Search for "Brønsted acid" in Full Text gives 153 result(s) in Beilstein Journal of Organic Chemistry.
Beilstein J. Org. Chem. 2023, 19, 1471–1502, doi:10.3762/bjoc.19.106
Graphical Abstract
Scheme 1: Sulfur-containing bioactive molecules.
Scheme 2: Scandium-catalyzed synthesis of thiosulfonates.
Scheme 3: Palladium-catalyzed aryl(alkyl)thiolation of unactivated arenes.
Scheme 4: Catalytic cycle for Pd-catalyzed aryl(alkyl)thiolation of unactivated arenes.
Scheme 5: Iron- or boron-catalyzed C–H arylthiation of substituted phenols.
Scheme 6: Iron-catalyzed azidoalkylthiation of alkenes.
Scheme 7: Plausible mechanism for iron-catalyzed azidoalkylthiation of alkenes.
Scheme 8: BF3·Et2O‑mediated electrophilic cyclization of aryl alkynoates.
Scheme 9: Tentative mechanism for BF3·Et2O‑mediated electrophilic cyclization of aryl alkynoates.
Scheme 10: Construction of 6-substituted benzo[b]thiophenes.
Scheme 11: Plausible mechanism for construction of 6-substituted benzo[b]thiophenes.
Scheme 12: AlCl3‑catalyzed cyclization of N‑arylpropynamides with N‑sulfanylsuccinimides.
Scheme 13: Synthetic utility of AlCl3‑catalyzed cyclization of N‑arylpropynamides with N‑sulfanylsuccinimides.
Scheme 14: Sulfenoamination of alkenes with sulfonamides and N-sulfanylsuccinimides.
Scheme 15: Lewis acid/Brønsted acid controlled Pd-catalyzed functionalization of aryl C(sp2)–H bonds.
Scheme 16: Possible mechanism for Lewis acid/Brønsted acid controlled Pd-catalyzed functionalization of aryl C...
Scheme 17: FeCl3-catalyzed carbosulfenylation of unactivated alkenes.
Scheme 18: Copper-catalyzed electrophilic thiolation of organozinc halides.
Scheme 19: h-BN@Copper(II) nanomaterial catalyzed cross-coupling reaction of sulfoximines and N‑(arylthio)succ...
Scheme 20: AlCl3‑mediated cyclization and sulfenylation of 2‑alkyn-1-one O‑methyloximes.
Scheme 21: Lewis acid-promoted 2-substituted cyclopropane 1,1-dicarboxylates with sulfonamides and N-(arylthio...
Scheme 22: Lewis acid-mediated cyclization of β,γ-unsaturated oximes and hydrazones with N-(arylthio/seleno)su...
Scheme 23: Credible pathway for Lewis acid-mediated cyclization of β,γ-unsaturated oximes with N-(arylthio)suc...
Scheme 24: Synthesis of 4-chalcogenyl pyrazoles via chalcogenation/cyclization of α,β-alkynic hydrazones.
Scheme 25: Controllable synthesis of 3-thiolated pyrroles and pyrrolines.
Scheme 26: Possible mechanism for controllable synthesis of 3-thiolated pyrroles and pyrrolines.
Scheme 27: Co-catalyzed C2-sulfenylation and C2,C3-disulfenylation of indole derivatives.
Scheme 28: Plausible catalytic cycle for Co-catalyzed C2-sulfenylation and C2,C3-disulfenylation of indoles.
Scheme 29: C–H thioarylation of electron-rich arenes by iron(III) triflimide catalysis.
Scheme 30: Difunctionalization of alkynyl bromides with thiosulfonates and N-arylthio succinimides.·
Scheme 31: Suggested mechanism for difunctionalization of alkynyl bromides with thiosulfonates and N-arylthio ...
Scheme 32: Synthesis of thioesters, acyl disulfides, ketones, and amides by N-thiohydroxy succinimide esters.
Scheme 33: Proposed mechanism for metal-catalyzed selective acylation and acylthiolation.
Scheme 34: AlCl3-catalyzed synthesis of 3,4-bisthiolated pyrroles.
Scheme 35: α-Sulfenylation of aldehydes and ketones.
Scheme 36: Acid-catalyzed sulfetherification of unsaturated alcohols.
Scheme 37: Enantioselective sulfenylation of β-keto phosphonates.
Scheme 38: Organocatalyzed sulfenylation of 3‑substituted oxindoles.
Scheme 39: Sulfenylation and chlorination of β-ketoesters.
Scheme 40: Intramolecular sulfenoamination of olefins.
Scheme 41: Plausible mechanism for intramolecular sulfenoamination of olefins.
Scheme 42: α-Sulfenylation of 5H-oxazol-4-ones.
Scheme 43: Metal-free C–H sulfenylation of electron-rich arenes.
Scheme 44: TFA-promoted C–H sulfenylation indoles.
Scheme 45: Proposed mechanism for TFA-promoted C–H sulfenylation indoles.
Scheme 46: Organocatalyzed sulfenylation and selenenylation of 3-pyrrolyloxindoles.
Scheme 47: Organocatalyzed sulfenylation of S-based nucleophiles.
Scheme 48: Conjugate Lewis base Brønsted acid-catalyzed sulfenylation of N-heterocycles.
Scheme 49: Mechanism for activation of N-sulfanylsuccinimide by conjugate Lewis base Brønsted acid catalyst.
Scheme 50: Sulfenylation of deconjugated butyrolactams.
Scheme 51: Intramolecular sulfenofunctionalization of alkenes with phenols.
Scheme 52: Organocatalytic 1,3-difunctionalizations of Morita–Baylis–Hillman carbonates.
Scheme 53: Organocatalytic sulfenylation of β‑naphthols.
Scheme 54: Acid-promoted oxychalcogenation of o‑vinylanilides with N‑(arylthio/arylseleno)succinimides.
Scheme 55: Lewis base/Brønsted acid dual-catalytic C–H sulfenylation of aryls.
Scheme 56: Lewis base-catalyzed sulfenoamidation of alkenes.
Scheme 57: Cyclization of allylic amide using a Brønsted acid and tetrabutylammonium chloride.
Scheme 58: Catalytic electrophilic thiocarbocyclization of allenes with N-thiosuccinimides.
Scheme 59: Suggested mechanism for electrophilic thiocarbocyclization of allenes with N-thiosuccinimides.
Scheme 60: Chiral chalcogenide-catalyzed enantioselective hydrothiolation of alkenes.
Scheme 61: Proposed mechanism for chalcogenide-catalyzed enantioselective hydrothiolation of alkenes.
Scheme 62: Organocatalytic sulfenylation for synthesis a diheteroatom-bearing tetrasubstituted carbon centre.
Scheme 63: Thiolative cyclization of yne-ynamides.
Scheme 64: Synthesis of alkynyl and acyl disulfides from reaction of thiols with N-alkynylthio phthalimides.
Scheme 65: Oxysulfenylation of alkenes with 1-(arylthio)pyrrolidine-2,5-diones and alcohols.
Scheme 66: Arylthiolation of arylamines with (arylthio)-pyrrolidine-2,5-diones.
Scheme 67: Catalyst-free isothiocyanatoalkylthiation of styrenes.
Scheme 68: Sulfenylation of (E)-β-chlorovinyl ketones toward 3,4-dimercaptofurans.
Scheme 69: HCl-promoted intermolecular 1, 2-thiofunctionalization of aromatic alkenes.
Scheme 70: Possible mechanism for HCl-promoted 1,2-thiofunctionalization of aromatic alkenes.
Scheme 71: Coupling reaction of diazo compounds with N-sulfenylsuccinimides.
Scheme 72: Multicomponent reactions of disulfides with isocyanides and other nucleophiles.
Scheme 73: α-Sulfenylation and β-sulfenylation of α,β-unsaturated carbonyl compounds.
Beilstein J. Org. Chem. 2023, 19, 956–981, doi:10.3762/bjoc.19.72
Graphical Abstract
Scheme 1: First organocatalyzed asymmetric aza-Friedel–Crafts reaction.
Scheme 2: Aza-Friedel–Crafts reaction between indoles and cyclic ketimines.
Scheme 3: Aza-Friedel–Crafts reaction utilizing trifluoromethyldihydrobenzoazepinoindoles as electrophiles.
Scheme 4: Aza-Friedel–Crafts reaction utilizing cyclic N-sulfimines as electrophiles.
