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Search for "environmentally friendly" in Full Text gives 168 result(s) in Beilstein Journal of Organic Chemistry.
Photosensitized direct C–H fluorination and trifluoromethylation in organic synthesis
- Shahboz Yakubov and
- Joshua P. Barham
Beilstein J. Org. Chem. 2020, 16, 2151–2192, doi:10.3762/bjoc.16.183
- , light is inexpensive, nontoxic, noncontaminating, ample (or “limitless” in the case of sunlight) and a renewable source of energy for environmentally-friendly and “green” chemical synthesis. As a consequence of comprehending the detrimental impact of human industry on the environment, new methods to
Graphical Abstract
Figure 1: Fluorine-containing drugs.
Figure 2: Fluorinated agrochemicals.
Scheme 1: Selectivity of fluorination reactions.
Scheme 2: Different mechanisms of photocatalytic activation. Sub = substrate.
Figure 3: Jablonski diagram showing visible-light-induced energy transfer pathways: a) absorption, b) IC, c) ...
Figure 4: Schematic illustration of TTET.
Figure 5: Organic triplet PSCats.
Figure 6: Additional organic triplet PSCats.
Figure 7: A) Further organic triplet PSCats and B) transition metal triplet PSCats.
Figure 8: Different fluorination reagents grouped by generation.
Scheme 3: Synthesis of Selectfluor®.
Scheme 4: General mechanism of PS TTET C(sp3)–H fluorination.
Scheme 5: Selective benzylic mono- and difluorination using 9-fluorenone and xanthone PSCats, respectively.
Scheme 6: Chen’s photosensitized monofluorination: reaction scope.
Scheme 7: Chen’s photosensitized benzylic difluorination reaction scope.
Scheme 8: Photosensitized monofluorination of ethylbenzene on a gram scale.
Scheme 9: Substrate scope of Tan’s AQN-photosensitized C(sp3)–H fluorination.
Scheme 10: AQN-photosensitized C–H fluorination reaction on a gram scale.
Scheme 11: Reaction mechanism of the AQN-assisted fluorination.
Figure 9: 3D structures of the singlet ground and triplet excited states of Selectfluor®.
Scheme 12: Associated transitions for the activation of acetophenone by violet light.
Scheme 13: Ethylbenzene C–H fluorination with various PSCats and conditions.
Scheme 14: Effect of different PSCats on the C(sp3)–H fluorination of cyclohexane (39).
Scheme 15: Reaction scope of Chen’s acetophenone-photosensitized C(sp3)–H fluorination reaction.
Figure 10: a) Site-selectivity of Chen’s acetophenone-photosensitized C–H fluorination reaction [201]. b) Site-sele...
Scheme 16: Formation of the AQN–Selectfluor® exciplex Int1.
Scheme 17: Generation of the C3 2° pentane radical and the Selectfluor® N-radical cation from the exciplex.
Scheme 18: Hydrogen atom abstraction by the Selectfluor® N-radical cation from pentane to give the C3 2° penta...
Scheme 19: Fluorine atom transfer from Selectfluor® to the C3 2° pentane radical to yield 3-fluoropentane and ...
Scheme 20: Barrierless fluorine atom transfer from Int1 to the C3 2° pentane radical to yield 3-fluoropentane,...
Scheme 21: Ketone-directed C(sp3)–H fluorination.
Scheme 22: Ketone-directed fluorination through a 5- and a 6-membered transition state, respectively.
Scheme 23: Effect of different PSCats on the photosensitized C(sp3)–H fluorination of 47.
Scheme 24: Substrate scope of benzil-photoassisted C(sp3)–H fluorinations.
Scheme 25: A) Benzil-photoassisted enone-directed C(sp3)–H fluorination. B) Classification of the reaction mod...
Scheme 26: A) Xanthone-photoassisted ketal-directed C(sp3)–H fluorination. B) Substrate scope. C) C–H fluorina...
Scheme 27: Rationale for the selective HAT at the C2 C–H bond of galactose acetonide.
Scheme 28: Photosensitized C(sp3)–H benzylic fluorination of a peptide using different PSCats.
Scheme 29: Peptide scope of 5-benzosuberenone-photoassisted C(sp3)–H fluorinations.
Scheme 30: Continuous flow PS TTET monofluorination of 72.
Scheme 31: Photosensitized C–H fluorination of N-butylphthalimide as a PSX.
Scheme 32: Substrate scope and limitations of the PSX C(sp3)–H monofluorination.
Scheme 33: Substrate crossover monofluorination experiment.
Scheme 34: PS TTET mechanism proposed by Hamashima and co-workers.
Scheme 35: Photosensitized TFM of 78 to afford α-trifluoromethylated ketone 80.
Scheme 36: Substrate scope for photosensitized styrene TFM to give α-trifluoromethylated ketones.
Scheme 37: Control reactions for photosensitized TFM of styrenes.
Scheme 38: Reaction mechanism for photosensitized TFM of styrenes to afford α-trifluoromethylated ketones.
Scheme 39: Reaction conditions for TFMs to yield the cis- and the trans-product, respectively.
Scheme 40: Substrate scope of trifluoromethylated (E)-styrenes.
Scheme 41: Strategies toward trifluoromethylated (Z)-styrenes.
Scheme 42: Substrate scope of trifluoromethylated (Z)-styrenes.
Scheme 43: Reaction mechanism for photosensitized TFM of styrenes to afford E- or Z-products.
When metal-catalyzed C–H functionalization meets visible-light photocatalysis
- Lucas Guillemard and
- Joanna Wencel-Delord
Beilstein J. Org. Chem. 2020, 16, 1754–1804, doi:10.3762/bjoc.16.147
- rapidly expanding domain of organic synthesis [1][2][3][4][5][6][7][8][9][10][11][12][13][14]. Indeed, this approach tends in rendering the classical metal-catalyzed cross-coupling more environmentally friendly, as simple, non-prefunctionalized substrates could be used in the presence of a metallic
Graphical Abstract
Figure 1: Concept of dual synergistic catalysis.
Figure 2: Classification of catalytic systems involving two catalysts.
Figure 3: General mechanism for the dual nickel/photoredox catalytic system.
Figure 4: General mechanisms for C–H activation catalysis involving different reoxidation strategies.
Figure 5: Indole synthesis via dual C–H activation/photoredox catalysis.
Figure 6: Proposed mechanism for the indole synthesis via dual catalysis.
Figure 7: Oxidative Heck reaction on arenes via the dual catalysis.
Figure 8: Proposed mechanism for the Heck reaction on arenes via dual catalysis.
Figure 9: Oxidative Heck reaction on phenols via the dual catalysis.
Figure 10: Proposed mechanism for the Heck reaction on phenols via dual catalysis.
Figure 11: Carbazole synthesis via dual C–H activation/photoredox catalysis.
Figure 12: Proposed mechanism for the carbazole synthesis via dual catalysis.
Figure 13: Carbonylation of enamides via the dual C–H activation/photoredox catalysis.
Figure 14: Proposed mechanism for carbonylation of enamides via dual catalysis.
Figure 15: Annulation of benzamides via the dual C–H activation/photoredox catalysis.
Figure 16: Proposed mechanism for the annulation of benzamides via dual catalysis.
Figure 17: Synthesis of indoles via the dual C–H activation/photoredox catalysis.
Figure 18: Proposed mechanism for the indole synthesis via dual catalysis.
Figure 19: General concept of dual catalysis merging C–H activation and photoredox catalysis.
Figure 20: The first example of dual catalysis merging C–H activation and photoredox catalysis.
Figure 21: Proposed mechanism for the C–H arylation with diazonium salts via dual catalysis.
Figure 22: Dual catalysis merging C–H activation/photoredox using diaryliodonium salts.
Figure 23: Direct arylation via the dual catalytic system reported by Xu.
Figure 24: Direct arylation via dual catalytic system reported by Balaraman.
