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Search for "electron withdrawing group (EWG)" in Full Text gives 19 result(s) in Beilstein Journal of Organic Chemistry.
Giese-type alkylation of dehydroalanine derivatives via silane-mediated alkyl bromide activation
- Perry van der Heide,
- Michele Retini,
- Fabiola Fanini,
- Giovanni Piersanti,
- Francesco Secci,
- Daniele Mazzarella,
- Timothy Noël and
- Alberto Luridiana
Beilstein J. Org. Chem. 2024, 20, 3274–3280, doi:10.3762/bjoc.20.271
- slight increase in chemical yield. Giese reaction: Radical addition on olefins with an electron-withdrawing group (EWG) followed by a HAT or SET and protonation; halogen-atom transfer: (a) tin-mediated XAT, (b) XAT initiated by a photocatalyst (PC) and mediated by boranes (B), silanes (Si) or alkylamines
Graphical Abstract
Figure 1: Giese reaction: Radical addition on olefins with an electron-withdrawing group (EWG) followed by a ...
Figure 2: Alkyl bromide and Dha derivative scope. Reaction conditions: Dha derivative (0.5 mmol), alkyl bromi...
Figure 3: Scaled-up reaction. Reaction conditions: Dha derivative (2.2 mmol), alkyl bromide (5.4 mmol), tris(...
Heterocycle-guided synthesis of m-hetarylanilines via three-component benzannulation
- Andrey R. Galeev,
- Maksim V. Dmitriev,
- Alexander S. Novikov and
- Andrey N. Maslivets
Beilstein J. Org. Chem. 2024, 20, 2208–2216, doi:10.3762/bjoc.20.188
- interrupted Kröhnke reaction (Scheme 1B) [51][52]. The main step of this process is an intermolecular cyclization of the formed 1,5-diketone followed by aromatization. Previously we have shown that 1,3-diketones bearing an electron-withdrawing group (EWG) adjacent to one of the carbonyls readily react with in
Graphical Abstract
Figure 1: The meta-hetarylaniline motif in bioactive molecules.
Scheme 1: Strategies to access meta-substituted anilines.
Figure 2: The model series of synthesized 1,3-diketones and corresponding calculated Hammett constants of het...
Scheme 2: Synthesis of meta-substituted anilines from 1,2,4-oxadiazol-5-yl substituted 1,3-diketone 1a. Condi...
Scheme 3: Synthesis of meta-substituted anilines from 1,3,4-oxadiazol-substituted 1,3-diketone 1b. Conditions...
Scheme 4: Synthesis of meta-substituted anilines from benzothiazol-2-yl and oxazol-2-yl-substituted 1,3-diket...
Scheme 5: Synthesis of meta-substituted aniline from isoxazol-3-yl-substituted 1,3-diketone 1e. Conditions B: ...
Figure 3: Scope of functionalized amines in three-component condensation. Conditions A: 1a,b,h,i (0.2–0.5 mmo...
Scheme 6: Proposed mechanism for the formation of meta-substituted anilines 3 via three-component benzannulat...
Decarboxylative 1,3-dipolar cycloaddition of amino acids for the synthesis of heterocyclic compounds
- Xiaofeng Zhang,
- Xiaoming Ma and
- Wei Zhang
Beilstein J. Org. Chem. 2023, 19, 1677–1693, doi:10.3762/bjoc.19.123
- classified as stabilized (A1–A4) which contain an electron-withdrawing group (EWG), semi-stabilized (B1–B4) which have an aryl (Ar) substituent, and non-stabilized (C1 and C2) which have neither an Ar group nor an EWG on the α-carbon atoms. The routes to access AMYs of different classes are shown in Scheme 1
Graphical Abstract
Figure 1: Classification of AMYs.
Scheme 1: Aminoester- and amino acid-based AMYs for single and double [3+2] cycloadditions.
Scheme 2: Formation of semi-stabilized AMYs B1 from pyrrolidines.
Scheme 3: Cyclic amine-based AMYs A3 and B1 for [3 + 2] cycloadditions.
Scheme 4: Proposed double cycloaddition reactions involving semi-stabilized AMYs.
Scheme 5: [3 + 2] Cycloaddition for the synthesis of trifluoromethylated pyrrolidines 9.
Figure 2: Biologically interesting pyrrolizidines.
Scheme 6: Double cycloadditions with glycine for the synthesis of products 10 (dr > 9:1).
Scheme 7: Double cycloadditions with α-substituted amino acids leading to products 11 (≈8.5:1 dr).
Scheme 8: Stereochemistry for the formation of products 10 or 11.
Scheme 9: One-pot and stepwise double cycloadditions. Conditions: i) MeCN (0.02 M), 90 °C, 6 h; ii) then AcOH...
Figure 3: Biologically interesting spirooxindole-pyrrolizidines.
Scheme 10: Double cycloadditions for the synthesis of bis[spirooxindole-pyrrolizidine]s.
Scheme 11: Mechanism for the diastereoselective synthesis of bis[spirooxindole-pyrrolizidine]s.
Scheme 12: Stepwise synthesis of triazolobenzodiazepine 21a.
Scheme 13: One-pot synthesis of triazolobenzodiazepines.
Figure 4: Bioactive triazolobenzodiazepine derivatives.
Scheme 14: One-pot synthesis of tetrahydropyrroloquinazolines.
Scheme 15: One-pot synthesis of tetrahydropyrrolobenzodiazepines.
Figure 5: Bioactive pyrroloquinazolines and pyrrolobenzodiazepines.
Scheme 16: Stepwise synthesis of pyrrolo[2,1-a]isoquinolines.
Figure 6: Bioactive pyrrolo[2,1-a]isoquinolines and hexahydropyrrolo[2,1-a]isoquinolines.
Figure 7: Bioactive tetrahydropyrrolothiazoles.
Scheme 17: Pseudo-four-component reaction for the synthesis of tetrahydropyrrolothiazoles 29 and 30 (>4:1 dr).
Scheme 18: One-pot two-step synthesis of spirooxindole-pyrrolothiazoles 31 (>4:1 dr).
Recent advances in Cu-catalyzed C(sp3)–Si and C(sp3)–B bond formation
- Balaram S. Takale,
- Ruchita R. Thakore,
- Elham Etemadi-Davan and
- Bruce H. Lipshutz
Beilstein J. Org. Chem. 2020, 16, 691–737, doi:10.3762/bjoc.16.67
- (Scheme 4). It should be mentioned that secondary triflates or halides are not suitable for this transformation, since they lead to products resulting from fast β-elimination. Considering this limitation, they designed alkyl triflates stabilized by a strong electron-withdrawing group (EWG) directly
Graphical Abstract
Scheme 1: Pharmaceuticals possessing a silicon or boron atom.
Scheme 2: The first Cu-catalyzed C(sp3)–Si bond formation.
Scheme 3: Conversion of benzylic phosphate 6 to the corresponding silane.
Scheme 4: Conversion of alkyl triflates to alkylsilanes.
Scheme 5: Conversion of secondary alkyl triflates to alkylsilanes.
Scheme 6: Conversion of alkyl iodides to alkylsilanes.
Scheme 7: Trapping of intermediate radical through cascade reaction.
Scheme 8: Radical pathway for conversion of alkyl iodides to alkylsilanes.
Scheme 9: Conversion of alkyl ester of N-hydroxyphthalimide to alkylsilanes.
