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Search for "alkene" in Full Text gives 548 result(s) in Beilstein Journal of Organic Chemistry. Showing first 200.
Synthesis of diaryl phosphates using phytic acid as a phosphorus source
- Kazuya Asao,
- Seika Matsumoto,
- Haruka Mori,
- Riku Yoshimura,
- Takeshi Sasaki,
- Naoya Hirata,
- Yasuyuki Hayakawa and
- Shin-ichi Kawaguchi
Beilstein J. Org. Chem. 2026, 22, 213–223, doi:10.3762/bjoc.22.15
- the other mechanism is based on an E2 reaction, which involves the elimination of phosphoric acid accompanied by alkene formation. The phosphoric acid ester of a secondary alcohol releases phosphoric acid and alkenes through thermal degradation, which has been previously observed using isosorbide
Graphical Abstract
Scheme 1: Structure of phytic acid.
Figure 1: Structures of representative phosphate esters.
Figure 2: Synthetic methods for phosphorus compounds bypassing white phosphorus or phosphorus chloride.
Figure 3: Conditions for the syntheses of diaryl phosphates using phytic acid as a phosphorus source and scop...
Scheme 2: Phosphoric acid diesterification reaction conducted in a previous study.
Scheme 3: Scale-up reaction conducted for the time-course analysis of phosphate esterification. The reaction ...
Figure 4: Time-course analysis plots of the diphenylphosphate formation from phytic acid and 1a. The beginnin...
Figure 5: A possible reaction pathway for the formation of phosphate ester using phytic acid as the phosphoru...
Figure 6: 31P NMR spectrum of phytic acid extracted from rice bran.
Scheme 4: Esterification reaction conditions using the extracted phytic acid. The yield refers to the isolate...
Total synthesis of natural products based on hydrogenation of aromatic rings
- Haoxiang Wu and
- Xiangbing Qi
Beilstein J. Org. Chem. 2026, 22, 88–122, doi:10.3762/bjoc.22.4
- chloride, and radical reduction. Subsequently, reduction of the cyanide group with DIBAL-H and a Wittig reaction afford alkene 114 in 82% yield. Sodium metal was then used as a single-electron reducing agent to provide the second cycloaddition precursor 115, which was converted to the enamine. The enamine
Graphical Abstract
Scheme 1: The association between dearomatization and natural product synthesis.
Scheme 2: Key challenges in hydrogenation of aromatic rings.
Scheme 3: Hydrogenation of heterocyclic aromatic rings.
Scheme 4: Hydrogenation of the carbocyclic aromatic rings.
Scheme 5: Hydrogenation of the heterocycle part in bicyclic aromatic rings.
Scheme 6: Hydrogenation of the heterocycle part in bicyclic aromatic rings.
Scheme 7: Hydrogenation of benzofuran, indole, and their analogues.
Scheme 8: Hydrogenation of benzofuran, indole, and their analogues.
Scheme 9: Total synthesis of (±)-keramaphidin B by Baldwin and co-workers.
Scheme 10: Total synthesis of (±)-LSD by Vollhardt and co-workers.
Scheme 11: Total synthesis of (±)-dihydrolysergic acid by Boger and co-workers.
Scheme 12: Total synthesis of (±)-lysergic acid by Smith and co-workers.
Scheme 13: Hydrogenation of (−)-tabersonine to (−)-decahydrotabersonine by Catherine Dacquet and co-workers.
Scheme 14: Total synthesis of (±)-nominine by Natsume and co-workers.
Scheme 15: Total synthesis of (+)-nominine by Gin and co-workers.
Scheme 16: Total synthesis of (±)-lemonomycinone and (±)-renieramycin by Magnus.
Scheme 17: Total synthesis of GB13 by Sarpong and co-workers.
Scheme 18: Total synthesis of GB13 by Shenvi and co-workers.
Scheme 19: Total synthesis of (±)-corynoxine and (±)-corynoxine B by Xia and co-workers.
Scheme 20: Total synthesis of (+)-serratezomine E and the putative structure of huperzine N by Bonjoch and co-...
Scheme 21: Total synthesis of (±)-serralongamine A and the revised structure of huperzine N and N-epi-huperzin...
Scheme 22: Early attempts to indenopiperidine core.
Scheme 23: Homogeneous hydrogenation and completion of the synthesis.
Scheme 24: Total synthesis of jorunnamycin A and jorumycin by Stoltz and co-workers.
Scheme 25: Early attempt towards (−)-finerenone by Aggarwal and co-workers.
Scheme 26: Enantioselective synthesis towards (−)-finerenone.
Scheme 27: Total synthesis of (+)-N-methylaspidospermidine by Smith, Grigolo and co-workers.
Scheme 28: Dearomatization approach towards matrine-type alkaloids.
Scheme 29: Asymmetric total synthesis to (−)-senepodine F via an asymmetric hydrogenation of pyridine.
Scheme 30: Selective hydrogenation of indole derivatives and application.
Scheme 31: Synthetic approaches to the oxindole alkaloids by Qi and co-workers.
Scheme 32: Total synthesis of annotinolide B by Smith and co-workers.
Synthesis and applications of alkenyl chlorides (vinyl chlorides): a review
- Daniel S. Müller
Beilstein J. Org. Chem. 2026, 22, 1–63, doi:10.3762/bjoc.22.1
- compound loss or degradation at the purification step. 1.2 Exchange reactions This chapter deals with exchange reactions, meaning that a given substituent on the alkene is formally exchanged for chlorine. The reactions are very different from each other in terms of mechanism and for a full discussion the
- alkenyl chloride 156 was isolated only in trace amounts, alongside isomerized alkene 157 and dichloride 158. Notably, only the sterically hindered tert-butyl-substituted alkyne afforded the desired product 155 in high yields, whereas hydrochlorination of 4-octyne proved inefficient to deliver compound 159
- access cyclohexenyl chlorides via chloride trapping of alkenyl cation intermediates (Scheme 48B) [157]. Comparable yields were obtained when either alkene or alcohol precursors were employed, consistent with the formation of a common cationic intermediate. The method proved limited to six-membered ring
Graphical Abstract
Figure 1: Representative alkenyl chloride motifs in natural products. References: Pinnaic acid [8], haterumalide ...
Figure 2: Representative alkenyl chloride motifs in pharmaceuticals and pesticides. References: clomifene [25], e...
Figure 3: Graphical overview of previously published reviews addressing the synthesis of alkenyl chlorides.