Scheme 5: Aza-Friedel–Crafts reaction involving N-unprotected imino ester as electrophile.
Scheme 6: Aza-Friedel–Crafts and lactonization cascade.
Scheme 7: One-pot oxidation and aza-Friedel–Crafts reaction.
Scheme 8: C1 and C2-symmetric phosphoric acids as catalysts.
Scheme 9: Aza-Friedel–Crafts reaction using Nps-iminophosphonates as electrophiles.
Scheme 10: Aza-Friedel–Crafts reaction between indole and α-iminophosphonate.
Scheme 11: [2.2]-Paracyclophane-derived chiral phosphoric acids as catalyst.
Scheme 12: Aza-Friedel–Crafts reaction through ring opening of sulfamidates.
Scheme 13: Isoquinoline-1,3(2H,4H)-dione scaffolds as electrophiles.
Scheme 14: Functionalization of the carbocyclic ring of substituted indoles.
Scheme 15: Aza-Friedel–Crafts reaction between unprotected imines and aza-heterocycles.
Scheme 16: Anilines and α-naphthols as potential nucleophiles.
Scheme 17: Solvent-controlled regioselective aza-Friedel–Crafts reaction.
Scheme 18: Generating central and axial chirality via aza-Friedel–Crafts reaction.
Scheme 19: Reaction between indoles and racemic 2,3-dihydroisoxazol-3-ol derivatives.
Scheme 20: Exploiting 5-aminoisoxazoles as nucleophiles.
Scheme 21: Reaction between unsubstituted indoles and 3-alkynylated 3-hydroxy-1-oxoisoindolines.
Scheme 22: Synthesis of unnatural amino acids bearing an aza-quaternary stereocenter.
Scheme 23: Atroposelective aza-Friedel–Crafts reaction.
Scheme 24: Coupling of 5-aminopyrazole and 3H-indol-3-ones.
Scheme 25: Pyrophosphoric acid-catalyzed aza-Friedel–Crafts reaction on phenols.
Scheme 26: Squaramide-assisted aza-Friedel–Crafts reaction.
Scheme 27: Thiourea-catalyzed aza-Friedel–Crafts reaction.
Scheme 28: Squaramide-catalyzed reaction between β-naphthols and benzothiazolimines.
Scheme 29: Thiourea-catalyzed reaction between β-naphthol and isatin-derived ketamine.
Scheme 30: Quinine-derived molecule as catalyst.
Scheme 31: Cinchona alkaloid as catalyst.
Scheme 32: aza-Friedel–Crafts reaction by phase transfer catalyst.
Scheme 33: Disulfonamide-catalyzed reaction.
Scheme 34: Heterogenous thiourea-catalyzed aza-Friedel–Crafts reaction.
Scheme 35: Total synthesis of (+)-gracilamine.
Scheme 36: Total synthesis of (−)-fumimycin.
Beilstein J. Org. Chem. 2023, 19, 928–955, doi:10.3762/bjoc.19.71
Graphical Abstract
Figure 1: Various pyrrole containing molecules.
Scheme 1: Various synthestic protocols for the synthesis of pyrroles.
Figure 2: A tree-diagram showing various conventional and green protocols for Clauson-Kaas pyrrole synthesis.
Scheme 2: A general reaction of Clauson–Kaas pyrrole synthesis and proposed mechanism.
Scheme 3: AcOH-catalyzed synthesis of pyrroles 5 and 7.
Scheme 4: Synthesis of N-substituted pyrroles 9.
Scheme 5: P2O5-catalyzed synthesis of N-substituted pyrroles 11.
Scheme 6: p-Chloropyridine hydrochloride-catalyzed synthesis of pyrroles 13.
Scheme 7: TfOH-catalyzed synthesis of N-sulfonylpyrroles 15, N-sulfonylindole 16, N-sulfonylcarbazole 17.
Scheme 8: Scandium triflate-catalyzed synthesis of N-substituted pyrroles 19.
Scheme 9: MgI2 etherate-catalyzed synthesis and proposed mechanism of N-arylpyrrole derivatives 21.
Scheme 10: Nicotinamide catalyzed synthesis of pyrroles 23.
Scheme 11: ZrOCl2∙8H2O catalyzed synthesis and proposed mechanism of pyrrole derivatives 25.
Scheme 12: AcONa catalyzed synthesis of N-substituted pyrroles 27.
Scheme 13: Squaric acid-catalyzed synthesis and proposed mechanism of N-substituted pyrroles 29.
Figure 3: Reusability of catalyst γ-Fe2O3@SiO2-Sb-IL in six cycles.
Scheme 14: Magnetic nanoparticle-supported antimony catalyst used in the synthesis of N-substituted pyrroles 31...
Scheme 15: Iron(III) chloride-catalyzed synthesis of N-substituted pyrroles 33.
Scheme 16: Copper-catalyzed Clauson–Kaas synthesis and mechanism of pyrroles 35.
Scheme 17: β-CD-SO3H-catalyzed synthesis and proposed mechanism of pyrroles 37.
Figure 4: Recyclability of β-cyclodextrin-SO3H.
Scheme 18: Solvent-free and catalyst-free synthesis and plausible mechanism of N-substituted pyrroles 39.
Scheme 19: Nano-sulfated TiO2-catalyzed synthesis of N-substituted pyrroles 41.
Figure 5: Plausible mechanism for the formation of N-substituted pyrroles catalyzed by nano-sulfated TiO2 cat...
Scheme 20: Copper nitrate-catalyzed Clauson–Kaas synthesis and mechanism of N-substituted pyrroles 43.
Scheme 21: Synthesis of N-substituted pyrroles 45 by using Co catalyst Co/NGr-C@SiO2-L.
Scheme 22: Zinc-catalyzed synthesis of N-arylpyrroles 47.
Scheme 23: Silica sulfuric acid-catalyzed synthesis of pyrrole derivatives 49.
Scheme 24: Bismuth nitrate-catalyzed synthesis of pyrroles 51.
Scheme 25: L-(+)-tartaric acid-choline chloride-catalyzed Clauson–Kaas synthesis and plausible mechanism of py...
Scheme 26: Microwave-assisted synthesis of N-substituted pyrroles 55 in AcOH or water.
Scheme 27: Synthesis of pyrrole derivatives 57 using a nano-organocatalyst.
Figure 6: Nano-ferric supported glutathione organocatalyst.
Scheme 28: Microwave-assisted synthesis of N-substituted pyrroles 59 in water.
Scheme 29: Iodine-catalyzed synthesis and proposed mechanism of pyrroles 61.
Scheme 30: H3PW12O40/SiO2-catalyzed synthesis of N-substituted pyrroles 63.
Scheme 31: Fe3O4@-γ-Fe2O3-SO3H-catalyzed synthesis of pyrroles 65.
Scheme 32: Mn(NO3)2·4H2O-catalyzed synthesis and proposed mechanism of pyrroles 67.
Scheme 33: p-TsOH∙H2O-catalyzed (method 1) and MW-assisted (method 2) synthesis of N-sulfonylpyrroles 69.
Scheme 34: ([hmim][HSO4]-catalyzed Clauson–Kaas synthesis of pyrroles 71.
Scheme 35: Synthesis of N-substituted pyrroles 73 using K-10 montmorillonite catalyst.
Scheme 36: CeCl3∙7H2O-catalyzed Clauson–Kaas synthesis of pyrroles 75.
Scheme 37: Synthesis of N-substituted pyrroles 77 using Bi(NO3)3∙5H2O.
Scheme 38: Oxone-catalyzed synthesis and proposed mechanism of N-substituted pyrroles 79.
Beilstein J. Org. Chem. 2023, 19, 477–486, doi:10.3762/bjoc.19.37
Graphical Abstract
Scheme 1: Experimental data (series a–d, k) and non-studied examples (series e–j) for transannular cycloaddit...
Figure 1: Optimized (m062x/6-31G(d)) geometries for the transition structures of series a–f.
Figure 2: Top: Cycloaddition of protonated hydrazones as inverse-demand reaction of cycloaddition of azomethi...
Figure 3: Global electron density transfer (GEDT). Dashed black line indicates both TS.
Figure 4: ELF analysis for the reaction of series b leading to a system 6-6. Black trace corresponds to IRC. ...
Figure 5: Quantitative NCI analysis [36] for the reaction of series a–f leading to fused cyclohexanes. The result...
Figure 6: (a) Transannular cycloadditons of compounds 1a–k. (b) Houk’s distortion model applied to the reacti...
