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Search for "tandem" in Full Text gives 402 result(s) in Beilstein Journal of Organic Chemistry. Showing first 200.
Visible-light-driven NHC and organophotoredox dual catalysis for the synthesis of carbonyl compounds
- Vasudevan Dhayalan
Beilstein J. Org. Chem. 2025, 21, 2584–2603, doi:10.3762/bjoc.21.200
- ]. Scheidt and co-workers used a tandem annulation strategy, merging NHC and organic photoredox catalysis for the convergent novel synthesis of α,β-disubstituted cyclohexyl ketone scaffolds 30. This cascade process rapidly forms two contiguous C–C bonds via a formal [5 + 1] cycloaddition. It represents a
Graphical Abstract
Scheme 1: NHC-catalyzed umpolung strategy for the metal-free synthesis of amide via dual catalysis.
Scheme 2: Visible-light promoted cooperative NHC/photoredox catalyzed ring-opening of aryl cyclopropanes.
Scheme 3: NHC-catalyzed benzylic C–H acylation by dual catalysis.
Scheme 4: NHC/photoredox-catalyzed three-component coupling reaction for the preparation of γ-aryloxy ketones....
Scheme 5: NHC-catalyzed silyl radical generation from silylboronate via dual catalysis.
Scheme 6: NHC-catalyzed C–H acylation of arenes and heteroarenes through photocatalysis.
Scheme 7: NHC-catalyzed iminoacylation of alkenes via photoredox dual organocatalysis.
Scheme 8: NHC/photoredox catalyzed direct synthesis of β-arylketoesters.
Scheme 9: Visible-light-driven NHC/photoredox catalyzed borylacylation of alkenes.
Scheme 10: NHC-catalyzed oxidative functionalization of cinnamaldehyde.
Scheme 11: NHC/photocatalyzed oxidative Smiles rearrangement.
Scheme 12: NHC-catalyzed synthesis of cyclohexanones through photocatalyzed annulation.
Scheme 13: Dual organocatalyzed meta-selective acylation of electron-rich arenes and heteroarenes using blue L...
Scheme 14: Asymmetric synthesis of fused pyrrolidinones via organophotoredox/N‑heterocyclic carbene dual catal...
Recent advances in total synthesis of illisimonin A
- Juan Huang and
- Ming Yang
Beilstein J. Org. Chem. 2025, 21, 2571–2583, doi:10.3762/bjoc.21.199
- substructure hidden inside the natural product’s cage-like ring system, Kalesse’s group chose to construct this architecture first using a tandem Nazarov/ene cyclization [36]. The cis-pentalene was subsequently assembled via a Ti(III)-mediated epoxide–ketone coupling reaction. Starting from the known
- deprotection and oxidation of the secondary alcohol, yielded the cyclization precursor 35. A B(C6F5)3-catalyzed tandem Nazarov/ene cyclization of 35 provided the key spirocyclic intermediate 37. The tertiary alcohol was protected in situ with TESOTf to suppress retro-aldol side reactions. Notably, prior TES
- Suzuki and co-workers in 2021 [44]. Their work proposed that this core structure could be generated from a highly oxidized allo-cedrane moiety through a tandem retro-Claisen/aldol reaction. Beginning with compound 100, a 6-step sequence afforded ortho-quinone 101 (Scheme 10). Heating 101 promoted an
Graphical Abstract
Figure 1: The categorization of Illicium sesquiterpenes and representative natural products.
Figure 2: The original assigned (−)-illisimonin A, revised (−)-illisimonin A, and their different draws.
Scheme 1: Proposed biosynthetic pathway of illisimonin A by Yu et al.
Scheme 2: Rychnovsky’s racemic synthesis of illisimonin A (1).
Scheme 3: The absolute configuration revision of (−)-illisimonin A.
Scheme 4: Kalesse’s asymmetric synthesis of (−)-illisimonin A.
Scheme 5: Yang group proposed biosynthetic pathway of illisimonin A.
Scheme 6: Yang’s bioinspired synthesis of illisimonin A.
Scheme 7: Dai’s asymmetric synthesis of (–)-illisimonin A.
Scheme 8: Lu’s total synthesis of illisimonin A.
Scheme 9: Initial efforts toward the total synthesis of illisimonin A by the Lu Group.
Scheme 10: Suzuki’s synthetic effort towards illisimonin A.
Total syntheses of highly oxidative Ryania diterpenoids facilitated by innovations in synthetic strategies
- Zhi-Qi Cao,
- Jin-Bao Qiao and
- Yu-Ming Zhao
Beilstein J. Org. Chem. 2025, 21, 2553–2570, doi:10.3762/bjoc.21.198
- successfully accomplished via an epoxide ring-opening/tandem lactonization/olefin hydration sequence. In total, 12 consecutive redox manipulations (7 oxidations and 5 reductions) established all stereocenters, with subsequent functional group transformations completing the total synthesis of garajonone (8
Graphical Abstract
Scheme 1: Representative Ryania diterpenoids and their derivatives.