Figure 25: Direct arylation via dual catalytic system reported by Guo.
Figure 26: C(sp3)–H bond arylation via the dual Pd/photoredox catalytic system.
Figure 27: Acetanilide derivatives acylation via the dual C–H activation/photoredox catalysis.
Figure 28: Proposed mechanism for the C–H acylation with α-ketoacids via dual catalysis.
Figure 29: Acylation of azobenzenes via the dual catalysis C–H activation/photoredox.
Figure 30: C2-acylation of indoles via the dual C–H activation/photoredox catalysis.
Figure 31: Proposed mechanism for the C2-acylation of indoles with aldehydes via dual catalysis.
Figure 32: C2-acylation of indoles via the dual C–H activation/photoredox catalysis.
Figure 33: Perfluoroalkylation of arenes via the dual C–H activation/photoredox catalysis.
Figure 34: Proposed mechanism for perfluoroalkylation of arenes via dual catalysis.
Figure 35: Sulfonylation of 1-naphthylamides via the dual C–H activation/photoredox catalysis.
Figure 36: Proposed mechanism for sulfonylation of 1-naphthylamides via dual catalysis.
Figure 37: meta-C–H Alkylation of arenes via visible-light metallaphotocatalysis.
Figure 38: Alternative procedure for meta-C–H alkylation of arenes via metallaphotocatalysis.
Figure 39: Proposed mechanism for meta-C–H alkylation of arenes via metallaphotocatalysis.
Figure 40: C–H borylation of arenes via visible-light metallaphotocatalysis.
Figure 41: Proposed mechanism for C–H borylation of arenes via visible-light metallaphotocatalysis.
Figure 42: Undirected C–H aryl–aryl cross coupling via dual gold/photoredox catalysis.
Figure 43: Proposed mechanism for the undirected C–H aryl–aryl cross-coupling via dual catalysis.
Figure 44: Undirected C–H arylation of (hetero)arenes via dual manganese/photoredox catalysis.
Figure 45: Proposed mechanism for the undirected arylation of (hetero)arenes via dual catalysis.
Figure 46: Photoinduced C–H arylation of azoles via copper catalysis.
Figure 47: Photo-induced C–H chalcogenation of azoles via copper catalysis.
Figure 48: Decarboxylative C–H adamantylation of azoles via dual cobalt/photoredox catalysis.
Figure 49: Proposed mechanism for the C–H adamantylation of azoles via dual catalysis.
Figure 50: General mechanisms for the “classical” (left) and Cu-free variant (right) Sonogoshira reaction.
Figure 51: First example of a dual palladium/photoredox catalysis for Sonogashira-type couplings.
Figure 52: Arylation of terminal alkynes with diazonium salts via dual gold/photoredox catalysis.
Figure 53: Proposed mechanism for the arylation of terminal alkynes via dual catalysis.
Figure 54: C–H Alkylation of alcohols promoted by H-atom transfer (HAT).
Figure 55: Proposed mechanism for the C–H alkylation of alcohols promoted by HAT.
Figure 56: C(sp3)–H arylation of latent nucleophiles promoted by H-atom transfer.
Figure 57: Proposed mechanism for the C(sp3)–H arylation of latent nucleophiles promoted by HAT.
Figure 58: Direct α-arylation of alcohols promoted by H-atom transfer.
Figure 59: Proposed mechanism for the direct α-arylation of alcohols promoted by HAT.
Figure 60: C–H arylation of amines via dual Ni/photoredox catalysis.
Figure 61: Proposed mechanism for the C–H arylation of amines via dual Ni/photoredox catalysis.
Figure 62: C–H functionalization of nucleophiles via excited ketone/nickel dual catalysis.
Figure 63: Proposed mechanism for the C–H functionalization enabled by excited ketones.
Figure 64: Selective sp3–sp3 cross-coupling promoted by H-atom transfer.
Figure 65: Proposed mechanism for the selective sp3–sp3 cross-coupling promoted by HAT.
Figure 66: Direct C(sp3)–H acylation of amines via dual Ni/photoredox catalysis.
Figure 67: Proposed mechanism for the C–H acylation of amines via dual Ni/photoredox catalysis.
Figure 68: C–H hydroalkylation of internal alkynes via dual Ni/photoredox catalysis.
Figure 69: Proposed mechanism for the C–H hydroalkylation of internal alkynes.
Figure 70: Alternative procedure for the C–H hydroalkylation of ynones, ynoates, and ynamides.
Figure 71: Allylic C(sp3)–H activation via dual Ni/photoredox catalysis.
Figure 72: Proposed mechanism for the allylic C(sp3)–H activation via dual Ni/photoredox catalysis.
Figure 73: Asymmetric allylation of aldehydes via dual Cr/photoredox catalysis.
Figure 74: Proposed mechanism for the asymmetric allylation of aldehydes via dual catalysis.
Figure 75: Aldehyde C–H functionalization promoted by H-atom transfer.
Figure 76: Proposed mechanism for the C–H functionalization of aldehydes promoted by HAT.
Figure 77: Direct C–H arylation of strong aliphatic bonds promoted by HAT.
Figure 78: Proposed mechanism for the C–H arylation of strong aliphatic bonds promoted by HAT.
Figure 79: Direct C–H trifluoromethylation of strong aliphatic bonds promoted by HAT.
Figure 80: Proposed mechanism for the C–H trifluoromethylation of strong aliphatic bonds.
In silico rationalisation of selectivity and reactivity in Pd-catalysed C–H activation reactions
- Liwei Cao,
- Mikhail Kabeshov,
- Steven V. Ley and
- Alexei A. Lapkin
Beilstein J. Org. Chem. 2020, 16, 1465–1475, doi:10.3762/bjoc.16.122
- developing machine learning models for predicting reaction outcomes. C–H activation reactions allow conversion of relatively inexpensive and abundant hydrocarbons into the more sophisticated value-added molecules [11]. With the notion of step-economical and environmentally friendly synthesis, direct
Graphical Abstract
Figure 1: An approximate energy map for the electrophilic aromatic substitution mechanism.
Scheme 1: Schematic representation of the two mechanisms of Pd-catalysed C–H activation reaction considered i...
An overview on disulfide-catalyzed and -cocatalyzed photoreactions
- Yeersen Patehebieke
Beilstein J. Org. Chem. 2020, 16, 1418–1435, doi:10.3762/bjoc.16.118
- gained some interest from researchers, their full potential has not been discovered and released yet. They are environmentally friendly and efficient catalyst that deserve more attention. [3 + 2] cyclization catalyzed by diaryl disulfide. [3 + 2] cycloaddition catalyzed by disulfide. Disulfide-bridged
Graphical Abstract
Scheme 1: [3 + 2] cyclization catalyzed by diaryl disulfide.
Scheme 2: [3 + 2] cycloaddition catalyzed by disulfide.
Scheme 3: Disulfide-bridged peptide-catalyzed enantioselective cycloaddition.
Scheme 4: Disulfide-catalyzed [3 + 2] methylenecyclopentane annulations.
Scheme 5: Disulfide as a HAT cocatalyst in the [4 + 2] cycloaddition reaction.
Scheme 6: Proposed mechanism of the [4 + 2] cycloaddition reaction using disulfide as a HAT cocatalyst.
Scheme 7: Disulfide-catalyzed ring expansion of vinyl spiro epoxides.
Scheme 8: Disulfide-catalyzed aerobic oxidation of diarylacetylene.
Scheme 9: Disulfide-catalyzed aerobic photooxidative cleavage of olefins.
Scheme 10: Disulfide-catalyzed aerobic oxidation of 1,3-dicarbonyl compounds.
Scheme 11: Proposed mechanism of the disulfide-catalyzed aerobic oxidation of 1,3-dicarbonyl compounds.
Scheme 12: Disulfide-catalyzed oxidation of allyl alcohols.