Figure 4: Classification of synthetic approaches to alkenyl chlorides.
Scheme 1: Early works by Friedel, Henry, and Favorsky.
Scheme 2: Product distribution obtained by H NMR integration of crude compound as observed by Kagan and co-wo...
Scheme 3: Side reactions observed for the reaction of 14 with PCl5.
Scheme 4: Only compounds 15 and 18 were observed in the presence of Hünig’s base.
Scheme 5: Efficient synthesis of dichloride 15 at low temperatures.
Scheme 6: Various syntheses of alkenyl chlorides on larger scale.
Scheme 7: Scope of the reaction of ketones with PCl5 in boiling cyclohexane.
Scheme 8: Side reactions occur when using excess amounts of PCl5.
Scheme 9: Formation of versatile β-chlorovinyl ketones.
Scheme 10: Mixture of PCl5 and PCl3 used for the synthesis of 49.
Scheme 11: Catechol–PCl3 reagents for the synthesis of alkenyl chlorides.
Scheme 12: (PhO)3P–halogen-based reagents for the synthesis of alkenyl halides.
Scheme 13: Preparation of alkenyl chlorides from alkenyl phosphates.
Scheme 14: Preparation of alkenyl chlorides by treatment of ketones with the Vilsmeier reagent.
Scheme 15: Preparation of electron-rich alkenyl chlorides by treatment of ketones with the Vilsmeier reagent.
Scheme 16: Cu-promoted synthesis of alkenyl chlorides from ketones and POCl3.
Figure 5: GC yield of 9 depending on time and reaction temperature.
Figure 6: Broken reaction flask after attempts to clean the polymerized residue.
Figure 7: GC yield of 9 depending on the amount of CuCl and time.
Scheme 17: Treatment of 4-chromanones with PCl3.
Scheme 18: Synthesis of alkenyl chlorides from the reaction of ketones with acyl chlorides.
Scheme 19: ZnCl2-promoted alkenyl chloride synthesis.
Scheme 20: Regeneration of acid chlorides by triphosgene.
Scheme 21: Alkenyl chlorides from ketones and triphosgene.
Scheme 22: Various substitution reactions.
Scheme 23: Vinylic Finkelstein reactions reported by Evano and co-workers.
Scheme 24: Challenge of selective monohydrochlorination of alkynes.
Scheme 25: Sterically encumbered internal alkynes furnish the hydrochlorination products in high yield.
Scheme 26: Recent work by Kropp with HCl absorbed on alumina.
Scheme 27: High selectivities for monhydrochlorination with nitromethane/acetic acid as solvent.
Figure 8: Functionalized alkynes which typically afford the monhydrochlorinated products.
Scheme 28: Related chorosulfonylation and chloroamination reactions.
Scheme 29: Reaction of organometallic reagents with chlorine electrophiles.
Scheme 30: Elimination reactions of dichlorides to furnish alkenyl chlorides.
Scheme 31: Elimination reactions of allyl chloride 182 to furnish alkenyl chloride 183.
Scheme 32: Detailed studies by Schlosser on the elimination of dichloro compounds.
Scheme 33: Stereoselective variation caused by change of solvent.
Scheme 34: Elimination of gem-dichloride 189 to afford alkene 190.
Scheme 35: Oxidation of enones to dichlorides and in situ elimination thereof.
Scheme 36: Oxidation of allylic alcohols to dichlorides and in situ elimination thereof.
Scheme 37: Chlorination of styrenes with SOCl2 and elimination thereof.
Scheme 38: Chlorination of styrenes with SOCl2 and elimination thereof.
Scheme 39: Fluorine–chlorine exchange followed by elimination.
Scheme 40: Intercepting cations with alkynes and trapping of the alkenyl cation intermediate with chloride.
Scheme 41: Investigations by Mayr and co-workers.
Scheme 42: In situ activation of benzyl alcohol 230 with BCl3.
Scheme 43: In situ activation of benzylic alcohols with TiCl4.
Scheme 44: In situ activation of benzylic alcohols with FeCl3.
Scheme 45: In situ activation of benzylic alcohols with FeCl3.
Scheme 46: In situ activation of aliphatic chlorides and alcohols with ZnCl2, InCl3, and FeCl3.
Scheme 47: In situ generation of benzylic cations and trapping thereof with alkynes.
Scheme 48: Intramolecular trapping reactions affording alkenyl halides.
Scheme 49: Intramolecular trapping reactions affording alkenyl chlorides.
Scheme 50: Intramolecular trapping reactions of oxonium and iminium ions affording alkenyl chlorides.
Scheme 51: Palladium and nickel-catalyzed coupling reactions to afford alkenyl chlorides.
Scheme 52: Rhodium-catalyzed couplings of 1,2-trans-dichloroethene with arylboronic esters.
Scheme 53: First report on monoselective coupling reactions for 1,1-dichloroalkenes.
Scheme 54: Negishi’s and Barluenga’s contributions.
Scheme 55: First mechanistic investigation by Johnson and co-workers.
Scheme 56: First successful cross-metathesis with choroalkene 260.
Scheme 57: Subsequent studies by Johnson.
Scheme 58: Hoveyda and Schrock’s work on stereoretentive cross-metathesis with molybdenum-based catalysts.
Scheme 59: Related work with (Z)-dichloroethene.
Scheme 60: Further ligand refinement and traceless protection of functional groups with HBpin.
Scheme 61: Alkenyl chloride synthesis by Wittig reaction.
Scheme 62: Alkenyl chloride synthesis by Julia olefination.
Scheme 63: Alkenyl chloride synthesis by reaction of ketones with Mg/TiCl4 mixture.
Scheme 64: Frequently used allylic substitution reactions which lead to alkenyl chlorides.
Scheme 65: Enantioselective allylic substitutions.
Scheme 66: Synthesis of alkenyl chlorides bearing an electron-withdrawing group.
Scheme 67: Synthesis of α-nitroalkenyl chlorides from aldehydes.
Scheme 68: Synthesis of alkenyl chlorides via elimination of an in situ generated geminal dihalide.
Scheme 69: Carbenoid approach reported by Pace.
Scheme 70: Carbenoid approach reported by Pace.
Scheme 71: Ring opening of cyclopropenes in the presence of MgCl2.
Scheme 72: Electrophilic chlorination of alkenyl MIDA boronates to Z- or E-alkenyl chlorides.
