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Search for "recyclable" in Full Text gives 84 result(s) in Beilstein Journal of Organic Chemistry.
Green and sustainable approaches for the Friedel–Crafts reaction between aldehydes and indoles
- Periklis X. Kolagkis,
- Eirini M. Galathri and
- Christoforos G. Kokotos
Beilstein J. Org. Chem. 2024, 20, 379–426, doi:10.3762/bjoc.20.36
- introduced nano n-propylsulfonated γ-Fe2O3 (NPS-γ-Fe2O3), which constitutes a magnetically recyclable heterogeneous catalyst that works in the exact same manner as HPA/TPI-Fe3O4 [103]. Some small differences between the two methods were the ability of ketones to form the respective BIMs, when NPS-γ-Fe2O3 was
- various oxidation and hydrogenation reactions [105]. NanoAg-Pt doped silicate constitutes an efficient and recyclable catalyst that can be reused without a notable loss in catalytic activity (Scheme 17). Wanting to avoid the use of conventional heating, Karthikeyan and his co-workers turned to microwave
Graphical Abstract
Scheme 1: Examples of BIMs used for their medicinal properties.
Scheme 2: Mechanisms for the synthesis of BIMs using protic or Lewis acids as catalysts.
Scheme 3: Synthesis of bis(indolyl)methanes using DBDMH.
Scheme 4: Competition experiments and synthesis of bis(indolyl)methanes using DBDMH.
Scheme 5: Proposed mechanism for formation of BIM of using DBDMH.
Scheme 6: Synthesis of bis(indolyl)methanes using I2.
Scheme 7: General reaction mechanism upon halogen bonding.
Scheme 8: Synthesis of bis(indolyl)methanes using I2, introduced by Ji.
Scheme 9: Synthesis of bis(indolyl)methanes using Br2 in CH3CN.
Scheme 10: Βidentate halogen-bond donors.
Scheme 11: Synthesis of bis(indolyl)methanes using bidentate halogen-bond donor 26.
Scheme 12: Proposed reaction mechanism.
Scheme 13: Synthesis of bis(indolyl)methanes using iodoalkyne as catalyst.
Scheme 14: Proposed reaction mechanism.
Scheme 15: Optimized reaction conditions used by Ramshini.
Scheme 16: Activation of the carbonyl group by HPA/TPI-Fe3O4.
Scheme 17: Synthesis of BIMs in the presence of nanoAg-Pt/SiO2-doped silicate.
Scheme 18: Mechanism of action proposed by Khalafi-Nezhad et al.
Scheme 19: Activation of the carbonyl group by the Cu–isatin Schiff base complex.
Scheme 20: Optimum reaction conditions published by Jain.
Scheme 21: Organocatalytic protocol utilizing nanoparticles introduced by Bankar.
Scheme 22: Activation of the carbonyl group by the AlCl3·6H2O-SDS-SiO2 complex.
Scheme 23: Optimal reaction conditions for the aforementioned nano-Fe3O4 based catalysts.
Scheme 24: Nanocatalytic protocol proposed by Kaur et al.
Scheme 25: Microwave approach introduced by Yuan.
Scheme 26: Microwave approach introduced by Zahran et al.
Scheme 27: Microwave irradiation protocol introduced by Bindu.
Scheme 28: Silica-supported microwave irradiation protocol.
Scheme 29: Proposed mechanism for formation of BIM by Nongkhlaw.
Scheme 30: Microwave-assisted synthesis of BIMs catalyzed by succinic acid.
Scheme 31: Proposed mechanism of action of MMO-4.
Scheme 32: Catalytic approach introduced by Muhammadpoor-Baltork et al.
Scheme 33: Reaction conditions used by Xiao-Ming.
Scheme 34: Ultrasonic irradiation-based protocol published by Saeednia.
Scheme 35: Pyruvic acid-mediated synthesis of BIMs proposed by Thopate.
Scheme 36: Synthesis of BIMs using [bmim]BF4 or [bmim]PF6 ionic liquids.
Scheme 37: Synthesis of BIMs utilizing In(OTf)3 in octylmethylimidazolium hexafluorophosphate as ionic liquid.
Scheme 38: FeCl3·6H2O-catalyzed synthesis of BIMs with use of ionic liquid.
Scheme 39: Synthesis of BIMs utilizing the [hmim]HSO4/EtOH catalytic system.
Scheme 40: Synthesis of BIMs utilizing acidic ionic liquid immobilized on silica gel (ILIS-SO2Cl).
Scheme 41: The [bmim][MeSO4]-catalyzed reaction of indole with various aldehydes.
Scheme 42: The role of [bmim][MeSO4] in catalyzing the reaction of indole with aldehydes.
Scheme 43: Synthesis of BIMs utilizing FeCl3-based ionic liquid ([BTBAC]Cl-FeCl3) as catalyst.
Scheme 44: Synthesis of BIMs using [Msim]Cl at room temperature.
Scheme 45: [Et3NH][H2PO4]-catalyzed synthesis of bis(indolyl)methanes.
Scheme 46: PILs-catalyzed synthesis of bis(indolyl)methanes.
Scheme 47: FSILs-mediated synthesis of bis(indolyl)methanes.
Scheme 48: Possible “release and catch” catalytic process.
Scheme 49: Synthesis of bis(indolyl)methanes by [DABCO-H][HSO4].
Scheme 50: Synthesis of bis(indolyl)methanes by [(THA)(SO4)].
Scheme 51: Synthesis of BBSI-Cl and BBSI-HSO4.
Scheme 52: Synthesis of BIMs in the presence of BBSI-Cl and BBSI-HSO4.
Scheme 53: Chemoselectivity of the present method.
Scheme 54: Synthesis of BIMs catalyzed by chitosan-supported ionic liquid.
Scheme 55: Proposed mechanism of action of CSIL.
Scheme 56: Optimization of the reaction in DESs.
Scheme 57: Synthesis of BIMs using ChCl/SnCl2 as DES.
Scheme 58: Synthesis of BIMs derivatives in presence of DES.
Scheme 59: BIMs synthesis in choline chloride/urea (CC/U).
Scheme 60: Flow chemistry-based synthesis of BIMs by Ley.
Scheme 61: Flow chemistry-based synthesis of BIMs proposed by Nam et al.
Scheme 62: Amino-catalyzed reaction of indole with propionaldehyde.
Scheme 63: Aminocatalytic synthesis of BIMs.
Scheme 64: Proposed mechanism for the aminocatalytic synthesis of BIMs.
Scheme 65: Enzymatic reaction of indole with aldehydes.
Scheme 66: Proposed mechanism for the synthesis of BIMs catalyzed by TLIM.
Scheme 67: Proposed reaction mechanism by Badsara.
Scheme 68: Mechanism proposed by D’Auria.
Scheme 69: Photoinduced thiourea catalysis.
Scheme 70: Proposed mechanism of photoacid activation.
Scheme 71: Proposed mechanism of action for CF3SO2Na.
Scheme 72: Proposed mechanism for the synthesis of BIMs by Mandawad.
Scheme 73: Proposed mechanism for the (a) acid generation and (b) synthesis of BIMs.
Scheme 74: a) Reaction conditions employed by Khaksar and b) activation of the carbonyl group by HFIP.
Scheme 75: Activation of the carbonyl group by the PPy@CH2Br through the formation of a halogen bond.
Scheme 76: Reaction conditions utilized by Mhaldar et al.
Scheme 77: a) Reaction conditions employed by López and b) activation of the carbonyl group by thiourea.
Scheme 78: Infrared irradiation approach introduced by Luna-Mora and his research group.
Scheme 79: Synthesis of BIMs with the use of the Fe–Zn BMOF.
A novel recyclable organocatalyst for the gram-scale enantioselective synthesis of (S)-baclofen
- Gyula Dargó,
- Dóra Erdélyi,
- Balázs Molnár,
- Péter Kisszékelyi,
- Zsófia Garádi and
- József Kupai
Beilstein J. Org. Chem. 2023, 19, 1811–1824, doi:10.3762/bjoc.19.133
- recycling of the organocatalysts can be achieved in a simple step by centrifugation or filtration. Previously, we have demonstrated the homogeneous and heterogeneous recycling of cinchona-based organocatalysts [20][25][26][29]. Continuing our work, we aimed to synthesize a novel, recyclable lipophilic
- this catalyst easily by incorporating a lipophilic unit, which leads to a drastic increase (5.78 to 28.8) in the logP value of the organocatalyst 2. The recyclable organocatalyst can be divided into three units: the catalytic unit, the linker, and the lipophilic tag with octadecyl chains (Figure 1
- literature [41]. Application of cinchona squaramide 1 and recyclable, lipophilic cinchona squaramide organocatalysts 2 in a new, gram-scale stereoselective synthesis of baclofen precursor. Classification of the tested non-polar solvents according to the GSK’s solvent sustainability guide [34]. Recycling of
Graphical Abstract
Figure 1: Application of cinchona squaramide 1 and recyclable, lipophilic cinchona squaramide organocatalysts ...
Scheme 1: Synthesis of demethylated cinchona squaramide organocatalyst and the incorporation of the flexible ...
Scheme 2: Synthesis of the lipophilic tag from methyl gallate (8) and attachment to the cinchona squaramide.
Figure 2: Classification of the tested non-polar solvents according to the GSK’s solvent sustainability guide ...
Figure 3: Recycling of the lipophilic organocatalyst in the stereoselective Michael addition by replacing the...
Scheme 3: A new, stereoselective synthetic route for baclofen.
Scheme 4: Gram-scale synthesis of (S)-baclofen hydrochloride.
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
- ) [70]. We expected that using olefinic oxindoles 14 as alkenes for the [3 + 2] cycloaddition could afford spirooxindole-pyrrolizidines. The method development revealed that recyclable zeolite HY acid is a good catalyst for the cycloaddition [70]. Thus, the zeolite HY-catalyzed reaction of glycine with
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).
Selective construction of dispiro[indoline-3,2'-quinoline-3',3''-indoline] and dispiro[indoline-3,2'-pyrrole-3',3''-indoline] via three-component reaction
- Ziying Xiao,
- Fengshun Xu,
- Jing Sun and
- Chao-Guo Yan
Beilstein J. Org. Chem. 2023, 19, 1234–1242, doi:10.3762/bjoc.19.91
- multicomponent reactions have been successfully developed to construct multifunctionalized or polycyclic spirooxindoles. For example, Zhang successfully developed a recyclable bifunctional cinchona/thiourea-catalyzed four-component Michael/Mannich cyclization sequence for the asymmetric synthesis of
Graphical Abstract
Scheme 1: Representative cascade reactions of Michael adducts of 3-methyleneoxindoles.
Figure 1: Crystal structure of dispiro compound 3a.