Scheme 13: Disulfide-catalyzed diboration of alkynes.
Scheme 14: Dehalogenative radical cyclization catalyzed by disulfide.
Scheme 15: Hydrodifluoroacetamidation of alkenes catalyzed by disulfide.
Scheme 16: Plausible mechanism of the hydrodifluoroacetamidation of alkenes catalyzed by disulfide.
Scheme 17: Disulfide-cocatalyzed anti-Markovnikov olefin hydration reactions.
Scheme 18: Disulfide-catalyzed decarboxylation of carboxylic acids.
Scheme 19: Proposed mechanism of the disulfide-catalyzed decarboxylation of carboxylic acids.
Scheme 20: Disulfide-catalyzed decarboxylation of carboxylic acids.
Scheme 21: Disulfide-catalyzed conversion of maleate esters to fumarates and 5H-furanones.
Scheme 22: Disulfide-catalyzed isomerization of difluorotriethylsilylethylene.
Scheme 23: Disulfide-catalyzed isomerization of allyl alcohols to carbonyl compounds.
Scheme 24: Proposed mechanism for the disulfide-catalyzed isomerization of allyl alcohols to carbonyl compound...
Scheme 25: Diphenyl disulfide-catalyzed enantioselective synthesis of ophirin B.
Scheme 26: Disulfide-catalyzed isomerization in the total synthesis of (+)-hitachimycin.
Scheme 27: Disulfide-catalyzed isomerization in the synthesis of (−)-gloeosporone.
Palladium-catalyzed regio- and stereoselective synthesis of aryl and 3-indolyl-substituted 4-methylene-3,4-dihydroisoquinolin-1(2H)-ones
- Valeria Nori,
- Antonio Arcadi,
- Armando Carlone,
- Fabio Marinelli and
- Marco Chiarini
Beilstein J. Org. Chem. 2020, 16, 1084–1091, doi:10.3762/bjoc.16.95
- -dioxane/H2O as the reaction medium (Table 1, entry 5). While MeCN, DMF, THF and DMSO as solvents gave worse results (Table 1, entries 6–9), the environmentally friendly EtOH proved to be the most efficient reaction medium (Table 1, entry 10). Further attempts to increase the yield of 4aa by tuning the
- presence of a catalytic amount of the ligand-free PdCl2 in environmentally friendly ethanol, achieve an efficient regio- and stereoselective synthesis of 4-methylene-3,4-dihydroisoquinolin-1(2H)-ones 4. It is worth noting that, during the preparation of this paper, a related article focused on the
Graphical Abstract
Scheme 1: Planned approach to tetrasubstituted-4-methylene-3,4-dihydroisoquinolin-1(2H)-ones 4 and 6.
Scheme 2: Preparation of the starting N-propargyl-2-iodobenzamides 2.
Scheme 3: Substrate scope of the reaction of N-propargyl-2-iodobenzamide 2a with arylboronic acids 3b–i.
Scheme 4: Substrate scope of the reaction of N-propargyl-2-iodobenzamides 2c–f with arylboronic acids 3a–c/j.
Scheme 5: Reaction of N-propargyl-2-iodobenzamides 2b,f with the 2-alkynyltrifluoroacetanilides 5a–c.
Aldehydes as powerful initiators for photochemical transformations
- Maria A. Theodoropoulou,
- Nikolaos F. Nikitas and
- Christoforos G. Kokotos
Beilstein J. Org. Chem. 2020, 16, 833–857, doi:10.3762/bjoc.16.76
- support through the programme “EPISTHMONIKES MELETES 2015” (PhotoOrganocatalysis: Development of new environmentally-friendly methods for the synthesis of compounds for the
Graphical Abstract
Scheme 1: Norrish type I and II dissociations.
Scheme 2: Proposed radical pair formation after the photolysis of benzaldehyde (8).
Scheme 3: Aldehydes in the Paterno–Büchi reaction.
Scheme 4: 2,3-Diazabicyclo[2.2.1]hept-2-ene (DBH).
Scheme 5: Dissociation pathways of benzaldehyde.
Scheme 6: Reactions that lead to polarized products detectable by CIDNP.
Scheme 7: MMA (26), DEABP (27), and Michler’s ketone (28).
Scheme 8: Radical intermediates of DEABP.
Scheme 9: Photoinitiated polymerization of monomeric MMA (26) using the quinoxalines 32 and benzaldehyde (8).
Scheme 10: Acetone (4) and formaldehyde (35) as photografting initiators.
Scheme 11: Photografting by employing acetaldehyde (36) as the photoinitiator.
Scheme 12: Proposed photolysis mechanism for aliphatic ketones 44 and formaldehyde (35).
Scheme 13: Initiator 50, reductant 51, and benzaldehyde derivatives 52–54 for the polymerization of the methac...
Scheme 14: Proposed mechanism of the photomediated atom transfer radical polymerization employing the benzalde...
Scheme 15: cis/trans isomerization employing triplet states of photosensitizers.
Scheme 16: Salicylaldehyde (68) forms an internal hydrogen bond.
Scheme 17: Olefin isomerization via energy transfer from a carbonyl compound.
Scheme 18: Mechanistic pathways for the Paterno–Büchi reaction.
Scheme 19: Isomeric oxetanes formed after photochemical addition of aryl aldehydes to 2-butenes.
Scheme 20: Rotation of the C3–C4 bond of the biradical intermediate may lead to all four conformations.
Scheme 21: Photolysis products of benzaldehyde (8) in different solvents. a) In benzene or ethanol. b) In hex-...
Scheme 22: N-tert-Butylbenzamide formation proceeds via a benzoyl radical.
Scheme 23: Photochemical pinacol coupling.
Scheme 24: Photochemical ATRA catalyzed by 4-anisaldehyde (52).
Scheme 25: Proposed triplet sensitization mechanism of the ATRA reaction in the presence of 4-anisaldehyde (52...
Scheme 26: Benzaldehyde-mediated photoredox CDC reaction: compatible amides and ethers.
Scheme 27: Photoredox cross-dehydrogenative coupling (CDC) conditions and proposed reaction mechanism.
Scheme 28: Optimized conditions for the photoredox merger reaction.
Scheme 29: Proposed mechanism for the C(sp3)–H alkylation/arylation of ethers.
Scheme 30: Substrate scope for the photochemical alkylation of ethers.
Scheme 31: C(sp3)–H Functionalization of N-containing molecules.
Scheme 32: Substrate scope for the photochemical alkylation of N-containing molecules.
Scheme 33: Additional products yielded by the photochemical alkylation reaction of N-containing molecules.
Scheme 34: C(sp3)–H functionalization of thioethers.
Scheme 35: Proposed mechanism for the C(sp3)–H alkylation/arylation of N-containing molecules and thioethers.
Scheme 36: Hydroacylation using 4-cyanobenzaldehyde (53) as the photoinitiator.
Scheme 37: Selectivity for the formation of the α,α-disubstituted aldehydes.
Scheme 38: Substrate scope for the photochemical addition of aldehydes to Michael acceptors.
Scheme 39: Proposed mechanism for the hydroacylation of Michael acceptors using 4-cyanobenzaldehyde (53) as th...
Scheme 40: Catalytic arylation of aromatic aldehydes by aryl bromides in which the reaction product acts as th...
Scheme 41: Proposed mechanism for the catalytic arylation of benzaldehydes by aryl bromides in which the react...
Scheme 42: Functionalization of the chiral cyclobutanes 180.
Scheme 43: Optimized reaction conditions and proposed mechanism for the sulfonylcyanation of cyclobutenes.