Scheme 73: Hydroalumination and hydroboration of alkynyl chlorides.
Scheme 74: Carbolithiation of chloroalkynes.
Scheme 75: Chlorination of enamine 420.
Scheme 76: Alkyne synthesis by elimination of alkenyl chlorides.
Scheme 77: Reductive lithiation of akenyl chlorides.
Scheme 78: Reactions of alkenyl chlorides with organolithium reagents.
Scheme 79: Reactions of alkenyl chlorides with organolithium reagents.
Scheme 80: Addition–elimination reaction of alkenyl chloride 9 with organolithium reagents.
Scheme 81: C–H insertions of lithiumcarbenoids.
Scheme 82: Pd-catalyzed coupling reactions with alkenyl chlorides as coupling partner.
Scheme 83: Ni-catalyzed coupling of alkenylcopper reagent with alkenyl chloride 183.
Scheme 84: Ni-catalyzed coupling of heterocycle 472 with alkenyl chloride 473.
Scheme 85: Synthesis of α-chloroketones by oxidation of alkenyl chlorides.
Scheme 86: Tetrahalogenoferrate(III)-promoted oxidation of alkenyl chlorides.
Scheme 87: Chlorine–deuterium exchange promoted by a palladium catalyst.
Scheme 88: Reaction of alkenyl chlorides with thiols in the presence of AIBN (azobisisobutyronitrile).
Scheme 89: Chloroalkene annulation.
Mechanistic insights into hydroxy(tosyloxy)iodobenzene-mediated ditosyloxylation of chalcones: a DFT study
- Jai Parkash,
- Sangeeta Saini,
- Vaishali Saini,
- Omkar Bains and
- Raj Kamal
Beilstein J. Org. Chem. 2025, 21, 2703–2715, doi:10.3762/bjoc.21.208
- ) compounds in polar nucleophilic or non-nucleophilic solvents [10][11][12][20][29][30][31][32][33][34][35][36]. Fujita discusses typical pathways of alkene oxidation with hypervalent iodine in great detail including the stereochemical course of reaction involving a cyclic iodonium ion [30]. In the literature
Graphical Abstract
Scheme 1: Structure of reactant (chalcone, compound A), geminal product (compound B), vicinal product (compou...
Scheme 2: Reaction mechanism of ditosyloxylation of chalcones with X = -OCH3 , -SCH3 followed by 1,2-aryl mig...
Scheme 3: Reaction mechanism of ditosyloxylation of chalcones with X = -Cl, -NO2 leading to the formation of ...
Figure 1: Relative Gibbs free energy profile for HTIB-mediated ditosyloxylation of chalcone with X = -SCH3 in...
Figure 2: Relative Gibbs free energy profile for HTIB-mediated ditosyloxylation of chalcone with X = -Cl invo...
Figure 3: Relative Gibbs free energy profile for HTIB-mediated ditosyloxylation of chalcone with X = -NO2 inv...
Scheme 4: Reaction mechanism of ditosyloxylation of chalcones with X = -OCH3, -SCH3, -Cl, -NO2 leading to the...
Figure 4: Relative Gibbs free energy profile for HTIB-mediated ditosyloxylation of chalcone with X = -OCH3 le...
Figure 5: Relative Gibbs free energy profile for HTIB-mediated ditosyloxylation of chalcone with X = -SCH3 le...
Figure 6: Relative Gibbs free energy profile for HTIB-mediated ditosyloxylation of chalcone with X = -Cl lead...
Figure 7: Relative Gibbs free energy profile for HTIB-mediated ditosyloxylation of chalcone with X = -NO2 lea...
Recent advancements in the synthesis of Veratrum alkaloids
- Morwenna Mögel,
- David Berger and
- Philipp Heretsch
Beilstein J. Org. Chem. 2025, 21, 2657–2693, doi:10.3762/bjoc.21.206
- the hydroxy moiety in C12 was performed, followed by Grignard addition of ethynylmagnesium bromide and then hydrocyanation to result in vinyl nitrile 57 over five steps. The key Wagner–Meerwein-type rearrangement occurred in 68% yield furnishing epoxide 58. Hydrogenation of the alkene moiety as well
- 63. The D-ring was saturated and the remaining alkene epoxidized – a strategy that we have observed in cyclopamine synthesis before. The sequence needed several protecting group manipulations. Therefore, epoxide 64 was synthesized in eleven steps from ketone 62. The key spirocyclization was performed
Graphical Abstract
Scheme 1: Representatives of steroid alkaloid classes. Marked in blue is the steroidal cholestane framework, ...
Scheme 2: Subclasses of Veratrum alkaloids: jervanine, veratramine and cevanine-type [8].
Scheme 3: Flow chart presentation of the synthesis of (−)-englerin A developed by the Christmann group [10].
Scheme 4: Structures and year of synthesis of the three types of Veratrum alkaloids reported in the literatur...
Scheme 5: Key step in the synthesis of cyclopamine (6) by the Giannis group [21].
Scheme 6: Overview of the semisynthesis of cyclopamine (6) reported by the Giannis group in 2009 [21].
Scheme 7: Key steps in the synthesis of cyclopamine (6) by the Baran group [23].
Scheme 8: Overview of the total synthesis of cyclopamine (6) by the Baran group in 2023 [23].
Scheme 9: Key steps in the synthesis of cyclopamine (6) by the Zhu/Gao group [25].
Scheme 10: Overview of the total synthesis of cyclopamine (6) by the group of Zhao/Gao in 2023 [25].
Scheme 11: Key steps in the synthesis of cyclopamine (6) by the Liu/Qin group [26].
Scheme 12: Overview of the semisynthesis of cyclopamine (6) by the Liu/Qin group in 2024 [26].
Scheme 13: Key steps in the synthesis of jervine (12) by the Masamune group [14].
Scheme 14: Overview of the total synthesis of jervine (12) by the Masamune group in 1968 [14].
Scheme 15: Color-coded schemes of the presented cyclopamine (6) syntheses by Giannis, Baran, Zhu/Gao, and Liu/...
Scheme 16: Key steps in the total synthesis of veratramine (13) by the Johnson group [15].
Scheme 17: Overview of the total synthesis of veratramine (13) by the Johnson group in 1967 [15].
Scheme 18: Key steps in the synthesis of veratramine (13) by the Zhu/Gao group [25].
Scheme 19: Shortened overview of the total synthesis of veratramine (13) by the Zhu/Gao group in 2023 [25].
