mannich-type reactions of CMF.
Scheme 128: Conversion of CMF to promising biomass-derived dyes.
Scheme 129: Radical transformation of CMF with styrenes.
Scheme 130: Synthesis of natural herbicide δ-aminolevulinic acid from CMF.
Scheme 131: Four step synthesis of the drug ranitidine from CMF.
Scheme 132: Pd/CO2 cooperative catalysis for the production of HHD and HXD.
Scheme 133: Different ruthenium (Ru) catalysts for the ring-opening of 5-HMF to HHD.
Scheme 134: Proposed pathways for preparing HXD from HMF.
Scheme 135: MCP formation and uses.
Scheme 136: Cu(I)-catalyzed highly selective oxidation of HHD to 2,5-dioxohexanal.
Scheme 137: Synthesis of N‑substituted 3‑hydroxypyridinium salts from 2,5-dioxohexanal.
Scheme 138: Ru catalyzed hydrogenations of HHD to 1,2,5-hexanetriol (a) see ref. [396]; b) see ref. [397]).
Scheme 139: Aviation fuel range quadricyclanes produced by HXD.
Scheme 140: Synthesis of HDGK from HXD and glycerol as a chain extender.
Scheme 141: Synthesis of serinol pyrrole from HXD and serinol.
Scheme 142: Synthesis of pyrroles from HXD and nitroarenes.
Scheme 143: Two-step production of PX from cellulose via HXD.
Scheme 144: Preparation of HCPN from HMF via hydrogenation and ring rearrangement.
Scheme 145: Suggested pathways from HMF to HCPN.
Scheme 146: α-Alkylation of HCPN with ethylene gas.
Scheme 147: Synthesis of 3-(hydroxymethyl)cyclopentylamine from HMF via reductive amination of HCPN.
Scheme 148: Production of LGO and Cyrene® from biomass.
Scheme 149: Synthesis of HBO from LGO and other applications.
Scheme 150: Construction of m-Cyrene® homopolymer.
Scheme 151: Conversion of Cyrene® to THFDM and 1,6-hexanediol.
Scheme 152: RAFT co-polymerization of LGO and butadienes.
Scheme 153: Polycondensation of HO-LGOL and diols with dimethyl adipate.
Scheme 154: Self-condensation of Cyrene® and Claisen–Schmidt reactions.
Scheme 155: Synthesis of 5-amino-2-(hydroxymethyl)tetrahydropyran from Cyrene®.
Solar thermal fuels: azobenzene as a cyclic photon–heat transduction platform
- Jie Yan,
- Shaodong Sun,
- Minghao Wang and
- Si Wu
Beilstein J. Org. Chem. 2025, 21, 2036–2047, doi:10.3762/bjoc.21.159
- charged solar thermal fuels for deicing tests [74], showing effective ice removal capability under green light irradiation (Figure 7a). Wang et al. developed a photostimulated self-heating wristband [94] that elevates surface temperature from 29 °C to 44 °C upon blue light irradiation, protecting users
- irradiation (550 nm). Figure 7a was reprinted with permission from [74] Copyright © 2020 American Chemical Society. This content is not subject to CC BY 4.0. (b) Real-time infrared thermal imaging images of a charged self-heating wristband under blue light irradiation (450 nm). Figure 7b was reprinted from
Graphical Abstract
Figure 1: Schematic diagram of molecular solar thermal energy storage system.
Figure 2: Photoisomerization of different types of molecular optical switches. Figure 2 was redrawn from [8].
Figure 3: Nanocarbon-based azobenzene polymer solar thermal fuels: (a) SWCNT templating. Figure 3a is from [43] (T. J. Kuc...
Figure 4: Conjugated azobenzene polymer solar thermal fuels: (a) Photoisomerization and thermally induced rev...
Figure 5: Linear azobenzene polymer solar thermal fuels: (a) Schematic illustration of the trans-to-cis isome...
Figure 6: Representative examples of azobenzene small-molecule derivative solar thermal fuels. (a) Polarized ...
Figure 7: (a) Deicing test of charged solar thermal fuels under green light irradiation (550 nm). Figure 7a was reprin...