Scheme 2: Deslongchamps’s total synthesis of ryanodol (4).
Scheme 3: Deslongchamps’s total synthesis of 3-epi-ryanodol (5).
Scheme 4: Inoue’s total synthesis of ryanodol (4).
Scheme 5: Inoue’s total synthesis of ryanodine (1) from ryanodol (4).
Scheme 6: Inoue’s total synthesis of cinncassiol A (9), cinncassiol B (7), cinnzeylanol (6), and 3-epi-ryanod...
Scheme 7: Reisman’s total synthesis of (+)-ryanodol (4).
Scheme 8: Reisman’s total synthesis of (+)-ryanodine (1) and (+)-20-deoxyspiganthine (2).
Scheme 9: Micalizio’s formal total synthesis of ryanodol (4).
Scheme 10: Zhao’s total synthesis of garajonone (8).
Scheme 11: Zhao’s formal total synthesis of ryanodol (4) and ryanodine (1).
Ni-promoted reductive cyclization cascade enables a total synthesis of (+)-aglacin B
- Si-Chen Yao,
- Jing-Si Cao,
- Jian Xiao,
- Ya-Wen Wang and
- Yu Peng
Beilstein J. Org. Chem. 2025, 21, 2548–2552, doi:10.3762/bjoc.21.197
- Abstract The total synthesis of bioactive (+)-aglacin B was achieved. The key steps include an asymmetric conjugate addition reaction induced by a chiral auxiliary and a nickel-promoted reductive tandem cyclization of the elaborated β-bromo acetal, which led to the efficient construction of the
- relies on a non-photocatalysis approach. Results and Discussion Retrosynthetic analysis of (+)-aglacin B Based on the retrosynthetic analysis shown in Scheme 1, both C8′–C8 and C7–C1 bonds in (+)-aglacin B (2) could be constructed in one-step from the β-bromo acetal 5 by a Ni-promoted tandem radical
- 2,4,4,6-tetrabromo-2,5-cyclohexadienone (TBCD) in CH2Cl2 followed by reaction with allyl alcohol, provided β-bromo acetal 5 in 30% overall yield starting from alcohol 6. With a successful preparation of the cyclization precursor 5, the designed nickel-promoted reductive tandem cyclization was pursued
Graphical Abstract
Figure 1: The structures of aglacins A, B, C, and E.
Scheme 1: Retrosynthetic analysis of (+)-aglacin B (2).
Scheme 2: Synthesis of cyclization precursor 5.
Scheme 3: Synthesis of (+)-aglacin B (2).
Pentacyclic aromatic heterocycles from Pd-catalyzed annulation of 1,5-diaryl-1,2,3-triazoles
- Kaylen D. Lathrum,
- Emily M. Hanneken,
- Katelyn R. Grzelak and
- James T. Fletcher
Beilstein J. Org. Chem. 2025, 21, 2524–2534, doi:10.3762/bjoc.21.194
- tandem deprotection/click chemistry followed by Pd-catalyzed annulation is summarized in Table 1. The alkyne-substituted analogs 1–6 [48][49][50][51][52] used in this study were prepared from commercially available aryl halides using microwave-promoted Sonogashira coupling (Table S1, Supporting
- modification of the base-catalyzed conditions reported by Kwok [53], where a stoichiometric plus additional catalytic amount of tetraethylammonium hydroxide base in DMSO solvent was used to promote tandem trimethylsilyl deprotection and cycloaddition in one preparation (Figure 3). Isolated yields of this
- tandem approach preparing 7–12 ranged from 43–85%, which were similar to running the deprotection and cycloaddition reactions sequentially. Pd-catalyzed annulation using a modification of previously reported reaction conditions [46] under microwave irradiation instead of thermal heating converted 1,5
Graphical Abstract
Figure 1: Examples of polycyclic aromatic heterocycle structures: phenanthridine (left), 1,5-naphthyridine (c...
Figure 2: Overview of the synthetic scheme employed by this study.
Figure 3: Base-catalyzed [53] tandem deprotection/cycloaddition reaction conditions used to prepare 1,5-diaryl-1,...
Figure 4: Identity of 1,5-diaryl-1,2,3-triazole control compounds prepared from tandem deprotection/click con...
Figure 5: Exemplary comparison of 1H NMR aromatic signal shifts for annulated and non-annulated compounds (CD...
Figure 6: UV–visible absorbance spectra of annulated 13–18 (black lines) compared with their non-annulated co...