Scheme 10: Conversion of gem-dibromides to bis-silylalkanes.
Scheme 11: Conversion of imines to α-silylated amines (A) and the reaction pathway (B).
Scheme 12: Conversion of N-tosylimines to α-silylated amines.
Scheme 13: Screening of diamine ligands.
Scheme 14: Conversion of N-tert-butylsulfonylimines to α-silylated amines.
Scheme 15: Conversion of aldimines to nonracemic α-silylated amines.
Scheme 16: Conversion of N-tosylimines to α-silylated amines.
Scheme 17: Reaction pathway [A] and conversion of aldehydes to α-silylated alcohols [B].
Scheme 18: Conversion of aldehydes to benzhydryl silyl ethers.
Scheme 19: Conversion of ketones to 1,2-diols (A) and conversion of imines to 1,2-amino alcohols (B).
Scheme 20: Ligand screening (A) and conversion of aldehydes to α-silylated alcohols (B).
Scheme 21: Conversion of aldehydes to α-silylated alcohols.
Scheme 22: 1,4-Additions to α,β-unsaturated ketones.
Scheme 23: 1,4-Additions to unsaturated ketones to give β-silylated derivatives.
Scheme 24: Additions onto α,β-unsaturated lactones to give β-silylated lactones.
Scheme 25: Conversion of α,β-unsaturated to β-silylated lactams.
Scheme 26: Conversion of N-arylacrylamides to silylated oxindoles.
Scheme 27: Conversion of α,β-unsaturated carbonyl compounds to silylated tert-butylperoxides.
Scheme 28: Catalytic cycle for Cu(I) catalyzed α,β-unsaturated compounds.
Scheme 29: Conversion of p-quinone methides to benzylic silanes.
Scheme 30: Conversion of α,β-unsaturated ketimines to regio- and stereocontrolled allylic silanes.
Scheme 31: Conversion of α,β-unsaturated ketimines to enantioenriched allylic silanes.
Scheme 32: Regioselective conversion of dienedioates to allylic silanes.
Scheme 33: Conversion of alkenyl-substituted azaarenes to β-silylated adducts.
Scheme 34: Conversion of conjugated benzoxazoles to enantioenriched β-silylated adducts.
Scheme 35: Conversion of α,β-unsaturated carbonyl indoles to α-silylated N-alkylated indoles.
Scheme 36: Conversion of β-amidoacrylates to α-aminosilanes.
Scheme 37: Conversion of α,β-unsaturated ketones to enantioenriched β-silylated ketones, nitriles, and nitro d...
Scheme 38: Regio-divergent silacarboxylation of allenes.
Scheme 39: Silylation of diazocarbonyl compounds, (A) asymmetric and (B) racemic.
Scheme 40: Enantioselective hydrosilylation of alkenes.
Scheme 41: Conversion of 3-acylindoles to indolino-silanes.
Scheme 42: Proposed mechanism for the silylation of 3-acylindoles.
Scheme 43: Silyation of N-chlorosulfonamides.
Scheme 44: Conversion of acyl silanes to α-silyl alcohols.
Scheme 45: Conversion of N-tosylaziridines to β-silylated N-tosylamines.
Scheme 46: Conversion of N-tosylaziridines to silylated N-tosylamines.
Scheme 47: Conversion of 3,3-disubstituted cyclopropenes to silylated cyclopropanes.
Scheme 48: Conversion of conjugated enynes to 1,3-bis(silyl)propenes.
Scheme 49: Proposed sequence for the Cu-catalyzed borylation of substituted alkenes.
Scheme 50: Cu-catalyzed synthesis of nonracemic allylic boronates.
Scheme 51: Cu–NHC catalyzed synthesis of α-substituted allylboronates.
Scheme 52: Synthesis of α-chiral (γ-alkoxyallyl)boronates.
Scheme 53: Cu-mediated formation of nonracemic cis- or trans- 2-substituted cyclopropylboronates.
Scheme 54: Cu-catalyzed synthesis of γ,γ-gem-difluoroallylboronates.
Scheme 55: Cu-catalyzed hydrofunctionalization of internal alkenes and vinylarenes.
Scheme 56: Cu-catalyzed Markovnikov and anti-Markovnikov borylation of alkenes.
Scheme 57: Cu-catalyzed borylation/ortho-cyanation/Cope rearrangement.
Scheme 58: Borylfluoromethylation of alkenes.
Scheme 59: Cu-catalyzed synthesis of tertiary nonracemic alcohols.
Scheme 60: Synthesis of densely functionalized and synthetically versatile 1,2- or 4,3-borocyanated 1,3-butadi...
Scheme 61: Cu-catalyzed trifunctionalization of allenes.
Scheme 62: Cu-catalyzed selective arylborylation of arenes.
Scheme 63: Asymmetric borylative coupling between styrenes and imines.
Scheme 64: Regio-divergent aminoboration of unactivated terminal alkenes.
Scheme 65: Cu-catalyzed 1,4-borylation of α,β-unsaturated ketones.
Scheme 66: Cu-catalyzed protodeboronation of α,β-unsaturated ketones.
Scheme 67: Cu-catalyzed β-borylation of α,β-unsaturated imines.
Scheme 68: Cu-catalyzed synthesis of β-trifluoroborato carbonyl compounds.
Scheme 69: Asymmetric 1,4-borylation of α,β-unsaturated carbonyl compounds.
Scheme 70: Cu-catalyzed ACB and ACA reactions of α,β-unsaturated 2-acyl-N-methylimidazoles.
Scheme 71: Cu-catalyzed diborylation of aldehydes.
Scheme 72: Umpolung pathway for chiral, nonracemic tertiary alcohol synthesis (top) and proposed mechanism for...
Scheme 73: Cu-catalyzed synthesis of α-hydroxyboronates.
Scheme 74: Cu-catalyzed borylation of ketones.
Scheme 75: Cu-catalyzed borylation of unactivated alkyl halides.
Scheme 76: Cu-catalyzed borylation of allylic difluorides.
Scheme 77: Cu-catalyzed borylation of cyclic and acyclic alkyl halides.
Scheme 78: Cu-catalyzed borylation of unactivated alkyl chlorides and bromides.
Scheme 79: Cu-catalyzed decarboxylative borylation of carboxylic acids.
Scheme 80: Cu-catalyzed borylation of benzylic, allylic, and propargylic alcohols.
Copper-catalyzed enantioselective conjugate addition of organometallic reagents to challenging Michael acceptors
- Delphine Pichon,
- Jennifer Morvan,
- Christophe Crévisy and
- Marc Mauduit
Beilstein J. Org. Chem. 2020, 16, 212–232, doi:10.3762/bjoc.16.24
- cyclic or aliphatic polyenic substrates [7][8][9]. Furthermore, Cu ECA transformations were also successfully applied to the synthesis of natural products [10]. Nevertheless, it is worth to underline that the choice of the electron-withdrawing group (EWG) on the Michael substrates appears not so simple
Graphical Abstract
Scheme 1: Competitive side reactions in the Cu ECA of organometallic reagents to α,β-unsaturated aldehydes.
Scheme 2: Cu-catalyzed ECA of α,β-unsaturated aldehydes with phosphoramidite- (a) and phosphine-based ligands...
Scheme 3: One-pot Cu-catalyzed ECA/organocatalyzed α-substitution of enals.