Figure 2: Crystal structure of compound 4a.
Scheme 2: Proposed reaction mechanism.
Enabling artificial photosynthesis systems with molecular recycling: A review of photo- and electrochemical methods for regenerating organic sacrificial electron donors
- Grace A. Lowe
Beilstein J. Org. Chem. 2023, 19, 1198–1215, doi:10.3762/bjoc.19.88
- artificial photosynthesis. Systems for photocatalytic carbon dioxide reduction are optimized using sacrificial electron donors. One strategy for coupling carbon dioxide reduction and water oxidation to achieve artificial photosynthesis is to use a redox mediator, or recyclable electron donor. This review
- decoupled water splitting research, are introduced as alternative recyclable sacrificial electron donors and their oxidation potentials are compared to the redox potentials of some model photosensitizers. The aim of this review is to act as a reference for researchers developing photocatalytic systems with
- sacrificial electron donors, and for researchers interested in designing new redox mediator and recyclable electron donor species. Keywords: artificial photosynthesis; photocatalysis; redox couple; sacrificial electron donor; solar fuels; Introduction Artificial photosynthesis research has resulted in the
Graphical Abstract
Figure 1: Diagram comparing the two reaction pathways for sacrificial electron donors (SD) in photocatalyzed ...
Figure 2: Diagram showing water-splitting systems developed by Girault, Scanlon, and co-workers that employ i...
Figure 3: Diagram illustrating the transfer of electrons in a photocatalytic particulate suspensions Z-scheme...
Figure 4: A. Structures of the molecules represented in part B. The numbers in brackets correspond to the com...
Figure 5: A. Structures of the molecules represented in part B. The numbers in brackets correspond to the com...
Clauson–Kaas pyrrole synthesis using diverse catalysts: a transition from conventional to greener approach
- Dileep Kumar Singh and
- Rajesh Kumar
Beilstein J. Org. Chem. 2023, 19, 928–955, doi:10.3762/bjoc.19.71
- 2013, Zhang and co-workers [67] reported the preparation of a new recyclable magnetic nanoparticle-supported antimony catalyst (γ-Fe2O3@SiO2-Sb-IL) and its application in the filtration-free, Clauson–Kaas synthesis of N-substituted pyrroles. This catalyst is fairly easy to make, air stable, and
- of reaction. Mahmoudi and Jafari [85] reported the preparation of a new on magnetic nanoparticles sulfonic acid-supported catalyst with maghemite coating as a magnetically recyclable catalyst Fe3O4@-γ-Fe2O3-SO3H. This heterogeneous catalyst is used for the synthesis of N-substituted pyrrole
Graphical Abstract
Figure 1: Various pyrrole containing molecules.
Scheme 1: Various synthestic protocols for the synthesis of pyrroles.
Figure 2: A tree-diagram showing various conventional and green protocols for Clauson-Kaas pyrrole synthesis.
Scheme 2: A general reaction of Clauson–Kaas pyrrole synthesis and proposed mechanism.
Scheme 3: AcOH-catalyzed synthesis of pyrroles 5 and 7.
Scheme 4: Synthesis of N-substituted pyrroles 9.
Scheme 5: P2O5-catalyzed synthesis of N-substituted pyrroles 11.
Scheme 6: p-Chloropyridine hydrochloride-catalyzed synthesis of pyrroles 13.
Scheme 7: TfOH-catalyzed synthesis of N-sulfonylpyrroles 15, N-sulfonylindole 16, N-sulfonylcarbazole 17.
Scheme 8: Scandium triflate-catalyzed synthesis of N-substituted pyrroles 19.
Scheme 9: MgI2 etherate-catalyzed synthesis and proposed mechanism of N-arylpyrrole derivatives 21.
Scheme 10: Nicotinamide catalyzed synthesis of pyrroles 23.
Scheme 11: ZrOCl2∙8H2O catalyzed synthesis and proposed mechanism of pyrrole derivatives 25.
Scheme 12: AcONa catalyzed synthesis of N-substituted pyrroles 27.
Scheme 13: Squaric acid-catalyzed synthesis and proposed mechanism of N-substituted pyrroles 29.
Figure 3: Reusability of catalyst γ-Fe2O3@SiO2-Sb-IL in six cycles.
Scheme 14: Magnetic nanoparticle-supported antimony catalyst used in the synthesis of N-substituted pyrroles 31...
Scheme 15: Iron(III) chloride-catalyzed synthesis of N-substituted pyrroles 33.
Scheme 16: Copper-catalyzed Clauson–Kaas synthesis and mechanism of pyrroles 35.
Scheme 17: β-CD-SO3H-catalyzed synthesis and proposed mechanism of pyrroles 37.
Figure 4: Recyclability of β-cyclodextrin-SO3H.
Scheme 18: Solvent-free and catalyst-free synthesis and plausible mechanism of N-substituted pyrroles 39.
Scheme 19: Nano-sulfated TiO2-catalyzed synthesis of N-substituted pyrroles 41.
Figure 5: Plausible mechanism for the formation of N-substituted pyrroles catalyzed by nano-sulfated TiO2 cat...
Scheme 20: Copper nitrate-catalyzed Clauson–Kaas synthesis and mechanism of N-substituted pyrroles 43.
Scheme 21: Synthesis of N-substituted pyrroles 45 by using Co catalyst Co/NGr-C@SiO2-L.
Scheme 22: Zinc-catalyzed synthesis of N-arylpyrroles 47.
Scheme 23: Silica sulfuric acid-catalyzed synthesis of pyrrole derivatives 49.
Scheme 24: Bismuth nitrate-catalyzed synthesis of pyrroles 51.
Scheme 25: L-(+)-tartaric acid-choline chloride-catalyzed Clauson–Kaas synthesis and plausible mechanism of py...
Scheme 26: Microwave-assisted synthesis of N-substituted pyrroles 55 in AcOH or water.
Scheme 27: Synthesis of pyrrole derivatives 57 using a nano-organocatalyst.
Figure 6: Nano-ferric supported glutathione organocatalyst.
Scheme 28: Microwave-assisted synthesis of N-substituted pyrroles 59 in water.
Scheme 29: Iodine-catalyzed synthesis and proposed mechanism of pyrroles 61.
Scheme 30: H3PW12O40/SiO2-catalyzed synthesis of N-substituted pyrroles 63.
Scheme 31: Fe3O4@-γ-Fe2O3-SO3H-catalyzed synthesis of pyrroles 65.
Scheme 32: Mn(NO3)2·4H2O-catalyzed synthesis and proposed mechanism of pyrroles 67.
Scheme 33: p-TsOH∙H2O-catalyzed (method 1) and MW-assisted (method 2) synthesis of N-sulfonylpyrroles 69.
Scheme 34: ([hmim][HSO4]-catalyzed Clauson–Kaas synthesis of pyrroles 71.
Scheme 35: Synthesis of N-substituted pyrroles 73 using K-10 montmorillonite catalyst.
Scheme 36: CeCl3∙7H2O-catalyzed Clauson–Kaas synthesis of pyrroles 75.
Scheme 37: Synthesis of N-substituted pyrroles 77 using Bi(NO3)3∙5H2O.
Scheme 38: Oxone-catalyzed synthesis and proposed mechanism of N-substituted pyrroles 79.
One-pot double annulations to confer diastereoselective spirooxindolepyrrolothiazoles
- Juan Lu,
- Bin Yao,
- Desheng Zhan,
- Zhuo Sun,
- Yun Ji and
- Xiaofeng Zhang
Beilstein J. Org. Chem. 2022, 18, 1607–1616, doi:10.3762/bjoc.18.171
- one-pot reactions with recyclable organocatalysts [69]. Notably, we conferred K10 acid to promote the C–H activation in the synthesis of spirooxindolepyrrolidines, and used Zeolite HY catalyst to synthesize diastereoselective dispiro[oxindolepyrrolidine]s with a butterfly shape (Scheme 1A and 1B) [70
Graphical Abstract
Scheme 1: The diastereoselective synthesis of spirooxindoles through MCRs.
Figure 1: Bioactive Spirooxindole-pyrrolothiazoles.
Scheme 2: The synthesis of spirooxindolepyrrolothiazoles.
Scheme 3: Four-component reaction for the synthesis of compound 5.
Scheme 4: Proposed mechanism for the double [3 + 2] cycloadditions.
Scheme 5: The synthesis of compound 5a with ᴅ- and ʟ-cysteine.
Scheme 6: Two-step (process A) vs cascade (process B) synthesis of 5a. i) 1.0:1.15 of 1a/2, EtOH (0.05 M), 25...
Figure 2: Graphical representation of the green metrics (AE, AEf, CE, RME, OE and MP) analysis for processes ...
Figure 3: Graphical representation of the green metrics (PMI, E-factor, and SI) analysis for processes A and ...
Heterogeneous metallaphotoredox catalysis in a continuous-flow packed-bed reactor
- Wei-Hsin Hsu,
- Susanne Reischauer,
- Peter H. Seeberger,
- Bartholomäus Pieber and
- Dario Cambié
Beilstein J. Org. Chem. 2022, 18, 1123–1130, doi:10.3762/bjoc.18.115
- light-mediated carbon–heteroatom cross-couplings of sodium sulfinates, carboxylic acids and sulphonamides with aryl halides (Figure 2) [28]. Although recyclable, batch reactions are characterized by long reaction times (24 h). Here, we present a detailed investigation of a continuous-flow strategy for
Graphical Abstract
Figure 1: Different approaches to heterogeneous photochemistry in flow. a) Serial micro-batch reactors (SMBR)...
Figure 2: Light-mediated carbon–heteroatom cross-couplings. The yields reported are the NMR yields obtained i...
Figure 3: Flow diagram of the experimental setup loaded in an injection loop with the reaction mixture.
Figure 4: Flow diagram of the experimental setup adopted and time necessary to obtain steady-state conditions...
Figure 5: The production campaign of 1 for a seven day experiment.
Figure 6: Photo of the packed column with a helical static mixer (polished SS316, 10 cm length, 15 mixing ele...
Scheme 1: C–O coupling between 4-iodobenzotrifluoride and N-(Boc)-proline.
Recent developments and trends in the iron- and cobalt-catalyzed Sonogashira reactions
- Surendran Amrutha,
- Sankaran Radhika and
- Gopinathan Anilkumar
Beilstein J. Org. Chem. 2022, 18, 262–285, doi:10.3762/bjoc.18.31
- , recyclable, and selective for the coupling between aryl halides and phenylacetylene in PEG as the solvent (Scheme 22). The effect of various reaction parameters such as solvent, base, temperature, and catalyst loading was assessed by the model reaction between bromobenzene and phenylacetylene. Optimization
- recyclable bimetallic magnetic particles called Fe3O4@PEG/Cu-Co, was found to be effective in catalyzing the Sonogashira coupling of aryl halides and phenylacetylene in water as the solvent (Scheme 32) [44]. Aryl halides containing functional groups such as amino, hydroxy, carboxy or formyl, were found
Graphical Abstract
Scheme 1: One pot Sonogashira coupling of aryl iodides with arylynols in the presence of iron(III) chloride h...