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
- construction of the tetracyclic core of Aspidosperma alkaloids. Our method involves an Ir-catalyzed PET reaction of K for the stereoselective formation of the cis-configured BC bicyclic core with an all-carbon quaternary center [25][26]. Computational studies suggest that the observed tandem PET reaction of K
- proceeds via an unusual 1,3-C shift to afford M, i.e. through an interrupted [2 + 2] cyclization/retro-Mannich reaction. Results and Discussion Conditions optimization Our study commenced with the evaluation of the proposed PET-based tandem [2 + 2] cyclization/retro-Mannich reaction. We selected compound
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
- formation of a mixture of ketone 194 and cyclic diene 195. Regio- and stereoselectivity was observed in the case of the epoxide 189. The cyclopentane derivative 194 was obtained stereoselectively and in high yield during the reaction with BF3·Et2O. An alternative example of the tandem epoxide rearrangement
- promotes tandem transformations with the Lewis acid, resulting in oxygen-containing bicyclic compounds 198 and 199 through the formation of oxonium intermediates E and F. In the work of Kulciţki et al. [89], a very attractive acid-induced rearrangement of homodrimanic epoxide 200 was described. This
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).
Comparative analysis of complanadine A total syntheses
- Reem Al-Ahmad and
- Mingji Dai
Beilstein J. Org. Chem. 2025, 21, 2334–2344, doi:10.3762/bjoc.21.178
- Scheme 5, the Dai synthesis starts with compound 58 which can be prepared from (+)-pulegone in three steps or via an organocatalyzed tandem sequence in one step. The terminal olefin of 58 was then converted to a primary azide via an anti-Markovnikov hydroazidation reaction with a combination of 59 and
- Paal–Knorr pyrrole synthesis delivered 63, which was unstable and spontaneously cyclized to provide 64. Compound 64 was then advanced to tetracyclic intermediate 67 in a one-pot tandem process, which initiated with Staudinger azide reduction with PPh3 to form a primary amine. After reversible
- hemiaminal opening and amine–ketone condensation, iminium ion 65 was produced for the next pyrrole nucleophilic addition to form a strategically important C–C bond and afford 66, which was protected as Boc carbamate in the same pot to give 67 in 96% yield from 64. In this tandem sequence, the nucleophilicity
Graphical Abstract
Scheme 1: Complanadine natural products and their plausible biosynthesis.
Scheme 2: The Siegel total synthesis of complanadine A enabled by [2 + 2 + 2] cycloadditions.
Scheme 3: The Sarpong total synthesis of complanadine A enabled by a biomimetic strategy and C–H activation.
Scheme 4: The Tsukano total synthesis of complanadine A enabled by Diels–Alder cycloaddition, Heck cyclizatio...
Scheme 5: The Dai total synthesis of complanadine A using single-atom skeletal editing.
Scheme 6: Comparative summary of the four complanadine A total syntheses.
Recent advances in Norrish–Yang cyclization and dicarbonyl photoredox reactions for natural product synthesis
- Peng-Xi Luo,
- Jin-Xuan Yang,
- Shao-Min Fu and
- Bo Liu
Beilstein J. Org. Chem. 2025, 21, 2315–2333, doi:10.3762/bjoc.21.177
- , employing a late-stage biomimetic Norrish−Yang cyclization to construct the highly compact cyclobutanone motif [21]. The task commenced with epoxide 2 (Scheme 2), which was accessible via a known five-step protocol from geranyl acetate (1). Compound 2 was advanced to 3 using a tandem cyclization developed
- synthesis of 49–57 via a bioinspired strategy, incorporating a Norrish–Yang cyclization/α-hydroxyketone rearrangement tandem reaction and late-stage biomimetic photooxidation as key steps. The synthetic endeavour began with the total synthesis of 49, which served as both the envisioned precursor for Norrish
- E/I (53/57), respectively. In this work, inspired by the biosynthetic pathway of natural products, the authors employed a tandem Norrish–Yang photocyclization and α-hydroxy ketone rearrangement as the key step to construct the unique bicyclo[3.2.0]heptane skeleton of gracilisoids. This strategy
Graphical Abstract
Scheme 1: a) The mechanism of Norrish type II reaction and Norrish–Yang cyclization; b) The mechanism of the ...
Scheme 2: Total synthesis of (+)-cyclobutastellettolide B.
Scheme 3: Norrish–Yang cyclization and 1,2-methyl migration.
Scheme 4: Synthetic study toward phainanoids.
Scheme 5: a) Mitsunobu reaction of the C9 ketal; b) Norrish–Yang cyclization of the saturated C5–C6; c) calcu...
Scheme 6: Total synthesis of avarane-type meroterpenoids.
Scheme 7: Total synthesis of gracilisoid A.
Scheme 8: Divergent total synthesis of gracilisoids B–I.
Scheme 9: Mechanism of the late-stage biomimetic photooxidation.
Scheme 10: Asymmetric total synthesis of lycoplatyrine A.
Scheme 11: Photoreaction of pyrrolidine-derived phenyl keto amide.
