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Search for "microwave-assisted reaction" in Full Text gives 12 result(s) in Beilstein Journal of Organic Chemistry.
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
- -dimethoxytetrahydrofuran; green synthesis; microwave-assisted reaction; N-substituted pyrrole; Introduction Heterocyclic compounds are the most explored molecules in organic chemistry in terms of their synthesis and various applications. Among the diverse heterocyclic compounds, N-containing heterocycles are found in
- -substituted pyrroles 55 through the microwave-assisted reaction of various primary amines 54 with 2,5-dimethoxytetrahydrofuran (2). In this protocol, without the use of any additional catalyst, the products were obtained in 12–74% yields in water and 59–96% yields in acetic acid, respectively (Scheme 26
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.
Silica gel and microwave-promoted synthesis of dihydropyrrolizines and tetrahydroindolizines from enaminones
- Robin Klintworth,
- Garreth L. Morgans,
- Stefania M. Scalzullo,
- Charles B. de Koning,
- Willem A. L. van Otterlo and
- Joseph P. Michael
Beilstein J. Org. Chem. 2021, 17, 2543–2552, doi:10.3762/bjoc.17.170
- . Yields of the bicyclic products were generally above 75%. The analogous microwave-assisted reaction to produce ethyl 2-aryl-5,6,7,8-tetrahydroindolizine-3-carboxylates from (E)-ethyl 2-[2-(2-oxo-2-arylethylidene)piperidin-1-yl]acetates failed in nonpolar solvents, but occurred in ethanol at lower
- , was reported as recently as 2018 [55]. More interestingly, conventional heating in acetic acid of an enaminone bearing a phenacylsulfanyl substituent adjacent to nitrogen on the C=C bond produced ethyl pyrrolo[2,1-b]thiazole-5-carboxylates in moderate yield, while the corresponding microwave-assisted
- reaction in the same solvent gave high yields of pyrrolo[2,1-b]thiazol-6-ones [56]. The former results from reaction between the α-methylene position of the ester and the electrophilic carbonyl component of the enaminone, while the latter arises from nucleophilic attack of the enaminone at the ester’s
Graphical Abstract
Figure 1: Examples of 2,3-dihydro-1H-pyrrolizines (1–7) and 5,6,7,8-tetrahydroindolizines (8–10).
Scheme 1: Previous [18] and proposed routes to 2,3-dihydro-1H-pyrrolizines from enaminones. Reagents and conditio...
Scheme 2: Synthesis of pyrrolizine 19a from lactam 16 via enaminone 15a. Reagents and conditions: (i) NaH, TH...
Scheme 3: Proposed mechanism for the formation of pyrrolizidine 19a from enaminone (E)-15a.
Scheme 4: Synthesis of tetrahydroindolizines 26a–c from lactam 23 via enaminones 25a–c. Reagents and conditio...
Scheme 5: Further functionalization of dihydropyrrolizine 19a. Reagents and conditions: (i) NBS, DMF, 0 °C, 1...
Microwave-assisted multicomponent reactions in heterocyclic chemistry and mechanistic aspects
- Shivani Gulati,
- Stephy Elza John and
- Nagula Shankaraiah
Beilstein J. Org. Chem. 2021, 17, 819–865, doi:10.3762/bjoc.17.71
- first systemic synthesis of biologically interesting bisheterocycles. A three-component microwave-assisted reaction of substituted benzimidazole-linked aminopyridine 135, aldehydes 5 and isocyanide 21 using Sc(OTf)3 as the catalyst under solvent-free conditions resulted in substituted benzimidazole
Graphical Abstract
Figure 1: Marketed drugs with acridine moiety.
Scheme 1: Synthesis of 4-arylacridinediones.
Scheme 2: Proposed mechanism for acridinedione synthesis.
Scheme 3: Synthesis of tetrahydrodibenzoacridinones.
Scheme 4: Synthesis of naphthoacridines.
Scheme 5: Plausible mechanism for naphthoacridines.
Figure 2: Benzoazepines based potent molecules.
Scheme 6: Synthesis of azepinone.
Scheme 7: Proposed mechanism for azepinone formation.
Scheme 8: Synthesis of benzoazulenen-1-one derivatives.
Scheme 9: Proposed mechanism for benzoazulene-1-one synthesis.
Figure 3: Indole-containing pharmacologically active molecules.
Scheme 10: Synthesis of functionalized indoles.
Scheme 11: Plausible mechanism for the synthesis of functionalized indoles.
Scheme 12: Synthesis of spirooxindoles.
Scheme 13: Synthesis of substituted spirooxindoles.
Scheme 14: Plausible mechanism for the synthesis of substituted spirooxindoles.
Scheme 15: Synthesis of pyrrolidinyl spirooxindoles.
Scheme 16: Proposed mechanism for pyrrolidinyl spirooxindoles.
Figure 4: Pyran-containing biologically active molecules.
Scheme 17: Synthesis of functionalized benzopyrans.
Scheme 18: Plausible mechanism for synthesis of benzopyran.
Scheme 19: Synthesis of indoline-spiro-fused pyran derivatives.
Scheme 20: Proposed mechanism for indoline-spiro-fused pyran.
Scheme 21: Synthesis of substituted naphthopyrans.
Figure 5: Marketed drugs with pyrrole ring.
Scheme 22: Synthesis of tetra-substituted pyrroles.
Scheme 23: Mechanism for silica-supported PPA-SiO2-catalyzed pyrrole synthesis.
Scheme 24: Synthesis of pyrrolo[1,10]-phenanthrolines.
Scheme 25: Proposed mechanism for pyrrolo[1,10]-phenanthrolines.