Scheme 20: Key steps in the synthesis of veratramine by the Liu/Qin group [26].
Scheme 21: Overview of the semisynthesis of veratramine (13) by the Liu/Qin group in 2024 [26].
Scheme 22: Key steps in the synthesis of veratramine (13) by the Trauner group [27].
Scheme 23: Overview of the total synthesis of veratramine (13) by the Trauner group in 2025 [27].
Scheme 24: Key steps in the synthesis of verarine (14) by the Kutney group [16-19].
Scheme 25: Overview of the total synthesis of verarine (14) by the Kutney group reported 1962–1968 [16-19].
Scheme 26: Color-coded schemes of the presented veratramine-type alkaloid synthesis of Zhu/Gao, Liu/Qin and Tr...
Scheme 27: Structures of veracevine (86), veratridine (87), and cevadine (88).
Scheme 28: Key step in the semisynthesis of verticine (15) by the Kutney group (1977) [20,46].
Scheme 29: Overview of the semisynthesis of verticine (15) by the Kutney group (1977) [20,46].
Scheme 30: Key step of the total synthesis of (±)-4-methylenegermine (17) by the Stork group (2017) [22].
Scheme 31: Overview of the total synthesis of (±)-4-methylenegermine (17) by the Stork group (2017) [22].
Scheme 32: Key step of the total synthesis of heilonine (16) by Cassaidy and Rawal (2021) [24].
Scheme 33: Overview of the total synthesis of heilonine (16) by Cassaidy and Rawal (2021) [24]. FGI: functional gr...
Scheme 34: Key steps of the synthesis of heilonine (16) by Dai and co-workers (2024) [28].
Scheme 35: Overview of the total synthesis of heilonine (16) by Dai and co-workers (2024) [28].
Scheme 36: Key steps of the total synthesis of zygadenine (18) reported by Luo and co-workers [29].
Scheme 37: Overview of the total synthesis of zygadenine (18) by Luo and co-workers (2023) [29].
Scheme 38: Key step of the divergent total syntheses of highly oxidized cevanine-type alkaloids by Luo and co-...
Scheme 39: Divergent syntheses of highly oxidized cevanine-type alkaloids by Luo and co-workers (2024) [30].
Scheme 40: Color-coded overview of the presented cevanine-type alkaloid syntheses [10,20,22,24,28-30,46]. LLS: longest linear sequen...
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
- of single-electron NHC catalysis by incorporating oxidatively generated aryloxymethyl radicals A as a key intermediate. A variety of γ-aryloxy ketones 12 were successfully prepared in the presence of NHC (15 mol %), photocatalyst (2 mol %), using 467 nm LED and a combination of alkene 11, amide 9
- for 18 h (Scheme 6) [56]. Gao, Ye, and co-workers reported the iminoacylation of alkenes 17 via photoredox NHC dual catalysis in the presence of NHC (20 mol %), photocatalyst (5 mol %), with Na2CO3 (1.2 equiv) using a 36 W blue LED. In this method, the alkene-attached iminyl radicals A and the NHC
- -attached ketyl radical B are generated under photoredox NHC catalysis under visible-light irradiation. The 5-exo-trig radical cyclization of the alkene-tethered iminyl radicals A furnished a dihydropyrrole-derived radical coupled with the NHC group attached ketyl radical B. This approach features readily
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
- [5.2.1.01,5]decane core with a cis-pentalene unit. The product was further processed into rearrangement precursor 46 (as an inseparable mixture, dr = 1:1.6) by TBS protection of the primary alcohol and epoxidation of the alkene with m-CPBA. Unlike Rychnovsky’s substrate, epoxy alcohol 46 underwent
- reaction of 87 was employed, generating both the kinetic product 88 and the desired thermodynamic product 89. Heating 88 promoted a retro-Diels–Alder/Diels–Alder equilibrium, favoring the more stable isomer 89. Palladium-catalyzed hydrogenation of the 1,2-disubstituted alkene in 89, followed by Mo(CO)6
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
- , provided compound 78. Finally, a sequence comprising terminal alkene reduction, epoxidation of the tetrasubstituted alkene, and LiDBB-promoted intramolecular reductive cyclization and deprotection completed the asymmetric total synthesis of (+)-ryanodine (1) in 17 steps. Notably, the additive used in the
- , terminal alkene reduction, and intramolecular reductive cyclization culminated in the completion of the first asymmetric total synthesis of (+)-20-deoxyspiganthine (2) in 19 steps. Micalizio’s formal total synthesis of ryanodol (4) In 2020, the Micalizio group at the University of California, San Diego
- epoxidation of the tetrasubstituted alkene followed by Grieco elimination yielded diene 92. Subsequent oxidation of the hemiacetal, saponification of the lactone, intramolecular epoxide opening, and Hoveyda–Grubbs (II)-catalyzed RCM afforded tetracyclic compounds 94 and its transesterification product 93
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).
Rapid access to the core of malayamycin A by intramolecular dipolar cycloaddition
- Yilin Liu,
- Yuchen Yang,
- Chen Yang,
- Sha-Hua Huang,
- Jian Jin and
- Ran Hong
Beilstein J. Org. Chem. 2025, 21, 2542–2547, doi:10.3762/bjoc.21.196
- functionality strategy employing oxazoline to unmask the 1,2-hydroxyamine moiety proves feasible, eliminating the need for alkene functionalization required in previous endeavours. This current strategy provides a reliable platform for accessing diverse uracil nucleosides and their derivatives, facilitating the
- three contiguous stereogenic centers (Scheme 1A). The pyran ring was constructed by a RCM reaction [16]. Subsequent functionalization of the alkene to install the 1,2-cis-hydroxy amine required 6 steps from the sterically more demanding side. In continuing our recent interest in accessing unusual
- position. Therefore, dihydroxylation [37] readily converted alkene 11 to diol 12 as a mixture of inseparable isomers. Without purification, oxidative cleavage with NaIO4 resulted in a compound with strong UV absorption, which was eventually identified as enone 14 (Scheme 3). It is assumed that the
Graphical Abstract
Figure 1: Selected natural uracil-containing nucleosides (the key perhydrofuropyran core highlighted in blue)....
Scheme 1: Synthetic strategies toward malayamycin A. (A) Previous synthetic route. (B) Our strategy toward th...
Scheme 2: Rational for intramolecular dipolar cycloaddition.