Scheme 4: Combination of copper and amino catalysis for enantioselective β-functionalizations of enals.
Scheme 5: Optimized conditions for the Cu ECAs of R2Zn, RMgBr, and AlMe3 with α,β-unsaturated aldehydes.
Scheme 6: CuECA of Grignard reagents to α,β-unsaturated thioesters and their application in the asymmetric to...
Scheme 7: Improved Cu ECA of Grignard reagents to α,β-unsaturated thioesters, and their application in the as...
Scheme 8: Catalytic enantioselective synthesis of vicinal dialkyl arrays via Cu ECA of Grignard reagents to γ...
Scheme 9: 1,6-Cu ECA of MeMgBr to α,β,γ,δ-bisunsaturated thioesters: an iterative approach to deoxypropionate...
Scheme 10: Tandem Cu ECA/intramolecular enolate trapping involving 4-chloro-α,β-unsaturated thioester 22.
Scheme 11: Cu ECA of Grignard reagents to 3-boronyl α,β-unsaturated thioesters.
Scheme 12: Cu ECA of alkylzirconium reagents to α,β-unsaturated thioesters.
Scheme 13: Conversion of acylimidazoles into aldehydes, ketones, acids, esters, amides, and amines.
Scheme 14: Cu ECA of dimethyl malonate to α,β-unsaturated acylimidazole 31 with triazacyclophane-based ligand ...
Scheme 15: Cu/L13-catalyzed ECA of alkylboranes to α,β-unsaturated acylimidazoles.
Scheme 16: Cu/hydroxyalkyl-NHC-catalyzed ECA of dimethylzinc to α,β-unsaturated acylimidazoles.
Scheme 17: Stereocontrolled synthesis of 3,5,7-all-syn and anti,anti-stereotriads via iterative Cu ECAs.
Scheme 18: Stereocontrolled synthesis of anti,syn- and anti,anti-3,5,7-(Me,OR,Me) units via iterative Cu ECA/B...
Scheme 19: Cu-catalyzed ECA of dialkylzinc reagents to α,β-unsaturated N-acyloxazolidinones.
Scheme 20: Cu/phosphoramidite L16-catalyzed ECA of dialkylzincs to α,β-unsaturated N-acyl-2-pyrrolidinones.
Scheme 21: Cu/(R,S)-Josiphos (L9)-catalyzed ECA of Grignard reagents to α,β-unsaturated amides.
Scheme 22: Cu/Josiphos (L9)-catalyzed ECA of Grignard reagents to polyunsaturated amides.
Scheme 23: Cu-catalyzed ECA of trimethylaluminium to N-acylpyrrole derivatives.
Recent advances in transition-metal-catalyzed incorporation of fluorine-containing groups
- Xiaowei Li,
- Xiaolin Shi,
- Xiangqian Li and
- Dayong Shi
Beilstein J. Org. Chem. 2019, 15, 2213–2270, doi:10.3762/bjoc.15.218
- substrates with or without an electron-withdrawing group (EWG) in the presence of Selectfluor (Scheme 39). Notably, an EWG beta to the benzylic position is efficient for an excellent selectivity of the benzylic fluorination. Moreover, Gouverneur and co-workers [87] established the decarboxylative
Graphical Abstract
Scheme 1: The main three strategies of fluorination: nucleophilic, electrophilic and radical fluorination.
Scheme 2: Doyle’s Pd-catalyzed fluorination of allylic chlorides.
Scheme 3: Allylic fluorination of 2- and 3-substituted propenyl esters.
Scheme 4: Regioselective allylic fluorination of cinnamyl phosphorothioate esters.
Scheme 5: Palladium-catalyzed aliphatic C–H fluorination reported by Doyle.
Scheme 6: Pd-catalyzed enantioselective fluorination of α-ketoesters followed by stereoselective reduction to...
Scheme 7: Pd-catalyzed C(sp3)–H fluorination of oxindoles.
Scheme 8: C–H fluorination of 8-methylquinoline derivatives with F− reagents.
Scheme 9: Fluorination of α-cyano acetates reported by van Leeuwen.
Scheme 10: The catalytic enantioselective electrophilic C–H fluorination of α-chloro-β-keto phosphonates.
Scheme 11: Fluorination of unactivated C(sp3)–H bonds directed by the bidentate PIP auxiliary.
Scheme 12: Fluorination of C(sp3)–H bonds at the β-position of carboxylic acids.
Scheme 13: Enantioselective benzylic C–H fluorination with a chiral transient directing group.
Scheme 14: Microwave-heated Pd-catalyzed fluorination of aryl alcohols.
Scheme 15: Fluorination of aryl potassium trifluoroborates.
Scheme 16: C(sp2)–F bond formation using precatalyst [L·Pd]2(cod).
Scheme 17: Pd-catalyzed fluorination of (hetero)aryl triflates and bromides.
Scheme 18: The Pd-catalyzed C–H fluorination of arenes with Selectfluor/NFSI.
Scheme 19: Pd(II)-catalyzed ortho-monofluorination protocol for benzoic acids.
Scheme 20: Pd-catalyzed C(sp2)–H bond fluorination of 2-arylbenzothiazoles.
Scheme 21: Nitrate-promoted fluorination of aromatic and olefinic C(sp2)–H bonds and proposed mechanism.
Scheme 22: Fluorination of oxalyl amide-protected benzylamine derivatives.
Scheme 23: C–H fluorination of benzaldehydes with orthanilic acids as transient directing group.
Scheme 24: Pd(II)-catalyzed aryl C–H fluorination with various directing groups.
Scheme 25: Cu-catalyzed aliphatic, allylic, and benzylic fluorination.
Scheme 26: Cu-catalyzed SN2 fluorination of primary and secondary alkyl bromides.
Scheme 27: Copper-catalyzed fluorination of alkyl triflates.
Scheme 28: Cu-catalyzed fluorination of allylic bromides and chlorides.
Scheme 29: Synthetic strategy for the fluorination of active methylene compounds.
Scheme 30: Fluorination of β-ketoesters using a tartrate-derived bidentate bisoxazoline-Cu(II) complex.
Scheme 31: Highly enantioselective fluorination of β-ketoesters and N-Boc-oxindoles.
Scheme 32: Amide group-assisted site-selective fluorination of α-bromocarbonyl compounds.
Scheme 33: Cu-mediated aryl fluorination reported by Sanford [77].
Scheme 34: Mono- or difluorination reactions of benzoic acid derivatives.
Scheme 35: Cu-catalyzed fluorination of diaryliodonium salts with KF.
Scheme 36: Copper(I)-catalyzed cross-coupling of 2-pyridylaryl bromides.
Scheme 37: AgNO3-catalyzed decarboxylative fluorination of aliphatic carboxylic acids.
Scheme 38: The Mn-catalyzed aliphatic and benzylic C–H fluorination.
Scheme 39: Iron(II)-promoted C–H fluorination of benzylic substrates.
Scheme 40: Ag-catalyzed fluorodecarboxylation of carboxylic acids.
Scheme 41: Vanadium-catalyzed C(sp3)–H fluorination.
Scheme 42: AgNO3-catalyzed radical deboronofluorination of alkylboronates and boronic acids.
Scheme 43: Selective heterobenzylic C–H fluorination with Selectfluor reported by Van Humbeck.
Scheme 44: Fe(II)-catalyzed site-selective fluorination guided by an alkoxyl radical.