Scheme 2: Reaction with simple models.
Beilstein J. Org. Chem. 2023, 19, 115–132, doi:10.3762/bjoc.19.12
Graphical Abstract
Scheme 1: 1,3-Dithianes as useful synthetic building blocks: a) general synthetic utility (in Corey–Seebach-t...
Scheme 2: Metalation of other saturated heterocycles is often problematic due to β-elimination [16,17].
Scheme 3: Thianes as synthetic building blocks in the construction of complex molecules [18].
Figure 1: a) 1,4-Dithiane-type building blocks that can serve as C2-synthons and b) examples of complex targe...
Scheme 4: Synthetic availability of 1,4-dithiane-type building blocks.
Scheme 5: Dithiins and dihydrodithiins as pseudoaryl groups [36-39].
Scheme 6: Metalation of other saturated heterocycles is often problematic due to β-elimination [40-42].
Figure 2: Reactive conformations leading to β-fragmentation for lithiated 1,4-dithianes and 1,4-dithiin.
Scheme 7: Mild metalation of 1,4-dithiins affords stable heteroaryl-magnesium and heteroaryl-zinc-like reagen...
Scheme 8: Dithiin-based dienophiles and their use in synthesis [33,49-54].
Scheme 9: Dithiin-based dienes and their use in synthesis [55-57].
Scheme 10: Stereoselective 5,6-dihydro-1,4-dithiin-based synthesis of cis-olefins [42,58].
Scheme 11: Addition to aldehydes and applications in stereoselective synthesis.
Figure 3: Applications in the total synthesis of complex target products with original attachment place of 1,...
Scheme 12: Direct C–H functionalization methods for 1,4-dithianes [82,83].
Scheme 13: Known cycloaddition reactivity modes of allyl cations [84-100].
Scheme 14: Cycloadditions of 1,4-dithiane-fused allyl cations derived from dihydrodithiin-methanol 90 [101-107].
Scheme 15: Dearomative [3 + 2] cycloadditions of unprotected indoles with 1,4-dithiane-fused allyl alcohol 90 [30]....
Scheme 16: Comparison of reactivity of dithiin-fused allyl alcohols and similar non-cyclic sulfur-substituted ...
Scheme 17: Applications of dihydrodithiins in the rapid assembly of polycyclic terpenoid scaffolds [108,109].
Scheme 18: Dihydrodithiin-mediated allyl cation and vinyl carbene cycloadditions via a gold(I)-catalyzed 1,2-s...
Scheme 19: Activation mode of ethynyldithiolanes towards gold-coordinated 1,4-dithiane-fused allyl cation and ...
Scheme 20: Desulfurization problems.
Scheme 21: oxidative decoration strategies for 1,4-dithiane scaffolds.
Beilstein J. Org. Chem. 2023, 19, 27–32, doi:10.3762/bjoc.19.2
Graphical Abstract
Scheme 1: Synthesis of acyclic (DIS) and cyclic (CDIS) diaryliodonium salts.
Figure 1: Substrate scope using the optimized conditions of Table 3. Yield is based on collecting for 3 h 20 min (2....
Beilstein J. Org. Chem. 2022, 18, 1672–1695, doi:10.3762/bjoc.18.179
Graphical Abstract
Scheme 1: Organocatalysis classification used in the present perspective.
Scheme 2: Oxidative processes catalyzed by amines.
Scheme 3: N-Heterocyclic carbene (NHC) catalysis in oxidative functionalization of aldehydes.
Scheme 4: Examples of asymmetric oxidative processes catalyzed by chiral Brønsted acids.
Scheme 5: Asymmetric aerobic α-hydroxylation of lactams under phase-transfer organocatalysis conditions emplo...
Scheme 6: Selective CH-oxidation of methylarenes to aldehydes or carboxylic acids.
Scheme 7: An example of the regioselective CH-amination by a sterically hindered imide-N-oxyl radical precurs...
Scheme 8: CH-amination of ethylbenzene and CH-fluorination of aldehydes catalyzed by N-hydroxybenzimidazoles,...
Scheme 9: Mixed hetero-/homogeneous TiO2/N-hydroxyimide photocatalysis in the selective benzylic oxidation.
Scheme 10: Electrochemical benzylic iodination and benzylation of pyridine by benzyl iodides generated in situ...
Scheme 11: Electrochemical oxidative C–O/C–N coupling of alkylarenes with NHPI. Electrolysis conditions: Const...
Scheme 12: Chemoselective alcohol oxidation catalyzed by TEMPO.
Scheme 13: ABNO-catalyzed oxidative C–N coupling of primary alcohols with primary amines.
Scheme 14: ACT-catalyzed electrochemical oxidation of primary alcohols and aldehydes to carboxylic acids.
Scheme 15: Electrocatalytic oxidation of benzylic alcohols by a TEMPO derivative immobilized on a graphite ano...
Scheme 16: Electrochemical oxidation of carbamates of cyclic amines to lactams and oxidative cyanation of amin...
Scheme 17: Hydrogen atom transfer (HAT) and single-electron transfer (SET) as basic principles of amine cation...
Scheme 18: Electrochemical quinuclidine-catalyzed oxidation involving unactivated C–H bonds.
Scheme 19: DABCO-mediated photocatalytic C–C cross-coupling involving aldehyde C–H bond cleavage.
Scheme 20: DABCO-derived cationic catalysts in inactivated C–H bond cleavage for alkyl radical addition to ele...
Scheme 21: Electrochemical diamination and dioxygenation of vinylarenes catalyzed by triarylamines.
Scheme 22: Electrochemical benzylic oxidation mediated by triarylimidazoles.
Scheme 23: Thiyl radical-catalyzed CH-arylation of allylic substrates by aryl cyanides.
Scheme 24: Synthesis of redox-active alkyl tetrafluoropyridinyl sulfides by unactivated C–H bond cleavage by t...
Scheme 25: Main intermediates in quinone oxidative organocatalysis.
Scheme 26: Electrochemical DDQ-catalyzed intramolecular dehydrogenative aryl–aryl coupling.
Scheme 27: DDQ-mediated cross-dehydrogenative C–N coupling of benzylic substrates with azoles.
Scheme 28: Biomimetic o-quinone-catalyzed benzylic alcohol oxidation.
Scheme 29: Electrochemical synthesis of secondary amines by oxidative coupling of primary amines and benzylic ...
Scheme 30: General scheme of dioxirane and oxaziridine oxidative organocatalysis.
Scheme 31: Dioxirane organocatalyzed CH-hydroxylation involving aliphatic C(sp3)–H bonds.
Scheme 32: Enantioselective hydroxylation of CH-acids catalyzed by chiral oxaziridines.
Scheme 33: Iodoarene-organocatalyzed vinylarene diamination.
Scheme 34: Iodoarene-organocatalyzed asymmetric CH-hydroxylation of benzylic substrates.
Scheme 35: Iodoarene-organocatalyzed asymmetric difluorination of alkenes with migration of aryl or methyl gro...
Scheme 36: Examples of 1,2-diiodo-4,5-dimethoxybenzene-catalyzed electrochemical oxidative heterocyclizations.
Scheme 37: Electrochemical N-ammonium ylide-catalyzed CH-oxidation.
Scheme 38: Oxidative dimerization of aryl- and alkenylmagnesium compounds catalyzed by quinonediimines.
Scheme 39: FLP-catalyzed dehydrogenation of N-substituted indolines.
Beilstein J. Org. Chem. 2022, 18, 1463–1465, doi:10.3762/bjoc.18.152
Beilstein J. Org. Chem. 2022, 18, 1236–1248, doi:10.3762/bjoc.18.129
Graphical Abstract
Scheme 1: Structures of vicinal ketoesters and examples for their typical reactivity.
Scheme 2: Doyle’s diastereoselective intramolecular aldol addition of α,β-diketoester.
Scheme 3: Synthesis of euphorikanin A (16) by intramolecular, nucleophilic addition [6].
Scheme 4: Ketoester cycloisomerization for the synthesis of preussochromone A (24) [10].
Scheme 5: Diastereoselective, intramolecular aldol reaction of an α-ketoester 28 in the synthesis of (−)-preu...
Scheme 6: Synthesis of an α-ketoester through Riley oxidation and its use in an α-ketol rearrangement in the ...
Scheme 7: Azomethine imine cycloaddition towards the synthesis of the proposed structure of palau’amine (44) [19]....