Scheme 3: Proposed pathway for the enone formation.
Scheme 4: Modified route to access the core of malayamycins.
Scheme 5: Attempting the Baeyer–Villiger reaction.
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
- leads to ketene D, which can undergo cycloaddition with an alkene to yield E. This fragmentation pathway dominates under various conditions (e.g., transition-metal catalysis, nucleophilic addition) and is driven by ring-strain release [11]. PET, an alternative to direct excitation and EnT, enables the
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),...
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
- , followed by diastereoselective α-alkylation, produced 38. A Wittig reaction and subsequent deketalization converted the ketone in 38 to the terminal alkene 39, allowing for subsequent sequential chemoselective hydrogenations: first, hydrogenation of the exo-olefin using Wilkinson’s catalyst proceeded with
- known two-step sequence to 61, followed by Mitsunobu reaction, ester reduction, thioether oxidation, and silylation of the primary alcohol to furnish sulfone 64. The two key fragments – aldehyde 60 and sulfone 64 – were merged via Julia–Kocienski olefination to construct alkene 65. Treatment of 65 with
- (C6F5)3B triggered a Meinwald rearrangement, generating aldehyde 66. Nucleophilic addition, oxidation of the resulting alcohol, and base-promoted epimerization at C6 of 67' delivered 67. Subsequent dihydroxylation of the alkene in 67 and protection of the resulting 1,2-diol as a cyclic carbonate
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.
Halogenated butyrolactones from the biomass-derived synthon levoglucosenone
- Johannes Puschnig,
- Martyn Jevric and
- Ben W. Greatrex
Beilstein J. Org. Chem. 2025, 21, 2297–2301, doi:10.3762/bjoc.21.175
- low, the synthesis of 7c via this method represents a substantial improvement on previous approaches to this material [24]. The Baeyer–Villiger oxidation of 7c was uneventful and the fluorinated alkene 17 was isolated in 50% yield. The α-trifluoromethylation of ketones and aldehydes can be performed
- cascade to give enone 21 in 42% yield. Baeyer–Villiger oxidation of this highly activated alkene promoted an epoxidation/Baeyer–Villiger oxidation cascade to yield lactone 22 in 67% yield (dr 2:1). The low diastereoselectivity suggested that the epoxidation happened subsequent to the ring contraction, as
Graphical Abstract
Figure 1: Halogen-containing butyrolactone-derived bioactives.
Scheme 1: Preparation of chlorinated and brominated lactones 8a,b and 11a,b.
Scheme 2: Preparation of fluorinated lactone 14.
Scheme 3: Fluorination of LGO (5) and conversion to lactone 17.
Scheme 4: Trifluoromethylation of 9a,b and 15 and subsequent Baeyer–Villiger oxidation.
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
- -trig cyclization and HAT furnished the enantioenriched products with up to 97:3 er. In addition to intramolecular radical reactions, intermolecular radical transformations have also been achieved using photoenzymatic catalysis, such as the addition of fluoroalkyl radicals to alkene substrates [36] and
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
- dichloromethane (DCM), gold(I)-catalyzed alkyne activation initiated 6-endo-dig cyclization of the conjugated alkene. Subsequent alkyl migration formed four-membered ring intermediate 9, which underwent fragmentation and rearrangement to yield phenanthrene derivative 10 (Scheme 3, path a). When tetrahydrofuran
- dihydrochromenone skeleton 24 (Scheme 6, path a). When DMSO was employed instead, the strongly coordinating solvent diverted the reaction towards 5-exo-dig cyclization, furnishing a Z-configured tetrasubstituted alkene product 26 (Scheme 6, path b). The isocoumarin-fused dihydrochromenones prepared by this strategy
- delivered tricyclic indole derivative 59 featuring an exocyclic Z-alkene (Scheme 13, path a). When the terminal substituent of the alkyne was an aryl group, C3-selective cyclization was triggered under BiCl3 catalysis to generate tricyclic iminium 60. Subsequent aryl-assisted Mannich cyclization efficiently
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.
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®.
The application of desymmetric enantioselective reduction of cyclic 1,3-dicarbonyl compounds in the total synthesis of terpenoid and alkaloid natural products
- Dong-Xing Tan and
- Fu-She Han
Beilstein J. Org. Chem. 2025, 21, 2085–2102, doi:10.3762/bjoc.21.164
- operation including azide–alkene dipolar cycloaddition, irradiation of the resulting triazoline to aziridine 80 and in situ ring opening followed by deacetylation achieved the first total synthesis of (−)-hunterine A (14). On the other hand, aza-Cope/Mannich reaction of 78 produced imine intermediate 81
- underwent dehydration with Martin′s sulfurane to afford the known intermediate 115 [83] and terminal alkene 116 (C12–C13 bond-cleaved byproduct). Thus, the formal total synthesis of (−)-platencin (24) was achieved. On the other hand, epoxidation of 113 followed by acid-mediated regioselective ring-opening
Graphical Abstract
Figure 1: Several representative terpenoid and alkaloid natural products synthesized by applying desymmetric ...
Figure 2: Selected terpenoid and alkaloid natural products synthesized by applying desymmetric enantioselecti...
Scheme 1: The total synthesis of (+)-aplysiasecosterol A (6) by Li [14].
Scheme 2: The total synthesis of (−)-cyrneine A by Han [31].
Scheme 3: The total syntheses of three cyrneine diterpenoids by Han [31,32].
Scheme 4: The total synthesis of (−)-hamigeran B and (−)-4-bromohamigeran B by Han [51].
Scheme 5: The total synthesis of (+)-randainin D by Baudoin [53].
Scheme 6: The total synthesis of (−)-hunterine A and (−)-aspidospermidine by Stoltz [58].
Scheme 7: The total synthesis of (+)-toxicodenane A by Han [65,66].
Scheme 8: The formal total synthesis of (−)-conidiogeone B and total synthesis of (−)-conidiogeone F by Lee a...
Scheme 9: The total syntheses of four conidiogenones natural products by Lee and Han [72].
Scheme 10: The total synthesis of (−)-platensilin by Lou and Xu [82].
Scheme 11: The total synthesis of (−)-platencin and (−)-platensimycin by Lou and Xu [82].
Scheme 12: The total synthesis of (+)-isochamaecydin and (+)-chamaecydin by Han [86].