Rhodium-catalyzed reductive carbonylation of aryl iodides to arylaldehydes with syngas
- Zhenghui Liu,
- Peng Wang,
- Zhenzhong Yan,
- Suqing Chen,
- Dongkun Yu,
- Xinhui Zhao and
- Tiancheng Mu
Beilstein J. Org. Chem. 2020, 16, 645–656, doi:10.3762/bjoc.16.61
- environmentally friendly than other frequently used hydrogen sources like hydrosilanes [17], tributyltin hydride (Bu3SnH) (often used in natural product syntheses) [18][19][20] and hydroboranes [21][22][23], since the only byproduct is water. The production, storage and use of H2 received much attention and
- pressure, cheap ligand and low metal dosage could significantly improve the practicability in both chemical researches and industrial applications. Keywords: cost-effective ligand; industrial catalysis; reductive carbonylation; rhodium catalyst; syngas; Introduction The exploration of environmentally
- friendly and highly effective synthetic methods has been a significant goal of research [1][2][3][4][5]. In this aspect, effective catalytic systems and organometallic chemistry are suitable technologies to accomplish these goals. Carbonylation processes are important transformations in the refinement and
Graphical Abstract
Figure 1: Rhodium-catalyzed reductive carbonylation of iodobenzene with CO and H2 to afford benzaldehyde. a) ...
Scheme 1: Scaled-up experiment of the reductive carbonylation of iodobenzene to benzaldehyde under the optimi...
Scheme 2: Catalytic species participating in the catalytic process.
Scheme 3: Substrate scope for the Rh-catalyzed reductive carbonylation of aryl iodides using CO and H2. React...
Scheme 4: Isotope-labeling experiments.
Scheme 5: Proposed reaction mechanism for the Rh-catalyzed reductive carbonylation of aryl iodides using CO a...
A systematic review on silica-, carbon-, and magnetic materials-supported copper species as efficient heterogeneous nanocatalysts in “click” reactions
- Pezhman Shiri and
- Jasem Aboonajmi
Beilstein J. Org. Chem. 2020, 16, 551–586, doi:10.3762/bjoc.16.52
- methodologies. These inorganic supported nanocatalysts have been found to be efficient, environmentally friendly, recyclable, and durable. In addition, one of the vital issues for expanding new, stable, and reusable catalysts is the discovery of unique catalysts. The basis and foundation of this review article
Graphical Abstract
Scheme 1: Chemical structure of the catalysts 1a and 1b and their catalytic application in CuAAC reactions.
Scheme 2: Synthetic route to the catalyst 11 and its catalytic application in CuAAC reactions.
Scheme 3: Synthetic route of dendrons, illustrated using G2-AMP 23.
Scheme 4: The catalytic application of CuYAu–Gx-AAA–SBA-15 in a CuAAC reaction.
Scheme 5: Synthetic route to the catalyst 36.
Scheme 6: Application of the catalyst 36 in CuAAC reactions.
Scheme 7: The synthetic route to the catalyst 45 and catalytic application of 45 in “click” reactions.
Scheme 8: Synthetic route to the catalyst 48 and catalytic application of 48 in “click” reactions.
Scheme 9: Synthetic route to the catalyst 58 and catalytic application of 58 in “click” reactions.
Scheme 10: Synthetic route to the catalyst 64 and catalytic application of 64 in “click” reactions.
Scheme 11: Chemical structure of the catalyst 68 and catalytic application of 68 in “click” reactions.
Scheme 12: Chemical structure of the catalyst 69 and catalytic application of 69 in “click” reactions.
Scheme 13: Synthetic route to, and chemical structure of the catalyst 74.
Scheme 14: Application of the cayalyst 74 in “click” reactions.
Scheme 15: Synthetic route to, and chemical structure of the catalyst 78 and catalytic application of 78 in “c...
Scheme 16: Synthetic route to the catalyst 85.
Scheme 17: Application of the catalyst 85 in “click” reactions.
Scheme 18: Synthetic route to the catalyst 87 and catalytic application of 87 in “click” reactions.
Scheme 19: Chemical structure of the catalyst 88 and catalytic application of 88 in “click” reactions.
Scheme 20: Synthetic route to the catalyst 90 and catalytic application of 90 in “click” reactions.
Scheme 21: Synthetic route to the catalyst 96 and catalytic application of 96 in “click” reactions.
Scheme 22: Synthetic route to the catalyst 100 and catalytic application of 100 in “click” reactions.
Scheme 23: Synthetic route to the catalyst 102 and catalytic application of 23 in “click” reactions.
Scheme 24: Synthetic route to the catalysts 108–111.
Scheme 25: Catalytic application of 108–111 in “click” reactions.
Scheme 26: Synthetic route to the catalyst 121 and catalytic application of 121 in “click” reactions.
Scheme 27: Synthetic route to 125 and application of 125 in “click” reactions.
Scheme 28: Synthetic route to the catalyst 131 and catalytic application of 131 in “click” reactions.
Scheme 29: Synthetic route to the catalyst 136.
Scheme 30: Application of the catalyst 136 in “click” reactions.
Scheme 31: Synthetic route to the catalyst 141 and catalytic application of 141 in “click” reactions.
Scheme 32: Synthetic route to the catalyst 144 and catalytic application of 144 in “click” reactions.
Scheme 33: Synthetic route to the catalyst 149 and catalytic application of 149 in “click” reactions.
Scheme 34: Synthetic route to the catalyst 153 and catalytic application of 153 in “click” reactions.
Scheme 35: Synthetic route to the catalyst 155 and catalytic application of 155 in “click” reactions.
Scheme 36: Synthetic route to the catalyst 157 and catalytic application of 157 in “click” reactions.
Scheme 37: Synthetic route to the catalyst 162.
Scheme 38: Application of the catalyst 162 in “click” reactions.
Scheme 39: Synthetic route to the catalyst 167 and catalytic application of 167 in “click” reactions.
Scheme 40: Synthetic route to the catalyst 169 and catalytic application of 169 in “click” reactions.
Scheme 41: Synthetic route to the catalyst 172.
Scheme 42: Application of the catalyst 172 in “click” reactions.
Regio- and stereoselective synthesis of new ensembles of diversely functionalized 1,3-thiaselenol-2-ylmethyl selenides by a double rearrangement reaction
- Svetlana V. Amosova,
- Andrey A. Filippov,
- Nataliya A. Makhaeva,
- Alexander I. Albanov and
- Vladimir A. Potapov
Beilstein J. Org. Chem. 2020, 16, 515–523, doi:10.3762/bjoc.16.47
- activity based on affordable and environmentally friendly materials is another important trend in organoselenium chemistry [17]. Reviews on the biological activity of organoselenium compounds reported examples exhibiting high antitumor, antiviral, antimicrobial, and neuroprotective activities [12][18][19
Graphical Abstract
Scheme 1: Possible formation of reaction products starting from 1 via seleniranium 2 or thiiranium cations 3.
Scheme 2: Unusual regio- and stereoselective nucleophilic reactions of thiaselenole 1 at two centers of the s...
Scheme 3: Reactions of thiaselenole 1 with С- and S-centered nucleophiles affording new families of linear un...
Scheme 4: The reactions of thiaselenole 1 with the formation of polyfunctionalized 2,3-dihydro-1,4-thiaseleni...
Scheme 5: The synthesis of new 1,3-thiaselenole ensembles by reactions of thiaselenole 1 with mercapto benzaz...
Scheme 6: The formation of product 4 via compound 5 by the reaction of thiaselenole 1 with potassium selenocy...
Figure 1: Monitoring the reaction of thiaselenole 1 with KSeCN by 1H NMR spectroscopy (in accordance with the...
Scheme 7: The reaction pathway for the formation of compounds 4 and 5.
Scheme 8: Synthesis of new ensembles of 1,3-thiaselenol-2-ylmethyl selenides 6a–l (77Se NMR data are included...
Scheme 9: The synthesis of vinyl selenides 7a,b through nucleophilic addition of 1,3-thiaselenol-2-ylmethylse...
Scheme 10: One-pot synthesis of diselenide 8 from thiaselenole 1 (77Se NMR data are included).