Scheme 2: The iron-catalyzed Sonogashira coupling of aryl iodides with terminal acetylenes in water under aer...
Scheme 3: Sonogashira coupling of aryl halides and phenylacetylene in the presence of iron nanoparticles.
Scheme 4: Sonogashira coupling catalyzed by a silica-supported heterogeneous Fe(III) catalyst.
Scheme 5: Suggested catalytic cycle for the Sonogashira coupling using a silica-supported heterogeneous Fe(II...
Scheme 6: Chemoselective iron-catalyzed cross coupling of 4-bromo-1-cyclohexen-1-yltrifluromethane sulfonate ...
Scheme 7: Fe-catalyzed Sonogashira coupling between terminal alkynes and aryl iodides.
Scheme 8: Iron-catalyzed domino Sonogashira coupling and hydroalkoxylation.
Scheme 9: Sonogashira coupling of aryl halides and phenylacetylene in the presence of Fe(III) acetylacetonate...
Scheme 10: Sonogashira coupling of aryl iodides and alkynes with Fe(acac)3/2,2-bipyridine catalyst.
Scheme 11: Sonogashira cross-coupling of terminal alkynes with aryl iodides in the presence of Fe powder/ PPh3...
Scheme 12: α-Fe2O3 nanoparticles-catalyzed coupling of phenylacetylene with aryl iodides.
Scheme 13: Sonogashira cross-coupling reaction between phenylacetylene and 4-substituted iodobenzenes catalyze...
Scheme 14: One-pot synthesis of 2-arylbenzo[b]furans via tandem Sonogashira coupling–cyclization protocol.
Scheme 15: Suggested mechanism of the Fe(III) catalyzed coupling of o-iodophenol with acetylene derivatives.
Scheme 16: Fe3O4@SiO2/Schiff base/Fe(II)-catalyzed Sonogashira–Hagihara coupling reaction.
Scheme 17: Sonogashira coupling using the Fe(II)(bdmd) catalyst in DMF/1,4-dioxane.
Scheme 18: Synthesis of 7-azaindoles using Fe(acac)3 as catalyst.
Scheme 19: Plausible mechanistic pathway for the synthesis of 7-azaindoles.
Scheme 20: Synthesis of Co@imine-POP catalyst.
Scheme 21: Sonogashira coupling of various arylhalides and phenylacetylene in the presence of Co@imine-POP cat...
Scheme 22: Sonogashira coupling of aryl halides and phenylacetylene using Co-DMM@MNPs/chitosan.
Scheme 23: Sonogashira cross-coupling of aryl halides with terminal acetylenes in the presence of Co-NHC@MWCNT...
Scheme 24: Sonogashira cross-coupling of aryl halides with terminal acetylenes in the presence of Co nanoparti...
Scheme 25: Sonogashira coupling reaction of aryl halides with phenylacetylene in the presence of Co nanopartic...
Scheme 26: PdCoNPs-3DG nanocomposite-catalyzed Sonogashira cross coupling of aryl halide and terminal alkynes.
Scheme 27: Sonogashira cross-coupling of aryl halides and phenylacetylene in the presence of graphene-supporte...
Scheme 28: Sonogashira cross-coupling with Pd/Co ANP-PPI-graphene.
Scheme 29: Pd-Co-1(H)-catalyzed Sonogashira coupling reaction.
Scheme 30: The coupling of aryl halides with terminal alkynes using cobalt hollow nanospheres as catalyst.
Scheme 31: A plausible mechanism for the cobalt-catalyzed Sonogashira coupling reaction.
Scheme 32: Sonogashira cross-coupling reaction of arylhalides with phenylacetylene catalyzed by Fe3O4@PEG/Cu-C...
Scheme 33: Plausible mechanism of Sonogashira cross-coupling reaction catalyzed by Fe3O4@PEG/Cu-Co.
Scheme 34: Sonogashira coupling reaction of para-substituted bromobenzenes with phenylacetylene in the presenc...
Scheme 35: Possible mechanism for the visible light-assisted cobalt complex-catalyzed Sonogashira coupling. (R...
Scheme 36: Sonogashira cross-coupling of aryl halides and phenylacetylene using cobalt as additive.
Scheme 37: Plausible mechanism of Sonogashira cross-coupling reaction over [LaPd*]. (Reproduced with permissio...
Green synthesis of C5–C6-unsubstituted 1,4-DHP scaffolds using an efficient Ni–chitosan nanocatalyst under ultrasonic conditions
- Soumyadip Basu,
- Sauvik Chatterjee,
- Suman Ray,
- Suvendu Maity,
- Prasanta Ghosh,
- Asim Bhaumik and
- Chhanda Mukhopadhyay
Beilstein J. Org. Chem. 2022, 18, 133–142, doi:10.3762/bjoc.18.14
- , India Department of Chemistry, Presidency University, Kolkata-700073, India Department of Chemistry, R. K. Mission Residential College, Narendrapur, Kolkata-700103, India 10.3762/bjoc.18.14 Abstract A heterogeneous and magnetically recyclable Ni–chitosan nanocatalyst was synthesized and thoroughly
- yield, the use of an eco-friendly solvent and a recyclable nanocatalyst, as well as reaction at room temperature. Keywords: 1,4-DHPs; green synthesis; magnetically recyclable catalyst; Ni–chitosan nanoparticles; ultrasonication; Introduction Homogeneous catalysts, despite having an outstanding
- , we synthesized a Ni–chitosan complex and exploited the coordination properties of the complex to use it as an effective and recyclable catalyst towards the green synthesis of C5–C6-unsubstituted 1,4-dihydropyridine (1,4-DHP) scaffolds. Ultrasonic irradiation is an important technique in the toolbox
Graphical Abstract
Figure 1: FTIR spectra of (a) the Ni–chitosan NPs and (b) bare chitosan.
Figure 2: PXRD data for the Ni–chitosan NPs.
Figure 3: TEM (a and b) and SEM images (c and d) of the Ni–chitosan NPs.
Figure 4: EDX spectrum of the Ni–chitosan NPs.
Figure 5: Synthesis of dialkyl 1,4-dihydropyridine-2,3-dicarboxylate derivatives.
Figure 6: ORTEP representation of product 4a (CCDC 1949329).
Scheme 1: A plausible mechanistic route for the synthesis of C5–C6-unsubstituted 1,4-DHP derivatives using th...
Figure 7: Recycling experiment of the Ni–chitosan nanocatalyst.
Catalyzed and uncatalyzed procedures for the syntheses of isomeric covalent multi-indolyl hetero non-metallides: an account
- Ranadeep Talukdar
Beilstein J. Org. Chem. 2021, 17, 2102–2122, doi:10.3762/bjoc.17.137
- with 5-iodoindole (182) in the presence of thiourea and a recyclable CuO nanoparticle catalyst (Scheme 26) [116]. This heterogeneous catalysis strategy bypasses the use of unpleasant aryl thiols, which are generally coupled with other aryl halides in the presence of transition-metal catalysts for
Graphical Abstract
Scheme 1: Synthesis of 2,2’-bis(indole)borinic ester 3.
Scheme 2: Synthesis of 2,2’-bisindole NHC·boranes by an SEAr mechanism.
Scheme 3: Syntheses of indolyl amines through Buchwald–Hartwig cross coupling.
Scheme 4: Synthesis of 3,3’-bis(indolyl) ethers.
Scheme 5: C–H silylation of indoles.
Scheme 6: n-BuLi-mediated syntheses of bis(indol-3-yl)silanes.
Scheme 7: Acid-catalyzed syntheses of bis(indol-3-yl)silanes and mechanisms.
Scheme 8: B(C6F5)3 and Al(C6F5)3-catalyzed syntheses of bis(indol-3-yl)silanes reported by Han.
Scheme 9: Base-mediated syntheses of bis and tris(indol-2-yl)phosphines.
Scheme 10: Synthesis of bis(indol-2-yl)sulfides using SL2-type reagents.
Scheme 11: Synthesis of 2,3’- and 2,2’-bis(indolyl)sulfides using disulfides as substrates.
Scheme 12: Synthesis of diindol-2-ylsulfide (84) from 2-iodoindole (92) and thiourea.
Scheme 13: Synthesis of bis(indol-3-yl)sulfides using N-silylated 3-bromoindole 93.
Scheme 14: Fischer indole synthesis of bis(indol-3-yl)sulfides using thio diketones.
Scheme 15: Oxidative synthesis of bis(indol-3-yl)sulfides using indoles and elemental sulfur.
Scheme 16: Synthesis of bis(indol-3-yl)sulfides using sulfoxides as sulfur source.
Scheme 17: Syntheses of bis(indol-2-yl)selanes.
Scheme 18: Syntheses of bis(indol-3-yl)selanes.
Scheme 19: Synthesis of bis(indol-2-yl)tellane 147.
Scheme 20: Synthesis of tris(indolyl)borane 154.
Scheme 21: Synthesis of bis(indol-4-yl)amines 159.
Scheme 22: Synthesis of bis(indol-5-yl)amines.
Scheme 23: Synthesis of 6,5’/6,6’-bis(indolyl)amines.
Scheme 24: Synthesis of potent HIV-inhibitors 6,6’-bis(indolyl) ethers.
Scheme 25: Synthesis of bis(indol-7-yl) ether.
Scheme 26: Synthesis of di(indol-5-yl)sulfide (183).
Scheme 27: Syntheses of 2,2’-diformyl-7,7’-bis(indolyl)selenides.
A recent overview on the synthesis of 1,4,5-trisubstituted 1,2,3-triazoles
- Pezhman Shiri,
- Ali Mohammad Amani and
- Thomas Mayer-Gall
Beilstein J. Org. Chem. 2021, 17, 1600–1628, doi:10.3762/bjoc.17.114
- bond functionalization reaction sequence with triazole-bearing aryl iodide 140, catalyzed by alloy-structured Pd/Cu bimetallic nanoparticles stabilized by a binaphthyl moiety, Pd/Cu-BNP 139. The Pd/Cu-BNP nanoparticles 139 were demonstrated to be an efficient and recyclable catalyst, and triazoles
- methodology for aerobic C–H activation; ii) PEG as green and recyclable reaction medium; and iii) a reusable palladium catalyst complex [65]. Fully functionalized 1,2,3-triazolo-fused chromenes 162, 164, and 166 were regioselectively prepared in moderate yield. The isoindoline-fused triazoles 164 were
Graphical Abstract
Figure 1: Some significant triazole derivatives [8,23-27].