Asymmetric total synthesis of tricyclic prostaglandin D2 metabolite methyl ester via oxidative radical cyclization
- Miao Xiao,
- Liuyang Pu,
- Qiaoli Shang,
- Lei Zhu and
- Jun Huang
Beilstein J. Org. Chem. 2025, 21, 1964–1972, doi:10.3762/bjoc.21.152
- used as a powerful method for synthesizing complex natural products [20][21]. We envisaged that the A-ring in 4 could be constructed from the alkene-substituted β-keto ester precursor A via a bioinspired oxidative radical cyclization (Scheme 1D). Herein, we report the full details of our efforts to
- connection of C8 and C12 in compound 21 could be realized through a photoredox-catalyzed radical cyclization of unactivated alkene-substituted β-ketoester 27. This reaction was expected to involve a 5-exo-trig radical cyclization via transition state TS-3 [38], in which the diastereoselectivity could be
- proposed mechanism to 21 involved the formation of an electron-deficient, resonance-stabilized radical species, followed by intramolecular alkylation of the unactivated alkene to generate radical 29 via a diastereoselective 5-exo-trig cyclization step. Radical intermediate 29 was trapped by 2,4,6
Graphical Abstract
Scheme 1: Representative prostaglandins and general synthetic strategy toward PGDM methyl ester 4.
Scheme 2: Retrosynthetic analysis for the first generation synthesis of PGDM methyl ester 4.
Scheme 3: Synthesis of bicyclic ketal 25.
Scheme 4: Retrosynthetic analysis for the second-generation synthesis of tricyclic PGDM methyl ester 4.
Scheme 5: Asymmetric total synthesis of tricyclic-PGDM methyl ester 4.
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
- reaction can also be used to prepare precursors for the Ullman–Goldberg coupling (Scheme 12B and 12C); however, in the presence of halogens, an alternative reduction pathway of the alkene with tosylhydrazine and NaOAc must be used [55]. Hetereodiazocines 35b and 35c are synthesised by coupling of o
Graphical Abstract
Figure 1: Energy diagram of a two-state photoswitch. Figure 1 was redrawn from [2].
Figure 2: Example of the absorption spectra of the isomers of a photoswitch with most efficient irradiation w...
Scheme 1: Photoswitch classes described in this review.
Figure 3: Azoheteroarenes.
Scheme 2: E–Z Isomerisation (top) and mechanisms of thermal Z–E isomerisation (bottom).
Scheme 3: Rotation mechanism favoured by the electron displacement in push–pull systems. Selected examples of...
Figure 4: A) T-shaped and twisted Z-isomers determine the thermal stability and the Z–E-PSS (selected example...
Figure 5: Effect of di-ortho-substitution on thermal half-life and PSS.
Figure 6: Selected thermal lifetimes of azoindoles in different solvents and concentrations. aConcentration o...
Figure 7: Aryliminopyrazoles: N-pyrazoles (top) and N-phenyl (bottom).
Scheme 4: Synthesis of symmetrical heteroarenes through oxidation (A), reduction (B), and the Bayer–Mills rea...
Scheme 5: Synthesis of diazonium salt (A); different strategies of azo-coupling: with a nucleophilic ring (B)...
Scheme 6: Synthesis of arylazothiazoles 25 (A) and heteroaryltriazoles 28 (B).
Scheme 7: Synthesis of heteroarylimines 31a,b [36-38].
Figure 8: Push–pull non-ionic azo dye developed by Velasco and co-workers [45].
Scheme 8: Azopyridine reported by Herges and co-workers [46].
Scheme 9: Photoinduced phase transitioning azobispyrazoles [47].
Figure 9: Diazocines.
Scheme 10: Isomers, conformers and enantiomers of diazocine.
Scheme 11: Partial overlap of the ππ* band with electron-donating substituents and effect on the PSS. Scheme 11 was ada...
Figure 10: Main properties of diazocines with different bridges. aMeasured in n-hexane [56]. bMeasured in THF. cMe...
Scheme 12: Synthesis of symmetric diazocines.
Scheme 13: Synthesis of asymmetric diazocines.
Scheme 14: Synthesis of O- and S-heterodiazocines.
Scheme 15: Synthesis of N-heterodiazocines.
Scheme 16: Puromycin diazocine photoswitch [60].
Figure 11: Indigoids.
Figure 12: The main representatives of the indigoid photoswitch class.
Scheme 17: Deactivation process that prevents Z-isomerisation of indigo.
Figure 13: Stable Z-indigo derivative synthesised by Wyman and Zenhäusern [67].
Figure 14: Selected examples of indigos with aliphatic and aromatic substituents [68]. Dashed box: proposed π–π in...
Scheme 18: Resonance structures of indigo and thioindigo involving the phenyl ring.
Scheme 19: Possible deactivation mechanism for 4,4'-dihydroxythioindigo [76].
Scheme 20: Effect of different heteroaryl rings on the stability and the photophysical properties of hemiindig...
Figure 15: Thermal half-lives of red-shifted hemithioindigos in toluene [79]. aMeasured in toluene-d8.
Scheme 21: Structures of pyrrole [81] and imidazole hemithioindigo [64].
Figure 16: Examples of fully substituted double bond hemithioindigo (left), oxidised hemithioindigos (centre),...
Scheme 22: Structure of iminothioindoxyl 72 (top) and acylated phenyliminoindolinone photoswitch 73 (bottom). ...
Scheme 23: (top) Transition states of iminothioindoxyl 72. The planar transition state is associated with a lo...
Scheme 24: Baeyer–Drewsen synthesis of indigo (top) and N-functionalisation strategies (bottom).
Scheme 25: Synthesis of hemiindigo.
Scheme 26: Synthesis of hemithioindigo and iminothioindoxyl.
Scheme 27: Synthesis of double-bond-substituted hemithioindigos.
Scheme 28: Synthesis of phenyliminoindolinone.
Scheme 29: Hemithioindigo molecular motor [85].
Figure 17: Arylhydrazones.
Scheme 30: Switching of arylhydrazones. Note: The definitions of stator and rotor are arbitrary.
Scheme 31: Photo- and acidochromism of pyridine-based phenylhydrazones.
Scheme 32: A) E–Z thermal inversion of a thermally stable push–pull hydrazone [109]. B) Rotation mechanism favoured...
Scheme 33: Effect of planarisation on the half-life.
Scheme 34: The longest thermally stable hydrazone switches reported so far (left). Modulation of thermal half-...
Figure 18: Dependency of t1/2 on concentration and hypothesised aggregation-induced isomerisation.