Switchable pathways of multicomponent heterocyclizations of 5-amino-1,2,4-triazoles with salicylaldehydes and pyruvic acid
- Yana I. Sakhno,
- Oleksander V. Buravov,
- Kostyantyn Yu. Yurkov,
- Anastasia Yu. Andryushchenko,
- Svitlana V. Shishkina and
- Valentyn A. Chebanov
Beilstein J. Org. Chem. 2025, 21, 2030–2035, doi:10.3762/bjoc.21.158
- -triazoles, pyruvic acid, and salicylaldehydes were studied under different conditions. Upon conventional heating, benzotriazolooxadiazocine-5-carboxylic acids were formed in the three-component reactions as single reaction products. Upon ultrasonic activation or mechanical stirring at room temperature, the
- -triazoles, salicylaldehydes, and pyruvic acid were studied under different reaction conditions. In particular, it was found that the three-component reaction of an equimolar mixture of 5-amino-3-methylthio(methoxy)-1,2,4-triazole 1a,b, salicylaldehydes 2a–f, and pyruvic acid (3) under conventional heating
- behavior in this MCR. In the case of 3-carbomethoxy- and 3-(trifluoromethyl)-5-amino-1,2,4-triazoles the treatment with pyruvic acid and salicylaldehydes under thermal heating in different solvents (AcOH, DMF, n-butanol), instead of oxygen-bridged compounds gave a mixture of unidentified products with
Graphical Abstract
Scheme 1: Diversity of heterocyclization products from reaction of aminoazoles with salicylaldehydes, and pyr...
Scheme 2: MCRs of 3-amino-5-methylthio-1,2,4-triazole (1a) and 3-amino-5-methoxy-1,2,4-triazole (1b) with sal...
Scheme 3: MCRs of 3-amino-5-methylthio-1,2,4-triazole (1a), salicylaldehydes 2a–c,f, and pyruvic acid (3) und...
Figure 1: Molecular structure of compound 4c according to X-ray diffraction data. Thermal ellipsoids are show...
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
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...
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
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...
Convenient alternative synthesis of the Malassezia-derived virulence factor malassezione and related compounds
- Karu Ramesh and
- Stephen L. Bearne
Beilstein J. Org. Chem. 2025, 21, 1730–1736, doi:10.3762/bjoc.21.135
- ) ketone, which could be converted to the corresponding bis(4-hydroxybenzyl) ketone (25c) by heating at 200 °C for 15 min to 3 h in the presence of pyridinium chloride [22][24]. Herein, we also show that the EDC-mediated coupling of 4-(benzyloxy)phenylacetic acid readily yields 25b, which may be
Graphical Abstract
Figure 1: Various natural indole-containing compounds isolated from Malassezia furfur.
Scheme 1: Synthetic routes to malassezione (1) from either A) an isonitrile precursor [18] or B) indole-3-acetic ...
Scheme 2: Various bis-substituted ketones prepared. a25c prepared from 25b.
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
- . Heating of indole 9a with azirine 2a in the presence of 5 mol % of Ni(hfacac)2 afforded the desired annulation product 10 in 41% yield (Scheme 5). Unfortunately, we were unable to find conditions that allowed a similar reaction of NH-indole 9b to occur. At the same time, when Ni(hfacac)2 was replaced with
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.
Azide–alkyne cycloaddition (click) reaction in biomass-derived solvent CyreneTM under one-pot conditions
- Zoltán Medgyesi and
- László T. Mika
Beilstein J. Org. Chem. 2025, 21, 1544–1551, doi:10.3762/bjoc.21.117
- capillary column (15 m × 0.25 mm × 0.25 µm) using H2 as a carrier gas. For the analysis, 10 μL of the reaction mixture was dissolved in 1 mL of ethyl acetate, followed by adding 10 μL toluene as the internal standard. Heating profile of GC–FID analysis: The initial temperature was 100 °C and was hold for
- 0.5 min. Heating rate: 40 °C/min up to the final temperature of 270 °C. The final temperature was held for 4.25 min. The water content of CyreneTM was measured on a Methrom 684 KF Coulometer at Balint Analitika Ltd, Budapest, Hungary. CyreneTM was purchased from Sigma-Aldrich Kft. Budapest, Hungary
Graphical Abstract
Scheme 1: Synthesis of CyreneTM (dihydrolevoglucosenone) from cellulose-based feeds via levoglucosenone (LG).
Scheme 2: Copper-catalyzed azide–alkyne cycloaddition of benzyl azide (1a) and phenylacetylene (2a) in variou...
Figure 1: Comparison of various solvents used in the CuAAC reaction. Reaction conditions: 1.15 mmol benzyl az...
Figure 2: Effect of the Cu source used in the click reaction of benzyl azide (1a, 1.15 mmol) and phenylacetyl...