Scheme 1: A general comparison between synthetic routes for disubstituted 1,2,3-triazole derivatives and full...
Scheme 2: Synthesis of formyltriazoles 3 from the treatment of α-bromoacroleins 1 with azides 2.
Scheme 3: A probable mechanism for the synthesis of formyltriazoles 5 from the treatment of α-bromoacroleins 1...
Scheme 4: Synthesis of 1,4,5-trisubstituted 1,2,3-triazoles 8 from the reaction of aryl azides 7 with enamino...
Scheme 5: Proposed mechanism for the synthesis of 1,4,5-trisubstituted 1,2,3-triazoles from the reaction of a...
Scheme 6: Synthesis of 1,4,5-trisubstituted 1,2,3-triazoles 11 from the reaction of primary amines 10 with 1,...
Scheme 7: The proposed mechanism for the synthesis of 1,4,5-trisubstituted 1,2,3-triazoles 11 from the reacti...
Scheme 8: Synthesis of fully decorated 1,2,3-triazoles 19 containing a sulfur-based side chain.
Scheme 9: Mechanism for the formation of fully decorated 1,2,3-triazoles 19 containing a sulfur-based side ch...
Scheme 10: Synthesis of fully decorated 1,2,3-triazole compounds 25 through the regioselective addition and cy...
Scheme 11: A reasonable mechanism for the synthesis of fully decorated 1,2,3-triazole compounds 25 through the...
Scheme 12: Synthesis of 1,4,5-trisubstituted glycosyl-containing 1,2,3-triazole derivatives 30 from the reacti...
Scheme 13: Synthesis of 1,4,5-trisubstituted 1,2,3-triazoles 34 via intramolecular cyclization reaction of ket...
Scheme 14: Synthesis of fully decorated 1,2,3-triazoles 38 from the reaction of aldehydes 35, amines 36, and α...
Scheme 15: A reasonable mechanism for the synthesis of fully decorated 1,2,3-triazoles 38 from the reaction of...
Scheme 16: Synthesis of functionally rich double C- and N-vinylated 1,2,3-triazoles 45 and 47.
Scheme 17: Synthesis of disubstituted 4-chloro-, 4-bromo-, and 4-iodo-1,2,3-triazoles 50.
Scheme 18: a) A general route for SPAAC in polymer chemistry and b) synthesis of a novel pH-sensitive polymeri...
Scheme 19: Synthesis of 5-allenyl-1,2,3-triazoles 60 by the treatment of alkynes 57, azides 58, and propargyli...
Scheme 20: A reasonable mechanism for the synthesis of 5-allenyl-1,2,3-triazoles 60 by the treatment of alkyne...
Scheme 21: Synthesis of 5‐alkynyl-1,2,3-triazoles 69.
Scheme 22: A reasonable mechanism for the synthesis of 5‐alkynyl-1,2,3-triazoles 69.
Scheme 23: Synthesis of sulfur-cycle-fused 1,2,3-triazoles 75 and 77.
Scheme 24: A reasonable mechanism for the synthesis of sulfur-cycle-fused 1,2,3‐triazoles 75 and 77.
Scheme 25: Synthesis of 5-selanyltriazoles 85 from the reaction of ethynylstibanes 82, organic azides 83, and ...
Scheme 26: A mechanism for the synthesis of 5-selanyltriazoles 85 from the reaction of ethynylstibanes 82, org...
Scheme 27: Synthesis of trisubstituted triazoles containing an Sb substituent at position C5 in 93 and 5-unsub...
Scheme 28: Synthesis of asymmetric triazole disulfides 98 from disulfide-containing tert-butyltosyl disulfide 97...
Scheme 29: A mechanism for the synthesis of asymmetric triazole disulfides 98 from disulfide-containing tert-bu...
Scheme 30: Synthesis of triazole-fused sultams 104.
Scheme 31: Synthesis of 1,2,3-triazole-fused tricyclic heterocycles 106.
Scheme 32: A reasonable mechanism for the synthesis of 1,2,3-triazole-fused tricyclic heterocycles 106.
Scheme 33: Synthesis of 5-aryl-substituted 1,2,3-triazole derivatives 112.
Scheme 34: A reasonable mechanism for the synthesis of 5-aryl-substituted 1,2,3-triazole derivatives 112.
Scheme 35: Synthesis of 1,4,5-trisubstituted 1,2,3-triazole-5-carboxamides 119.
Scheme 36: A probable mechanism for the synthesis of 1,4,5-trisubstituted 1,2,3-triazole-5-carboxamides 119.
Scheme 37: Synthesis of fully decorated triazoles 125 via the Pd/C-catalyzed arylation of disubstituted triazo...
Scheme 38: Synthesis of triazolo[1,5-a]indolones 131.
Scheme 39: Synthesis of unsymmetrically substituted triazole-fused enediyne systems 135 and 5-aryl-4-ethynyltr...
Scheme 40: Synthesis of Pd/Cu-BNP 139 and application of 139 in the synthesis of polycyclic triazoles 142.
Scheme 41: A probable mechanism for the synthesis of polycyclic triazoles 142.
Scheme 42: Synthesis of highly functionalized 1,2,3-triazole-fused 5-, 6-, and 7-membered rings 152–154.
Scheme 43: A probable mechanism for the synthesis of highly functionalized 1,2,3-triazole-fused 5-, 6-, and 7-...
Scheme 44: Synthesis of fully functionalized 1,2,3-triazolo-fused chromenes 162, 164, and 166 via the intramol...
Scheme 45: Ru-catalyzed synthesis of fully decorated triazoles 172.
Scheme 46: Synthesis of 4-cyano-1,2,3-triazoles 175.
Scheme 47: Synthesis of functionalized triazoles from the reaction of 1-alkyltriazenes 176 and azides 177 and ...
Scheme 48: Mechanism for the synthesis of functionalized triazoles from the reaction of 1-alkyltriazenes 176 a...
A comprehensive review of flow chemistry techniques tailored to the flavours and fragrances industries
- Guido Gambacorta,
- James S. Sharley and
- Ian R. Baxendale
Beilstein J. Org. Chem. 2021, 17, 1181–1312, doi:10.3762/bjoc.17.90
Graphical Abstract
Figure 1: Representative shares of the global F&F market (2018) segmented on their applications [1].
Figure 2: General structure of an international fragrance company [2].
Figure 3: The Michael Edwards fragrance wheel.
Figure 4: Examples of oriental (1–3), woody (4–7), fresh (8–10), and floral (11 and 12) notes.
Figure 5: A basic depiction of batch vs flow.
Scheme 1: Examples of reactions for which flow processing outperforms batch.
Scheme 2: Some industrially important aldol-based transformations.
Scheme 3: Biphasic continuous aldol reactions of acetone and various aldehydes.
Scheme 4: Aldol synthesis of 43 in flow using LiHMDS as the base.
Scheme 5: A semi-continuous synthesis of doravirine (49) involving a key aldol reaction.
Scheme 6: Enantioselective aldol reaction using 5-(pyrrolidin-2-yl)tetrazole (51) as catalyst in a microreact...
Scheme 7: Gröger's example of asymmetric aldol reaction in aqueous media.
Figure 6: Immobilised reagent column reactor types.
Scheme 8: Photoinduced thiol–ene coupling preparation of silica-supported 5-(pyrrolidin-2-yl)tetrazole 63 and...
Scheme 9: Continuous-flow approach for enantioselective aldol reactions using the supported catalyst 67.
Scheme 10: Ötvös’ employment of a solid-supported peptide aldol catalyst in flow.
Scheme 11: The use of proline tetrazole packed in a column for aldol reaction between cyclohexanone (65) and 2...
Scheme 12: Schematic diagram of an aminosilane-grafted Si-Zr-Ti/PAI-HF reactor for continuous-flow aldol and n...
Scheme 13: Continuous-flow condensation for the synthesis of the intermediate 76 to nabumetone (77) and Microi...
Scheme 14: Synthesis of ψ-Ionone (80) in continuous-flow via aldol condensation between citral (79) and aceton...
Scheme 15: Synthesis of β-methyl-ionones (83) from citral (79) in flow. The steps are separately described, an...
Scheme 16: Continuous-flow synthesis of 85 from 84 described by Gavriilidis et al.
Scheme 17: Continuous-flow scCO2 apparatus for the synthesis of 2-methylpentanal (87) and the self-condensed u...
Scheme 18: Chen’s two-step flow synthesis of coumarin (90).
Scheme 19: Pechmann condensation for the synthesis of 7-hydroxyxcoumarin (93) in flow. The setup extended to c...
Scheme 20: Synthesis of the dihydrojasmonate 35 exploiting nitro derivative proposed by Ballini et al.
Scheme 21: Silica-supported amines as heterogeneous catalyst for nitroaldol condensation in flow.
Scheme 22: Flow apparatus for the nitroaldol condensation of p-hydroxybenzaldehyde (102) to nitrostyrene 103 a...
Scheme 23: Nitroaldol reaction of 64 to 105 employing a quaternary ammonium functionalised PANF.
Scheme 24: Enantioselective nitroaldol condensation for the synthesis of 108 under flow conditions.
Scheme 25: Enatioselective synthesis of 1,2-aminoalcohol 110 via a copper-catalysed nitroaldol condensation.
Scheme 26: Examples of Knoevenagel condensations applied for fragrance components.
Scheme 27: Flow apparatus for Knoevenagel condensation described in 1989 by Venturello et al.
Scheme 28: Knoevenagel reaction using a coated multichannel membrane microreactor.
Scheme 29: Continuous-flow apparatus for Knoevenagel condensation employing sugar cane bagasse as support deve...
Scheme 30: Knoevenagel reaction for the synthesis of 131–135 in flow using an amine-functionalised silica gel. ...
Scheme 31: Continuous-flow synthesis of compound 137, a key intermediate for the synthesis of pregabalin (138)...
Scheme 32: Continuous solvent-free apparatus applied for the synthesis of compounds 140–143 using a TSE. Throu...
Scheme 33: Lewis et al. developed a spinning disc reactor for Darzens condensation of 144 and a ketone to furn...
Scheme 34: Some key industrial applications of conjugate additions in the F&F industry.
Scheme 35: Continuous-flow synthesis of 4-(2-hydroxyethyl)thiomorpholine 1,1-dioxide (156) via double conjugat...
Scheme 36: Continuous-flow system for Michael addition using CsF on alumina as the catalyst.
Scheme 37: Calcium chloride-catalysed asymmetric Michael addition using an immobilised chiral ligand.
Scheme 38: Continuous multistep synthesis for the preparation of (R)-rolipram (173). Si-NH2: primary amine-fun...
Scheme 39: Continuous-flow Michael addition using ion exchange resin Amberlyst® A26.