Scheme 11: Synthesis of compounds 6a–j from diselenide 8.
Recent developments in photoredox-catalyzed remote ortho and para C–H bond functionalizations
- Rafia Siddiqui and
- Rashid Ali
Beilstein J. Org. Chem. 2020, 16, 248–280, doi:10.3762/bjoc.16.26
- groundbreaking advancements were accomplished in this wonderful area of research, transforming a specific C–H bond effectively and selectively under favorable conditions (viz, room temperature, without external oxidant, cost-effective, sustainable, and environmentally friendly) still remains a highly challenging
- observed a number of interesting facts, viz: (i) the reaction proceeded with environmentally friendly molecular oxygen as oxidant, (ii) water was the only byproduct of the reaction, (iii) no reaction occurred without the involvement of a photocatalyst, (iv) high yields were obtained with electron-donating
- reported the synthesis of coumarin derivatives using photoredox catalyst 12 and CF3SO2Cl as a potent radical source [111]. In comparison to other reported methods, the reaction was carried out under mild as well as environmentally friendly conditions, and the reaction remarkably showed much tolerance for
Graphical Abstract
Figure 1: List of photoredox catalysts used for C–H bond functionalizations.
Figure 2: List of metal-based photoredox catalysts used in this review article.
Figure 3: Jablonski diagram.
Figure 4: Photoredox catalysis via reductive or oxidative pathways. D = donor, A = acceptor, S = substrate, P...
Figure 5: Schematic representation of the combination of photoredox catalysis and transition metal catalysis.
Scheme 1: Weinreb amide C–H olefination.
Figure 6: Mechanism for the formation of 21 from 19 using photoredox catalyst 11.
Scheme 2: C–H olefination of phenolic ethers.
Scheme 3: Decarboxylative acylation of acetanilides.
Figure 7: Mechanism for the formation of 30 from acetanilide derivatives.
Scheme 4: Synthesis of fluorenone derivatives by intramolecular deoxygenative acylation of biaryl carboxylic ...
Figure 8: Mechanism for the photoredox-catalyzed synthesis of fluorenone derivatives.
Scheme 5: Synthesis of benzothiazoles via aerobic C–H thiolation.
Figure 9: Plausible mechanism for the construction of benzothiazoles from benzothioamides.
Scheme 6: Synthesis of benzothiazoles via oxidant-free C–H thiolation.
Figure 10: Mechanism involved in the synthesis of benzothiazoles via oxidant-free C–H thiolation.
Scheme 7: Synthesis of indoles via C–H cyclization of anilides with alkynes.
Scheme 8: Preparation of 3-trifluoromethylcoumarins via C–H cyclization of arylpropiolate esters.
Figure 11: Mechanistic pathway for the synthesis of coumarin derivatives via C–H cyclization.
Scheme 9: Monobenzoyloxylation without chelation assistance.
Figure 12: Plausible mechanism for the formation of 71 from 70.
Scheme 10: Aryl-substituted arenes prepared by inorganic photoredox catalysis using 12a.
Figure 13: Proposed mechanism for C–H arylations in the presence of 12a and a Pd catalyst.
Scheme 11: Arylation of purines via dual photoredox catalysis.
Scheme 12: Arylation of substituted arenes with an organic photoredox catalyst.
Scheme 13: C–H trifluoromethylation.
Figure 14: Proposed mechanism for the trifluoromethylation of 88.
Scheme 14: Synthesis of benzo-3,4-coumarin derivatives.
Figure 15: Plausible mechanism for the synthesis of substituted coumarins.
Scheme 15: Oxidant-free oxidative phosphonylation.
Figure 16: Mechanism proposed for the phosphonylation reaction of 100.
Scheme 16: Nitration of anilines.
Figure 17: Plausible mechanism for the nitration of aniline derivatives via photoredox catalysis.
Scheme 17: Synthesis of carbazoles via intramolecular amination.
Figure 18: Proposed mechanism for the formation of carbazoles from biaryl derivatives.
Scheme 18: Synthesis of substituted phenols using QuCN.
Figure 19: Mechanism for the synthesis of phenol derivatives with photoredox catalyst 8.
Scheme 19: Synthesis of substituted phenols with DDQ (5).
Figure 20: Possible mechanism for the generation of phenols with the aid of photoredox catalyst 5.
Scheme 20: Aerobic bromination of arenes using an acridinium-based photocatalyst.
Scheme 21: Aerobic bromination of arenes with anthraquinone.
Figure 21: Proposed mechanism for the synthesis of monobrominated compounds.
Scheme 22: Chlorination of benzene derivatives with Mes-Acr-MeClO4 (2).
Figure 22: Mechanism for the synthesis of 131 from 132.
Scheme 23: Chlorination of arenes with 4CzIPN (5a).
Figure 23: Plausible mechanism for the oxidative photocatalytic monochlorination using 5a.
Scheme 24: Monofluorination using QuCN-ClO4 (8).
Scheme 25: Fluorination with fluorine-18.
Scheme 26: Aerobic amination with acridinium catalyst 3a.
Figure 24: Plausible mechanism for the aerobic amination using acridinium catalyst 3a.
Scheme 27: Aerobic aminations with semiconductor photoredox catalyst 18.
Scheme 28: Perfluoroalkylation of arenes.
Scheme 29: Synthesis of benzonitriles in the presence of 3a.
Figure 25: Plausible mechanism for the synthesis of substituted benzonitrile derivatives in the presence of 3a....
A green, economical synthesis of β-ketonitriles and trifunctionalized building blocks from esters and lactones
- Daniel P. Pienaar,
- Kamogelo R. Butsi,
- Amanda L. Rousseau and
- Dean Brady
Beilstein J. Org. Chem. 2019, 15, 2930–2935, doi:10.3762/bjoc.15.287
- hydroxy ester 4 followed by reaction with acetonitrile (CH3CN), a multistep approach would be less economical in industry (Scheme 1). Results and Discussion To date, the most economically appealing conditions from an environmentally friendly perspective entail relatively mild base-promoted (potassium tert
- ether resulted in recovery complications for some of the other compounds (e.g., when this methodology was applied to δ-valerolactone and γ-butyrolactone) and may therefore not be universally beneficial. Conclusion In conclusion, mild, environmentally friendly procedures were developed for the
Graphical Abstract
Scheme 1: Proposed retrosynthesis of the free diol 1.
Scheme 2: Preparation of O-unprotected, trifunctionalized synthons from lactones.
α-Photooxygenation of chiral aldehydes with singlet oxygen
- Dominika J. Walaszek,
- Magdalena Jawiczuk,
- Jakub Durka,
- Olga Drapała and
- Dorota Gryko
Beilstein J. Org. Chem. 2019, 15, 2076–2084, doi:10.3762/bjoc.15.205
- ], TEMPO [4], or benzoyl peroxide [5][6][7][8]. Therefore, the use of environmentally friendly reagents instead is highly desirable. Along this line, singlet oxygen by being easily photochemically generated from triplet oxygen in the presence of organic dyes seems promising. Despite its high reactivity and
Graphical Abstract
Scheme 1: Asymmetric α-photooxygenation of chiral aldehydes.
Scheme 2: α-Photooxygenation of β-substituted aldehydes.
Scheme 3: Synthesis and α-photooxygenation of 3,4-diphenylbutanal (1).
Scheme 4: Stereoselective α-photooxygenation of 3,4-diphenylbutanal (1) with 1O2.
Scheme 5: Schematic representation of the in situ methodology and preferred conformation of diols with Mo2 co...
Figure 1: ECD spectra of diols syn-6 and anti’-6 recorded a) with 19 in DMSO and b) in acetonitrile compared ...
Scheme 6: Asymmetric synthesis of 3,4-diphenylbutane-1,2-diol.