Scheme 45: Fluorination of allylic trichloroacetimidates reported by Nguyen et al.
Scheme 46: Iridium-catalyzed fluorination of allylic carbonates with TBAF(t-BuOH)4.
Scheme 47: Iridium-catalyzed asymmetric fluorination of allylic trichloroacetimidates.
Scheme 48: Cobalt-catalyzed α-fluorination of β-ketoesters.
Scheme 49: Nickel-catalyzed α-fluorination of various α-chloro-β-ketoesters.
Scheme 50: Ni(II)-catalyzed enantioselective fluorination of oxindoles and β-ketoesters.
Scheme 51: Scandium(III)-catalyzed asymmetric C–H fluorination of unprotected 3-substituted oxindoles.
Scheme 52: Iron-catalyzed directed C–H fluorination.
Scheme 53: Electrophilic silver-catalyzed Ar–F bond-forming reaction from arylstannanes.
Figure 1: Nucleophilic, electrophilic and radical CF3 sources.
Scheme 54: Cu(I)-catalyzed allylic trifluoromethylation of unactivated terminal olefins.
Scheme 55: Direct copper-catalyzed trifluoromethylation of allylsilanes.
Scheme 56: Cupper-catalyzed enantioselective trifluoromethylation of five and six-membered ring β-ketoesters.
Scheme 57: Cu-catalyzed highly stereoselective trifluoromethylation of secondary propargyl sulfonates.
Scheme 58: Remote C(sp3)–H trifluoromethylation of carboxamides and sulfonamides.
Scheme 59: Trifluoromethylation of allylsilanes with photoredox catalysis.
Scheme 60: Ag-catalyzed decarboxylative trifluoromethylation of aliphatic carboxylic acids in aqueous CH3CN.
Scheme 61: Decarboxylative trifluoromethylation of aliphatic carboxylic acids via combined photoredox and copp...
Scheme 62: Palladium-catalyzed Ar–CF3 bond-forming reaction.
Scheme 63: Palladium-catalyzed trifluoromethylation of arenes with diverse heterocyclic directing groups.
Scheme 64: Pd-catalyzed trifluoromethylation of indoles as reported by Liu.
Scheme 65: Pd-catalyzed trifluoromethylation of vinyl triflates and vinyl nonaflates.
Scheme 66: Pd(II)-catalyzed ortho-trifluoromethylation of aromatic C–H bonds.
Scheme 67: Visible-light-induced Pd(OAc)2-catalyzed ortho-trifluoromethylation of acetanilides with CF3SO2Na.
Scheme 68: CuI-catalyzed trifluoromethylation of aryl- and alkenylboronic acids.
Scheme 69: Cu-catalyzed trifluoromethylation of aryl- and vinylboronic acids.
Scheme 70: Copper-catalyzed trifluoromethylation of α,β-unsaturated carboxylic acids.
Scheme 71: Formation of C(sp2)–CF3 bond catalyzed by copper(I) complex.
Scheme 72: Loh’s Cu(I)-catalyzed trifluoromethylation of enamides and electron-deficient alkenes.
Scheme 73: Copper and iron-catalyzed decarboxylative tri- and difluoromethylation.
Scheme 74: Cu-catalyzed trifluoromethylation of hydrazones developed by Bouyssi.
Scheme 75: Cu(I)-catalyzed trifluoromethylation of terminal alkenes.
Scheme 76: Cu/Ag-catalyzed decarboxylative trifluoromethylation of cinnamic acids.
Scheme 77: Copper-catalyzed direct alkenyl C–H trifluoromethylation.
Scheme 78: Copper(I/II)-catalyzed direct trifluoromethylation of styrene derivatives.
Scheme 79: Regioselective trifluoromethylation of pivalamido arenes and heteroarenes.
Scheme 80: Synthesis of trifluoromethylquinones in the presence of copper(I).
Scheme 81: Oxidative trifluoromethylation of imidazoheterocycles in ionic liquid/water.
Scheme 82: A mild and fast continuous-flow trifluoromethylation of coumarins using a CuI/CF3SO2Na/TBHP system.
Scheme 83: Copper-catalyzed oxidative trifluoromethylation of various 8-aminoquinolines.
Scheme 84: PA-directed copper-catalyzed trifluoromethylation of anilines.
Scheme 85: Trifluoromethylation of potassium vinyltrifluoroborates catalyzed by Fe(II).
Scheme 86: Alkenyl trifluoromethylation catalyzed by Ru(phen)3Cl2 as photocatalyst.
Scheme 87: Ru-catalyzed trifluoromethylation of alkenes by Akita’s group.
Scheme 88: Ir-catalyzed Cvinyl–CF3 bond formation of α,β-unsaturated carboxylic acids.
Scheme 89: Ag(I)-catalyzed denitrative trifluoromethylation of β-nitrostyrenes.
Scheme 90: Photocatalyzed direct trifluoromethylation of aryl and heteroaryl C–H bonds.
Scheme 91: Rhenium (MTO)-catalyzed direct trifluoromethylation of aromatic substrates.
Scheme 92: Trifluoromethylation of unprotected anilines under [Ir(ppy)3] catalyst.
Scheme 93: Oxidative trifluoromethylation of imidazopyridines and imidazoheterocycles.
Scheme 94: Ruthenium-catalyzed trifluoromethylation of (hetero)arenes with trifluoroacetic anhydride.
Scheme 95: Phosphovanadomolybdic acid-catalyzed direct C–H trifluoromethylation.
Scheme 96: Picolinamide-assisted ortho-trifluoromethylation of arylamines.
Scheme 97: A nickel-catalyzed C–H trifluoromethylation of free anilines.
Scheme 98: Cu-mediated trifluoromethylation of terminal alkynes reported by Qing.
Scheme 99: Huang’s C(sp)–H trifluoromethylation using Togni’s reagent.
Scheme 100: Cu-catalyzed methods for trifluoromethylation with Umemoto’s reagent.
Scheme 101: The synthesis of alkynyl-CF3 compounds in the presence of fac-[Ir(ppy)3] under visible-light irradi...
Scheme 102: Pd-catalyzed Heck reaction reported by Reutrakul.
Scheme 103: Difluoromethylation of enamides and ene-carbamates.
Scheme 104: Difluoromethylation of α,β-unsaturated carboxylic acids.
Scheme 105: Copper-catalyzed direct C(sp2)–H difluoroacetylation reported by Pannecoucke and co-workers.
Scheme 106: Difluoroalkylation of aldehyde-derived hydrazones with functionalized difluoromethyl bromides.
Scheme 107: Photoredox-catalyzed C–H difluoroalkylation of aldehyde-derived hydrazones.
Scheme 108: Synergistic ruthenium(II)-catalyzed C–H difluoromethylation reported by Ackermann.
Scheme 109: Visible-light photocatalytic decarboxylation of α,β-unsaturated carboxylic acids.
Scheme 110: Synthesis of difluorinated ketones via S-alkyl dithiocarbamates obtained from acyl chlorides and po...
Scheme 111: Synthesis of aryl and heteroaryl difluoromethylated phosphonates.
Scheme 112: Difluoroalkylation of secondary propargyl sulfonates using Cu as the catalyst.
Scheme 113: Ru(II)-mediated para-selective difluoromethylation of anilides and their derivatives.
Scheme 114: Bulky diamine ligand promoted cross-coupling of difluoroalkyl bromides.