Scheme 40: Preparation of the heterogeneous catalyst 181 developed by Paixão et al. exploiting Ugi multicompon...
Scheme 41: Continuous-flow system developed by the Paixão’s group for the preparation of Michael asymmetric ad...
Scheme 42: Continuous-flow synthesis of nitroaldols catalysed by supported catalyst 184 developed by Wennemers...
Scheme 43: Heterogenous polystyrene-supported catalysts developed by Pericàs and co-workers.
Scheme 44: PANF-supported pyrrolidine catalyst for the conjugate addition of cyclohexanone (65) and trans-β-ni...
Scheme 45: Synthesis of (−)-paroxetine precursor 195 developed by Ötvös, Pericàs, and Kappe.
Scheme 46: Continuous-flow approach for the 5-step synthesis of (−)-oseltamivir (201) as devised by Hayashi an...
Scheme 47: Continuous-flow enzyme-catalysed Michael addition.
Scheme 48: Continuous-flow copper-catalysed 1,4 conjugate addition of Grignard reagents to enones. Reprinted w...
Scheme 49: A collection of commonly encountered hydrogenation reactions.
Figure 7: The ThalesNano H-Cube® continuous-flow hydrogenator.
Scheme 50: Chemoselective reduction of an α,β-unsaturated ketone using the H-Cube® reactor.
Scheme 51: Incorporation of Lindlar’s catalyst into the H-Cube® reactor for the reduction of an alkyne.
Scheme 52: Continuous-flow semi-hydrogenation of alkyne 208 to 209 using SACs with H-Cube® system.
Figure 8: The standard setups for tube-in-tube gas–liquid reactor units.
Scheme 53: Homogeneous hydrogenation of olefins using a tube-in-tube reactor setup.
Scheme 54: Recyclable heterogeneous flow hydrogenation system.
Scheme 55: Leadbeater’s reverse tube-in-tube hydrogenation system for olefin reductions.
Scheme 56: a) Hydrogenation using a Pd-immobilised microchannel reactor (MCR) and b) a representation of the i...
Scheme 57: Hydrogenation of alkyne 238 exploiting segmented flow in a Pd-immobilised capillary reactor.
Scheme 58: Continuous hydrogenation system for the preparation of cyrene (241) from (−)-levoglucosenone (240).
Scheme 59: Continuous hydrogenation system based on CSMs developed by Hornung et al.
Scheme 60: Chemoselective reduction of carbonyls (ketones over aldehydes) in flow.
Scheme 61: Continuous system for the semi-hydrogenation of 256 and 258, developed by Galarneau et al.
Scheme 62: Continuous synthesis of biodiesel fuel 261 from lignin-derived furfural acetone (260).
Scheme 63: Continuous synthesis of γ-valerolacetone (263) via CTH developed by Pineda et al.
Scheme 64: Continuous hydrogenation of lignin-derived biomass (products 265, 266, and 267) using a sustainable...
Scheme 65: Ru/C or Rh/C-catalysed hydrogenation of arene in flow as developed by Sajiki et al.
Scheme 66: Polysilane-immobilized Rh–Pt-catalysed hydrogenation of arenes in flow by Kobayashi et al.
Scheme 67: High-pressure in-line mixing of H2 for the asymmetric reduction of 278 at pilot scale with a 73 L p...
Figure 9: Picture of the PFR employed at Eli Lilly & Co. for the continuous hydrogenation of 278 [287]. Reprinted ...
Scheme 68: Continuous-flow asymmetric hydrogenation using Oppolzer's sultam 280 as chiral auxiliary.
Scheme 69: Some examples of industrially important oxidation reactions in the F&F industry. CFL: compact fluor...
Scheme 70: Gold-catalysed heterogeneous oxidation of alcohols in flow.
Scheme 71: Uozumi’s ARP-Pt flow oxidation protocol.
Scheme 72: High-throughput screening of aldehyde oxidation in flow using an in-line GC.
Scheme 73: Permanganate-mediated Nef oxidation of nitroalkanes in flow with the use of in-line sonication to p...
Scheme 74: Continuous-flow aerobic anti-Markovnikov Wacker oxidation.
Scheme 75: Continuous-flow oxidation of 2-benzylpyridine (312) using air as the oxidant.
Scheme 76: Continuous-flow photo-oxygenation of monoterpenes.
Scheme 77: A tubular reactor design for flow photo-oxygenation.
Scheme 78: Glucose oxidase (GOx)-mediated continuous oxidation of glucose using compressed air and the FFMR re...
Scheme 79: Schematic continuous-flow sodium hypochlorite/TEMPO oxidation of alcohols.
Scheme 80: Oxidation using immobilised TEMPO (344) was developed by McQuade et al.
Scheme 81: General protocol for the bleach/catalytic TBAB oxidation of aldehydes and alcohols.
Scheme 82: Continuous-flow PTC-assisted oxidation using hydrogen peroxide. The process was easily scaled up by...
Scheme 83: Continuous-flow epoxidation of cyclohexene (348) and in situ preparation of m-CPBA.
Scheme 84: Continuous-flow epoxidation using DMDO as oxidant.
Scheme 85: Mukayama aerobic epoxidation optimised in flow mode by the Favre-Réguillon group.
Scheme 86: Continuous-flow asymmetric epoxidation of derivatives of 359 exploiting a biomimetic iron catalyst.
Scheme 87: Continuous-flow enzymatic epoxidation of alkenes developed by Watts et al.
Scheme 88: Engineered multichannel microreactor for continuous-flow ozonolysis of 366.
Scheme 89: Continuous-flow synthesis of the vitamin D precursor 368 using multichannel microreactors. MFC: mas...
Scheme 90: Continuous ozonolysis setup used by Kappe et al. for the synthesis of various substrates employing ...
Scheme 91: Continuous-flow apparatus for ozonolysis as developed by Ley et al.
Scheme 92: Continuous-flow ozonolysis for synthesis of vanillin (2) using a film-shear flow reactor.
Scheme 93: Examples of preparative methods for ajoene (386) and allicin (388).
Scheme 94: Continuous-flow oxidation of thioanisole (389) using styrene-based polymer-supported peroxytungstat...
Scheme 95: Continuous oxidation of thiosulfinates using Oxone®-packed reactor.
Scheme 96: Continuous-flow electrochemical oxidation of thioethers.
Scheme 97: Continuous-flow oxidation of 400 to cinnamophenone (235).
Scheme 98: Continuous-flow synthesis of dehydrated material 401 via oxidation of methyl dihydrojasmonate (33).
Scheme 99: Some industrially important transformations involving Grignard reagents.
Scheme 100: Grachev et al. apparatus for continuous preparation of Grignard reagents.
Scheme 101: Example of fluidized Mg bed reactor with NMR spectrometer as on-line monitoring system.
Scheme 102: Continuous-flow synthesis of Grignard reagents and subsequent quenching reaction.
Figure 10: Membrane-based, liquid–liquid separator with integrated pressure control [52]. Adapted with permission ...
Scheme 103: Continuous-flow synthesis of 458, an intermediate to fluconazole (459).
Scheme 104: Continuous-flow synthesis of ketones starting from benzoyl chlorides.
Scheme 105: A Grignard alkylation combining CSTR and PFR technologies with in-line infrared reaction monitoring....
Scheme 106: Continuous-flow preparation of 469 from Grignard addition of methylmagnesium bromide.
Scheme 107: Continuous-flow synthesis of Grignard reagents 471.
Scheme 108: Preparation of the Grignard reagent 471 using CSTR and the continuous process for synthesis of the ...
Scheme 109: Continuous process for carboxylation of Grignard reagents in flow using tube-in-tube technology.
Scheme 110: Continuous synthesis of propargylic alcohols via ethynyl-Grignard reagent.
Scheme 111: Silica-supported catalysed enantioselective arylation of aldehydes using Grignard reagents in flow ...
Scheme 112: Acid-catalysed rearrangement of citral and dehydrolinalool derivatives.
Scheme 113: Continuous stilbene isomerisation with continuous recycling of photoredox catalyst.
Scheme 114: Continuous-flow synthesis of compound 494 as developed by Ley et al.
Scheme 115: Selected industrial applications of DA reaction.
Scheme 116: Multistep flow synthesis of the spirocyclic structure 505 via employing DA cycloaddition.
Scheme 117: Continuous-flow DA reaction developed in a plater flow reactor for the preparation of the adduct 508...
Scheme 118: Continuous-flow DA reaction using a silica-supported imidazolidinone organocatalyst.
Scheme 119: Batch vs flow for the DA reaction of (cyclohexa-1,5-dien-1-yloxy)trimethylsilane (513) with acrylon...
Scheme 120: Continuous-flow DA reaction between 510 and 515 using a shell-core droplet system.
Scheme 121: Continuous-flow synthesis of bicyclic systems from benzyne precursors.
Scheme 122: Continuous-flow synthesis of bicyclic scaffolds 527 and 528 for further development of potential ph...
Scheme 123: Continuous-flow inverse-electron hetero-DA reaction to pyridine derivatives such as 531.
Scheme 124: Comparison between batch and flow for the synthesis of pyrimidinones 532–536 via retro-DA reaction ...
Scheme 125: Continuous-flow coupled with ultrasonic system for preparation of ʟ-ascorbic acid derivatives 539 d...
Scheme 126: Two-step continuous-flow synthesis of triazole 543.
Scheme 127: Continuous-flow preparation of triazoles via CuAAC employing 546-based heterogeneous catalyst.
Scheme 128: Continuous-flow synthesis of compounds 558 through A3-coupling and 560 via AgAAC both employing the...
Scheme 129: Continuous-flow photoinduced [2 + 2] cycloaddition for the preparation of bicyclic derivatives of 5...
Scheme 130: Continuous-flow [2 + 2] and [5 + 2] cycloaddition on large scale employing a flow reactor developed...
Scheme 131: Continuous-flow preparation of the tricyclic structures 573 and 574 starting from pyrrole 570 via [...
Scheme 132: Continuous-flow [2 + 2] photocyclization of cinnamates.
Scheme 133: Continuous-flow preparation of cyclobutane 580 on a 5-plates photoreactor.
Scheme 134: Continuous-flow [2 + 2] photocycloaddition under white LED lamp using heterogeneous PCN as photocat...
Figure 11: Picture of the parallel tube flow reactor (PTFR) "The Firefly" developed by Booker-Milburn et al. a...
Scheme 135: Continuous-flow acid-catalysed [2 + 2] cycloaddition between silyl enol ethers and acrylic esters.
Scheme 136: Continuous synthesis of lactam 602 using glass column reactors.
Scheme 137: In situ generation of ketenes for the Staudinger lactam synthesis developed by Ley and Hafner.