Molecular basis for the plasticity of aromatic prenyltransferases in hapalindole biosynthesis
- Takayoshi Awakawa and
- Ikuro Abe
Beilstein J. Org. Chem. 2019, 15, 1545–1551, doi:10.3762/bjoc.15.157
- useful catalysts that control the regiospecificity in an environmentally friendly manner. The information from their X-ray structures will contribute to future engineering of PTases. Furthermore, the structure of AmbP1 can serve as a model to alter the reaction through creating a metal binding site
Graphical Abstract
Figure 1: The reactions of aromatic PTases.
Figure 2: The reactions catalyzed by AmbP1 (A) and AmbP3 (B).
Figure 3: The overall structure of apo-AmbP1 (A), the Mg2+-free structure (B), and the Mg2+-bound structure (...
Figure 4: The active site structure of AmbP1. 1 and GSPP were bound in the active site without Mg2+ (A, Mg2+-...
Figure 5: The active site structure of AmbP3 with substrates. The AmbP3 structure in complex with hapalindole...
Figure 6: Multiple amino acid sequence alignment of AmbP1, AmbP3, and other ABBA PTases, visualized by ESPrip...
Understanding the unexpected effect of frequency on the kinetics of a covalent reaction under ball-milling conditions
- Ana M. Belenguer,
- Adam A. L. Michalchuk,
- Giulio I. Lampronti and
- Jeremy K. M. Sanders
Beilstein J. Org. Chem. 2019, 15, 1226–1235, doi:10.3762/bjoc.15.120
- crystals into smaller particles followed by the accumulation of energy in crystal defects. In recent years, manual and ball-mill grinding have become increasingly routine solid-state synthesis tools [1]. Generally referred to as mechanochemistry, these methods are more environmentally friendly and usually
Graphical Abstract
Scheme 1: Solid-state exchange reaction through ball-mill grinding under neat ball-mill-grinding conditions (...
Figure 1: Solid-state studies reacting 1-1 and 2-2 in an equimolar ratio in the presence of DBU as catalyst t...
Scheme 2: Schematic representation of a solid + solid mechanochemical reaction. Subscript denote macroscopic ...
Scheme 3: Simplified reaction equation for the mechanochemical transformation. Note that [AB] is a physical c...
Figure 2: Reaction profiles for mechanochemical milling according to Equation 4. (a) Kinetic profiles for 30 Hz, 25 Hz,...
Figure 3: Modelled kinetic profiles for 15 Hz neat milling, with variation in the magnitude of the mixing ter...
Figure 4: Reaction profiles for LAG mechanochemical milling according to Equation 4. The modelled curves are given for ...
Unexpected polymorphism during a catalyzed mechanochemical Knoevenagel condensation
- Sebastian Haferkamp,
- Andrea Paul,
- Adam A. L. Michalchuk and
- Franziska Emmerling
Beilstein J. Org. Chem. 2019, 15, 1141–1148, doi:10.3762/bjoc.15.110
- materials [1]. Interest in these methods stems largely from the fact that they are efficient and more environmentally friendly as compared to traditional approaches [2][3]. Mechanochemistry is a well-established method for the synthesis of coordination polymers, the formation of cocrystals, and in C–C
Graphical Abstract
Scheme 1: Catalyzed mechanochemical Knoevenagel condensation of fluorobenzaldehydes and malonodinitrile. The ...
Figure 1: Comparison of XRPD pattern of malonodinitrile (2) and (p-fluorobenzylidene) malonodinitrile (3a). T...
Figure 2: a) XRPD pattern of (p-fluorobenzylidene)malonodinitrile (3a) direct after the synthesis with differ...
Figure 3: Mass spectra of the different products of 3a. Red: peak off the molecular ion [M + H]+ of piperidin...
Figure 4: a) In situ XRPD pattern of the mechanochemical Knoevenagel condensation of 1a and 2 with 2 µL catal...
Figure 5: Comparison of XRPD patterns of both polymorphs of the product 3a. Red: triclinic polymorph t3a. Blu...
Figure 6: Results of multivariate data analysis of Raman spectra for 30 Hz milling experiments. Principal com...
Precious metal-free molecular machines for solar thermal energy storage
- Meglena I. Kandinska,
- Snejana M. Kitova,
- Vladimira S. Videva,
- Stanimir S. Stoyanov,
- Stanislava B. Yordanova,
- Stanislav B. Baluschev,
- Silvia E. Angelova and
- Aleksey A. Vasilev
Beilstein J. Org. Chem. 2019, 15, 1096–1106, doi:10.3762/bjoc.15.106
- other processes, quenching the photoisomerization; (v) the energy storing MOST materials have to utilize light in the visible range of the spectrum; (vi) it will be a crucial benefit for the MOST technology, if toxic and precious metals are avoided. Focusing on environmentally friendly MOST system is an
Graphical Abstract
Scheme 1: Quaternization of 2-methylbenzothiazoles with alkane sultones.
Scheme 2: Synthesis of 4-(aza-15-crown-5)benzocarbaldehyde (3) [22].
Scheme 3: Synthesis of dyes 4a–d.
Figure 1: a–c) Dependence of the absorption spectra of the dyes 4b, 4c and 4d, respectively (cL = 1.0 × 10−5 ...
Figure 2: Dependence of the fluorescence of 4b on the concentration of the Ba2+ ions. Excitation wavelength λ...
Figure 3: a) Dependence of absorption spectra of dye 4b (cL = 1.0 × 10−4 M) with Ba2+ (cM = 1 M) on the irrad...
Figure 4: UV–vis absorption spectra of dye 4b (1.0 × 10−4 M) free and in complex with Ba2+ (1 M) before and a...
Figure 5: Optimized structures of the cis and trans isomers of dyes 4a–d.
Figure 6: Optimized structures of the Ba2+-complexes of cis and trans isomer of 4b.
Figure 7: Simulated spectra with spectral lifetime broadening TDPBE0 spectra in ACN for dye 4b and its Ba2+ c...
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
- acid catalyst for this transformation. At room temperature, the product of this environmentally friendly Strecker reaction is nitrile derivative 53 (R2 = CN, Scheme 15, method A), while at reflux carboxamide 53 (R2 = CONH2, Scheme 15, method A) is obtained. Notoriously, aromatic amines 2 did not work
- heterocycle containing five- and six-membered fused N-heterocyclic rings (Scheme 16), including the γ-lactam unit. The first synthesis of this class of compounds was reported by Pal et al. [96] with the aid of montmorillonite K10 as a recyclable catalyst in ethanol. With these environmentally friendly
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.
Mechanochemistry of supramolecules
- Anima Bose and
- Prasenjit Mal
Beilstein J. Org. Chem. 2019, 15, 881–900, doi:10.3762/bjoc.15.86
- . Contrastingly, achieving syntheses through mechanochemical methods are generally time-saving, environmentally friendly and more economical. This review is written to shed some light on supramolecular chemistry and the synthesis of various supramolecules through mechanochemistry. Keywords: ball milling
Graphical Abstract
Figure 1: A generalized overview of coordination-driven self-assembly.
Figure 2: Examples of self-assembly or self-sorting and subsequent substitution.
Figure 3: Synthesis of salen-type ligand followed by metal-complex formation in the same pot [55].
Figure 4: Otera’s solvent-free approach by which the formation of self-assembled supramolecules could be acce...
Figure 5: Synthesis of a Pd-based metalla-supramolecular assembly through mechanochemical activation for C–H-...
Figure 6: a) Schematic representation for the construction of a [2]rotaxane. b) Chiu’s ball-milling approach ...
Figure 7: Mechanochemical synthesis of the smallest [2]rotaxane.
Figure 8: Solvent-free mechanochemical synthesis of pillar[5]arene-containing [2]rotaxanes [61].
Figure 9: Mechanochemical liquid-assisted one-pot two-step synthesis of [2]rotaxanes under high-speed vibrati...