Scheme 8: Intramolecular diastereoselective carbonyl-ene reaction of an α-ketoester in the synthesis of jatro...
Scheme 9: Grignard addition to an α-ketoester and subsequent Friedel–Crafts cyclization in the synthesis of (...
Scheme 10: Diastereoselective addition to an auxiliary modified α-ketoester in the formal synthesis of (+)-cam...
Scheme 11: Intramolecular photoreduction of an α-ketoester in the synthesis of (rac)-isoretronecanol (69) [26].
Scheme 12: α-Ketoester as nucleophile in a Tsuji–Trost reaction in the synthesis of (rac)-corynoxine (76) [27].
Scheme 13: Mannich reaction of an α-ketoester in the synthesis of (+)-gracilamine (83) [28].
Scheme 14: Enantioselective aldol reaction using an α-ketoester in the synthesis of (−)-irofulven (87) [29].
Scheme 15: Allylboration of a mesoxalic acid ester in the synthesis of (+)-awajanomycin (92) [30,31].
Scheme 16: Condensation of a diamine with mesoxolate in the synthesis of (−)-aplaminal (96) [32].
Scheme 17: Synthesis of mesoxalic ester amide 102 and its use in the synthesis of (rac)-cladoniamide G (103) [33].
Scheme 18: The thermodynamically controlled, intramolecular aldol addition of a vic-tricarbonyl compound in th...
Beilstein J. Org. Chem. 2022, 18, 1070–1078, doi:10.3762/bjoc.18.109
Graphical Abstract
Figure 1: Diverse bioactive compounds based on the privileged 1,4-DHIQ scaffold.
Figure 2: Strategy investigated in this work.
Scheme 1: Preparation of 3(2H)-isoquinolones 11. aObtained as a 10:1 mixture of regioisomers; purified by cry...
Scheme 2: Preparation of 4-diazo-3(2H)-isoquinolones 10. aConfirmed by single-crystal X-ray crystallography (...
Scheme 3: TfOH-promoted arylation of diazo substrates 10. aStructure confirmed by single-crystal X-ray analys...
Scheme 4: Unexpected outcome of the TfOH-promoted arylation of 10a with N-formyl-N-methylaniline giving rise ...
Scheme 5: Plausible mechanism for the conversion of diazo substrates 10 to 4-aryl products 9 (shown for ArH =...
Beilstein J. Org. Chem. 2022, 18, 707–721, doi:10.3762/bjoc.18.71
Graphical Abstract
Figure 1: Examples of endoperoxide-containing natural products.
Scheme 1: Reactions of COXs.
Figure 2: Structures of COXs [52,53]. (A) The overall structure of ovine COX-1. (B and C) Comparison of the cyclooxy...
Scheme 2: Proposed reaction mechanisms of COXs [24].
Scheme 3: General reaction mechanism of Fe/2OG oxygenases.
Scheme 4: Reaction of FtmOx1 [68-71].
Figure 3: Structure of FtmOx1 [71]. (A) The FtmOx1 binary structure in complex with 2OG. (B and C) Comparison of ...
Scheme 5: Proposed COX-like mechanism of FtmOx1 [68].
Scheme 6: Proposed CarC-like mechanism of FtmOx1 [70].
Scheme 7: Reaction of NvfI [28].
Scheme 8: Possible reaction pathways leading to fumigatonoid A [28].
Figure 4: Structure of NvfI [28]. (A–C) Conformational changes of loop regions: (A) open conformation, (B) partia...
Scheme 9: Another possible reaction pathway for the formation of fumigatonoid A [28].
Beilstein J. Org. Chem. 2022, 18, 337–349, doi:10.3762/bjoc.18.38
Graphical Abstract
Scheme 1: Resorcin[4]arene 1 forming the corresponding hexameric capsule 16 and the species used for control ...
Scheme 2: Carbonyl–ene intramolecular cyclization of (S)-citronellal to the corresponding diastereoisomeric c...
Figure 1: 1H NMR spectra in water-saturated CDCl3 except for G. A: [16] (7.5 mM); B: citronellal; C: citronel...
Scheme 3: Dehydration reaction of 1,1-diphenylethanol to 1,1-diphenylethylene.
Figure 2: 1H NMR spectra in water-saturated CDCl3 except for G. A: [16] (7.5 mM); B: 1,1-diphenylethanol; C: ...
Scheme 4: Possible isomerization products from β-pinene and α-pinene.
Figure 3: 1H NMR spectra in water-saturated CDCl3 except for G. A: [16] (7.5 mM); B: α-pinene; C: α-pinene (7...
Figure 4: 1H NMR spectra in water-saturated CDCl3 except for G. A: [16] (7.5 mM); B: β-pinene; C: β-pinene (7...
Figure 5: 1H NMR spectra in water-saturated CDCl3, except for E. A: [16] (7.5 mM); B: β-pinene; C: β-pinene (...
Beilstein J. Org. Chem. 2022, 18, 325–330, doi:10.3762/bjoc.18.36
Graphical Abstract
Scheme 1: Proposal of a Se···O bonding catalysis approach.
Scheme 2: Se···O bonding catalysis approach to the synthesis of calix[4]pyrrole 2a.
Scheme 3: Reaction scope.
Scheme 4: Proposed activation mode.
Beilstein J. Org. Chem. 2022, 18, 240–242, doi:10.3762/bjoc.18.28
Beilstein J. Org. Chem. 2021, 17, 2787–2794, doi:10.3762/bjoc.17.189
Graphical Abstract
Figure 1: Pyrrolo[1,2-a]quinazoline derivatives – analogs of vasicinone alkaloids and their biological activi...
Scheme 1: Synthetic approaches to 2,3-dihydropyrrolo[1,2-a]quinazolin-5(1H)-one derivatives.
Scheme 2: Plausible mechanism for the formation of 6.
Figure 2: X-ray crystal structure of compound 6f.
Beilstein J. Org. Chem. 2021, 17, 2611–2620, doi:10.3762/bjoc.17.174
Graphical Abstract
Figure 1: Structures of the steroidal tetrazoles that showed anticancer potential in vitro.
Figure 2: Mechanism of the Schmidt reaction.
Scheme 1: Synthesis of 12-oxo intermediates. Reagents and conditions: a) EtOAc, pTsOH, reflux, 14 h (81%); b)...
Scheme 2: Synthesis of 7-oxo intermediate 11 from chenodeoxycholic acid (9). Reagents and conditions: a) EtOA...
Figure 3: Mercury [51] drawing of the molecular structures of compounds 13 and 14, with labelling of nonhydrogen ...
Figure 4: Dose dependence of the cytotoxicity of tested compounds on treated cell lines. All compounds were t...
Beilstein J. Org. Chem. 2021, 17, 2570–2584, doi:10.3762/bjoc.17.172
Graphical Abstract
Figure 1: Generalized α-ketol or α-iminol rearrangement.
Figure 2: Nickel(II)-catalyzed enantioselective rearrangement of ketol 3 to form the ring-expanded and chiral...
Figure 3: Enantioselective ring expansion of β-hydroxy-α-dicarbonyl 6 catalyzed by a chiral copper-bisoxazoli...
Figure 4: Enantioselective rearrangement of ketols 9 and 12 and hydroxyaldimine 14 catalyzed by Al(III) or Sc...
Figure 5: Asymmetric rearrangement of α,α-dialkyl-α-siloxyaldehydes 16 to α-siloxyketones 17 catalyzed by chi...
Figure 6: BF3-promoted diastereospecific rearrangement of α-ketol 21 to difluoroalkoxyborane 22.
Figure 7: In the presence of a gold catalyst and water in 1,4-dioxane, 1-alkynylbutanol derivatives undergo t...
Figure 8: The diastereospecific α-ketol rearrangement of 32 to 33, part of the total synthesis of periconiano...
Figure 9: Two α-ketol rearrangements, one catalyzed by silica gel on 38 and the other by NaOMe on both 38 and ...
Figure 10: α-Ketol rearrangement of triumphalone (41) to isotriumphalone (42) via ring contraction.
Figure 11: Tandem reaction of strophasterol A synthetic intermediate 43 to 44 through a vinylogous α-ketol rea...
Figure 12: Tandem reaction consisting of a Diels–Alder cycloaddition followed by an α-ketol rearrangement, par...
Figure 13: Single-pot reaction consisting of Claisen and α-ketol rearrangements, part of the total synthesis o...
