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Search for "aromatic chlorination" in Full Text gives 3 result(s) in Beilstein Journal of Organic Chemistry.
Ring contraction and ring expansion reactions in terpenoid biosynthesis and their application to total synthesis
- Nicolas Kratena,
- Nicolas Heinzig and
- Peter Gärtner
Beilstein J. Org. Chem. 2026, 22, 289–343, doi:10.3762/bjoc.22.21
- ) directly. From here another oxy-cyclisation and aromatic chlorination leads to the most complex member of the indole meroterpenoids, penitrem A (46). Another example of a ring expansion reaction, in this case of the aromatic 5-membered ring of an indole, was discovered to be operational in the biosynthetic
Graphical Abstract
Scheme 1: Mechanistic overview of enzymes involved in ring-size-altering reactions: A: Difference in ionisati...
Scheme 2: A: Ring contraction through involvement of carbocationic intermediates in thujane monoterpene biosy...
Scheme 3: Examples of concerted ring expansions of carbocation intermediates in PxaTPS8-catalysed cyclisation...
Scheme 4: Sequential ring expansions during astellifadiene (17) synthesis reported by Abe and co-workers.
Scheme 5: Cyclobutane ring expansion and sequential ring contractions catalysed by the synthase AITS in the b...
Scheme 6: Ring expansion and transannular ring contraction of a cyclopentane to cyclobutane in the biosynthes...
Scheme 7: Computationally elucidated concerted cyclisations/alkyl/hydride shifts during the biosynthesis of t...
Scheme 8: Cyclisation events and 6→5-ring contraction during the construction of epi-isozizaene (26) catalyse...
Scheme 9: Transannular cyclisations and 4→5-membered ring expansion through dyotropic 1,2-rearrangement of al...
Scheme 10: Ring expansion in presilphiperfolan-8b-ol (31) biosynthesis and ring contraction of the presilphipe...
Scheme 11: Ring contraction via transannular cyclopropanation and opening of cyclopropane in the biosynthesis ...
Scheme 12: The crucial CYP450-catalysed oxidative rearrangement defining the skeleton in gibberellin biosynthe...
Scheme 13: CYP450-mediated oxidation of cyclopentane methylene expanding the 8-membered ring in the biosynthes...
Scheme 14: CYP450-mediated oxidation of an exocyclic methyl group to effect transannular cyclisation across th...
Scheme 15: Non-enzymatic transannular aldol reaction enables the formation of the 5/13/3-tricyclic ring system...
Scheme 16: A: Oxidative ring expansion of a cyclopentane by incorporation of a methyl group in the biosynthesi...
Scheme 17: Rearrangement and ring expansion in the construction of the complex bridged carbon framework of and...
Scheme 18: Ketoglutarate-mediated oxidations of preaustinoid A1 (53) en route to complex meroterpenoids, B-rin...
Scheme 19: Proposed putative biosynthetic formation of the tigliane skeleton from an E,E,Z-triene.
Scheme 20: Photocatalytic tandem ring expansion/contraction of santonin to give photosantonin products and gua...
Scheme 21: A: Proposed biosynthesis of stelleroid B (66) from stelleranoid I (65) by ketol rearrangement; B: o...
Scheme 22: Singular examples of A,B-ring contractions and expansions in the biosynthesis of sesquiterpenoids e...
Scheme 23: A: plausible proposed biosynthetic pathway for the tigliane/ingenane skeletal rearrangement and 1,2...
Scheme 24: A: Multiple ring-size alterations during xenovulene A (90) biosynthesis; B: Ring contraction and re...
Scheme 25: Proposed biosyntheses of the complex, polycyclic terpenoid illisimonin A (97) and the bridged antro...
Scheme 26: Proposed biogenetic origin for the meroterpenoid liphagal (104) via epoxide-mediated ring expansion....
Scheme 27: Proposed biogenetic origin for the ring-contracted members of the taiwaniaquinol family.