Figure 3: Copper-catalyzed azide–alkyne cycloaddition of benzyl azide (1a) and various acetylenes 2a–h in Cyr...
Figure 4: Consecutive synthesis of various N-substituted-4-phenyl-1H-1,2,3-triazoles in CyreneTM. Reaction co...
Figure 5: “One-pot” synthesis of various 1-allyl-4-substituted-1H-1,2,3-triazoles in CyreneTM. Reaction condi...
Figure 6: Solvent recovery for the CuAAC reaction of 1a and 2a. Reaction conditions: 12.5 mL CyreneTM, 1 mol ...
Ambident reactivity of enolizable 5-mercapto-1H-tetrazoles in trapping reactions with in situ-generated thiocarbonyl S-methanides derived from sterically crowded cycloaliphatic thioketones
- Grzegorz Mlostoń,
- Małgorzata Celeda,
- Marcin Palusiak,
- Heinz Heimgartner,
- Marta Denel-Bobrowska and
- Agnieszka B. Olejniczak
Beilstein J. Org. Chem. 2025, 21, 1508–1519, doi:10.3762/bjoc.21.113
- regioselectivity in high yields. Upon heating to 65 °C in toluene solution, in analogy to the well-known compounds 2a and 2b, they extruded N2 and the in situ-generated reactive thiocarbonyl S-methanides 1c and 1d, in absence of any trapping reagent, underwent 1,3-dipolar electrocyclization yielding the
Graphical Abstract
Scheme 1: Typical [3 + 2] cycloaddition (above) and trapping (below) reactions of thiocarbonyl S-methanides 1a...
Scheme 2: Ambident reactivity of 5-mercapto-1H-tetrazoles 4 towards dimethyl 2-arylcyclopropane dicarboxylate...
Scheme 3: Regioselectivity of [3 + 2] cycloadditions of diazomethane with adamantanethione (7a) [22,24,25], and sterica...
Scheme 4: The in situ generation of sterically crowded thiocarbonyl S-methanides 1c,d (via a 1,3-dipolar cycl...
Scheme 5: Reactions of the in situ-generated thiocarbonyl S-methanides 1 (from 1,3,4-thiadiazolines 2) with e...
Figure 1: (a) Molecular structure of the N-insertion product (thioaminal) 9i. Atoms are represented by therma...
Scheme 6: Stepwise mechanism of the competitive N- and S-insertion reactions between the in situ-generated th...
Scheme 7: Mechanism of the isomerization of initially formed thioaminals 9 to dithioacetals 10.
Microwave-enhanced additive-free C–H amination of benzoxazoles catalysed by supported copper
- Andrei Paraschiv,
- Valentina Maruzzo,
- Filippo Pettazzi,
- Stefano Magliocco,
- Paolo Inaudi,
- Daria Brambilla,
- Gloria Berlier,
- Giancarlo Cravotto and
- Katia Martina
Beilstein J. Org. Chem. 2025, 21, 1462–1476, doi:10.3762/bjoc.21.108
- reported in numerous green protocols, offer significant advantages over the use of conventional heating. The goal was to utilise selective, volumetric dielectric heating to save time and energy, enable selective catalysis and generally achieve higher selectivity and yields [53][55][56]. Building on the
- experiment confirms that MW irradiation activates the catalyst independently of bulk temperature, as reported in previous studies [57][58]. We can hypothesise that MW heating is likely associated with the generation of hot spots on metal sites, resulting in an accelerated reaction rate and improved
- . SIPERNAT 320 amorphous silica was supplied by Evonik. Reactions were monitored by TLC on Merck 60 F254 (0.25 mm) plates (Milan, Italy), which were visualised by UV inspection and/or by heating after spraying with 0.5% ninhydrin in ethanol or phosphomolybdic acid. Homogeneously catalysed reactions were
Graphical Abstract
Scheme 1: Representative synthetic routes for the C–H amination of benzoxazole using supported copper catalys...
Figure 1: Reaction of benzimidazole with piperidine. a) Reaction scheme including intermaidates and b) conver...
Figure 2: Reaction rate comparison between conventional (oil bath) and MW heating. Reaction conditions: benzo...
Scheme 2: Graphical representation of Si-MonoAm-Cu(I) and Si-DiAm-Cu(I) preparation.
Figure 3: TGA profiles of SIPERNAT silica and Si-MonoAm and Si-DiAm.
Scheme 3: Scope of the MW-promoted C2-amination of benzoxazole catalysed by Si-MonoAm-Cu(I). Reaction conditi...