Figure 14: Enzyme-catalyzed α-ketol rearrangements. a) Ketol-acid reductoisomerase (KAR) catalyzes the rearran...
Figure 15: The conversion of asperfloroid (73) to asperflotone (72), featuring the ring-expanding α-ketol rear...
Figure 16: Hypothetical interconversion of natural products prekinamycin (76) and isoprekinamycin (77) and che...
Figure 17: Proposed biosynthetic pathway converting acylphloroglucinol (87) to isolated elodeoidins A–H 92–96....
Figure 18: α-Iminol rearrangements catalyzed by VANOL Zr (99). The rearrangement can be conducted with preform...
Figure 19: α-Iminol rearrangements catalyzed by silica gel and montmorillonite K 10. a) For 102a (102 with R =...
Figure 20: Synthesis of tryptamines 110 via a ring-contracting α‑iminol rearrangement. A mechanism for the fin...
Figure 21: Tandem synthesis of functionalized α-amino cyclopentanones 119 from heteroarenes 115 and cyclobutan...
Figure 22: Four eburnane-type alkaloid natural products 122–125 were synthesized from common intermediate 127,...
Beilstein J. Org. Chem. 2021, 17, 2433–2440, doi:10.3762/bjoc.17.160
Graphical Abstract
Figure 1: Synthetic strategies employing chiral Brønsted acid catalysis.
Scheme 1: The substrate scope of the aminalization reaction for different aldehydes. aAfter recrystallization...
Scheme 2: The substrate scope of the intermolecular aminalization reaction for anthranilamide derivatives. aA...
Figure 2: X-ray single-crystal structure of aminal 3l with the displacement ellipsoids drawn at the 30% proba...
Beilstein J. Org. Chem. 2021, 17, 2270–2286, doi:10.3762/bjoc.17.145
Graphical Abstract
Figure 1: a) Binding interactions in the chloride channel of E. coli. and b) examples of chloride, cyanide, n...
Figure 2: a) H-bond vs anion-binding catalysis and b) activation modes in anion-binding catalysis.
Scheme 1: First proposed anion-binding mechanism in the thiourea-catalyzed acetalization of benzaldehyde.
Scheme 2: a) Thiourea-catalyzed enantioselective acyl-Pictet–Spengler reaction of tryptamine-derived imines 4...
Scheme 3: Proposed mechanism of the thiourea-catalyzed enantioselective Pictet–Spengler reaction of hydroxyla...
Scheme 4: a) Thiourea-catalyzed intramolecular Pictet–Spengler-type cyclization of hydroxylactam-derived N-ac...
Scheme 5: Enantioselective Reissert-type reactions of a) (iso)quinolines with silyl ketene acetals, and b) vi...
Figure 3: Role of the counter-anion: a) Anion acting as a spectator and b) anion participating directly as th...
Scheme 6: Enantioselective selenocyclization catalyzed by squaramide 28.
Scheme 7: Desymmetrization of meso-aziridines catalyzed by bifunctional thiourea catalyst 31.
Scheme 8: Anion-binding-catalyzed desymmetrization of a) meso-aziridines catalyzed by chiral triazolium catal...
Scheme 9: Bis-urea-catalyzed enantioselective fluorination of a) β-bromosulfides and b) β-haloamines by Gouve...
Scheme 10: a) Bifunctional thiourea anion-binding – basic/nucleophilic catalysts. Selected applications in b) ...
Scheme 11: Thiourea-catalyzed enantioselective polycyclization reaction of hydroxylactams 51 through cation–π ...
Scheme 12: Enantioselective aza-Sakurai cyclization of hydroxylactams 56 implicating additional cation–π and L...
Scheme 13: Enantioselective tail-to-head cyclization of neryl chloride derivatives.
Scheme 14: Cation–π interactions in anion binding-catalyzed asymmetric addition reactions: a) addition of indo...
Scheme 15: Bisthiourea catalyzed oxa-Pictet–Spengler reaction of indole-based alcohols and aromatic aldehydes ...
Scheme 16: Anion-binding catalyst development in the enantioselective addition of silyl ketene acetals to 1-ch...
Scheme 17: a) Macrocyclic bis-thiourea catalyst in a diastereoselective glycosylation reaction. b) Competing SN...
Scheme 18: a) Folding mechanism of oligotriazoles upon anion recognition. b) Representative tetratriazole 82 c...
Scheme 19: Switchable chiral tetratriazole catalyst 86 in the enantioselective addition of silyl ketene acetal...
Beilstein J. Org. Chem. 2021, 17, 2203–2208, doi:10.3762/bjoc.17.142
Graphical Abstract
Scheme 1: Synthesis of 4a: (i) phenol, K2CO3, DMF, reflux, 2 h, 91%; (ii) PhMgBr, dry THF, 0 °C, 2 h, 86%; (i...
Figure 1: Scope of substrates for intramolecular FCA by activation of 4a–l and their isolated yields. aCondit...
Scheme 2: Plausible reaction mechanism for the cyclization reaction of alkene 4a.
Beilstein J. Org. Chem. 2021, 17, 2102–2122, doi:10.3762/bjoc.17.137
Graphical Abstract
Scheme 1: Synthesis of 2,2’-bis(indole)borinic ester 3.
Scheme 2: Synthesis of 2,2’-bisindole NHC·boranes by an SEAr mechanism.
Scheme 3: Syntheses of indolyl amines through Buchwald–Hartwig cross coupling.
Scheme 4: Synthesis of 3,3’-bis(indolyl) ethers.
Scheme 5: C–H silylation of indoles.
Scheme 6: n-BuLi-mediated syntheses of bis(indol-3-yl)silanes.
Scheme 7: Acid-catalyzed syntheses of bis(indol-3-yl)silanes and mechanisms.
Scheme 8: B(C6F5)3 and Al(C6F5)3-catalyzed syntheses of bis(indol-3-yl)silanes reported by Han.
Scheme 9: Base-mediated syntheses of bis and tris(indol-2-yl)phosphines.
Scheme 10: Synthesis of bis(indol-2-yl)sulfides using SL2-type reagents.
Scheme 11: Synthesis of 2,3’- and 2,2’-bis(indolyl)sulfides using disulfides as substrates.
Scheme 12: Synthesis of diindol-2-ylsulfide (84) from 2-iodoindole (92) and thiourea.
Scheme 13: Synthesis of bis(indol-3-yl)sulfides using N-silylated 3-bromoindole 93.
Scheme 14: Fischer indole synthesis of bis(indol-3-yl)sulfides using thio diketones.
Scheme 15: Oxidative synthesis of bis(indol-3-yl)sulfides using indoles and elemental sulfur.
Scheme 16: Synthesis of bis(indol-3-yl)sulfides using sulfoxides as sulfur source.
Scheme 17: Syntheses of bis(indol-2-yl)selanes.
Scheme 18: Syntheses of bis(indol-3-yl)selanes.
Scheme 19: Synthesis of bis(indol-2-yl)tellane 147.
Scheme 20: Synthesis of tris(indolyl)borane 154.
Scheme 21: Synthesis of bis(indol-4-yl)amines 159.
Scheme 22: Synthesis of bis(indol-5-yl)amines.
Scheme 23: Synthesis of 6,5’/6,6’-bis(indolyl)amines.
Scheme 24: Synthesis of potent HIV-inhibitors 6,6’-bis(indolyl) ethers.
Scheme 25: Synthesis of bis(indol-7-yl) ether.
Scheme 26: Synthesis of di(indol-5-yl)sulfide (183).
Scheme 27: Syntheses of 2,2’-diformyl-7,7’-bis(indolyl)selenides.
Beilstein J. Org. Chem. 2021, 17, 1952–1980, doi:10.3762/bjoc.17.128
Graphical Abstract
Figure 1: Coumarin-derived commercially available drugs.
Figure 2: Inhibition of acetylcholinesterase by coumarin derivatives.
Scheme 1: Michael addition of 4-hydroxycoumarins 1 to α,β‐unsaturated enones 2.
Scheme 2: Organocatalytic conjugate addition of 4-hydroxycoumarin 1 to α,β-unsaturated aldehydes 2 followed b...
Scheme 3: Synthesis of 3,4-dihydrocoumarin derivatives 10 through decarboxylative and dearomatizative cascade...
Scheme 4: Total synthesis of (+)-smyrindiol (17).
Scheme 5: Michael addition of 4-hydroxycoumarin (1) to enones 2 through a bifunctional modified binaphthyl or...