Scheme 28: A: Schenck ene/Hock/Aldol cascade effecting B-ring contraction in atheronal B (113); B: Selective C...
Scheme 29: A: D-ring expansion of buxenone (118) via cyclopropanation towards buxaustroine A (119); B: Propose...
Scheme 30: Biosynthetic origin of alstoscholarinoids A (124) and B (125) via cascade oxidative rearrangement c...
Scheme 31: Biogenetic origin of the hedgehog signalling inhibitor cyclopamine (129) by tandem ring contraction...
Scheme 32: Proposed biogenetic origin of the B-ring contracted spirocyclic triterpenoid spirochensilide A (131...
Scheme 33: A: Proposed B-ring contraction during the biosynthesis of holophyllane A (133); B: B-ring contracti...
Scheme 34: Radical and ionic/polar mechanisms for the C-ring-contracted triterpenoids phomopsterone B (139) an...
Scheme 35: A: Plausible mechanism for the formation of schiglautone A (144) from anwuweizic acid (145); B: Pro...
Scheme 36: Reported biosynthetic proposal for the formation of B-ring expanded triterpenoids rhodoterpenoids A...
Scheme 37: A: Final reaction step in the synthesis of euphorikanin A (154), benzilic acid-type ring contractio...
Scheme 38: Tricyclic ring expansion in the Gui synthesis of gibbosterol A (158) and sarocladione (160) via Ru-...
Scheme 39: A: A-ring expansion during the Gui synthesis of rubriflordilactone B (161); B: Mechanism for the bi...
Scheme 40: Photosantonin rearrangement effects A/B ring contraction/expansion in Li’s synthesis of the complex...
Scheme 41: Tandem A/B ring expansion/contraction of an ergosterol derivative via pinacol rearrangement in the ...
Scheme 42: Synthetic studies towards cyclocitrinol (179) by A) the semisynthetic approach by Gui et al. using ...
Scheme 43: A: Bioinspired synthesis of spirochensilide A (131) by the Heretsch group via selective 8,9-epoxida...
Scheme 44: Baran’s synthesis of cortistatin A (191), expanding the B-ring through a cyclopropane fragmentation....
Scheme 45: Ding’s total synthesis of retigeranic acid (198) showcasing sequential 6→5 ring contractions.
Scheme 46: A: Oxa-di-π-methane (ODPM) rearrangement of a bicyclic ketone en route to silphiperfolenone (203); ...
Scheme 47: Biomimetic synthesis of liphagal (104) from sclareolide (221) by George and co-workers.
Scheme 48: Wu’s bioinspired synthesis of cucurbalsaminones B (224) and C (225) by photocatalytic oxa-di-π-meth...
Scheme 49: Baran’s total synthesis of maoecrystal V (230) featuring a pinacol rearrangement for ring expansion...
Scheme 50: A: Ketol rearrangement leading to ring contraction in the total synthesis of preaustinoid B; B: Ben...
Scheme 51: A: Scheidt’s synthesis of isovelleral (251) by pinacol rearrangement triggered by Mitsunobu conditi...
Scheme 52: Biomimetic transformations of simplified test substrates related to Euphorbia diterpenoids.
Scheme 53: A: First generation synthesis of taiwaniaquinones by benzilic acid-type rearrangement of the B-ring...
Scheme 54: A: Norrish type 1 radical recombination leading to ring contraction en route to cuparenone (272): 1...
Scheme 55: Ring contraction of a bridged D-ring system in the total synthesis of andrastatin D (280), terrenoi...
Scheme 56: Biomimetic synthesis of hyperjapone A (284) and hyperjaponol C (285) by George et al.
Scheme 57: Heretsch’ synthesis of dankastarones A (288) and B (289), swinhoeisterol A (290), and periconiaston...
Scheme 58: A: Zhang’s ring contraction during the synthesis of stemar-13-ene (295) by pinacol rearrangement; B...