Scheme 138: Application of [2 + 2 + 2] cycloadditions in flow employed by Ley et al.
Scheme 139: Examples of FC reactions applied in F&F industry.
Scheme 140: Continuous-flow synthesis of ibuprofen developed by McQuade et al.
Scheme 141: The FC acylation step of Jamison’s three-step ibuprofen synthesis.
Scheme 142: Synthesis of naphthalene derivative 629 via FC acylation in microreactors.
Scheme 143: Flow system for rapid screening of catalysts and reaction conditions developed by Weber et al.
Scheme 144: Continuous-flow system developed by Buorne, Muller et al. for DSD optimisation of the FC acylation ...
Scheme 145: Continuous-flow FC acylation of alkynes to yield β-chlorovinyl ketones such as 638.
Scheme 146: Continuous-flow synthesis of tonalide (619) developed by Wang et al.
Scheme 147: Continuous-flow preparation of acylated arene such as 290 employing Zr4+-β-zeolite developed by Kob...
Scheme 148: Flow system applied on an Aza-FC reaction catalysed by the thiourea catalyst 648.
Scheme 149: Continuous hydroformylation in scCO2.
Scheme 150: Two-step flow synthesis of aldehyde 655 through a sequential Heck reaction and subsequent hydroform...
Scheme 151: Single-droplet (above) and continuous (below) flow reactors developed by Abolhasani et al. for the ...
Scheme 152: Continuous hydroformylation of 1-dodecene (655) using a PFR-CSTR system developed by Sundmacher et ...
Scheme 153: Continuous-flow synthesis of the aldehyde 660 developed by Eli Lilly & Co. [32]. Adapted with permissio...
Scheme 154: Continuous asymmetric hydroformylation employing heterogenous catalst supported on carbon-based sup...
Scheme 155: Examples of acetylation in F&F industry: synthesis of bornyl (S,R,S-664) and isobornyl (S,S,S-664) ...
Scheme 156: Continuous-flow preparation of bornyl acetate (S,R,S-664) employing the oscillating flow reactor.
Scheme 157: Continuous-flow synthesis of geranyl acetate (666) from acetylation of geraniol (343) developed by ...
Scheme 158: 12-Ttungstosilicic acid-supported silica monolith-catalysed acetylation in flow.
Scheme 159: Continuous-flow preparation of cyclopentenone 676.
Scheme 160: Two-stage synthesis of coumarin (90) via acetylation of salicylaldehyde (88).
Scheme 161: Intensification process for acetylation of 5-methoxytryptamine (677) to melatonin (678) developed b...
Scheme 162: Examples of macrocyclic musky odorants both natural (679–681) and synthetic (682 and 683).
Scheme 163: Flow setup combined with microwave for the synthesis of macrocycle 686 via RCM.
Scheme 164: Continuous synthesis of 2,5-dihydro-1H-pyrroles via ring-closing metathesis.
Scheme 165: Continuous-flow metathesis of 485 developed by Leadbeater et al.
Figure 12: Comparison between RCM performed using different routes for the preparation of 696. On the left the...
Scheme 166: Continuous-flow RCM of 697 employed the solid-supported catalyst 698 developed by Grela, Kirschning...
Scheme 167: Continuous-flow RORCM of cyclooctene employing the silica-absorbed catalyst 700.
Scheme 168: Continuous-flow self-metathesis of methyl oleate (703) employing SILP catalyst 704.
Scheme 169: Flow apparatus for the RCM of 697 using a nanofiltration membrane for the recovery and reuse of the...
Scheme 170: Comparison of loadings between RCMs performed with different routes for the synthesis of 709.
Heterogeneous photocatalytic cyanomethylarylation of alkenes with acetonitrile: synthesis of diverse nitrogenous heterocyclic compounds
- Guanglong Pan,
- Qian Yang,
- Wentao Wang,
- Yurong Tang and
- Yunfei Cai
Beilstein J. Org. Chem. 2021, 17, 1171–1180, doi:10.3762/bjoc.17.89
- .17.89 Abstract A visible light-mediated heterogeneous photocatalytic cyanomethylarylation of alkenes with acetonitrile has been established using K-modified carbon nitride (CN-K) as a recyclable semiconductor photocatalyst. This protocol, employing readily accessible alkyl N-hydroxyphthalimide (NHPI
- photocatalysis; recyclable; Introduction Nitrogenous heterocyclic compounds, such as indolines [1][2][3][4], oxindoles [5][6][7], isoquinolinones [8][9][10], and isoquinolinediones [11][12], are pivotal structural motifs in numerous pharmaceuticals, agrochemicals, and bioactive natural products. The oxidative
Graphical Abstract
Scheme 1: CN-K-Catalyzed cyanomethylarylation of alkenes to access diverse heterocyclic compounds.
Scheme 2: CN-K-catalyzed cyanomethylarylation of N-arylallylamines for the synthesis of indolines. Reaction c...
Scheme 3: CN-K-catalyzed cyanomethylarylation of N-benzoylallylamines for the synthesis of isoquinolinones. R...
Scheme 4: CN-K-catalyzed cyanomethylarylation of N-aryl acrylamides for the synthesis of oxindoles. Reaction ...
Scheme 5: CN-K-catalyzed cyanomethylarylation of N-benzoyl acrylamides for the synthesis of isoquinolinedione...
Figure 1: Evaluation of catalyst recycling. Reaction conditions: 1a (0.1 mmol, 1 equiv), 2d (0.2 mmol, 2 equi...
Scheme 6: Further survey of reaction scope and derivatization studies of 8a.
Scheme 7: Experiments for the mechanistic study.
Scheme 8: Plausible mechanism of the CN-K-catalyzed cyanomethylarylation of alkenes.
Recent advances in palladium-catalysed asymmetric 1,4–additions of arylboronic acids to conjugated enones and chromones
- Jan Bartáček,
- Jan Svoboda,
- Martin Kocúrik,
- Jaroslav Pochobradský,
- Alexander Čegan,
- Miloš Sedlák and
- Jiří Váňa
Beilstein J. Org. Chem. 2021, 17, 1048–1085, doi:10.3762/bjoc.17.84
- excellent both in terms of enantioselectivities and conversions (up to 98%; up to 83% ee; Table 28). The reuse of the heterogeneous catalyst has not been studied in this case. In 2020, our group reported the first heterogeneous polystyrene-supported recyclable catalyst for the asymmetric conjugate additions
- , continuous-flow reactions are currently a general challenge, especially for the pharmaceutical industry. The prerequisite for a successful continuous synthesis in the field of asymmetric addition reactions to enones is the mastery of recyclable heterogeneous catalysis. Very recently, we reported [57] the
- first heterogeneous polystyrene-supported recyclable catalyst for asymmetric conjugate addition reactions of arylboronic acids to five and six-membered enones. In our laboratory, we also attempted to perform this reaction under flow conditions. However, the change from batch to flow arrangement itself
Graphical Abstract
Scheme 1: Synthesis of optically pure 4-phenylchroman-2-one [34].
Scheme 2: Synthesis of (R)-tolterodine [3].
Scheme 3: Catalytic cycle of the Pd(II)-catalysed 1,4-addition of organoboron reagents to enones [3,26,35].
Scheme 4: Enantioselective β-arylation of cyclohexanone [38].
Scheme 5: Application of L2/Pd(OAc)2 in the total synthesis of terpenes [8].
Scheme 6: Plausible catalytic cycle for the addition of phenylboronic acid to 2-cyclohexenone catalysed by L3...
Scheme 7: Microwave-assisted addition of phenylboronic acid to 2-cyclohexenone catalysed by L4/Pd2(dba)3·CHCl3...
Scheme 8: Plausible catalytic cycle of the addition of phenylboronic acid to 2-cyclohexenone catalysed by pal...
Scheme 9: Proposed catalytic cycle for the addition of phenylboronic acids to 2-cyclohexenone catalysed by Pd...
Scheme 10: Usage of addition reactions of boronic acids to various chromones in the syntheses of potentially a...
Scheme 11: Multigram-scale synthesis of ABBV-2222 [6].
Scheme 12: Application of the asymmetric addition of phenylboronic acid to a chromone derivative for the total...
Scheme 13: Plausible catalytic cycle for the addition of phenylboronic acid to 3-methyl-2-cyclohexenone cataly...
Scheme 14: Total syntheses of naturally occurring terpenoids [10,11].
Scheme 15: Use of the L9/Pd(TFA)2 catalytic system for the synthesis of intermediates of biologically active c...
Scheme 16: Usage of a Michael addition catalysed by L9/Pd(TFA)2 in the total synthesis of (–)-ar-tenuifolene [12].
Scheme 17: Synthesis of terpenoids by Michael addition to 3-methyl-2-cyclopentenone [13].
Scheme 18: Rh-catalysed isomerisation of 3-alkyl-3-arylcyclopentanones to 1-tetralones [53].
Scheme 19: Addition reaction of phenylboronic acid to 3-methyl-2-cyclohexenone catalysed by L9/Pd(TFA)2 in wat...
Scheme 20: Micellar nanoreactor PdL10c for the synthesis of flavanones [58].
Scheme 21: Plausible catalytic cycle for the desymmetrisation of polycyclic cyclohexenediones by the addition ...
Scheme 22: Attempt to use the catalytic system L2/Pd(TFA)2 for the addition of phenylboronic acid to 3-methyl-...
Scheme 23: Ring opening of an enantioenriched tetrahydropyran-2-one derivative as alternative strategy to line...
Scheme 24: Synthesis of biologically active compounds from addition products [14-16].
Scheme 25: Chiral 1,10-phenantroline derivative L15 as ligand for the Pd-catalysed addition reactions of pheny...
Scheme 26: The Rh-catalysed addition reaction of phenylboronic acid to a 3-substituted enone [20].
Scheme 27: Underdeveloped methodologies [14,15,65-67].
Scheme 28: Flowchart for the selection of the proper catalytic system.
Valorisation of plastic waste via metal-catalysed depolymerisation
- Francesca Liguori,
- Carmen Moreno-Marrodán and
- Pierluigi Barbaro
Beilstein J. Org. Chem. 2021, 17, 589–621, doi:10.3762/bjoc.17.53
Graphical Abstract
Figure 1: Potential classification of plastic recycling processes. The area covered by the present review is ...
Figure 2: EG produced during glycolytic depolymerisation of PET using DEG + DPG as solvent and titanium(IV) n...
Scheme 1: Simplified representation of the conversion of 1,4-PBD to C16–C44 macrocycles using Ru metathesis c...
Figure 3: Main added-value monomers obtainable by catalytic depolymerisation of PET via chemolytic methods.
Scheme 2: Hydrogenolytic depolymerisation of PET by ruthenium complexes.
Scheme 3: Depolymerisation of PET via catalytic hydrosilylation by Ir(III) pincer complex.