Scheme 12: Photoredox reactions of naphthoquinones.
Scheme 13: Synthetic study toward γ-rubromycin.
Scheme 14: Substituent-dependent conformational preferences.
Scheme 15: Total synthesis of preussomerins EG1, EG2, and EG3.
Enantioselective radical chemistry: a bright future ahead
- Anna C. Renner,
- Sagar S. Thorat,
- Hariharaputhiran Subramanian and
- Mukund P. Sibi
Beilstein J. Org. Chem. 2025, 21, 2283–2296, doi:10.3762/bjoc.21.174
- [22][23]. In these studies, alkyl radicals underwent conjugate addition to N-enoyloxazolidinones. Sibi later described enantioselective tandem radical conjugate addition–trapping reactions that formed two carbon–carbon bonds and created two vicinal stereocenters in a single transformation (Scheme 1
Graphical Abstract
Figure 1: Methods of radical generation (A) and general types of radical reactions (B).
Figure 2: Chiral catalysis in enantioselective radical chemistry [13-37].
Scheme 1: Diastereo- and enantioselective additions of nucleophilic radicals to N-enoyloxazolidinone and pyrr...
Scheme 2: Organocatalyzed formal [3 + 2] cycloadditions affording substituted pyrrolidines.
Scheme 3: Synthesis of a hexacyclic compound via an organocatalyzed enantioselective polyene cyclization.
Scheme 4: Nickel-catalyzed asymmetric cross-coupling reactions.
Scheme 5: Chiral cobalt–porphyrin metalloradical-catalyzed radical cyclization reactions.
Scheme 6: Enantioselective radical chaperone catalysis.
Scheme 7: Enantioselective radical addition by decatungstate/iminium catalysis.
Scheme 8: An ene-reductase-catalyzed photoenzymatic enantioselective radical cyclization/enantioselective HAT...
Scheme 9: Photoenzymatic oxidative C(sp3)–C(sp3) coupling reactions between organoboron compounds and amino a...
Scheme 10: Electrochemical α-alkenylation reactions of 2-acylimidazoles catalyzed by a chiral-at-rhodium Lewis...
Scheme 11: Regio- and enantioselective electrochemical reactions of silyl polyenolates catalyzed by a chiral n...
Pathway economy in cyclization of 1,n-enynes
- Hezhen Han,
- Wenjie Mao,
- Bin Lin,
- Maosheng Cheng,
- Lu Yang and
- Yongxiang Liu
Beilstein J. Org. Chem. 2025, 21, 2260–2282, doi:10.3762/bjoc.21.173
- , the Liu group developed a gold-catalyzed tandem cycloisomerization, offering controllable synthesis of either indolo[2,3-a]quinolizine or indolizino[8,7-b]indole derivatives (Scheme 10) [17]. When the indole nitrogen of the substrate was substituted with electron-donating groups (EDGs) and the alkyne
- of propiolamide was equipped with a bulky substituent, the 6-exo-dig cyclization was initially triggered under gold(I)-catalysis, leading to intermediate 43. Then the indolizino[8,7-b]indole skeleton 44 ultimately was constructed via a tandem 5-exo-dig cyclization (Scheme 10, path a). When the indole
- nitrogen was strategically functionalized with an electron-withdrawing groups (EWGs) and the alkyne of propiolamide was modified with a less bulky substituent. A 6-exo-dig cyclization yielded intermediate 45. Finally, a tandem 6-endo-dig cyclization enabled the successful assembly of the indolo[2,3-a
Graphical Abstract
Scheme 1: Economical synthesis and pathway economy.
Scheme 2: Au(I)-catalyzed cascade cyclization paths of 1,5-enynes.
Scheme 3: Au(I)-catalyzed cyclization paths of 1,7-enynes.
Scheme 4: I2/TBHP-mediated radical cycloisomerization paths of 1,n-enyne.
Scheme 5: Au(I)-catalyzed cycloisomerization paths of 3-allyloxy-1,6-diynes.
Scheme 6: Pd(II)-catalyzed cycloisomerization paths of 2-alkynylbenzoate-cyclohexadienone.
Scheme 7: Stereoselective cyclization of 1,5-enynes.
Scheme 8: Substituent-controlled cycloisomerization of propargyl vinyl ethers.
Scheme 9: Au(I)-catalyzed pathway-controlled domino cyclization of 1,2-diphenylethynes.
Scheme 10: Au(I)-catalyzed tandem cyclo-isomerization of tryptamine-N-ethynylpropiolamide.
Scheme 11: Au(I)-catalyzed tunable cyclization of 1,6-cyclohexenylalkyne.
Scheme 12: Substituent-controlled 7-exo- and 8-endo-dig-selective cyclization of 2-propargylaminobiphenyl deri...
Scheme 13: BiCl3-catalyzed cycloisomerization of tryptamine-ynamide derivatives.