Scheme 4: C2-Amination of substituted benzoxazoles. Reaction conditions: benzoxazole (1.0 mmol), piperidine (...
Figure 4: Hot filtration test for the Si-MonoAm-Cu(I)-catalysed C2-amination of benzoxazole with piperidine i...
Figure 5: FTIR spectra of samples on the left 3800–2400 cm−1 wavenumber on the right 1750–1350 cm−1 wavenumbe...
Figure 6: Si-MonoAm-Cu(I) catalyst reuse.
Figure 7: FESEM images of sample a) Si-MonoAm-Cu(I) 5 wt % and c) Si-MonoAm-Cu(I) 5 wt % used.
Figure 8: EDS maps of a) Si-MonoAm-Cu(I) and b) Si-MonoAm-Cu(I) used.
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
- alcohols 13 and a binary Al/TBAB catalyst (Scheme 5) [40]. The reaction is carried out in toluene upon mild heating, providing the bicyclic products in high to excellent yields. Both electron-rich and electron-poor phenyls as well as aliphatic chains worked well, however, increased temperature and catalyst
- under mildly basic conditions to prevent possible side-reactions, specifically iododesilylation and oxetane opening by the relatively nucleophilic succinimide. Attempts to prepare the bulkier 2,3,3,4,4-pentasubstitued oxetanes were unsuccessful due to very poor conversions (<5%) and heating those
- , anhydrous conditions and mild heating to afford the products in moderate to good yields. The reaction worked well for both aliphatic and aryl-substituted substrates but best results were obtained for shorter hydrocarbon side chains and 2,6-disubstituted phenyls. The authors demonstrated the applicability of
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
- insight in the development of novel methods for amidyl radical-mediated photocatalytic direct intermolecular hydrogen atom transfer. Although, amidyl radicals employed in many reactions as HAT reagents via heating conditions have been summarized in several studies [52][53][54][55][56][57][58]. To advance
- effective, the use of heating conditions resulted in a higher yield of the corresponding products. This advancement prompted scientists to explore alternative pathways for generating amidyl radicals, as an alternative to the traditional SET reduction of the N–O bond [80][81][82]. The SET reduction is able
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
- (Scheme 24). Further heating on the Au(111) surface led to products with partial skeletal rearrangement, driven by intramolecular structural strain. Both nanographenes, 186 and 187, contain six formal azulene subunits and exhibit nearly planar geometry. However, theoretical analysis of NICS values
- -dibromoazulene (203) was annealed on an Au(111) surface, leading to the formation of 2,6-polyazulene chains 204. Upon heating these chains to 730 K, laterally fused chains were observed. The distinctive phagraphene nanoribbon 205 and the THP-graphene nanoribbon 206 were formed. This transformation provides solid
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.
Selective monoformylation of naphthalene-fused propellanes for methylene-alternating copolymers
- Kenichi Kato,
- Tatsuki Hiroi,
- Seina Okada,
- Shunsuke Ohtani and
- Tomoki Ogoshi
Beilstein J. Org. Chem. 2025, 21, 1183–1191, doi:10.3762/bjoc.21.95
- heating process. T90 and CY of [3.3.3]_branch (415 °C and 64 wt %) were lower than those of [3.3.3]_linear because of two-step decay profile (Figure S703a in Supporting Information File 1). All the samples showed broad powder X-ray diffraction (PXRD) patterns with unclear peaks at around 2θ = 11° and 20
Graphical Abstract
Figure 1: Chemical structures of fully π-fused propellanes and their typical reaction patterns toward electro...
Figure 2: a) Synthesis of methylene-alternating copolymers of fully π-fused propellanes. DCE, 1,2-dichloroeth...
Figure 3: Gas adsorption (filled circles) and desorption (open circles) isotherms of [3.3.3]_oligo (dark red)...
Synthetic approach to borrelidin fragments: focus on key intermediates
- Yudhi Dwi Kurniawan,
- Zetryana Puteri Tachrim,
- Teni Ernawati,
- Faris Hermawan,
- Ima Nurasiyah and
- Muhammad Alfin Sulmantara
Beilstein J. Org. Chem. 2025, 21, 1135–1160, doi:10.3762/bjoc.21.91
- )-configurations, respectively. The macrocyclization study of borrelidin was subsequently carried out using model compounds 155a and 155b (Scheme 24). Heating compound 155a in dichloromethane for 18 hours in the presence of 5 mol % Grubbs’ second generation catalyst yielded coupling product 156a and unreacted
- starting material 155a. Encouragingly, the addition of an extra 5 mol % of the catalyst followed by further heating for 28 hours successfully converted the remaining 155a into 156a, which was isolated in 54% yield. A trace amount of an unwanted dimer of 155a was also detected. In contrast, different
Graphical Abstract
Figure 1: Chemical structure of borrelidin (1).