Scheme 4: Catalytic hydrolysis (top) and methanolysis (bottom) reactions of PET.
Scheme 5: Depolymerisation of PET by glycolysis with ethylene glycol.
Figure 4: Glycolysis of PET: evolution of BHET yield over time, with and without zinc acetate catalyst (196 °...
Scheme 6: Potential activated complex for the glycolysis reaction of PET catalysed by metallated ILs and evol...
Scheme 7: One-pot, two-step process for PET repurposing via chemical recycling.
Scheme 8: Synthetic routes to PLA.
Scheme 9: Structures of the zinc molecular catalysts used for PLA-methanolysis in various works. a) See [265], b) ...
Scheme 10: Depolymerisation of PLLA by Zn–N-heterocyclic carbene complex.
Scheme 11: Salalen ligands.
Scheme 12: Catalytic hydrogenolysis of PLA.
Scheme 13: Catalytic hydrosilylation of PLA.
Scheme 14: Hydrogenative depolymerisation of PBT and PCL by molecular Ru catalysts.
Scheme 15: Glycolysis reaction of PCT by diethylene glycol.
Scheme 16: Polymerisation–depolymerisation cycle of 3,4-T6GBL.
Scheme 17: Polymerisation–depolymerisation cycle of 2,3-HDB.
Scheme 18: Hydrogenative depolymerisation of PBPAC by molecular Ru catalysts.
Scheme 19: Catalytic hydrolysis (top), alcoholysis (middle) and aminolysis (bottom) reactions of PBPAC.
Scheme 20: Hydrogenative depolymerisation of PPC (top) and PEC (bottom) by molecular Ru catalysts.
Scheme 21: Polymerisation-depolymerisation cycle of BEP.
Scheme 22: Hydrogenolysis of polyamides using soluble Ru catalysts.
Scheme 23: Catalytic depolymerisation of epoxy resin/carbon fibres composite.
Scheme 24: Depolymerisation of polyethers with metal salt catalysts and acyl chlorides.
Scheme 25: Proposed mechanism for the iron-catalysed depolymerisation reaction of polyethers. Adapted with per...
A novel and robust heterogeneous Cu catalyst using modified lignosulfonate as support for the synthesis of nitrogen-containing heterocycles
- Bingbing Lai,
- Meng Ye,
- Ping Liu,
- Minghao Li,
- Rongxian Bai and
- Yanlong Gu
Beilstein J. Org. Chem. 2020, 16, 2888–2902, doi:10.3762/bjoc.16.238
- tricyclic indoles bearing 3,4-fused seven-membered rings, 2‑arylpyridines, aminonaphthalenes and 3-phenylisoquinolines. In addition, this catalyst showed to be recyclable and could be reused several times without significant loss in activity during the course of the reaction process. Keywords: biomass
- , ring-closing, metathesis, cycloadditions, radical reactions and microwave-assisted reactions [38][39][40]. In this work, we attempt to develop a greener, simpler, more efficient and recyclable system to synthesize arylpyridine derivatives. Initially, the reaction of acetophenone (5a) and 1,3
Graphical Abstract
Figure 1: Schematic illustration for the preparation of the catalyst in this work.
Figure 2: FTIR spectra of LS, LS-FAS, and LS-FAS-Cu.
Figure 3: Thermogravimetric weight loss of the obtained materials LS-FAS and LS-FAS-Cu.
Figure 4: FSEM imagine of LS-FAS-Cu in different scale label a) 1 μm, b) 200 nm; FTEM images of LS-FAS-Cu in ...
Figure 5: XPS spectra of LS-FAS-Cu in the regions of C 1s, O 1s, Cu 2p3/2 and Cu LMM (inset).
Scheme 1: Substrate scope of LS-FAS-Cu catalyzed three-component reactions of 4-aminoindoles, alkynes and ald...
Figure 6: Recyclability of LS-FAS-Cu, LS-FM-Cu and Resin-Cu in the reaction between compounds 1a, 2a and 3a.
One-pot synthesis of isosorbide from cellulose or lignocellulosic biomass: a challenge?
- Isaline Bonnin,
- Raphaël Mereau,
- Thierry Tassaing and
- Karine De Oliveira Vigier
Beilstein J. Org. Chem. 2020, 16, 1713–1721, doi:10.3762/bjoc.16.143
- increased production of insoluble byproducts. The productivity of isosorbide can reach 40.2 g·L−1·h−1with a purity of 73%. The recycling of the metal-supported catalyst (Ru/C) was studied and a high catalytic activity decrease was observed after the first run, showing that the catalyst was not recyclable
Graphical Abstract
Scheme 1: Conversion of cellulose to isosorbide.
Scheme 2: Combination of mineral acids or heteropolyacids and a supported metal catalyst to produce isosorbid...
Scheme 3: Conversion of sorbitol to isosorbide via the formation of sorbitans.
Scheme 4: Conversion of cellulose to isosorbide in the presence of heteropolyacids and metal-supported cataly...
Scheme 5: Summary of the results obtained in one-pot one step processes [21-25].
Scheme 6: Conversion of (ligno)cellulose to isosorbide in the presence of Amberlyt 70 and a Ru/C catalyst [26,27].
Scheme 7: Use of Ru-supported on mesoporous nobium phosphate (mNbPO) for the synthesis of isosorbide from cel...
Heterogeneous photocatalysis in flow chemical reactors
- Christopher G. Thomson,
- Ai-Lan Lee and
- Filipe Vilela
Beilstein J. Org. Chem. 2020, 16, 1495–1549, doi:10.3762/bjoc.16.125
- -workers to be an effective, stable, and recyclable HPCat for a large scope of arene and heteroarene functionalisation reactions, traditionally performed with transition metal complexes (Scheme 2) [128]. The group were able to bifunctionalise N-phenylpyrrole with a variety of functional groups at room
Graphical Abstract
Figure 1: A) Bar chart of the publications per year for the topics “Photocatalysis” (49,662 instances) and “P...
Figure 2: A) Professor Giacomo Ciamician and Dr. Paolo Silber on their roof laboratory at the University of B...
Scheme 1: PRC trifluoromethylation of N-methylpyrrole (1) using hazardous gaseous CF3I safely in a flow react...
Figure 3: A) Unit cells of the three most common crystal structures of TiO2: rutile, brookite, and anatase. R...
Figure 4: Illustration of the key semiconductor photocatalysis events: 1) A photon with a frequency exceeding...
Figure 5: Photocatalytic splitting of water by oxygen vacancies on a TiO2(110) surface. Reprinted with permis...
Figure 6: Proposed adsorption modes of A) benzene, B) chlorobenzene, C) toluene, D) phenol, E) anisole, and F...
Figure 7: Structures of the sulfonate-containing organic dyes RB5 (3) and MX-5B (4) and the adsorption isothe...
Figure 8: Idealised triclinic unit cell of a g-C3N4 type polymer, displaying possible hopping transport scena...
Figure 9: Idealised structure of a perfect g-C3N4 sheet. The central unit highlighted in red represents one t...
Figure 10: Timeline of the key processes of charge transport following the photoexcitation of g-C3N4, leading ...
Scheme 2: Photocatalytic bifunctionalisation of heteroarenes using mpg-C3N4, with the selected examples 5 and ...
Figure 11: A) Structure of four linear conjugated polymer photocatalysts for hydrogen evolution, displaying th...
Figure 12: Graphical representation of the common methods used to immobilise molecular photocatalysts (PC) ont...
Figure 13: Wireless light emitter-supported TiO2 (TiO2@WLE) HPCat spheres powered by resonant inductive coupli...
Figure 14: Graphical representation of zinc–perylene diimide (Zn-PDI) supramolecular assembly photocatalysis v...
Scheme 3: Upconversion of NIR photons to the UV frequency by NaYF4:Yb,Tm nanocrystals sequentially coated wit...
Figure 15: Types of reactors employed in heterogeneous photocatalysis in flow. A) Fixed bed reactors and the s...
Figure 16: Electrochemical potential of common semiconductor, transition metal, and organic dye-based photocat...
Scheme 4: Possible mechanisms of an immobilised molecular photoredox catalyst by oxidative or reductive quenc...
Scheme 5: Scheme of the CMB-C3N4 photocatalytic decarboxylative fluorination of aryloxyacetic acids, with the...
Scheme 6: Scheme of the g-C3N4 photocatalytic desilylative coupling reaction in flow and proposed mechanism [208].
Scheme 7: Proposed mechanism of the radical cyclisation of unsaturated alkyl 2-bromo-1,3-dicarbonyl compounds...
Scheme 8: N-alkylation of benzylamine and schematic of the TiO2-coated microfluidic device [213].
Scheme 9: Proposed mechanism of the Pt@TiO2 photocatalytic deaminitive cyclisation of ʟ-lysine (23) to ʟ-pipe...
Scheme 10: A) Proposed mechanism for the photocatalytic oxidation of phenylboronic acid (24). B) Photos and SE...
Scheme 11: Proposed mechanism for the DA-CMP3 photocatalytic aza-Henry reaction performed in a continuous flow...
Scheme 12: Proposed mechanism for the formation of the cyclic product 32 by TiO2-NC HPCats in a slurry flow re...
Scheme 13: Reaction scheme for the photocatalytic synthesis of homo and hetero disulfides in flow and scope of...
Scheme 14: Reaction scheme for the MoOx/TiO2 HPCat oxidation of cyclohexane (34) to benzene. The graph shows t...
Scheme 15: Proposed mechanism of the TiO2 HPC heteroarene C–H functionalisation via aryl radicals generated fr...
Scheme 16: Scheme of the oxidative coupling of benzylamines with the HOTT-HATN HPCat and selected examples of ...
Scheme 17: Photocatalysis oxidation of benzyl alcohol (40) to benzaldehyde (41) in a microflow reactor coated ...
Figure 17: Mechanisms of Dexter and Forster energy transfer.
Scheme 18: Continuous flow process for the isomerisation of alkenes with an ionic liquid-immobilised photocata...
Scheme 19: Singlet oxygen synthetic step in the total synthesis of canataxpropellane [265].
Scheme 20: Scheme and proposed mechanism of the singlet oxygen photosensitisation by CMP_X HPCats, with the st...
Scheme 21: Structures of CMP HPCat materials applied by Vilela and co-workers for the singlet oxygen photosens...
Scheme 22: Polyvinylchloride resin-supported TDCPP photosensitisers applied for singlet oxygen photosensitisat...
Scheme 23: Structure of the ionically immobilised TPP photosensitiser on amberlyst-15 ion exchange resins (TPP...
Scheme 24: Photosensitised singlet oxygen oxidation of citronellol (46) in scCO2, with automatic phase separat...