Scheme 14: Au(I)-mediated substituent-controlled cycloisomerization of 1,6-enynes.
Scheme 15: Ligand-controlled regioselective cyclization of 1,6-enynes.
Scheme 16: Ligand-dependent cycloisomerization of 1,7-enyne esters.
Scheme 17: Ligand-controlled cycloisomerization of 1,5-enynes.
Scheme 18: Ligand-controlled cyclization strategy of alkynylamide tethered alkylidenecyclopropanes.
Scheme 19: Ag(I)-mediated pathway-controlled cycloisomerization of tryptamine-ynamides.
Scheme 20: Gold-catalyzed cycloisomerization of indoles with alkynes.
Scheme 21: Catalyst-dependent cycloisomerization of dienol silyl ethers.
Scheme 22: Cycloisomerization of aromatic enynes governed by catalyst.
Scheme 23: Catalyst-dependent 1,2-migration in cyclization of 1-(indol-2-yl)-3-alkyn-1-ols.
Scheme 24: Gold-catalyzed cycloisomerization of N-propargyl-N-vinyl sulfonamides.
Scheme 25: Gold(I)-mediated enantioselective cycloisomerizations of ortho-(alkynyl)styrenes.
Scheme 26: Catalyst-controlled intramolecular cyclization of 1,7-enynes.
Scheme 27: Brønsted acid-catalyzed cycloisomerizations of tryptamine ynamides.
Scheme 28: Catalyst-controlled cyclization of indolyl homopropargyl amides.
Scheme 29: Angle strain-dominated 6-endo-trig cyclization of propargyl vinyl ethers.
Scheme 30: Angle strain-controlled cycloisomerization of alkyn-tethered indoles.
Scheme 31: Geometrical isomeration-dependent cycloisomerization of 1,3-dien-5-ynes.
Scheme 32: Temperature-controlled cyclization of 1,7-enynes.
Scheme 33: Cycloisomerizations of n-(o-ethynylaryl)acrylamides through temperature modulation.
Scheme 34: Temperature-controlled boracyclization of biphenyl-embedded 1,3,5-trien-7-ynes.
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
- transferred to LC vials and stored at −20 °C until LC–MS/MS analysis. The concentration of the parent compound remaining in each sample was determined using liquid chromatography coupled with tandem mass spectrometry (LC–MS/MS). The percentage of the remaining substrate was calculated relative to the time
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...
Electrochemical cyclization of alkynes to construct five-membered nitrogen-heterocyclic rings
- Lifen Peng,
- Ting Wang,
- Zhiwen Yuan,
- Bin Li,
- Zilong Tang,
- Xirong Liu,
- Hui Li,
- Guofang Jiang,
- Chunling Zeng,
- Henry N. C. Wong and
- Xiao-Shui Peng
Beilstein J. Org. Chem. 2025, 21, 2173–2201, doi:10.3762/bjoc.21.166
- benzamides with terminal alkynes, 5-exo-dig aza-cyclization of 2-alkynylbenzamides as well as reductive cascade annulation of o-alkynylbenzamides. Pyrroles and imidazoles were formed efficiently via electrochemical annulation of alkynes with enamides and tandem Michael addition/azidation/cyclization of
- , oxidant, and base-free conditions. An electrochemical enantioselective tandem C–H indolization of 2-alkynylanilines with 3-functionalized indoles towards 2,3′-biindolyl atropisomers was achieved by Zeng in 2025 (Scheme 7) [204]. After screening the reaction carefully, the optimal conditions were gained as
- electricity as a sustainable and green oxidant, noble metal catalyst (Rh) was required to achieve reasonable yields. An electrochemical synthesis of imidazoles through tandem Michael addition/azidation/intramolecular cyclization of alkynes, amines and azides was realized by Chen in 2022 (Scheme 17) [267
Graphical Abstract
Figure 1: Natural products and functional molecules possessing five-membered rings.
Scheme 1: Electrochemical intramolecular coupling of ureas to form indoles.
Scheme 2: Electrochemical dehydrogenative annulation of alkynes with anilines.
Scheme 3: Electrochemical annulations of o-arylalkynylanilines.
Scheme 4: Electrochemical cyclization of 2-ethynylanilines.
Scheme 5: Electrochemical selenocyclization of diselenides and 2-ethynylanilines.
Scheme 6: Electrochemical cascade approach towards 3-selenylindoles.
Scheme 7: Electrochemical C–H indolization.
Scheme 8: Electrochemical annulation of benzamides and terminal alkynes.
Scheme 9: Electrochemical synthesis of isoindolinone by 5-exo-dig aza-cyclization.
Scheme 10: Electrochemical reductive cascade annulation of o-alkynylbenzamide.
Scheme 11: Electrochemical intramolecular 1,2-amino oxygenation of alkyne.