Scheme 1: Synthetic strategy for Morken’s C2–C12 intermediate 20 as reported by Uguen et al. [41].
Scheme 2: Preparation of monoacetates 37 and ent-38 by Uguen et al. [41].
Scheme 3: Preparation of sulfones 27 and ent-27 by Uguen et al. [41].
Scheme 4: Attempts to couple sulfones 27 and ent-27 with epoxides 23a–c reported by Uguen et al. [41].
Scheme 5: Modified synthetic plan for Morken’s C2–C12 intermediate by Uguen [41].
Scheme 6: Revised synthetic strategy for Morken’s C2–C12 intermediate 20 by Uguen [41].
Scheme 7: Iterative synthesis of polydeoxypropionates developed by Zhou et al. [40].
Scheme 8: Application of iterative synthesis of polydeoxypropionate to construct the C3–C11 fragment 60 of bo...
Scheme 9: Retrosynthetic analysis of borrelidin by Yadav et al. [39].
Scheme 10: Two-carbon homologation of precursor 66 in the synthesize C1–C11 fragment 61 of borrelidin [39].
Scheme 11: Synthesis of the C1–C11 fragment 61 of borrelidin from monoalcohol 65 [39].
Scheme 12: Synthetic plan for Theodorakis’ C3–C11 fragment 82 of borrelidin by Laschat et al. [38].
Scheme 13: Synthesis of Theodorakis’ C3–C11 fragment 82 from compound 88 [38].
Scheme 14: Retrosynthesis of 61 and 62b by Minnaard and Madduri [37].
Scheme 15: Synthesis of intermediate 98 by Minnaard and Madduri [37].
Scheme 16: Synthesis of Ōmura’s C1–C11 fragment 61 by Minnaard and Madduri [37].
Scheme 17: Synthesis of fragment 62b of borrelidin as proposed by Minnaard and Madduri [37].
Scheme 18: Iterative directed allylation for the synthesis of deoxypropionates by Herber and Breit [33].
Scheme 19: Iterative copper-mediated directed allyl substitution for the synthesis of Theodorakis’ C3–C11 frag...
Scheme 20: Retrosynthesis of the C3–C17 fragment of borrelidin by Iqbal and co-workers [35].
Scheme 21: Synthesis of key intermediates 137 and 147 for the synthesis of the C3–C17 fragment of borrelidin.
Scheme 22: Synthesis of the C3–C17 fragment 150a,b of borrelidin.
Scheme 23: Synthesis of the C11–C15 fragment 155a of borrelidin.
Scheme 24: Macrocyclization of borrelidin model compounds 155a and 155b using ring-closing metathesis.
Gold extraction at the molecular level using α- and β-cyclodextrins
- Susana Santos Braga
Beilstein J. Org. Chem. 2025, 21, 1116–1125, doi:10.3762/bjoc.21.89
- processes with high energetic costs such as heating or applying high pressure. Seeking to find an eco-friendlier method to strip the gold from carbon, the Stoddart group investigated the use of α-CD in a series of tests at the laboratory scale in which suspensions of KAu(CN)2-loaded carbon (50 mg
Graphical Abstract
Figure 1: Schematic depiction of the α-CD channels containing the polyionic {[K(OH2)6]+[AuBr4]−}n chain insid...
Figure 2: Complexes of α-CD with MAuBr4 salts. Left) Co-precipitation yields from aqueous solutions of α-CD (...
Figure 3: Crystal structures of the complexes of α-CD with KAuCN2 salts, with tubular representation for α-CD...
Figure 4: Solid-state structure of the complex 2β-CD·HAuBr4·DBC. (a) Capped-stick and space-filling represent...
Figure 5: Schematic depiction of the selective removal of AuCl4− and its precipitation as solid gold from e-w...
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
- into the near-IR (λem = 780 nm, ϕ = 0.8% in toluene). While the ϕ of TTM-TTM is low, no photoluminescence has been reported for PTM-PTM. ΔEST of TTM-TTM is at −1.22 kcal mol−1 indicating a singlet ground state as well; however, the value is larger than for PTM-PTM, requiring heating to observe
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...