Scheme 25: Schematic of PS-Est-BDP-Cl2 being applied for singlet oxygen photosensitisation in flow. A) Pseudo-...
Scheme 26: Reaction scheme of the singlet oxygen oxidation of furoic acid (54) using a 3D-printed microfluidic...
Figure 18: A) Photocatalytic bactericidal mechanism by ROS oxidative cleavage of membrane lipids (R = H, amino...
Figure 19: A) Suggested mechanisms for the aqueous pollutant degradation by TiO2 in a slurry flow reactor [284-287]. B)...
Figure 20: Schematic of the flow system used for the degradation of aqueous oxytetracycline (56) solutions [215]. M...
Scheme 27: Degradation of a salicylic acid (57) solution by a coupled solar photoelectro-Fenton (SPEF) process...
Figure 21: A) Schematic flow diagram using the TiO2-coated NETmix microfluidic device for an efficient mass tr...
The charge-assisted hydrogen-bonded organic framework (CAHOF) self-assembled from the conjugated acid of tetrakis(4-aminophenyl)methane and 2,6-naphthalenedisulfonate as a new class of recyclable Brønsted acid catalysts
- Svetlana A. Kuznetsova,
- Alexander S. Gak,
- Yulia V. Nelyubina,
- Vladimir A. Larionov,
- Han Li,
- Michael North,
- Vladimir P. Zhereb,
- Alexander F. Smol'yakov,
- Artem O. Dmitrienko,
- Michael G. Medvedev,
- Igor S. Gerasimov,
- Ashot S. Saghyan and
- Yuri N. Belokon
Beilstein J. Org. Chem. 2020, 16, 1124–1134, doi:10.3762/bjoc.16.99
Graphical Abstract
Scheme 1: The synthesis of F-1.
Figure 1: View of the crystal structure of F-1 (F-1a phase), with representation of atoms by thermal ellipsoi...
Figure 2: View of the crystal structure of F-1 (F-1a’ phase), with representation of the atoms via thermal el...
Figure 3: SEM image of F-1.
Figure 4: SEM image of F-1 with an F-1a phase.
Figure 5: TGA-DSC analysis of a sample of F-1. The TGA plot is shown in green, the DSC curve is shown in blue...
Scheme 2: Uncrystallized F-1 or F-1 with an F-1a phase promoted the two- and three-phase reactions of styrene...
Scheme 3: CAHOF F-1-promoted reactions of cyclohexene oxide (5) with alcohols and water.
Scheme 4: F-1-promoted Diels–Alder reaction.
Reaction of indoles with aromatic fluoromethyl ketones: an efficient synthesis of trifluoromethyl(indolyl)phenylmethanols using K2CO3/n-Bu4PBr in water
- Thanigaimalai Pillaiyar,
- Masoud Sedaghati and
- Gregor Schnakenburg
Beilstein J. Org. Chem. 2020, 16, 778–790, doi:10.3762/bjoc.16.71
- recyclable of the catalyst (Figure 2C). Results and Discussion The optimization studies were carried out with model substrates 5-methoxyindole (1a, 3.4 mmol) and 2,2,2-trifluoroacetophenone (2a, 3.70 mmol) in water (5 mL, see Table 1 for results). Using water as a solvent has the advantage that the formed
Graphical Abstract
Figure 1: Structures of trifluoromethylated compounds and their biological activities.
Figure 2: Synthetic approaches toward hydroxyalkylation of indole.
Figure 3: Structures of heterocycles that did not react with ketone 2a.
Scheme 1: Gram-scale synthesis of 2,2,2-trifluoro-1-(1H-indol-3-yl)-1-phenylethan-1-ols (3a and 3p).
Figure 4: Recyclability of the catalytic system n-Bu4PBr/K2CO3 for the preparation of 2,2,2-trifluoro-1-(5-me...
Scheme 2: Synthesis of trifluoromethylated unsymmetrical 3,3'- and 3,6'-DIMs (9–11).
Scheme 3: Proposed mechanism for the preparation of 3a as an example.
Scheme 4: Control experiments.
Combining enyne metathesis with long-established organic transformations: a powerful strategy for the sustainable synthesis of bioactive molecules
- Valerian Dragutan,
- Ileana Dragutan,
- Albert Demonceau and
- Lionel Delaude
Beilstein J. Org. Chem. 2020, 16, 738–755, doi:10.3762/bjoc.16.68
- dihydroartemisinic acid (DHAA) [64][65]. Also, high efficient and recyclable catalytic systems based on metal-organic frameworks (MOFs) have also been reported for the tandem hemisynthesis of artemisinin [66]. In a remarkable work, this antimalarial drug was obtained by a new route involving enyne metathesis as the
Graphical Abstract
Scheme 1: Intramolecular (A) and intermolecular (B) enyne metathesis reactions.
Scheme 2: Ene–yne and yne–ene mechanisms for intramolecular enyne metathesis reactions.
Scheme 3: Metallacarbene mechanism in intermolecular enyne metathesis.
Scheme 4: The Oguri strategy for accessing artemisinin analogs 1a–c through enyne metathesis.
Scheme 5: Access to the tetracyclic core of nanolobatolide (2) via tandem enyne metathesis followed by an Eu(...
Scheme 6: Synthesis of (−)-amphidinolide E (3) using an intermolecular enyne metathesis as the key step.
Scheme 7: Synthesis of amphidinolide K (4) by an enyne metathesis route.
Scheme 8: Trost synthesis of des-epoxy-amphidinolide N (5) [72].
Scheme 9: Enyne metathesis between the propargylic derivative and the allylic alcohol in the synthesis of the...
Scheme 10: Synthetic route to amphidinolide N (6a).
Scheme 11: Synthesis of the stereoisomeric precursors of amphidinolide V (7a and 7b) through alkyne ring-closi...
Scheme 12: Synthesis of the anthramycin precursor 8 from ʟ-methionine by a tandem enyne metathesis–cross metat...
Scheme 13: Synthesis of (−)‐clavukerin A (9) and (−)‐isoclavukerin A (10) by an enyne metathesis route startin...
Scheme 14: Synthesis of (−)-isoguaiene (11) through an enyne metathesis as the key step.
Scheme 15: Synthesis of erogorgiaene (12) by a tandem enyne metathesis/cross metathesis sequence using the sec...
Scheme 16: Synthesis of (−)-galanthamine (13) from isovanilin by an enyne metathesis.
Scheme 17: Application of enyne metathesis for the synthesis of kempene diterpenes 14a–c.
Scheme 18: Synthesis of the alkaloid (+)-lycoflexine (15) through enyne metathesis.
Scheme 19: Synthesis of the AB subunits of manzamine A (16a) and E (16b) by enyne metathesis.
Scheme 20: Jung's synthesis of rhodexin A (17) by enyne metathesis/cross metathesis reactions.
Scheme 21: Total synthesis of (−)-flueggine A (18) and (+)-virosaine B (19) from Weinreb amide by enyne metath...
Scheme 22: Access to virgidivarine (20) and virgiboidine (21) by an enyne metathesis route.
Scheme 23: Enyne metathesis approach to (−)-zenkequinone B (22).
Scheme 24: Access to C-aryl glycoside 23 by an intermolecular enyne metathesis/Diels–Alder cycloaddition.
Scheme 25: Synthesis of spiro-C-aryl glycoside 24 by a tandem intramolecular enyne metathesis/Diels–Alder reac...
Scheme 26: Pathways to (−)-exiguolide (25) by Trost’s Ru-catalyzed enyne cross-coupling and cross-metathesis [94].
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
- applications that focused on the title catalysts in CuAAC reactions. Review Copper anchored on functionalized silica materials: efficient and recyclable catalysts for CuAAC reactions In recent years, silica or silicon dioxide nanomaterials have received much attention from researchers and industry and have
- in HCl/H2O using 0.1 mol % of Cu@PyIm–SBA-15 (69, Scheme 12). Copper anchored on functionalized carbon materials: efficient and recyclable catalysts for CuAAC reactions Carbon nanomaterials have attracted the interest of researchers due to the high electrical and thermal conductivities, low
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.
Oligomeric ricinoleic acid preparation promoted by an efficient and recoverable Brønsted acidic ionic liquid
- Fei You,
- Xing He,
- Song Gao,
- Hong-Ru Li and
- Liang-Nian He
Beilstein J. Org. Chem. 2020, 16, 351–361, doi:10.3762/bjoc.16.34
- difficulties. Therefore, it is urgently desirable to develop an efficient, green and recyclable catalyst and design simple operating procedures for the preparation of estolides oligomeric ricinoleic acid. Ionic liquids (ILs) have been proved to be efficient catalysts in various organic syntheses due to the
Graphical Abstract
Scheme 1: [HSO3-BDBU]H2PO4-promoted oligomerization and separation.
Scheme 2: Structures of ILs used in this work.
Figure 1: Monitoring oligomerization process by 1H NMR (400 MHz, CDCl3).
Figure 2: Reusability of the IL catalyst. Reaction conditions: 10 g (30 mmol) ricinoleic acid, 190 °C, 6 h, 5...
Figure 3: 1H NMR (400 MHz, DMSO-d6) spectra of [HSO3-BDBU]H2PO4: a) Fresh one; b) used one after five cycles.
Scheme 3: Proposed mechanism for [HSO3-BDBU]H2PO4 catalyzed oligomeric ricinoleic acid synthesis.
Synthesis of 3-alkenylindoles through regioselective C–H alkenylation of indoles by a ruthenium nanocatalyst
- Abhijit Paul,
- Debnath Chatterjee,
- Srirupa Banerjee and
- Somnath Yadav
Beilstein J. Org. Chem. 2020, 16, 140–148, doi:10.3762/bjoc.16.16
- recyclable up to four cycles. Also, the catalyst acts through a heterogeneous mechanism, which has been proven by various techniques, such as ICPMS and three-phase tests. The nature of the Ru nanocatalyst surface has also been thoroughly examined by various techniques, and it has been found that the oxides
- reaction of aza compounds [43][44]. Again, a Ru nanoparticle-catalysed C–H selenylation of indoles was reported by Lin et al. [45]. Herein, we report the Ru-catalysed regioselective synthesis of C3 alkenylindoles using a near-naked, surfactant-free, and recyclable Ru nanocatalyst in a heterogeneous manner
Graphical Abstract
Figure 1: Biologically and medicinally important 3-alkenylindoles.
Scheme 1: a) Previous and b) present work related to the synthesis of 3-alkenylindoles.
Scheme 2: Substrate scope for the C–H alkenylation of the indoles 1. Reaction conditions: 1 (1 mmol), 2 (2 mm...
Scheme 3: a) Three-phase test to determine a homogeneous or heterogeneous catalytic mechanism of action for t...
Scheme 4: Probable catalytic mechanism for the transformation of 1a by the RuNC.