Scheme 12: Electrochemical multicomponent reaction of nitrile, (thio)xanthene, terminal alkyne and water.
Scheme 13: Electrochemical aminotrifluoromethylation/cyclization of alkynes.
Scheme 14: Electrochemical cyclization of o-nitrophenylacetylene.
Scheme 15: Electrochemical annulation of alkynyl enaminones.
Scheme 16: Electrochemical annulation of alkyne and enamide.
Scheme 17: Electrochemical tandem Michael addition/azidation/cyclization.
Scheme 18: Electrochemical [3 + 2] cyclization of heteroarylamines.
Scheme 19: Electrochemical CuAAC to access 1,2,3-triazole.
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
- [188]. Conversion of furfural to pyrrole and proline: Zhou and Yan reported a route bridging commercial biomass feedstock with high-value N-containing chemicals through pyrrole as a hub molecule. Furfural was converted into pyrrole in 75% yield via tandem decarbonylation–amination reactions over tailor
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®.
Further elaboration of the stereodivergent approach to chaetominine-type alkaloids: synthesis of the reported structures of aspera chaetominines A and B and revised structure of aspera chaetominine B
- Jin-Fang Lü,
- Jiang-Feng Wu,
- Jian-Liang Ye and
- Pei-Qiang Huang
Beilstein J. Org. Chem. 2025, 21, 2072–2081, doi:10.3762/bjoc.21.162
- aspera chaetominine B. Keywords: epoxidation; selective epimerization; stereodivergent synthesis; structural revision; tandem reaction; Introduction In contemporary organic chemistry, due to the widespread application of modern separation and analytical techniques, the structural elucidation and
Graphical Abstract
Figure 1: Structures of some reported chaetominine-type alkaloids and revised structures via our total synthe...
Scheme 1: Improved total synthesis of (–)-isochaetominine A (4) and diastereomer 16.
Scheme 2: Diastereoconvergent transformations of 17 and 18 into two diastereomers of versiquinazoline H.
Scheme 3: Mono- and double epimerization-based enantiodivergent syntheses of chaetominine-type alkaloids and ...
Scheme 4: Enantioselective synthesis of the proposed structure of aspera chaetominine A.
Scheme 5: Enantioselective syntheses of both the proposed and revised structures of aspera chaetominine B.
α-Ketoglutaric acid in Ugi reactions and Ugi/aza-Wittig tandem reactions
- Vladyslav O. Honcharov,
- Yana I. Sakhno,
- Olena H. Shvets,
- Vyacheslav E. Saraev,
- Svitlana V. Shishkina,
- Tetyana V. Shcherbakova and
- Valentyn A. Chebanov
Beilstein J. Org. Chem. 2025, 21, 2021–2029, doi:10.3762/bjoc.21.157
- substituted 3-(3-oxo-3,4-dihydroquinoxalin-2-yl)propanoic acids containing a pharmacophore quinoxalinone moiety. The tandem Ugi/aza-Wittig combination was also carried out in a one-pot procedure without isolation of the intermediate. Keywords: α-ketoglutaric acid; aza-Wittig reaction; multicomponent reaction
- for the preparation of benzodiazepinone derivatives, which showed promising psychotropic effects [20][21][22][23][24], using a tandem combination of Ugi/azide–alkyne cycloaddition reactions. From this point of view, azido amines are promising reagents for use in the Ugi reaction, opening up the
- an additional reaction center for post-cyclizations, is scarcely reported in the literature [25][30][31]. Among the numerous tandem synthetic approaches, the combination of Ugi/aza-Wittig reactions is of particular interest. In recent years, several works have been dedicated to the synthesis of
Graphical Abstract
Figure 1: Some biologically active quinoxalinone derivatives.
Scheme 1: Known multicomponent reactions of KGA.
Scheme 2: Ugi reaction involving KGA.
Scheme 3: Tandem Ugi/aza-Wittig combination involving KGA.
Figure 2: Molecular structure of 3-(4-(2-(tert-butylamino)-1-(4-methoxyphenyl)-2-oxoethyl)-5,7-dimethyl-3-oxo...
Enantioselective desymmetrization strategy of prochiral 1,3-diols in natural product synthesis
- Lihua Wei,
- Rui Yang,
- Zhifeng Shi and
- Zhiqiang Ma
Beilstein J. Org. Chem. 2025, 21, 1932–1963, doi:10.3762/bjoc.21.151
- sequence including oxidation and subsequent hydrogenation. The Huang group reported their synthesis of (+)-brazilin and its racemic form in 2022 (Scheme 5) [34]. They first evaluated the feasibility of the Prins/Friedel–Crafts tandem reaction in the construction of the 6/6/5/6 tetracyclic skeleton
- 62% ee. A two-step conversion of 34 gave diol 35, which underwent Prins/Friedel–Crafts tandem cyclization to construct tetracyclic compound 36. Final deprotection delivered (+)-brazilin (37). Candida antarctica lipase (CAL) CAL is a type of lipase originating from the yeast Candida antarctica and
Graphical Abstract
Scheme 1: General mechanism of a lipase-catalyzed esterification.