Scheme 59: Trauner’s biomimetic synthesis of preuisolactone A (307) featuring a ring contraction via benzilic ...
Scheme 60: Bioinspired approaches for ring contraction/expansion reactions in the synthesis of alstoscholarino...
Scheme 61: A: Sarpong and Li, Wang and co-workers’ ring expansion of cephanolide A (313) to reach harringtonol...
A review of recent advances in electrochemical and photoelectrochemical late-stage functionalization classified by anodic oxidation, cathodic reduction, and paired electrolysis
- Nian Li,
- Ruzal Sitdikov,
- Ajit Prabhakar Kale,
- Joost Steverlynck,
- Bo Li and
- Magnus Rueping
Beilstein J. Org. Chem. 2024, 20, 2500–2566, doi:10.3762/bjoc.20.214
- products were obtained in good yields (51–81%). The reaction involves the catalytic dehydrochlorination of DCE at the cathode, simultaneously with anodic oxidative aromatic chlorination using cathodically released HCl as the chloride source (Scheme 13). Additionally, the Lei group demonstrated a double
Graphical Abstract
Figure 1: Classification of LSF reactions in this review.
Scheme 1: C(sp2)–H trifluoromethylation of heteroarenes.
Scheme 2: C(sp2)–H and C(sp3)–H alkylation of complex molecules.
Scheme 3: Electrochemical oxidation-induced intermolecular aromatic C–H sulfonamidation.
Scheme 4: Bioconjugation of tyrosine with (a) phenothiazine and (b) urazole derivatives.
Scheme 5: Electrochemical iodoamination of indoles using unactivated amines.
Scheme 6: Allylic C(sp3)–H aminations with sulfonamides.
Scheme 7: Electrochemical benzylic oxidation of C–H bonds.
Scheme 8: Site-selective electrooxidation of methylarenes to aromatic acetals.
Scheme 9: Electrochemical activation of C–H by electron-deficient W2C nanocrystals.
Scheme 10: α-Acyloxy sulfide preparation via C–H/OH cross-dehydrogenative coupling.
Scheme 11: Aromatic C–H-bond thiolation.
Scheme 12: C(sp2)–H functionalization for the installation of sulfonamide groups.
Scheme 13: Preparation of (hetero)aryl chlorides and vinyl chloride with 1,2-dichloroethane. aCu(OAc)2 (0.05 e...
Scheme 14: Electrochemical dual-oxidation enables access to α-chlorosulfoxides.
Scheme 15: Regio- and chemoselective formyloxylation–bromination/chlorination/trifluoromethylation of alkenes.
Scheme 16: Aziridine formation by coupling amines and alkenes.
Scheme 17: Formation of iminosulfide ethers via difunctionalization of an isocyanide.
Scheme 18: Synthesis of 1,3-difunctionalized molecules via C–C-bond cleavage of arylcyclopropane.
Scheme 19: Electrooxidative amino- and oxyselenation of alkenes. VBImBr = 1-butyl-3-vinylimidazolium bromide.
Scheme 20: Electrooxidative dehydrogenative [4 + 2] annulation of indole derivatives.
Scheme 21: Electrochemical cyclization combined with alkoxylation of triticonazole.
Scheme 22: Electrochemically tuned oxidative [4 + 2] annulation of olefins with hydroxamic acids.
Scheme 23: Electrosynthesis of indole derivatives via cyclization of 2-ethynylanilines.
Scheme 24: Allylic C–H oxidation of mono-, di-, and sesquiterpenes.
Scheme 25: Oxidation of unactivated C–H bonds.
Scheme 26: Fluorination of C(sp3)–H bonds. rAP = rapid alternating polarity.
Scheme 27: C(sp3)–H α-cyanation of secondary piperidines.
Scheme 28: Selective electrochemical hydrolysis of hydrosilanes to silanols.