Scheme 6: Michael addition of ketones 20 to 3-aroylcoumarins 19 using a cinchona alkaloid-derived primary ami...
Scheme 7: Enantioselective reaction of cyclopent-2-enone-derived MBH alcohols 24 with 4-hydroxycoumarins 1.
Scheme 8: Sequential Michael addition/hydroalkoxylation one-pot approach to annulated coumarins 28 and 30.
Scheme 9: Michael addition of 4-hydroxycoumarins 1 to enones 2 using a binaphthyl diamine catalyst 31.
Scheme 10: Asymmetric Michael addition of 4-hydroxycoumarin 1 with α,β-unsaturated ketones 2 catalyzed by a ch...
Scheme 11: Catalytic asymmetric β-C–H functionalization of ketones via enamine oxidation.
Scheme 12: Enantioselective synthesis of polycyclic coumarin derivatives 37 catalyzed by an primary amine-imin...
Scheme 13: Allylic alkylation reaction between 3-cyano-4-methylcoumarins 39 and MBH carbonates 40.
Scheme 14: Enantioselective synthesis of cyclopropa[c]coumarins 45.
Scheme 15: NHC-catalyzed lactonization of 2-bromoenals 46 with 4-hydroxycoumarin (1).
Scheme 16: NHC-catalyzed enantioselective synthesis of dihydrocoumarins 51.
Scheme 17: Domino reaction of enals 2 with hydroxylated malonate 53 catalyzed by NHC 55.
Scheme 18: Oxidative [4 + 2] cycloaddition of enals 57 to coumarins 56 catalyzed by NHC 59.
Scheme 19: Asymmetric [3 + 2] cycloaddition of coumarins 43 to azomethine ylides 60 organocatalyzed by quinidi...
Scheme 20: Synthesis of α-benzylaminocoumarins 64 through Mannich reaction between 4-hydroxycoumarins (1) and ...
Scheme 21: Asymmetric addition of malonic acid half-thioesters 67 to coumarins 66 using the sulphonamide organ...
Scheme 22: Enantioselective 1,4-addition of azadienes 71 to 3-homoacyl coumarins 70.
Scheme 23: Michael addition/intramolecular cyclization of 3-acylcoumarins 43 to 3-halooxindoles 74.
Scheme 24: Enantioselective synthesis of 3,4-dihydrocoumarins 78 catalyzed by squaramide 73.
Scheme 25: Organocatalyzed [4 + 2] cycloaddition between 2,4-dienals 79 and 3-coumarincarboxylates 43.
Scheme 26: Enantioselective one-pot Michael addition/intramolecular cyclization for the synthesis of spiro[dih...
Scheme 27: Michael/hemiketalization addition enantioselective of hydroxycoumarins (1) to: (a) enones 2 and (b)...
Scheme 28: Synthesis of 2,3-dihydrofurocoumarins 89 through Michael addition of 4-hydroxycoumarins 1 to β-nitr...
Scheme 29: Synthesis of pyrano[3,2-c]chromene derivatives 93 via domino reaction between 4-hydroxycoumarins (1...
Scheme 30: Conjugated addition of 4-hydroxycoumarins 1 to nitroolefins 95.
Scheme 31: Michael addition of 4-hydroxycoumarin 1 to α,β-unsaturated ketones 2 promoted by primary amine thio...
Scheme 32: Enantioselective synthesis of functionalized pyranocoumarins 99.
Scheme 33: 3-Homoacylcoumarin 70 as 1,3-dipole for enantioselective concerted [3 + 2] cycloaddition.
Scheme 34: Synthesis of warfarin derivatives 107 through addition of 4-hydroxycoumarins 1 to β,γ-unsaturated α...
Scheme 35: Asymmetric multicatalytic reaction sequence of 2-hydroxycinnamaldehydes 109 with 4-hydroxycoumarins ...
Scheme 36: Mannich asymmetric addition of cyanocoumarins 39 to isatin imines 112 catalyzed by the amide-phosph...
Scheme 37: Enantioselective total synthesis of (+)-scuteflorin A (119).
Beilstein J. Org. Chem. 2021, 17, 1752–1813, doi:10.3762/bjoc.17.123
Graphical Abstract
Scheme 1: Fluorination with N-F amine 1-1.
Scheme 2: Preparation of N-F amine 1-1.
Scheme 3: Reactions of N-F amine 1-1.
Scheme 4: Synthesis of N-F perfluoroimides 2-1 and 2-2.
Scheme 5: Synthesis of 1-fluoro-2-pyridone (3-1).
Scheme 6: Fluorination with 1-fluoro-2-pyridone (3-1).
Figure 1: Synthesis of N-F sulfonamides 4-1a–g.
Scheme 7: Fluorination with N-F reagent 4-1b,c,f.
Scheme 8: Fluorination of alkenyllithiums with N-F 4-1h.
Scheme 9: Synthesis of N-fluoropyridinium triflate (5-4a).
Scheme 10: Synthetic methods for N-F-pyridinium salts.
Figure 2: Synthesis of various N-fluoropyridinium salts. Note: athis yield was the one by the improved method...
Scheme 11: Fluorination power order of N-fluoropyridinium salts.
Scheme 12: Fluorinations with N-F salts 5-4.
Scheme 13: Fluorination of Corey lactone 5-7 with N-F-bis(methoxymethyl) salt 5-4l.
Scheme 14: Fluorination with NFPy.
Scheme 15: Synthesis of the N-F reagent, N-fluoroquinuclidinium fluoride (6-1).
Scheme 16: Fluorinations achieved with N-F fluoride 6-1.
Scheme 17: Synthesis of N-F imides 7-1a–g.
Scheme 18: Fluorination with (CF3SO2)2NF, 7-1a.
Scheme 19: Fluorination reactions of various substrates with 7-1a.
Scheme 20: Synthesis of N-F triflate 8-1.
Scheme 21: Synthesis of chiral N-fluoro sultams 9-1 and 9-2.
Scheme 22: Fluorination with chiral N-fluoro sultams 9-1 and 9-2.
Scheme 23: Synthesis of saccharin-derived N-fluorosultam 10-2.
Scheme 24: Fluorination with N-fluorosultam 10-2.
Scheme 25: Synthesis of N-F reagent 11-2.
Scheme 26: Fluorination with N-F reagent 11-2.
Scheme 27: Synthesis and reaction of N-fluorolactams 12-1.
Scheme 28: Synthesis of NFOBS 13-2.
Scheme 29: Fluorination with NFOBS 13-2.
Scheme 30: Synthesis of NFSI (14-2).
Scheme 31: Fluorination with NFSI 14-2.
Scheme 32: Synthesis of N-fluorosaccharin (15-1) and N-fluorophthalimide (15-2).
Scheme 33: Synthesis of N-F salts 16-3.
Scheme 34: Fluorination with N-F salts 16-3.
Figure 3: Monofluorination with Selectfluor (16-3a).
Figure 4: Difluorination with Selectfluor (16-3a).
Scheme 35: Transfer fluorination of Selectfluor (16-3a).
Scheme 36: Fluorination of substrates with Selectfluor (16-3a).
Scheme 37: Synthesis of chiral N-fluoro-sultam 17-2.
Scheme 38: Asymmetric fluorination with chiral 17-2.
Figure 5: Synthesis of Zwitterionic N-fluoropyridinium salts 18-2a–h.
Scheme 39: Fluorinating power order of zwitterionic N-fluoropyridinium salts.
Scheme 40: Fluorination with zwitterionic 18-2.
Scheme 41: Activation of salt 18-2h with TfOH.
Scheme 42: Synthesis of NFTh, 19-2.
Scheme 43: Fluorination with NFTh, 19-2.
Scheme 44: Synthesis of 3-fluorobenzo-1,2,3-oxathiazin-4-one 2,2-dioxide (20-2).
Scheme 45: Fluorination with 20-2.
Scheme 46: Synthesis of N-F amide 21-3.
Scheme 47: Fluorination with N-F amide 21-2.
Scheme 48: Synthesis of N,N’-difluorodiazoniabicyclo[2.2.2]octane salts 22-1.
Scheme 49: One-pot synthesis of N,N’-difluoro-1,4-diazoniabicyclo[2.2.2]octane bistetrafluoroborate salt (22-1d...
Figure 6: Fluorination of anisole with 22-1a, d, e.
Scheme 50: Fluorination with N,N’-diF bisBF4 22-1d.
Scheme 51: Synthesis of bis-N-F reagents 23-1–5.