Scheme 115: Copper-catalyzed C3–H difluoroacetylation of quinoxalinones.
Scheme 116: Copper(I) chloride-catalyzed trifluoromethylthiolation of enamines, indoles and β-ketoesters.
Scheme 117: Copper-boxmi-catalyzed asymmetric trifluoromethylthiolation of β-ketoesters.
Scheme 118: Direct Cu-catalyzed trifluoromethylthiolation of boronic acids and alkynes.
Scheme 119: Cu-catalyzed synthesis of α-trifluoromethylthio-substituted ketones.
Scheme 120: Trifluoromethylthiolation reactions promoted by diazotriflone and copper.
Scheme 121: Halide activation of N-(trifluoromethylthio)phthalimide.
Scheme 122: The visible light-promoted trifluoromethylthiolation reported by Glorius.
Scheme 123: Synthesis of α-trifluoromethylthioesters via Goossen’s approach.
Scheme 124: Photoinduced trifluoromethylthiolation of diazonium salts.
Scheme 125: Ag-mediated trifluoromethoxylation of aryl stannanes and arylboronic acids.
Scheme 126: Catalytic (hetero)aryl C–H trifluoromethoxylation under visible light.
Scheme 127: Photoinduced C–H-bond trifluromethoxylation of (hetero)arenes.
Synthesis of aryl cyclopropyl sulfides through copper-promoted S-cyclopropylation of thiophenols using cyclopropylboronic acid
- Emeline Benoit,
- Ahmed Fnaiche and
- Alexandre Gagnon
Beilstein J. Org. Chem. 2019, 15, 1162–1171, doi:10.3762/bjoc.15.113
- temperatures [18]. In addition, an electron-withdrawing group (EWG) must be present on the aryl fluoride 16 for the SNAr reaction to proceed. Aryl cyclopropyl sulfides can also be accessed by the addition of thiophenols 14 to cyclopropenes 18 (Scheme 2c) [19][20] or to exo-methylenecyclopropanes 20 (Scheme 2d
Graphical Abstract
Scheme 1: Synthetic uses of aryl cyclopropyl sulfides 1.
Scheme 2: Synthesis of aryl cyclopropyl sulfides.
Scheme 3: Substrate scope in the copper-promoted S-cyclopropylation of thiophenols 14 using cyclopropylboroni...
Scheme 4: Copper-catalyzed S-cyclopropylation of 4-tert-butylbenzenethiol (14a) using potassium cyclopropyl t...
Multicomponent reactions (MCRs): a useful access to the synthesis of benzo-fused γ-lactams
- Edorta Martínez de Marigorta,
- Jesús M. de Los Santos,
- Ana M. Ochoa de Retana,
- Javier Vicario and
- Francisco Palacios
Beilstein J. Org. Chem. 2019, 15, 1065–1085, doi:10.3762/bjoc.15.104
- chiral amines, very low diastereoselectivity was obtained, probably due to the harsh reaction conditions employed. In addition to carbonyl and carboxyl derivatives, pyridine was also used successfully as an electron-withdrawing group (EWG) in the Michael acceptor 105. A simple control experiment allowed
Graphical Abstract
Figure 1: γ-Lactam-derived structures considered in this review.
Figure 2: Alkaloids containing an isoindolinone moiety.
Figure 3: Alkaloids containing the 2-oxindole ring system.
Figure 4: Drugs and biological active compounds containing an isoindolinone moiety.
Figure 5: Drugs and biologically active compounds bearing a 2-oxindole skeleton.
Scheme 1: Three-component reaction of benzoic acid 1, amides 2 and DMSO (3).
Scheme 2: Copper-catalysed three-component reaction of 2-iodobenzoic acids 10, alkynylcarboxylic acids 11 and...
Scheme 3: Proposed mechanism for the formation of methylene isoindolinones 13.
Scheme 4: Copper-catalysed three-component reaction of 2-iodobenzamide 17, terminal alkyne 18 and pyrrole or ...
Scheme 5: Palladium-catalysed three-component reaction of ethynylbenzamides 21, secondary amines 22 and CO (23...
Scheme 6: Proposed mechanism for the formation of methyleneisoindolinones 24.
Scheme 7: Copper-catalysed three-component reaction of formyl benzoate 29, amines 2 and alkynes 18.
Scheme 8: Copper-catalysed three-component reaction of formylbenzoate 29, amines 2 and ketones 31.
Scheme 9: Non-catalysed (A) and phase-transfer catalysed (B) three-component reactions of formylbenzoic acids ...
Scheme 10: Proposed mechanism for the formation of isoindolinones 36.
Scheme 11: Three-component reaction of formylbenzoic acid 33, amines 2 and fluorinated silyl ethers 39.
Scheme 12: Three-component Ugi reaction of 2-formylbenzoic acid (33), diamines 41 and isocyanides 42.
Scheme 13: Non-catalysed (A, B) and chiral phosphoric acid promoted (C) three-component Ugi reactions of formy...
Scheme 14: Proposed mechanism for the enantioselective formation of isoindolinones 46.
Scheme 15: Three-component reaction of benzoic acids 33 or 54, amines 2 and TMSCN (52).
Scheme 16: Several variations of the three-component reaction of formylbenzoic acids 33, amines 2 and isatoic ...
Scheme 17: Proposed mechanism for the synthesis of isoindoloquinazolinones 57.
Scheme 18: Three-component reaction of isobenzofuranone 61, amines 2 and isatoic anhydrides 56.
Scheme 19: Palladium-catalysed three-component reaction of 2-aminobenzamides 59, 2-bromobenzaldehydes 62 and C...
Scheme 20: Proposed mechanism for the palladium-catalysed synthesis of isoindoloquinazolinones 57.
Scheme 21: Four-component reaction of 2-vinylbenzoic acids 67, aryldioazonium tetrafluoroborates 68, DABCO·(SO2...
Scheme 22: Plausible mechanism for the formation of isoindolinones 71.
Scheme 23: Three-component reaction of trimethylsilylaryltriflates 77, isocyanides 42 and CO2 (78).
Scheme 24: Plausible mechanism for the three-component synthesis of phthalimides 79.
Scheme 25: Copper-catalysed three-component reaction of 2-formylbenzonitriles 85, arenes 86 and diaryliodonium...
Scheme 26: Copper-catalysed three-component reaction of 2-formylbenzonitriles 85, diaryliodonium salts 87 and ...
Scheme 27: Proposed mechanism for the formation of 2,3-diarylisoindolinones 88, 89 and 92.
Scheme 28: Palladium-catalysed three-component reaction of chloroquinolinecarbaldehydes 97 with isocyanides 42...
Scheme 29: Palladium-catalysed three-component reaction of imines 99 with CO (23) and ortho-iodoarylimines 100....
Scheme 30: Palladium-catalysed three-component reaction of amines 2 with CO (23) and aryl iodide 105.
Scheme 31: Three-component reaction of 2-ethynylanilines 109, perfluoroalkyl iodides 110 and carbon monoxide (...
Scheme 32: Ultraviolet-induced three-component reaction of N-(2-iodoaryl)acrylamides 113, DABCO·(SO2)2 (69) an...
Scheme 33: Proposed mechanism for the preparation of oxindoles 115.
Scheme 34: Three-component reaction of acrylamide 113, CO (23) and 1,4-benzodiazepine 121.