Figure 19: Structure–property relationship of acylhydrazones.
Scheme 35: Synthesis of arylhydrazones.
Scheme 36: Synthesis of acylhydrazones.
Scheme 37: Photoswitchable fluorophore by Aprahamian et al. [115].
Scheme 38: The four-state photoswitch synthesised by the Cigáň group [116].
Figure 20: Diarylethenes.
Scheme 39: Isomerisation and oxidation pathway of E-stilbene to phenanthrene.
Scheme 40: Strategies adapted to avoid E–Z isomerisation and oxidation.
Scheme 41: Molecular orbitals and mechanism of electrocyclisation for a 6π system.
Figure 21: Aromatic stabilisation energy correlated with the thermal stability of the diarylethenes [127,129].
Figure 22: Half-lives of diarylethenes with increasing electron-withdrawing groups [128,129].
Scheme 42: Photochemical degradation pathway promoted by electron-donating groups [130].
Figure 23: The diarylethenes studied by Hanazawa et al. [134]. Increased rigidity leads to bathochromic shift.
Scheme 43: The dithienylethene synthesised by Nakatani's group [135].
Scheme 44: Synthesis of perfluoroalkylated diarylethenes.
Scheme 45: Synthesis of 139 and 142 via McMurry coupling.
Scheme 46: Synthesis of symmetrical derivatives 145 via Suzuki–Miyaura coupling.
Scheme 47: Synthesis of acyclic 148, malonic anhydride 149, and maleimide derivatives 154.
Figure 24: Gramicidin S (top left) and two of the modified diarylethene derivatives: first generation (bottom ...
Scheme 48: Pyridoxal 5'-phosphate and its reaction with an amino acid (top). The analogous dithienylethene der...
Figure 25: Fulgides.
Scheme 49: The three isomers of fulgides.
Scheme 50: Thermal and photochemical side products of unsubstituted fulgide [150].
Figure 26: Maximum absorption λc of the closed isomer compared with the nature of the aromatic ring and the su...
Scheme 51: Possible rearrangement of the excited state of 5-dimethylaminoindolylfulgide [153].
Figure 27: Quantum yields of ring closure (ΦE→C) and E–Z isomerisation (ΦE→Z) correlated with the increasing s...
Scheme 52: Active (Eα) and inactive (Eβ) conformers (left) and the bicyclic sterically blocked fulgide 169 (ri...
Scheme 53: Quantum yield of ring-opening (ΦC→E) and E–Z isomerisation (ΦE→Z) for different substitution patter...
Scheme 54: Stobbe condensation pathway for the synthesis of fulgides 179, fulgimides 181 and fulgenates 178.
Scheme 55: Alternative synthesis of fulgides through Pd-catalysed carbonylation.
Scheme 56: Optimised synthesis of fulgimides [166].
Scheme 57: Photoswitchable FRET with a fulgimide photoswitch [167].
Scheme 58: Three-state fulgimide strategy by Slanina's group.
Figure 28: Spiropyrans.
Scheme 59: Photochemical (left) and thermal (right) ring-opening mechanisms for an exemplary spiropyran with a...
Figure 29: Eight possible isomers of the open merocyanine according to the E/Z configurations of the bonds hig...
Scheme 60: pH-Controlled photoisomerisation between the closed spiropyran 191-SP and the open E-merocyanine 19...
Scheme 61: Behaviour of spiropyran in water buffer according to Andréasson and co-workers [180]. 192-SP in an aqueo...
Scheme 62: (left box) Proposed mechanism of basic hydrolysis of MC [184]. (right box) Introduction of electron-dona...
Scheme 63: Photochemical interconversion of naphthopyran 194 (top) and spirooxazine 195 (bottom) photoswitches...
Scheme 64: Synthesis of spiropyrans and spirooxazines 198 and the dicondensation by-product 199.
Scheme 65: Alternative synthesis of spiropyrans and spirooxazines with indolenylium salt 200.
Scheme 66: Synthesis of 4’-substituted spiropyrans 203 by condensation of an acylated methylene indoline 201 w...
Scheme 67: Synthesis of spironaphthopyrans 210 by acid-catalysed condensation of naphthols and diarylpropargyl...
Scheme 68: Photoswitchable surface wettability [194].
Figure 30: Some guiding principles for the choice of the most suitable photoswitch. Note that this guide is ve...
Fe-catalyzed efficient synthesis of 2,4- and 4-substituted quinolines via C(sp2)–C(sp2) bond scission of styrenes
- Prafull A. Jagtap,
- Manish M. Petkar,
- Vaishnavi R. Sawant and
- Bhalchandra M. Bhanage
Beilstein J. Org. Chem. 2025, 21, 1799–1807, doi:10.3762/bjoc.21.142
- the FeIII species. An alternative mechanism involving a concerted [4 + 2] cycloaddition between the aza-butadiene moiety in II and the alkene, leading to intermediate IV, cannot be ruled out. Conclusion In summary, we have successfully developed a highly efficient method for the oxidative C–C bond
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.
Influence of the cation in hypophosphite-mediated catalyst-free reductive amination
- Natalia Lebedeva,
- Fedor Kliuev,
- Olesya Zvereva,
- Klim Biriukov,
- Evgeniya Podyacheva,
- Maria Godovikova,
- Oleg I. Afanasyev and
- Denis Chusov
Beilstein J. Org. Chem. 2025, 21, 1661–1670, doi:10.3762/bjoc.21.130
- an important role in medicinal and pharmaceutical chemistry [23][24][25] (Scheme 1a). Sodium hypophosphite exhibited good chemoselectivity – it selectively reduced imines while leaving other functional groups intact, e.g., nitro (NO₂), cyano (CN), alkene (C=C), and benzyloxy (OBn) groups. In contrast
Graphical Abstract
Scheme 1: Rationale of the current study: a) Our previous work [20]; b) this work.
Scheme 2: Comparison of KH2PO2 and NaH2PO2 under the optimal conditions.
Figure 1: Substrate scope. Reaction conditions: carbonyl compound (1.45 mmol, 1 equiv), amine (1.81 mmol, 1.2...
Scheme 3: Control experiments.
Scheme 4: Experiments with D3PO2.
Scheme 5: Principal steps of the mechanism of the reductive amination with K2CO3/H3PO2 reducing system.
Figure 2: Reaction profile and DFT energies of intermediates and transition states. M062X functional with the...