Scheme 2: Shishido’s synthesis of (−)-xanthorrhizol (4) and (+)-heliannuol D (8).
Scheme 3: Shishido’s synthesis of a) (−)-heliannuol A (15) and b) heliannuol G (20) and heliannuol H (21).
Scheme 4: Deska’s synthesis of hyperione A (30) and ent-hyperione B (31).
Scheme 5: Huang’s synthesis of (+)-brazilin (37).
Scheme 6: Shishido’s synthesis of (−)-heliannuol D (42) and (+)-heliannuol A (43).
Scheme 7: Chênevert’s synthesis of (S)-α-tocotrienol (49).
Scheme 8: Kita’s synthesis of monoester 53.
Scheme 9: Kita’s synthesis of fredericamycin A (60).
Scheme 10: Takabe’s synthesis of (E)-3,7-dimethyl-2-octene-1,8-diol (64).
Scheme 11: Takabe’s synthesis of (18S)-variabilin (70).
Scheme 12: Kawasaki’s synthesis of (S)-Rosaphen (74) and (R)-Rosaphen (75).
Scheme 13: Tokuyama’s synthesis of a) (−)-petrosin (84) and b) (+)-petrosin (86).
Scheme 14: Fukuyama’s synthesis of leustroducsin B (96).
Scheme 15: Nanda’s synthesis of a) fragment 100, b) fragment 106 and c) (−)-rasfonin (109).
Scheme 16: Davies’ synthesis of (+)-pilocarpine (115) and (+)-isopilocarpine (116).
Scheme 17: Ōmura’s synthesis of salinosporamide A (125).
Scheme 18: Kang’s synthesis of ʟ-cladinose (124) and its derivative.
Scheme 19: Kang’s preparation of fragment 139.
Scheme 20: Kang’s synthesis of azithromycin (149).
Scheme 21: Kang’s synthesis of (−)-dysiherbaine (156).
Scheme 22: Kang’s synthesis of (−)-kaitocephalin (166).
Scheme 23: Kang’s synthesis of laidlomycin (180).
Scheme 24: Snyder’s synthesis of arboridinine (190).
Scheme 25: Ma’s synthesis of (+)-alstrostine G (203).
Scheme 26: Trost’s synthesis of (−)-18-epi-peloruside A (215).
Scheme 27: Lindel’s synthesis of (–)-dihydroraputindole (223).
Scheme 28: Iwata’s synthesis of a) (−)-talaromycin B (232) and b) (+)-talaromycin A (235).
Scheme 29: Cook’s synthesis of a) (−)-vincamajinine (240) and b) (−)-11-methoxy-17-epivincamajine (245).
Scheme 30: Cook’s synthesis of (+)-dehydrovoachalotine (249) and voachalotine (250).
Scheme 31: Cook’s synthesis of a) (−)-12-methoxy-Nb-methylvoachalotine (257) and b) (+)-polyneuridine, macusin...
Scheme 32: Trauner’s synthesis of stephadiamine (273).
Scheme 33: Garg’s synthesis of (–)-ψ-akuammigine (285).
Scheme 34: Ding’s synthesis of (+)-18-benzoyldavisinol (293) and (+)-davisinol (294).
Preparation of spirocyclic oxindoles by cyclisation of an oxime to a nitrone and dipolar cycloaddition
- Beth L. Ritchie,
- Alexandra Longcake and
- Iain Coldham
Beilstein J. Org. Chem. 2025, 21, 1890–1896, doi:10.3762/bjoc.21.146
- of an oxime, itself prepared in situ from an aldehyde. The stereochemistry of one of the spirooxindoles was determined by single crystal X-ray diffraction studies via crystallisation using encapsulated nanodroplet crystallisation (ENaCt) protocols. The chemistry involves cascade or tandem
Graphical Abstract
Figure 1: Representative oxindole alkaloids.
Scheme 1: Proposed synthetic approach.
Scheme 2: Preparation of the aldehyde 4.
Scheme 3: Cycloaddition with N-methylmaleimide.
Figure 2: Orientation for the cycloaddition (left) and the crystal structure of the major stereoisomer 5a (ri...
Scheme 4: Cycloaddition with N-phenylmaleimide.
Scheme 5: Cycloaddition with dimethyl fumarate and dimethyl maleate.
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
- cycloaddition, tandem annulation, intramolecular cyclization, and cross-coupling reactions are commonly employed under thermal conditions, utilizing metal catalysts based on Pd, Ru, Au, Cu, and Fe to access a wide array of substituted quinoline frameworks [29][30][31][32][33][34][35][36][37][38]. Conversely, in
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.