Scheme 52: Fluorination with 23-2, 4, 5.
Figure 7: Synthesis of N,N’-difluorobipyridinium salts 24-2.
Figure 8: Controlled fluorination of N,N’-diF 24-2.
Scheme 53: Fluorinating power of N,N’-diF salts 24-2 and N-F salt 5-4a.
Scheme 54: Fluorination reactions with SynfluorTM (24-2b).
Scheme 55: Additional fluorination reactions with SynfluorTM (24-2b).
Scheme 56: Synthesis of N-F 25-1.
Scheme 57: Fluorination of polycyclic aromatics with 25-1.
Scheme 58: Synthesis of 26-1 and dimethyl analog 26-2.
Scheme 59: Fluorination with reagents 26-1, 26-2, 1-1, and 26-3.
Scheme 60: Synthesis of N-F reagent 27-2.
Scheme 61: Synthesis of chiral N-F reagents 27-6.
Scheme 62: Synthesis of chiral N-F 27-7–9.
Scheme 63: Asymmetric fluorination with 27-6.
Scheme 64: Synthesis of chiral N-F reagents 28-3.
Scheme 65: Asymmetric fluorination with 28-3.
Scheme 66: Synthesis of chiral N-F reagents 28-7.
Figure 9: Asymmetric fluorination with 28-7.
Scheme 67: In situ formation of N-fluorinated cinchona alkaloids with SelectfluorTM.
Scheme 68: Asymmetric fluorination with N-F alkaloids formed in situ.
Scheme 69: Synthesis of N-fluorocinchona alkaloids with Selectfluor.
Scheme 70: Asymmetric fluorination with 30-1–4.
Scheme 71: Transfer fluorination from various N-F reagents.
Figure 10: Asymmetric fluorination of silyl enol ethers.
Scheme 72: Synthesis of N-fluoro salt 32-2.
Scheme 73: Reactivity of N-fluorotriazinium salt 32-2.
Scheme 74: Synthesis of bulky N-fluorobenzenesulfonimide NFBSI 33-3.
Scheme 75: Comparison of NFSI and NFBSI.
Scheme 76: Synthesis of p-substituted N-fluorobenzenesulfonimides 34-3.
Figure 11: Asymmetric fluorination with 34-3 and a chiral catalyst 34-4.
Scheme 77: 1,4-Fluoroamination with Selecfluor and a chiral catalyst.
Figure 12: Asymmetric fluoroamination with 35-5a, b.
Scheme 78: Synthesis of Selectfluor analogs 35-5a, b.
Scheme 79: Synthesis of chiral dicationic DABCO-based N-F reagents 36-5.
Scheme 80: Asymmetric fluorocyclization with chiral 36-5b.
Scheme 81: Synthesis of chiral 37-2a,b.
Scheme 82: Asymmetric fluorination with chiral 37-2a,b.
Scheme 83: Asymmetric fluorination with chiral 37-2b.
Scheme 84: Reaction of indene with chiral 37-2a,b.
Scheme 85: Synthesis of Me-NFSI, 38-2.
Scheme 86: Fluorination of active methine compounds with Me-NFSI.
Scheme 87: Fluorination of malonates with Me-NFSI.
Scheme 88: Fluorination of keto esters with Me-NFSI.
Scheme 89: Synthesis of N-F 39-3 derived from the ethylene-bridged Tröger’s base.
Scheme 90: Fluorine transfer from N-F 39-3.
Scheme 91: Fluorination with N-F 39-3.
Scheme 92: Synthesis of SelectfluorCN.
Scheme 93: Bistrifluoromethoxylation of alkenes using SelectfluorCN.
Figure 13: Synthesis of NFAS 41-2.
Scheme 94: Radical fluorination with different N-F reagents.
Scheme 95: Radical fluorination of alkenes with NFAS 41-2.
Scheme 96: Radical fluorination of alkenes with NFAS 41-2f.
Scheme 97: Decarboxylative fluorination with NFAS 41-2a,f.
Scheme 98: Fluorine plus detachment (FPD).
Figure 14: FPD values of representative N-F reagents in CH2Cl2 and CH3CN (in parentheses). Adapted with permis...
Scheme 99: N-F homolytic bond dissociation energy (BDE).
Figure 15: BDE values of representative N-F reagents in CH3CN. Adapted with permission from ref. [127]. Copyright 2...
Figure 16: Quantitative reactivity scale for popular N-F reagents. Adapted with permission from ref. [138], publish...
Scheme 100: SET and SN2 mechanisms.
Scheme 101: Radical clock reactions.
Scheme 102: Reaction of potassium enolate of citronellic ester with N-F reagents, 10-1, NFSI, and 8-1.
Scheme 103: Reaction of compound IV with Selectfluor (OTf) and NFSI.
Scheme 104: Reaction of TEMPO with Selecfluor.
Beilstein J. Org. Chem. 2021, 17, 1565–1590, doi:10.3762/bjoc.17.112
Graphical Abstract
Figure 1: Some examples of natural products and drugs containing quaternary carbon centers.
Scheme 1: Simplified mechanism for olefin hydrofunctionalization using an electrophilic transition metal as a...
Scheme 2: Selected examples of quaternary carbon centers formed by the intramolecular hydroalkylation of β-di...
Scheme 3: Control experiments and the proposed mechanism for the Pd(II)-catalyzed intermolecular hydroalkylat...
Scheme 4: Intermolecular olefin hydroalkylation of less reactive ketones under Pd(II) catalysis using HCl as ...
Scheme 5: A) Selected examples of Pd(II)-mediated quaternary carbon center synthesis by intermolecular hydroa...
Scheme 6: Selected examples of quaternary carbon center synthesis by gold(III) catalysis. This is the first r...
Scheme 7: Selected examples of inter- (A) and intramolecular (B) olefin hydroalkylations promoted by a silver...
Scheme 8: A) Intermolecular hydroalkylation of N-alkenyl β-ketoamides under Au(I) catalysis in the synthesis ...
Scheme 9: Asymmetric pyrrolidine synthesis through intramolecular hydroalkylation of α-substituted N-alkenyl ...
Scheme 10: Proposed mechanism for the chiral gold(I) complex promotion of the intermolecular olefin hydroalkyl...
Scheme 11: Selected examples of carbon quaternary center synthesis by gold and evidence of catalytic system pa...
Scheme 12: Synthesis of a spiro compound via an aza-Michael addition/olefin hydroalkylation cascade promoted b...
Scheme 13: A selected example of quaternary carbon center synthesis using an Fe(III) salt as a catalyst for th...
Scheme 14: Intermolecular hydroalkylation catalyzed by a cationic iridium complex (Fuji (2019) [47]).
Scheme 15: Generic example of an olefin hydrofunctionalization via MHAT (Shenvi (2016) [51]).
Scheme 16: The first examples of olefin hydrofunctionalization run under neutral conditions (Mukaiyama (1989) [56]...
Scheme 17: A) Aryl olefin dimerization catalyzed by vitamin B12 and triggered by HAT. B) Control experiment to...
Scheme 18: Generic example of MHAT diolefin cycloisomerization and possible competitive pathways. Shenvi (2014...
Scheme 19: Selected examples of the MHAT-promoted cycloisomerization reaction of unactivated olefins leading t...
Scheme 20: Regioselective carbocyclizations promoted by an MHAT process (Norton (2008) [76]).
Scheme 21: Selected examples of quaternary carbon centers synthetized via intra- (A) and intermolecular (B) MH...
Scheme 22: A) Proposed mechanism for the Fe(III)/PhSiH3-promoted radical conjugate addition between olefins an...
Scheme 23: Examples of cascade reactions triggered by HAT for the construction of trans-decalin backbone uniti...
Scheme 24: A) Selected examples of the MHAT-promoted radical conjugate addition between olefins and p-quinone ...
Scheme 25: A) MHAT triggered radical conjugate addition/E1cB/lactonization (in some cases) cascade between ole...
Scheme 26: A) Spirocyclization promoted by Fe(III) hydroalkylation of unactivated olefins. B) Simplified mecha...
Scheme 27: A) Selected examples of the construction of a carbon quaternary center by the MHAT-triggered radica...
Scheme 28: Hydromethylation of unactivated olefins under iron-mediated MHAT (Baran (2015) [95]).
Scheme 29: The hydroalkylation of unactivated olefins via iron-mediated reductive coupling with hydrazones (Br...