Figure 10: Mechanochemical (ball-milling) synthesis of molecular sphere-like nanostructures [63].
Figure 11: High-speed vibration milling (HSVM) synthesis of boronic ester cages of type 22 [64].
Figure 12: Mechanochemical synthesis of borasiloxane-based macrocycles.
Figure 13: Mechanochemical synthesis of 2-dimensional aromatic polyamides.
Figure 14: Nitschke’s tetrahedral Fe(II) cage 25.
Figure 15: Mechanochemical one-pot synthesis of the 22-component [Fe4(AD2)6]4− 26, 11-component [Fe2(BD2)3]2− ...
Figure 16: a) Subcomponent synthesis of catalyst and reagent and b) followed by multicomponent reaction for sy...
Figure 17: A dynamic combinatorial library (DCL) could be self-sorted to two distinct products.
Figure 18: Mechanochemical synthesis of dynamic covalent systems via thermodynamic control.
Figure 19: Preferential formation of hexamer 33 under mechanochemical shaking via non-covalent interactions of...
Figure 20: Anion templated mechanochemical synthesis of macrocycles cycHC[n] by validating the concept of dyna...
Figure 21: Hydrogen-bond-assisted [2 + 2]-cycloaddition reaction through solid-state grinding. Hydrogen-bond d...
Figure 22: Formation of the cage and encapsulation of [2.2]paracyclophane guest molecule in the cage was done ...
Figure 23: Formation of the 1:1 complex C60–tert-butylcalix[4]azulene through mortar and pestle grinding of th...
Figure 24: Formation of a 2:2 complex between the supramolecular catalyst and the reagent in the transition st...
Figure 25: Halogen-bonded co-crystals via a) I···P, b) I···As, and c) I···Sb bonds [112].
Figure 26: Transformation of contact-explosive primary amines and iodine(III) into a successful chemical react...
Figure 27: Undirected C–H functionalization by using the acidic hydrogen to control basicity of the amines [114]. a...
Homo- and hetero-difunctionalized β-cyclodextrins: Short direct synthesis in gram scale and analysis of regiochemistry
- Gábor Benkovics,
- Mihály Bálint,
- Éva Fenyvesi,
- Erzsébet Varga,
- Szabolcs Béni,
- Konstantina Yannakopoulou and
- Milo Malanga
Beilstein J. Org. Chem. 2019, 15, 710–720, doi:10.3762/bjoc.15.66
- the 6A,6B-ditosyl-β-CD prepared in reaction 1, see Supporting Information File 1, Figures S18–S19). In summary, the direct ditosylation in environmentally friendly aqueous medium affords the 6A,6C- and 6A,6D-ditosyl-β-CDs, from which the 6A,6C- and 6A,6D-diazides are obtained in overall 29% and 21
Graphical Abstract
Figure 1: Schematic representation of β-CD with glucopyranose atom numbering and with alphabetic labeling of ...
Scheme 1: Syntheses of 6A,6X-diazido-β-CDs as reference compounds using the “capping” literature method [11,12].
Scheme 2: Syntheses of homo-difunctionalized β-CDs using different reaction conditions.
Figure 2: HPLC chromatograms of the authentic 6A,6X-diazido-β-CDs with known regiochemistry (references 1–3, Scheme 1...
Figure 3: NMR spectral regions of the three ditosyl regioisomers in D2O (500 MHz). The signals of the tosylat...
Scheme 3: Syntheses of 6A-monoazido-6X-monotosyl-β-CDs using starting materials obtained from different react...
Figure 4: Reversed-phase HPLC chromatograms of 6A-monoazido-6X-monotosyl-β-CDs prepared through reactions 4–8....
Figure 5: HPLC separation of regioisomers and pseudoenantiomers of 6A-monoazido-6X-monotosyl-β-CD prepared in...
Figure 6: Reversed-phase HPLC chromatograms of 6A,6X-diazido-β-CDs prepared in reactions 9–13.
Catalyst-free assembly of giant tris(heteroaryl)methanes: synthesis of novel pharmacophoric triads and model sterically crowded tris(heteroaryl/aryl)methyl cation salts
- Rodrigo Abonia,
- Luisa F. Gutiérrez,
- Braulio Insuasty,
- Jairo Quiroga,
- Kenneth K. Laali,
- Chunqing Zhao,
- Gabriela L. Borosky,
- Samantha M. Horwitz and
- Scott D. Bunge
Beilstein J. Org. Chem. 2019, 15, 642–654, doi:10.3762/bjoc.15.60
- ]. Furthermore, it is highly desirable to perform these reactions in environmentally friendly solvents such as water, ethanol, and PEG [6][7]. Motifs bearing triarylmethane (Ar3CH) [8][9][10] and their heterocyclic variants (Het-Ar)3CH [8][9][10][11][12], constitute an integral part of a number of bioactive
- of higher complexity by employing simpler, more efficient, catalytic methods that are also environmentally friendly. Molecular hybridization has emerged as an interesting strategy for the synthesis of bioactive molecules with improved properties by combining two or more pharmacophore fragments in a
Graphical Abstract
Scheme 1: Representative examples of tris(hetero/aryl)methanes, molecular hybrids and bis(indolyl)methanes wi...
Scheme 2: Previous synthetic approaches for the synthesis of triarylmethane analogues in comparison to the pr...
Scheme 3: Synthesis of the starting N-alkylindoles 1{4–10}.
Scheme 4: General procedure for the synthesis of the starting quinoline-/quinolone aldehydes 6{1–7}.
Scheme 5: Chemset of coumarins 7{1–4} for elaboration in the MCR experiments.
Scheme 6: Exploratory reaction leading to isolation of products 8{1,1,1} and 9{1,1,1}.
Figure 1: Pseudo-three-component synthesis of bisindole triads 8 employing quinoline-/quinolone-CHO 6{1–6}, c...
Scheme 7: Chemset of further aldehydes 6{8–10} for elaboration in the MCR experiments.
Figure 2: Three-component synthesis of tris(heteroaryl)methane triads 9. aThis product was obtained as an ins...
Figure 3: Thermal ellipsoid plot (40% probability level) of the tris(heteroaryl)methane triad 9{4,7,1}.
Figure 4: DFT-optimized structure of 9{4,7,1} triad.
Scheme 8: Synthesis of crowed (Het12Het2/Ar2)C+PF6− salts 10.
Figure 5: 1D- and 2D-based NMR assignments for methylium-PF6 salt 10{4,4,8}.
Figure 6: 1D- and 2D-based NMR assignments for methylium-PF6 salt 10{4,4,11}.
Figure 7: Optimized geometry of methylium-PF6 salts 10{4,4,8}.
Figure 8: Optimized geometry of methylium-PF6 salt 10{4,4,11}.
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
- ][24]. Water is inexpensive, non-flammable, non-toxic and environmentally friendly, all characteristics that make it an ideal solvent. Furthermore, water is the media of biochemical reactions, and metathesis is a bioorthogonal reaction that can be exploited in a biological setting. Figure 1 illustrates
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.
Reusable and highly enantioselective water-soluble Ru(II)-Amm-Pheox catalyst for intramolecular cyclopropanation of diazo compounds
- Hamada S. A. Mandour,
- Yoko Nakagawa,
- Masaya Tone,
- Hayato Inoue,
- Nansalmaa Otog,
- Ikuhide Fujisawa,
- Soda Chanthamath and
- Seiji Iwasa
Beilstein J. Org. Chem. 2019, 15, 357–363, doi:10.3762/bjoc.15.31
- diazoamide; Ru(II)-Pheox; water-soluble catalyst; Weinreb amide; Introduction Water-soluble transition metal complexes have been attracting increasing interest for catalytic applications because of their many advantages such as simple product separation, low cost, safety, and environmentally friendly
Graphical Abstract
Figure 1: A comparison of the solubility of Ru(II)-Pheox (cat. 1) and Ru(II)-Amm-Pheox (cat. 2).