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
- reaction between alkene 43 and 2,2′-dienone 44. The corresponding spirooxindole 45 was obtained in >19:1 dr, 63% yield, and 89% ee. Dynamic kinetic resolution of configurationally labile bridged biaryls The catalytic asymmetric dynamic kinetic resolution (DKR) of configurationally labile bridged biaryls
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.
Transition-state aromaticity and its relationship with reactivity in pericyclic reactions
- Israel Fernández
Beilstein J. Org. Chem. 2025, 21, 1613–1626, doi:10.3762/bjoc.21.125
- resembles the trends found for Diels–Alder reactions discussed above. For the parent Alder–ene reaction, which involves an alkene as the enophile, we previously reported that the corresponding six-membered transition state can be considered as in-plane aromatic in view of its highly negative NICS(3, +1
- the destabilizing 4-electron interaction with the C–C double bond of the alkene partner, dramatically reducing the barrier of the process. Other non-catalyzed pericyclic reactions Double group transfer reactions Double group transfer reactions (DGTRs) are a particular type of pericyclic reaction
Graphical Abstract
Scheme 1: (a) Diels–Alder cycloaddition reaction between butadiene and ethylene. (b) Gold(I)-catalyzed propar...
Figure 1: Transition states computed for the Diels–Alder cycloaddition reaction between isoprene and methyl a...
Figure 2: Comparative activation strain analyses (a) and energy decomposition analysis (b) of the Diels–Alder...
Figure 3: (a) Evolution of the NICS(3, +1) values along a z-axis perpendicular to the molecular plane of the ...
Figure 4: Comparative activation strain analyses (a) and energy decomposition analysis (b) of the carbonyl–en...
Figure 5: AICD (a) and EDDB (b) plots for the transition state involved in the DGRT between ethene and ethane....
Figure 6: Comparative activation strain analyses (a) and energy decomposition analysis (b) of the DGRT betwee...
Scheme 2: Representative cycloisomerization reaction of 1,3-hexadien-5-yne.
Figure 7: AICD plots of the transition states associated with the Hopf cyclization reactions involving cis-he...
Figure 8: Comparative activation strain analyses of the Hopf cyclization involving ene–ene–ynes E=CH–CH=CH–C≡...
Scheme 3: 1,3-Dipolar cycloaddition reactions between t-BuN3 and cyaphide complexes.
Figure 9: Evolution of the NICS(3, +1) values along a z-axis perpendicular to the molecular plane of the TSs ...
Figure 10: Comparative activation strain analyses (a) and energy decomposition analysis (b) of the 1,3-dipolar...
General method for the synthesis of enaminones via photocatalysis
- Paula Pérez-Ramos,
- Raquel G. Soengas and
- Humberto Rodríguez-Solla
Beilstein J. Org. Chem. 2025, 21, 1535–1543, doi:10.3762/bjoc.21.116
- -bromochromones via a Michael reaction of an amine with an electron-deficient alkene moiety and subsequent photocatalyzed debromination. With this dual catalytic system, a range of structurally diverse enaminone derivatives have been achieved in good yields with total trans selectivity. Mechanistic studies
Graphical Abstract
Figure 1: Examples of compounds with medicinal effects containing an enaminone structural moiety.
Scheme 1: Synthesis of enaminones.
Scheme 2: Substrate scope.
Scheme 3: Scale-up synthesis of enaminone 9a.
Scheme 4: Mechanistic studies.
Scheme 5: Proposed mechanism.
Wittig reaction of cyclobisbiphenylenecarbonyl
- Taito Moribe,
- Junichiro Hirano,
- Hideaki Takano,
- Hiroshi Shinokubo and
- Norihito Fukui
Beilstein J. Org. Chem. 2025, 21, 1454–1461, doi:10.3762/bjoc.21.107
- formation between carbonyl and alkene units. Keywords: bathtub; chirality; cyclobisbiphenylenecarbonyl; figure-eight; Wittig reaction; Introduction Figure-eight π-conjugated molecules represent chiral macrocycles with a twisted crossover structure [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15
- conformation (Sa,Sa)-A is feasible with a small activation barrier of 9.9 kcal mol−1. The figure-eight conformer (M,M)-B untwists to adopt an achiral conformation C with the exo-alkene units rotated inwards in opposite directions. These conformational changes are almost identical to those of CBBC 1. However
- conditions. Mono-olefin 3 undergoes a reductive carbon–carbon-bond formation between carbonyl and alkene units upon treatment with TiCl4. The current study demonstrates that the transformation of the carbonyl groups of CBBC results in products with altered physical and chemical properties which may be
Graphical Abstract
Figure 1: Synthesis and structures of CBBC 1.
Scheme 1: Wittig reactions of CBBC 1.
Figure 2: X-ray crystal structures of (a) 3, (b) 4, and (c) 5 with thermal ellipsoids at 50% probability; all...
Figure 3: VT 1H NMR spectra of 5 in CD2Cl2 at (a) 298 K, (b) 243 K, and (c) 203 K. Blue circle and red triang...
Figure 4: Simulated dynamics of bis-olefin 5 at the B3LYP/6-31G(d) level of theory. The description for the c...
Figure 5: (a) UV–vis absorption (solid lines) and emission (dashed lines) spectra of 1 (black), 3 (blue), and ...
Scheme 2: Conversion of mono-olefin 3 to internally functionalized DBC derivative 6.
Oxetanes: formation, reactivity and total syntheses of natural products
- Peter Gabko,
- Martin Kalník and
- Maroš Bella
Beilstein J. Org. Chem. 2025, 21, 1324–1373, doi:10.3762/bjoc.21.101
- of the resulting alkene [36]. In addition, this intramolecular etherification corresponds to the 4-exo-tet cyclisation which, in terms of kinetics, is the least favoured n-exo-tet cyclisation mode where n ≤ 7 [37]. Nevertheless, the Williamson etherification still remains one of the most common
- /RPC mechanism starts with a single-electron oxidation of the cobalt catalyst followed by a reaction with the siloxane to generate a cobalt–hydride complex. Subsequent hydride transfer to the alkene produces radical pair 23 which collapses to alkylcobalt intermediate 24. Another single-electron
- butyraldehyde in a mercury vapour illuminator and since then, the reaction has become known as the Paternò–Büchi reaction. Throughout the years after the report, investigations in this field were focused on identifying new reactive alkene and carbonyl components, developing photosensitisers that would allow
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.