Scheme 29: Organocatalytic electrochemical amination of benzylic C–H bonds.
Scheme 30: Iodide ion-initiated anodic oxidation reactions.
Scheme 31: Mn(III/IV) electro-catalyzed C(sp3)–H azidation.
Scheme 32: Tailored cobalt–salen complexes enable electrocatalytic intramolecular allylic C–H functionalizatio...
Scheme 33: Cobalt–salen complexes-induced electrochemical (cyclo)additions.
Scheme 34: Electrochemical 1,2-diarylation of alkenes enabled by direct dual C–H functionalization of electron...
Scheme 35: Cobalt-electrocatalyzed atroposelective C–H annulation.
Scheme 36: Nickel-electrocatalyzed C(sp2)–H alkoxylation with secondary alcohols.
Scheme 37: Nickel-catalyzed electrochemical enantioselective amination.
Scheme 38: Ruthenium-electrocatalyzed C(sp2)–H mono- and diacetoxylation.
Scheme 39: Rhodium(III)-catalyzed aryl-C–H phosphorylation enabled by anodic oxidation-induced reductive elimi...
Scheme 40: Asymmetric Lewis-acid catalysis for the synthesis of non-racemic 1,4-dicarbonyl compounds.
Scheme 41: Electrochemical enantioselective C(sp3)–H alkenylation.
Scheme 42: Palladium-catalyzed electrochemical dehydrogenative cross-coupling.
Scheme 43: Ir-electrocatalyzed vinylic C(sp2)–H activation for the annulation between acrylic acids and alkyne...
Scheme 44: Electrochemical gold-catalyzed C(sp3)–C(sp) coupling of alkynes and arylhydrazines.
Scheme 45: Photoelectrochemical alkylation of C–H heteroarenes using organotrifluoroborates.
Scheme 46: Mn-catalyzed photoelectro C(sp3)–H azidation.
Scheme 47: Photoelectrochemical undirected C–H trifluoromethylations of (Het)arenes.
Scheme 48: Photoelectrochemical dehydrogenative cross-coupling of heteroarenes with aliphatic C–H bonds.
Scheme 49: C–H amination via photoelectrochemical Ritter-type reaction.
Scheme 50: Photoelectrochemical multiple oxygenation of C–H bonds.
Scheme 51: Accelerated C(sp3)–H heteroarylations by the f-EPC system.
Scheme 52: Photoelectrochemical cross-coupling of amines.
Scheme 53: Birch electroreduction of arenes. GSW = galvanized steel wire.
Scheme 54: Electroreductive deuterations.
Scheme 55: Chemoselective electrosynthesis using rapid alternating polarity.
Scheme 56: Electroreductive olefin–ketone coupling.
Scheme 57: Electroreductive approach to radical silylation.
Scheme 58: Electrochemical borylation of alkyl halides. CC = carbon close.
Scheme 59: Radical fluoroalkylation of alkenes.
Scheme 60: Electrochemical defluorinative hydrogenation/carboxylation.
Scheme 61: Electrochemical decarboxylative olefination.
Scheme 62: Electrochemical decarboxylative Nozaki–Hiyama–Kishi coupling.
Scheme 63: Nickel-catalyzed electrochemical reductive relay cross-coupling.
Scheme 64: Electrochemical chemo- and regioselective difunctionalization of 1,3-enynes.
Scheme 65: Electrocatalytic doubly decarboxylative crosscoupling.
Scheme 66: Electrocatalytic decarboxylative crosscoupling with aryl halides.
Scheme 67: Nickel-catalyzed electrochemical reductive coupling of halides.
Scheme 68: Nickel-electrocatalyzed enantioselective carboxylation with CO2.
Scheme 69: Reductive electrophotocatalysis for borylation.
Scheme 70: Electromediated photoredox catalysis for selective C(sp3)–O cleavages of phosphinated alcohols to c...