Catalytic asymmetric reactions of isocyanides for constructing non-central chirality
- Jia-Yu Liao
Beilstein J. Org. Chem. 2025, 21, 1648–1660, doi:10.3762/bjoc.21.129
- lactones with carbon nucleophiles. The success lies in the tandem enantioselective ring-opening of lactones with α-acidic isocyanides, followed by a rapid cyclization driven by aromatization, overcoming the long-standing stereochemical leakage problem caused by the undesired lactol formation [45
Graphical Abstract
Figure 1: a) Common types of chirality. b) Representative functional molecules bearing non-central chirality.
Scheme 1: Construction of planar chirality.
Scheme 2: Construction of axial chirality.
Scheme 3: Construction of inherent chirality.
Scheme 4: Construction of helical chirality.
Scheme 5: CPA-catalyzed enantioselective Groebke–Blackburn–Bienaymé reaction.
Scheme 6: Construction of axially chiral 3-arylpyrroles via de novo pyrrole formation.
Scheme 7: Synthesis of atropoisomeric 3-arylpyrroles via central-to-axial chirality transfer.
Scheme 8: Dynamic kinetic resolution of bridged biaryls with α-acidic isocyanides.
Scheme 9: Desymmetrization of prochiral compounds with α-acidic isocyanides.
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
- 178 from 3-aryloxetan-3-ols through a tandem Friedel–Crafts alkylation/intramolecular ring opening (Scheme 45) [87]. The reaction was mostly high yielding and best results were obtained for electron-rich para-substituted phenols, while substituents in the ortho/meta-positions diverted the
- –2021, Kuduk and co-workers published three different tandem, one-pot methodologies towards complex polycyclic heterocycles [100][101][102]. All of them are two-step reactions consisting of an intermolecular coupling followed by an intramolecular, base-induced oxetane opening (Scheme 48). The first one
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 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
- can also serve as valuable synthetic tools for constructing azulene subunits in the final step. For example, Ma and co-workers reported a modular synthetic strategy for the synthesis of diverse azulene-embedded PAHs via a tandem Suzuki coupling and base-promoted Knoevenagel-type condensation
- synthetic strategy. The tandem Suzuki coupling/Knoevenagel condensation strategy leading to PAH 85 was independently reported by Liu [61] and Mastalerz (Scheme 12) [62]. The first group reported a cascade formal [3 + 4] annulation between triple boronic ester 83 and naphthalene 84 which combines a Suzuki
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
- with α-carbonylalkyl bromides using palladium (Scheme 29) [17]. This reaction was initiated by a Heck insertion and required Ag2CO3 as an oxidant. It proceeded via a tandem C–Br/C–H functionalization and cyclization steps, ultimately realizing an oxidative radical pathway. The process exhibited a broad
- undergoes a tandem sequence of addition to the C=C bond, cyclization, oxidation, and hydrogen abstraction to yield the final product. In the second pathway, a σ-arylpalladium(II) intermediate I is formed, initiated by the active [PdIIX2Ln] species. This intermediate then undergoes a carbopalladation process
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.
Investigations of amination reactions on an antimalarial 1,2,4-triazolo[4,3-a]pyrazine scaffold
- Henry S. T. Smith,
- Ben Giuliani,
- Kanchana Wijesekera,
- Kah Yean Lum,
- Sandra Duffy,
- Aaron Lock,
- Jonathan M. White,
- Vicky M. Avery and
- Rohan A. Davis
Beilstein J. Org. Chem. 2025, 21, 1126–1134, doi:10.3762/bjoc.21.90
- ). Reactions were set up in tandem and samples from both reaction vessels were taken, at 2, 4 and 6 h time points and used for TLC analysis to monitor reaction progress. The reactions proceeded in parallel, and both reactions had reached completion at 6 h. After isolation in high purity (≥95%) by silica flash
Graphical Abstract
Figure 1: (A) Position numbering on the pyrazine ring of 1,2,4-triazolo[4,3-a]pyrazine. (B) Illustration of i...
Scheme 1: Treatment of 1 with phenethylamine (PEA) under two different reaction conditions, (i) or (ii), gave ...
Figure 2: Key COSY (–), HMBC (→) and ROESY (↔) correlations for compound 2.
Figure 3: Thermal ellipsoid plot of compound 2.
Scheme 2: Chemical structures, reagents and conditions used to synthesise the new aminated triazolopyrazines 2...
Figure 4: Thermal ellipsoid plots for compounds 7 (A), 10 (B) and 15 (C).
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
- accumulation in soil and water [17]. The shortage of natural resources in tandem with the increasing market demand for gold are driving the need to obtain this commodity from low grade ores, typically containing less than 1 wt % in gold, materials of difficult extraction, such as the gold-bearing silicates and
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...