Scheme 35: Multicomponent reaction of sulfonylacrylamides 123, aryldiazonium tetrafluoroborates 68 and DABCO·(...
Scheme 36: Proposed mechanism for the preparation of oxindoles 124.
Scheme 37: Three-component reaction of N-arylpropiolamides 128, aryl iodides 129 and boronic acids 130.
Scheme 38: Proposed mechanism for the formation of diarylmethylene- and diarylallylideneoxindoles 131 and 132.
Scheme 39: Three-component reaction of cyclohexa-1,3-dione (136), amines 2 and alkyl acetylenedicarboxylates 1...
Scheme 40: Proposed mechanism for the formation of 2-oxindoles 138.
Aqueous olefin metathesis: recent developments and applications
- Valerio Sabatino and
- Thomas R. Ward
Beilstein J. Org. Chem. 2019, 15, 445–468, doi:10.3762/bjoc.15.39
- ). Catalysts 3 and 4 showed modest activities in the ROMP of substrate 35. In 2006, Grela and co-workers reported the synthesis of the metathesis catalyst 5 also bearing a quaternary ammonium tag [57]. Following their previous studies highlighting the beneficial effect of an electron-withdrawing group (EWG) on
Graphical Abstract
Scheme 1: Most common metathesis reactions. Ring-opening metathesis polymerization (ROMP), acyclic diene meta...
Scheme 2: Catalytic cycle for metathesis proposed by Chauvin.
Figure 1: Some of the most representative catalysts for aqueous metathesis. a) Well-defined ruthenium catalys...
Scheme 3: First aqueous ROMP reactions catalyzed by ruthenium(III) salts.
Scheme 4: Degradation pathway of first generation Grubbs catalyst (G-I) in methanol.
Scheme 5: Synthesis of Blechert-type catalysts 19 and 20.
Figure 2: Chemical structure and components of amphiphilic molecule PTS and derivatives.
Scheme 6: RCM of selected substrates in the presence of the surfactant PTS. Conditionsa: The reaction was car...
Scheme 7: RCM reactions of substrates 31 and 33 with the encapsulated G-II catalyst.
Scheme 8: Living ROMP of norbornene derivatives 35 and 36 with phosphine-based catalysts bearing quaternary a...
Scheme 9: Synthesis of water-soluble catalysts 3 and 4 bearing quaternary ammonium tags.
Scheme 10: In situ formation of catalyst 5 bearing a quaternary ammonium group.
Scheme 11: Catalyst recycling of an ammonium-bearing catalyst.
Scheme 12: Removal of the water-soluble catalyst 12 through host–guest interaction with silica-gel-supported β...
Scheme 13: Selection of artificial metathases reported by Ward and co-workers (ArM 1 based on biotin–(strept)a...
Figure 3: In vivo metathesis with an artificial metalloenzyme based on the biotin–streptavidin technology.
Scheme 14: Artificial metathase based on covalent anchoring approach. α-Chymotrypsin interacts with catalyst 66...
Scheme 15: Assembling an artificial metathase (ArM 4) based on the small heat shock protein from M. Jannaschii...
Scheme 16: Artificial metathases based on cavity-size engineered β-barrel protein nitrobindin (NB4exp). The HG...
Scheme 17: Artificial metathase based on cutinase (ArM 8) and resulting metathesis activities.
Scheme 18: Site-specific modification of proteins via aqueous cross-metathesis. The protein structure is based...
Scheme 19: a) Allyl homocysteine (Ahc)-modified proteins as CM substrates. b) Incorporation of Ahc in the Fc p...
Scheme 20: On-DNA cross-metathesis reaction of allyl sulfide 99.
Scheme 21: Preparation of BODIPY-containing profluorescent probes 102 and 104.
Scheme 22: Metathesis-based ethylene detection in live cells.
Scheme 23: First example of stapled peptides via olefin metathesis.
The selective electrochemical fluorination of S-alkyl benzothioate and its derivatives
- Shunsuke Kuribayashi,
- Tomoyuki Kurioka,
- Shinsuke Inagi,
- Ho-Jung Lu,
- Biing-Jiun Uang and
- Toshio Fuchigami
Beilstein J. Org. Chem. 2018, 14, 389–396, doi:10.3762/bjoc.14.27
- organosulfur and amino compounds was generally enhanced by the presence of an α-electron-withdrawing group (EWG) such as a CF3 group. Here, the deprotonation of an anodically generated radical cation intermediate is accelerated by an EWG [7][8]. Based on these facts, we successfully achieved the first anodic
Graphical Abstract
Figure 1: Cyclic voltammograms of 0.1 M Bu4NBF4/MeCN with a Pt disk working electrode in the absence (brown l...
Figure 2: Calculated HOMO diagram of 1a.
Figure 3: Calculated HOMO diagrams of 1h, 1i and 1j.
Scheme 1: Plausible reaction paths of the anodic oxidation of 1i in Et4NF·4HF/CH2Cl2.
Scheme 2: Anodic fluorination of 1k.
Scheme 3: Anodic fluorination of cyclic derivative 1l.
Scheme 4: Anodic oxidation of 1m and 1n in Et4NF·4HF/CH2Cl2.
Scheme 5: General reaction mechanism for the anodic fluorination of 1.
Scheme 6: Reaction mechanism for the anodic oxidation of carboxylic acids 1m and 1n in the presence of a fluo...
Trifluoromethyl-substituted tetrathiafulvalenes
- Olivier Jeannin,
- Frédéric Barrière and
- Marc Fourmigué
Beilstein J. Org. Chem. 2015, 11, 647–658, doi:10.3762/bjoc.11.73
- dyads with a strong pairing of the radical species in a singlet state. Keywords: electrochemistry; electron withdrawing group (EWG); fluorine; tetrathiafulvalene (TTF); Introduction Following three decades of extensive work toward the elaboration of conducting radical cation salts from
Graphical Abstract
Scheme 1: Mesomeric forms of 1,3-dithiole rings substituted with EWG.
Scheme 2: Investigated TTF derivatives bearing EWG.
Scheme 3: Synthetic procedures to the CF3-substituted 4bc, 1c and 2ac molecules.
Scheme 4: Synthetic procedure to 3bc.
Figure 1: Correlation between the first oxidation potential E1/2 and the sum of the Hammet σmeta parameters. ...
Figure 2: Calculated frontier orbitals of geometry-optimized [B3LYP/6-31G(d)] model compounds TTF, TTF-CF3, T...
Figure 3: View of the 2ac molecule. Thermal ellipsoids are shown at the 50% probability level.
Figure 4: View of the 2bc molecule. Thermal ellipsoids are shown at the 50% probability level.
Figure 5: View of the two crystallographically independent 4bc molecules. Thermal ellipsoids are shown at the...
Figure 6: View of the 3bc molecule. Note the disordered CF3 groups as well as the CO2Me group orthogonal to t...
Figure 7: A view of the alternated stacks along the b axis in (1c)2(TCNQ).
Figure 8: Detail of the overlap between donor and acceptor molecules in (1c)2(TCNQ).
Figure 9: Projection view along the a axis of the unit cell of (1c+•)(FeCl4−).