Scheme 71: Stereoselective electro-2-deoxyglycosylation from glycals. MFE = methyl nonafluorobutyl ether.
Scheme 72: Electrochemical peptide modifications.
Scheme 73: Electrochemical α-deuteration of amides.
Scheme 74: Electrochemical synthesis of gem-diselenides.
Scheme 75: Site-selective electrochemical aromatic C–H amination.
Scheme 76: Electrochemical coupling of heteroarenes with heteroaryl phosphonium salts.
Scheme 77: Redox-neutral strategy for the dehydroxyarylation reaction.
Scheme 78: Nickel-catalyzed electrochemical C(sp3)–C(sp2) cross-coupling of benzyl trifluoroborate and halides....
Scheme 79: Paired electrocatalysis for C(sp3)–C(sp2) coupling.
Scheme 80: Redox-neutral strategy for amination of aryl bromides.
Scheme 81: Redox-neutral cross-coupling of aryl halides with weak N-nucleophiles. aProtocol with (+) RVC | RVC...
Scheme 82: Nickel-catalyzed N-arylation of NH-sulfoximines with aryl halides.
Scheme 83: Esterification of carboxylic acids with aryl halides.
Scheme 84: Electrochemically promoted nickel-catalyzed carbon–sulfur-bond formation. GFE = graphite felt elect...
Scheme 85: Electrochemical deoxygenative thiolation by Ni-catalysis. GFE = graphite felt electrode; NFE = nick...
Scheme 86: Electrochemical coupling of peptides with aryl halides.
Scheme 87: Paired electrolysis for the phosphorylation of aryl halides. GFE = graphite felt electrode, FNE = f...
Scheme 88: Redox-neutral alkoxyhalogenation of alkenes.
Divergent role of PIDA and PIFA in the AlX3 (X = Cl, Br) halogenation of 2-naphthol: a mechanistic study
- Kevin A. Juárez-Ornelas,
- Manuel Solís-Hernández,
- Pedro Navarro-Santos,
- J. Oscar C. Jiménez-Halla and
- César R. Solorio-Alvarado
Beilstein J. Org. Chem. 2024, 20, 1580–1589, doi:10.3762/bjoc.20.141
- halogenation via PhIX2. Keywords: aromatic bromination; aromatic chlorination; density functional theory (DFT); hypervalent iodine; iodine(III); Introduction Hypervalent iodine(III) reagents have gained attention as strong oxidants with a low toxicity [1][2][3][4][5][6][7][8] and due to the ability to mimic
- less probable route. This result also confirms the relevance of using two equivalents of aluminum chloride. The aromatic chlorination with iodine(III) reagents broadly employs PhICl2 [7]. Thus, we explored two alternatives for the chlorination of 2-naphthol to identify or rule out this potential
- -naphthol in the presence of PIDA and AlBr3. Representative protocols for the oxidative aromatic chlorination and bromination with iodine(III) reagents. Chlorination of 2-naphthol using the PIFA/AlCl3, 1:2 system. Bromination of 2-naphthol using the PIDA/AlBr3, 1:2 system. Reaction mechanism for the
Graphical Abstract
Scheme 1: Representative protocols for the oxidative aromatic chlorination and bromination with iodine(III) r...
Scheme 2: Chlorination of 2-naphthol using the PIFA/AlCl3, 1:2 system.
Scheme 3: Bromination of 2-naphthol using the PIDA/AlBr3, 1:2 system.
Scheme 4: Reaction mechanism for the chlorination of 2-naphthol using the PIFA/AlCl3, 1:2 system.
Figure 1: Energy profile for the chlorination of 2-naphthol in the presence of PIFA and AlCl3.
Scheme 5: Calculated reaction mechanism for the bromination of 2-naphthol using the PIDA/AlBr3, 1:2 system.
Figure 2: Calculated mechanism for the bromination of 2-naphthol in the presence of PIDA and AlBr3.