Scheme 30: Selected examples of the Co(II)-catalyzed bicyclization of dialkenylarenes through the olefin hydro...
Scheme 31: Proposed mechanism for the bicyclization of dialkenylarenes triggered by a MHAT process (Vanderwal ...
Scheme 32: Enantioconvergent cross-coupling between olefins and tertiary halides (Fu (2018) [108]).
Scheme 33: Proposed mechanism for the Ni-catalyzed cross-coupling reaction between olefins and tertiary halide...
Scheme 34: Proposed catalytic cycles for a MHAT/Ni cross-coupling reaction between olefins and halides (Shenvi...
Scheme 35: Selected examples of the hydroalkylation of olefins by a dual catalytic Mn/Ni system (Shenvi (2019) ...
Scheme 36: A) Selected examples of quaternary carbon center synthesis by reductive atom transfer; TBC: 4-tert-...
Scheme 37: A) Selected examples of quaternary carbon centers synthetized by radical addition to unactivated ol...
Scheme 38: A) Selected examples of organophotocatalysis-mediated radical polyene cyclization via a PET process...
Scheme 39: A) Sc(OTf)3-mediated carbocyclization approach for the synthesis of vicinal quaternary carbon cente...
Scheme 40: Scope of the Lewis acid-catalyzed methallylation of electron-rich styrenes. Method A: B(C6F5)3 (5.0...
Scheme 41: The proposed mechanism for styrene methallylation (Oestreich (2019) [123]).
Beilstein J. Org. Chem. 2021, 17, 932–963, doi:10.3762/bjoc.17.77
Graphical Abstract
Scheme 1: General strategy for the synthesis of THPs.
Scheme 2: Developments towards the Prins cyclization.
Scheme 3: General stereochemical outcome of the Prins cyclization.
Scheme 4: Regioselectivity in the Prins cyclization.
Scheme 5: Mechanism of the oxonia-Cope reaction in the Prins cyclization.
Scheme 6: Cyclization of electron-deficient enantioenriched alcohol 27.
Scheme 7: Partial racemization through 2-oxonia-Cope allyl transfer.
Scheme 8: Partial racemization by reversible 2-oxonia-Cope rearrangement.
Scheme 9: Rychnovsky modification of the Prins cyclization.
Scheme 10: Synthesis of (−)-centrolobine and the C22–C26 unit of phorboxazole A.
Scheme 11: Axially selective Prins cyclization by Rychnovsky et al.
Scheme 12: Mechanism for the axially selectivity Prins cyclization.
Scheme 13: Mukaiyama aldol–Prins cyclization reaction.
Scheme 14: Application of the aldol–Prins reaction.
Scheme 15: Hart and Bennet's acid-promoted Prins cyclization.
Scheme 16: Tetrahydropyran core of polycarvernoside A as well as (−)-clavoslide A and D.
Scheme 17: Scheidt and co-workers’ route to tetrahydropyran-4-one.
Scheme 18: Mechanism for the Lewis acid-catalyzed synthesis of tetrahydropyran-4-one.
Scheme 19: Hoveyda and co-workers’ strategy for 2,6-disubstituted 4-methylenetetrahydropyran.
Scheme 20: Funk and Cossey’s ene-carbamates strategy.
Scheme 21: Yadav and Kumar’s cyclopropane strategy for THP synthesis.
Scheme 22: 2-Arylcylopropylmethanolin in centrolobine synthesis.
Scheme 23: Yadav and co-workers’ strategy for the synthesis of THP.
Scheme 24: Yadav and co-workers’ Prins–Ritter reaction sequence for 4-amidotetrahydropyran.
Scheme 25: Yadav and co-workers’ strategy to prelactones B, C, and V.
Scheme 26: Yadav and co-workers’ strategy for the synthesis of (±)-centrolobine.
Scheme 27: Loh and co-workers’ strategy for the synthesis of zampanolide and dactylolide.
Scheme 28: Loh and Chan’s strategy for THP synthesis.
Scheme 29: Prins cyclization of cyclohexanecarboxaldehyde.
Scheme 30: Prins cyclization of methyl ricinoleate (127) and benzaldehyde (88).
Scheme 31: AlCl3-catalyzed cyclization of homoallylic alcohol 129 and aldehyde 130.
Scheme 32: Martín and co-workers’ stereoselective approach for the synthesis of highly substituted tetrahydrop...
Scheme 33: Ene-IMSC strategy by Marko and Leroy for the synthesis of tetrahydropyran.
Scheme 34: Marko and Leroy’s strategy for the synthesis of tetrahydropyrans 146.
Scheme 35: Sakurai dimerization/macrolactonization reaction for the synthesis of cyanolide A.
Scheme 36: Hoye and Hu’s synthesis of (−)-dactyloide by intramolecular Sakurai cyclization.
Scheme 37: Minehan and co-workers’ strategy for the synthesis of THPs 157.
Scheme 38: Yu and co-workers’ allylic transfer strategy for the construction of tetrahydropyran 161.
Scheme 39: Reactivity enhancement in intramolecular Prins cyclization.
Scheme 40: Floreancig and co-workers’ Prins cyclization strategy to (+)-dactyloide.
Scheme 41: Panek and Huang’s DHP synthesis from crotylsilanes: a general strategy.
Scheme 42: Panek and Huang’s DHP synthesis from syn-crotylsilanes.
Scheme 43: Panek and Huang’s DHP synthesis from anti-crotylsilanes.
Scheme 44: Roush and co-workers’ [4 + 2]-annulation strategy for DHP synthesis [82].
Scheme 45: TMSOTf-promoted annulation reaction.
Scheme 46: Dobb and co-workers’ synthesis of DHP.
Scheme 47: BiBr3-promoted tandem silyl-Prins reaction by Hinkle et al.
Scheme 48: Substrate scope of Hinkle and co-workers’ strategy.
Scheme 49: Cho and co-workers’ strategy for 2,6 disubstituted 3,4-dimethylene-THP.
Scheme 50: Furman and co-workers’ THP synthesis from propargylsilane.
Scheme 51: THP synthesis from silyl enol ethers.
Scheme 52: Rychnovsky and co-workers’ strategy for THP synthesis from hydroxy-substituted silyl enol ethers.
Scheme 53: Li and co-workers’ germinal bissilyl Prins cyclization strategy to (−)-exiguolide.
Scheme 54: Xu and co-workers’ hydroiodination strategy for THP.
Scheme 55: Wang and co-workers’ strategy for tetrahydropyran synthesis.
Scheme 56: FeCl3-catalyzed synthesis of DHP from alkynylsilane alcohol.
Scheme 57: Martín, Padrón, and co-workers’ proposed mechanism of alkynylsilane Prins cyclization for the synth...
Scheme 58: Marko and co-workers’ synthesis of 2,6-anti-configured tetrahydropyran.
Scheme 59: Loh and co-workers’ strategy for 2,6-syn-tetrahydropyrans.
Scheme 60: Loh and co-workers’ strategy for anti-THP synthesis.
Scheme 61: Cha and co-workers’ strategy for trans-2,6-tetrahydropyran.
Scheme 62: Mechanism proposed by Cha et al.
Scheme 63: TiCl4-mediated cyclization to trans-THP.
Scheme 64: Feng and co-workers’ FeCl3-catalyzed Prins cyclization strategy to 4-hydroxy-substituted THP.
Scheme 65: Selectivity profile of the Prins cyclization under participation of an iron ligand.
Scheme 66: Sequential reactions involving Prins cyclization.
Scheme 67: Banerjee and co-workers’ strategy of Prins cyclization from cyclopropane carbaldehydes and propargy...
Scheme 68: Mullen and Gagné's (R)-[(tolBINAP)Pt(NC6F5)2][SbF6]2-catalyzed asymmetric Prins cyclization strateg...
Scheme 69: Yu and co-workers’ DDQ-catalyzed asymmetric Prins cyclization strategy to trisubstituted THPs.
Scheme 70: Lalli and Weghe’s chiral-Brønsted-acid- and achiral-Lewis-acid-promoted asymmetric Prins cyclizatio...
Scheme 71: List and co-workers’ iIDP Brønsted acid-promoted asymmetric Prins cyclization strategy.
Scheme 72: Zhou and co-workers’ strategy for chiral phosphoric acid (CPA)-catalyzed cascade Prins cyclization.
Scheme 73: List and co-workers’ approach for asymmetric Prins cyclization using chiral imidodiphosphoric acid ...