Diastereoselective and enantioselective conjugate addition reactions utilizing α,β-unsaturated amides and lactams
- Katherine M. Byrd
Beilstein J. Org. Chem. 2015, 11, 530–562, doi:10.3762/bjoc.11.60
- compounds [6][7][8][9][10][11]. A conjugate addition (CA) reaction involves the addition of a nucleophile to an electron-deficient double or triple bond (Scheme 1). The addition takes place at the carbon that is β to the electron-withdrawing group (EWG), resulting in the formation of a stabilized carbanion
Graphical Abstract
Scheme 1: Generic mechanism for the conjugate addition reaction.
Figure 1: Methods to activate unsaturated amide/lactam systems.
Scheme 2: DCA of Grignard reagents to an L-ephedrine derived chiral α,β–unsaturated amide.
Figure 2: Chiral auxiliaries used in DCA reactions.
Scheme 3: Comparison between auxiliary 5 and the Oppolzer auxiliary in a DCA reaction.
Scheme 4: Use of Evans auxiliary in a DCA reaction.
Figure 3: Lewis acid complex of the Evans auxiliary [43].
Scheme 5: DCA reactions of α,β-unsaturated amides utilizing (S,S)-(+)-pseudoephedrine and the OTBS-derivative...
Figure 4: Proposed model accounting for the diastereoselectivity observed in the 1,4-addition of Bn2NLi to α,...
Scheme 6: An example of a tandem conjugate addition–α-alkylation reaction of an α,β-unsaturated amide utilizi...
Scheme 7: Conjugate addition to an α,β-unsaturated bicyclic lactam leading to (+)-paroxetine and (+)-femoxeti...
Scheme 8: Intramolecular conjugate addition reaction to α,β-unsaturated amide.
Scheme 9: Conjugate addition to an α,β-unsaturated pyroglutamate derivative.
Scheme 10: Cu(I)–NHC-catalyzed asymmetric silylation of α,β-unsaturated lactams and amides.
Scheme 11: Asymmetric copper-catalyzed 1,4-borylation of an α,β-unsaturated amide.
Scheme 12: Asymmetric cross-coupling 49 to phenyl chloride.
Scheme 13: Rhodium-catalyzed asymmetric 1,4-arylation of an α,β-unsaturated lactam.
Scheme 14: Rhodium-catalyzed asymmetric 1,4-arylation of an α,β-unsaturated amide.
Scheme 15: Rhodium-catalyzed asymmetric 1,4-arylation of an α,β-unsaturated amide using a chiral bicyclic dien...
Scheme 16: Synthesis of (R)-(−)-baclofen through a rhodium-catalyzed asymmetric 1,4-arylation of lactam 58.
Scheme 17: Rhodium-catalyzed asymmetric 1,4-arylation of an α,β-unsaturated amide and lactam employing organo[...
Scheme 18: Rhodium-catalyzed asymmetric 1,4-arylation of an α,β-unsaturated lactam employing benzofuran-2-ylzi...
Figure 5: Further chiral ligands that have been used in rhodium-catalyzed 1,4-additions of α,β-unsaturated am...
Scheme 19: Palladium-catalyzed asymmetric 1,4-arylation of arylsiloxanes to a α,β-unsaturated lactam.
Scheme 20: SmI2-mediated cyclization of α,β-unsaturated Weinreb amides.
Figure 6: Chiral Lewis acid complexes used in the Mukaiyama–Michael addition of α,β-unsaturated amides.
Scheme 21: Mukaiyama–Michael addition of thioester silylketene acetal to α,β-unsaturated N-alkenoyloxazolidino...
Scheme 22: Asymmetric 1,4-addition of aryl acetylides to α,β-unsaturated thioamides.
Scheme 23: Asymmetric 1,4-addition of alkyl acetylides to α,β-unsaturated thioamides.
Scheme 24: Asymmetric vinylogous conjugate additions of unsaturated butyrolactones to α,β-unsaturated thioamid...
Scheme 25: Gd-catalyzed asymmetric 1,4-cyanation of α,β-unsaturated N-acylpyrroles [205].
Scheme 26: Lewis acid-catalyzed asymmetric 1,4-cyanation of α,β-unsaturated N-acylpyrazole 107.
Scheme 27: Lewis acid mediated 1,4-addition of dibenzyl malonate to α,β-unsaturated N-acylpyrroles.
Scheme 28: Chiral Lewis acid mediated 1,4-radical addition to α,β-unsaturated N-acyloxazolidinone [224].
Scheme 29: Aza-Michael addition of O-benzylhydroxylamine to an α,β-unsaturated N-acylpyrazole.
Scheme 30: An example of the aza-Michael addition of secondary aryl amines to an α,β-unsaturated N-acyloxazoli...
Scheme 31: Aza-Michael additions of anilines to a α,β-unsaturated N-alkenoyloxazolidinone catalyzed by palladi...
Scheme 32: Aza-Michael additions of aniline to an α,β-unsaturated N-alkenoylbenzamide and N-alkenoylcarbamate ...
Scheme 33: Difference between aza-Michael addition ran using the standard protocol versus the slow addition pr...
Scheme 34: Aza-Michael additions of aryl amines salts to an α,β-unsaturated N-alkenoyloxazolidinone catalyzed ...
Scheme 35: Aza-Michael addition of N-alkenoyloxazolidiniones catalyzed by samarium diiodide [244].
Scheme 36: Asymmetric aza-Michael addition of p-anisidine to α,β-unsaturated N-alkenoyloxazolidinones catalyze...
Scheme 37: Asymmetric aza-Michael addition of O-benzylhydroxylamine to N-alkenoyloxazolidinones catalyzed by i...
Scheme 38: Asymmetric 1,4-addition of purine to an α,β-unsaturated N-alkenoylbenzamide catalyzed by (S,S)-(sal...
Scheme 39: Asymmetric 1,4-addition of phosphites to α,β-unsaturated N-acylpyrroles.
Scheme 40: Asymmetric 1,4-addition of phosphine oxides to α,β-unsaturated N-acylpyrroles.
Scheme 41: Tandem Michael-aldol reaction catalyzed by a hydrogen-bonding organocatalyst.
Scheme 42: Examples of the sulfa-Michael–aldol reaction employing α,β-unsaturated N-acylpyrazoles.
Scheme 43: Example of the sulfa-Michael addition of α,β-unsaturated N-alkenoyloxazolidinones.
Figure 7: Structure of cinchona alkaloid-based squaramide catalyst.
Scheme 44: Asymmetric intramolecular oxa-Michael addition of an α,β-unsaturated amide.
Scheme 45: Formal synthesis atorvastatin.
Secondary amine-initiated three-component synthesis of 3,4-dihydropyrimidinones and thiones involving alkynes, aldehydes and thiourea/urea
- Jie-Ping Wan,
- Yunfang Lin,
- Kaikai Hu and
- Yunyun Liu
Beilstein J. Org. Chem. 2014, 10, 287–292, doi:10.3762/bjoc.10.25
- protocol of the corresponding DHPMs synthesis. For reactions involving aromatic aldehydes, the electronic properties of the substituent exhibited evident impact on the product yield. Aldehydes containing an electron withdrawing group (EWG) facilitated the reactions to give related DHPMs with evidently
Graphical Abstract
Figure 1: Some DHPMs-based lead compounds.
Scheme 1: Regioselective 1,3-thiazines and DHPMs via aldehydes, ureas/thioureas and alkynes.
Scheme 2: Synthesis of enamino ester intermediate and its transformation to DHPM.
Scheme 3: Proposed reaction mechanism.