Scheme 1: Intramolecular cyclopropanation of various trans-allylic diazo Weinreb amide derivatives catalyzed....
Scheme 2: Synthetic transformation of cyclopropane products 2d and 2f.
Oxidative radical ring-opening/cyclization of cyclopropane derivatives
- Yu Liu,
- Qiao-Lin Wang,
- Zan Chen,
- Cong-Shan Zhou,
- Bi-Quan Xiong,
- Pan-Liang Zhang,
- Chang-An Yang and
- Quan Zhou
Beilstein J. Org. Chem. 2019, 15, 256–278, doi:10.3762/bjoc.15.23
- exploration and many questions to be addressed. Although oxidative radical ring-opening/cyclization of functionalized cyclopropane derivatives has been well developed, the ring-opening/cyclization of common cyclopropane derivatives is conspicuously absent. On the other hand, green and environmentally friendly
Graphical Abstract
Scheme 1: The oxidative radical ring-opening/cyclization of cyclopropane derivatives.
Scheme 2: Mn(OAc)3-mediated oxidative radical ring-opening and cyclization of MCPs with malonates.
Scheme 3: Mn(III)-mediated oxidative radical ring-opening and cyclization of MCPs with 1,3-dicarbonyl compoun...
Scheme 4: Heat-promoted ring-opening/cyclization of MCPs with elemental chalgogens.
Scheme 5: Copper(II) acetate-mediated oxidative radical ring-opening and cyclization of MCPs with diphenyl di...
Scheme 6: AIBN-promoted oxidative radical ring-opening and cyclization of MCPs with benzenethiol.
Scheme 7: AIBN-mediated oxidative radical ring-opening and cyclization of MCPs with diethyl phosphites.
Scheme 8: Organic-selenium induced radical ring-opening and cyclization of MCPs derivatives (cyclopropylaldeh...
Scheme 9: Copper(I)-catalyzed oxidative radical trifluoromethylation/ring-opening/cyclization of MCPs with To...
Scheme 10: Ag(I)-mediated trifluoromethylthiolation/ring-opening/cyclization of MCPs with AgSCF3.
Scheme 11: oxidative radical ring-opening and cyclization of MCPs with α-C(sp3)-–H of ethers.
Scheme 12: Oxidative radical ring-opening and cyclization of MCPs with aldehydes.
Scheme 13: Cu(I) or Fe(II)-catalyzed oxidative radical trifluoromethylation/ring-opening/cyclization of MCPs d...
Scheme 14: Rh(II)-catalyzed oxidative radical ring-opening and cyclization of MCPs.
Scheme 15: Ag(I)-catalyzed oxidative radical amination/ring-opening/cyclization of MCPs derivatives.
Scheme 16: Heating-promoted radical ring-opening and cyclization of MCP derivatives (arylvinylidenecyclopropan...
Scheme 17: Bromine radical-mediated ring-opening of alkylidenecyclopropanes.
Scheme 18: Fluoroalkyl (Rf) radical-mediated ring-opening of MCPs.
Scheme 19: Visible-light-induced alkylation/ring-opening/cyclization of cyclopropyl olefins with bromides.
Scheme 20: Mn(III)-mediated ring-opening and [3 + 3]-annulation of cyclopropanols and vinyl azides.
Scheme 21: Ag(I)-catalyzed oxidative ring-opening of cyclopropanols with quinones.
Scheme 22: Ag(I)-catalyzed oxidative ring-opening of cyclopropanols with heteroarenes.
Scheme 23: Cu(I)-catalyzed oxidative ring-opening/trifluoromethylation of cyclopropanols.
Scheme 24: Cu(I)-catalyzed oxidative ring-opening and trifluoromethylation/trifluoromethylthiolation of cyclop...
Scheme 25: Ag(I)-mediated oxidative ring-opening/fluorination of cyclopropanols with Selectfluor.
Scheme 26: Photocatalyzed ring-opening/fluorination of cyclopropanols with Selectfluor.
Scheme 27: Na2S2O8-promoted ring-opening/alkynylation of cyclopropanols with EBX.
Scheme 28: Ag(I)-catalyzed ring-opening and chlorination of cyclopropanols with aldehydes.
Scheme 29: Ag(I)-catalyzed ring-opening/alkynylation of cyclopropanols with EBX.
Scheme 30: Na2S2O8-promoted ring-opening/alkylation of cyclopropanols with acrylamides.
Scheme 31: Cyclopropanol ring-opening initiated tandem cyclization with acrylamides or 2-isocyanobiphenyls.
Scheme 32: Ag(II)-mediated oxidative ring-opening/fluorination of cyclopropanols with AgF2.
Scheme 33: Cu(II)-catalyzed ring-opening/fluoromethylation of cyclopropanols with sulfinate salts.
Scheme 34: Cu(II)-catalyzed ring-opening/sulfonylation of cyclopropanols with sulfinate salts.
Scheme 35: Na2S2O8-promoted ring-opening/arylation of cyclopropanols with propiolamides.
Scheme 36: The ring-opening and [3 + 2]-annulation of cyclopropanols with α,β-unsaturated aldehydes.
Scheme 37: Cu(II)-catalyzed ring-opening/arylation of cyclopropanols with aromatic nitrogen heterocyles.
Scheme 38: Ag(I)-catalyzed ring-opening and difluoromethylthiolation of cyclopropanols with PhSO2SCF2H.
Scheme 39: Ag(I)-catalyzed ring-opening and acylation of cyclopropanols with aldehydes.
Scheme 40: Aerobic oxidation ring-opening of cyclopropanols for the synthesis of 2-oxyranyl ketones.
Scheme 41: Aerobic oxidation ring-opening of cyclopropanols for the synthesis of linear enones.
Scheme 42: Aerobic oxidation ring-opening of cyclopropanols for the synthesis of metabolite.
Ammonium-tagged ruthenium-based catalysts for olefin metathesis in aqueous media under ultrasound and microwave irradiation
- Łukasz Gułajski,
- Andrzej Tracz,
- Katarzyna Urbaniak,
- Stefan J. Czarnocki,
- Michał Bieniek and
- Tomasz K. Olszewski
Beilstein J. Org. Chem. 2019, 15, 160–166, doi:10.3762/bjoc.15.16
- -heterocyclic carbene (NHC) ligand were revealed. The presented methodology allows for preparation of a variety of polar and non-polar metathesis products under environmentally friendly conditions. Keywords: catalysis; green chemistry; microwave; N-heterocyclic carbene; olefin metathesis; ruthenium; ultrasound
Graphical Abstract
Figure 1: Structures of the Ru-based catalysts used in this study.
The influence of the cationic carbenes on the initiation kinetics of ruthenium-based metathesis catalysts; a DFT study
- Magdalena Jawiczuk,
- Angelika Janaszkiewicz and
- Bartosz Trzaskowski
Beilstein J. Org. Chem. 2018, 14, 2872–2880, doi:10.3762/bjoc.14.266
- stable in water and, therefore, environmentally-friendly. The idea of incorporating a quaternary ammonium moiety into the imidazole part of the carbene was later expanded by several other groups, including a number of new water-soluble catalysts synthesized by Skowerski et al. [23][24]. In the meantime
Graphical Abstract
Scheme 1: NHC’s and their ruthenium complexes studied in this work; L = carbene 1, 2 or 3.
Scheme 2: Schematic representation of carbene dimerization and atom numbering scheme used throughout this wor...
Scheme 3: Dissociative mechanism of initiation for Grubbs-like 1–3-GrI and M1 indenylidene type complexes 1–3...
Scheme 4: Dissociative mechanism of initiation of 2nd generation Grubbs-like saturated 1–3-GrII and unsaturat...
Scheme 5: Dissociative mechanism of activation for complexes 1–3-Hov; L = carbene 1, 2 or 3.