3D-printed devices for continuous-flow organic chemistry
- Vincenza Dragone,
- Victor Sans,
- Mali H. Rosnes,
- Philip J. Kitson and
- Leroy Cronin
Beilstein J. Org. Chem. 2013, 9, 951–959, doi:10.3762/bjoc.9.109
- meta-position of the aniline ring gives a higher percentage conversion than does an electron-withdrawing group (EWG) [28]. In fact, Table 2 shows that the conversion of benzaldehyde (1a) to imine 3a (Table 2, entry 1; obtained by reacting 1a with 2a), is higher than with the conversion of 1a to imine
Graphical Abstract
Figure 1: Schematic representation of the 3D-printed reactionware devices employed in this work showing the i...
Figure 2: Flow system setup, where a R1 is connected to the syringe pumps and the ATR-IR flow cell with stand...
Figure 3: Carbonyl compounds and primary amines used in the syntheses reported in this work. Carbonyl compoun...
Figure 4: ATR-IR spectra of the synthesis of compounds 3b (on the left) and 3d (on the right). The spectrum o...
Figure 5: (a) IR spectra of benzaldehyde at different concentrations. The solvent peak at 1022 cm−1 remains c...
Figure 6: Comparison of the IR spectra of imine 3a, derived from benzaldehyde (1a) and aniline (2a), synthesi...
Figure 7: Representation of the setup for the two-step flow reaction employed in this work. The first reactor...
Figure 8: Example of an ATR-IR graph in which an imine spectrum is compared with the reduced imine spectrum.
Diastereoselective synthesis of nitroso acetals from (S,E)-γ-aminated nitroalkenes via multicomponent [4 + 2]/[3 + 2] cycloadditions promoted by LiCl or LiClO4
- Leandro Lara de Carvalho,
- Robert Alan Burrow and
- Vera Lúcia Patrocinio Pereira
Beilstein J. Org. Chem. 2013, 9, 838–845, doi:10.3762/bjoc.9.96
- + 2]-step the role of the Lewis acid is not well established; however, it is reasonable to imagine that lithium can be transferred from the nitronate to the electron-withdrawing group (EWG) of the 1,3-dipolarophile causing a decrease in the activation energy of this step, as similarly proposed by
Graphical Abstract
Scheme 1: Reactivity of nitroalkenes and/or their respective nitronates in cycloaddition reactions.
Scheme 2: Synthetic route toward the chiral (S,E)-γ-aminated nitroalkenes 5a–c and their 1,3-diamine derivati...
Figure 1: ORTEP for nitroso acetal 11b.
Figure 2: 1D NOESY correlation between H2, H3a, H4 and H6 for all nitroso acetals.
Scheme 3: Transition-state models to stereoselective approaches in the multicomponent cycloadditions of 5a–c.
Scheme 4: Hydrogenolysis of 9c to pyrrolizidin-3-one 14c.
Asymmetric Diels–Alder reaction with >C=P– functionality of the 2-phosphaindolizine-η1-P-aluminium(O-menthoxy) dichloride complex: experimental and theoretical results
- Rajendra K. Jangid,
- Nidhi Sogani,
- Neelima Gupta,
- Raj K. Bansal,
- Moritz von Hopffgarten and
- Gernot Frenking
Beilstein J. Org. Chem. 2013, 9, 392–400, doi:10.3762/bjoc.9.40
- -phosphaindolizines having an electron-withdrawing group (EWG) only at the 3-position (1b, Z = Me) failed to undergo DA reaction even on heating under reflux in toluene alone or in the presence of sulfur [18] (Scheme 1). It was demonstrated that the dienophilic reactivity of the >C=P– functionality of phosphinines
Graphical Abstract
Scheme 1: Diels–Alder reaction of 2-phosphaindolizines.
Scheme 2: Diels–Alder reaction of 2-phosphaindolizine-η1-P-aluminium(O-menthoxy) dichloride with 2,3-dimethyl...
Scheme 3: Formation of the cationic 1:1 complex of the dienophile and dialkylaluminium.
Scheme 4: Disproportionation of the 1:1 complex of 2-phosphaindolizine and Al(O-menthoxy)Cl2.
Scheme 5: Attack of 1,3-butadiene on Si and Re faces of >C=P– functionality of 2-phosphaindolizine complex.
Figure 1: Geometries of 2-phosphaindolizine-η1-P-aluminium(O-menthoxy) dichloride, the transition structures,...
Reactions of nitroxides XIII: Synthesis of the Morita–Baylis–Hillman adducts bearing a nitroxyl moiety using 4-acryloyloxy-2,2,6,6-tetramethylpiperidine-1-oxyl as a starting compound, and DABCO and quinuclidine as catalysts
- Jerzy Zakrzewski
Beilstein J. Org. Chem. 2012, 8, 1515–1522, doi:10.3762/bjoc.8.171
- aldehydes. Keywords: 4-acryloyloxy-2,2,6,6-tetramethylpiperidine-1-oxyl; DABCO; Morita–Baylis–Hillman reaction; nitroxides; quinuclidine; Introduction In the Morita–Baylis–Hillman (MBH) reaction, aldehydes react with a double bond activated by an electron-withdrawing group (EWG). The vinylic carbon
Graphical Abstract
Scheme 1: MBH adducts 5a–o from 4-acryloyloxy-2,2,6,6-tetramethylpiperidine-1-oxyl.
Heavy atom effects in the Paternò–Büchi reaction of pyrimidine derivatives with 4,4’-disubstituted benzophenones
- Feng-Feng Kong,
- Jian-Bo Wang and
- Qin-Hua Song
Beilstein J. Org. Chem. 2011, 7, 113–118, doi:10.3762/bjoc.7.16
- gradually for both DMT/DMU photochemical systems from 1a to 1f. That is, a halogen atom as an electron-withdrawing group (EWG) has a pronounced effect on the regioselectivity. However, the photochemical efficiency of the 1e systems did not show the expected increase, but decreased relative to systems with
Graphical Abstract
Scheme 1: The Paternò–Büchi reaction of DMT/DMU with benzophenones to generate two regioisomeric photoproduct...
Figure 1: The yield and the ratio of 2/3 at different reaction times in the Paternò–Büchi reaction of DMT wit...
Figure 2: Eyring plots for the photoreaction of DMT with compounds 1b–e.
Scheme 2: The formational processes of two regioisomers in the Paternò–Büchi reaction of DMT/DMU with benzoph...
New library of aminosulfonyl-tagged Hoveyda–Grubbs type complexes: Synthesis, kinetic studies and activity in olefin metathesis transformations
- Etienne Borré,
- Frederic Caijo,
- Christophe Crévisy and
- Marc Mauduit
Beilstein J. Org. Chem. 2010, 6, 1159–1166, doi:10.3762/bjoc.6.132
- demanding substrate, was more problematic since low conversions were observed after 24 h of reaction at 2 mol % catalyst loading (entries 11–15). Unexpectedly, complex 4c was half as efficient as the other analogues (entry 13). So, the nature of the electron-withdrawing group (EWG) appears to have a rather
Graphical Abstract
Figure 1: Ruthenium precatalysts for olefin metathesis.
Figure 2: Structure of precatalyst 3 and 4.
Scheme 1: Synthesis of catalysts 4a–g.
Figure 3: Kinetic studies of RCM of 8 (0.1 M) with precatalysts 4a–g (1 mol %) in CD2Cl2 at 30 °C.