Figure 6: Marketed drugs and molecules containing pyrimidine and pyrimidinones skeletons.
Scheme 26: MWA-MCR pyrimidinone synthesis.
Scheme 27: Two proposed mechanisms for pyrimidinone synthesis.
Scheme 28: MWA multicomponent synthesis of dihydropyrimidinones.
Scheme 29: Proposed mechanism for dihydropyrimidinones.
Figure 7: Biologically active fused pyrimidines.
Scheme 30: MWA- MCR for the synthesis of pyrrolo[2,3-d]pyrimidines.
Scheme 31: Proposed mechanism for pyrrolo[2,3-d]pyrimidines.
Scheme 32: Synthesis of substituted pyrrolo[2,3-d]pyrimidine-2,4-diones.
Scheme 33: Probable pathway for pyrrolo[2,3-d]pyrimidine-2,4-diones.
Scheme 34: Synthesis of pyridopyrimidines.
Scheme 35: Plausible mechanism for the synthesis of pyridopyrimidines.
Scheme 36: Synthesis of dihydropyridopyrimidine and dihydropyrazolopyridine.
Scheme 37: Proposed mechanism for the formation of dihydropyridopyrimidine.
Scheme 38: Synthesis of thiopyrano[4,3-d]pyrimidines.
Scheme 39: Plausible mechanism for the synthesis of thiopyrano[4,3-d]pyrimidines.
Scheme 40: Synthesis of decorated imidazopyrimidines.
Scheme 41: Proposed mechanism for imidazopyrimidine synthesis.
Figure 8: Pharmacologically active molecules containing purine bases.
Scheme 42: Synthesis of aza-adenines.
Scheme 43: Synthesis of 5-aza-7-deazapurines.
Scheme 44: Proposed mechanism for deazapurines synthesis.
Figure 9: Biologically active molecules containing pyridine moiety.
Scheme 45: Synthesis of steroidal pyridines.
Scheme 46: Proposed mechanism for steroidal pyridine.
Scheme 47: Synthesis of N-alkylated 2-pyridones.
Scheme 48: Two possible mechanisms for pyridone synthesis.
Scheme 49: Synthesis of pyridone derivatives.
Scheme 50: Postulated mechanism for synthesis of pyridone.
Figure 10: Biologically active fused pyridines.
Scheme 51: Benzimidazole-imidazo[1,2-a]pyridines synthesis.
Scheme 52: Mechanism for the synthesis of benzimidazole-imidazo[1,2-a]pyridines.
Scheme 53: Synthesis of pyrazolo[3,4-b]pyridine-5-spirocycloalkanedione derivatives.
Scheme 54: Proposed mechanism for spiro-pyridines.
Scheme 55: Functionalized macrocyclane-fused pyrazolo[3,4-b]pyridine derivatives.
Scheme 56: Mechanism postulated for macrocyclane-fused pyrazolo[3,4-b]pyridine.
Scheme 57: Generation of pyrazolo[3,4-b]pyridines.
Scheme 58: Proposed mechanism for the synthesis of pyrazolo[3,4-b]pyridines.
Scheme 59: Proposed mechanism for the synthesis of azepinoindole.
Figure 11: Pharmaceutically important molecules with quinoline moiety.
Scheme 60: Povarov-mediated quinoline synthesis.
Scheme 61: Proposed mechanism for Povarov reaction.
Scheme 62: Synthesis of pyrazoloquinoline.
Scheme 63: Plausible mechanism for pyrazoloquinoline synthesis.
Figure 12: Quinazolinones as pharmacologically significant scaffolds.
Scheme 64: Four-component reaction for dihydroquinazolinone.
Scheme 65: Proposed mechanism for dihydroquinazolinones.
Scheme 66: Synthesis purine quinazolinone and PI3K-δ inhibitor.
Scheme 67: Synthesis of fused benzothiazolo/benzoimidazoloquinazolinones.
Scheme 68: Proposed mechanism for fused benzothiazolo/benzoimidazoloquinazolinones.
Scheme 69: On-water reaction for synthesis of thiazoloquinazolinone.
Scheme 70: Proposed mechanism for the thiazoloquinazolinone synthesis.
Scheme 71: β-Cyclodextrin-mediated synthesis of indoloquinazolinediones.
Scheme 72: Proposed mechanism for synthesis of indoloquinazolinediones.
Figure 13: Triazoles-containing marketted drugs and pharmacologically active molecules.
Scheme 73: Cu(I) DAPTA-catalyzed 1,2,3-triazole formation.
Scheme 74: Mechanism for Cu(I) DAPTA-catalyzed triazole formation.
Scheme 75: Synthesis of β-hydroxy-1,2,3-triazole.
Scheme 76: Proposed mechanism for synthesis of β-hydroxy-1,2,3-triazoles.
Scheme 77: Synthesis of bis-1,2,4-triazoles.
Scheme 78: Proposed mechanism for bis-1,2,4-triazoles synthesis.
Figure 14: Thiazole containing drugs.
Scheme 79: Synthesis of a substituted thiazole ring.
Scheme 80: Synthesis of pyrazolothiazoles.
Figure 15: Chromene containing drugs.
Scheme 81: Magnetic nanocatalyst-mediated aminochromene synthesis.
Scheme 82: Proposed mechanism for the synthesis of chromenes.
Functionalization of the imidazo[1,2-a]pyridine ring in α-phosphonoacrylates and α-phosphonopropionates via microwave-assisted Mizoroki–Heck reaction
- Damian Kusy,
- Agata Wojciechowska,
- Joanna Małolepsza and
- Katarzyna M. Błażewska
Beilstein J. Org. Chem. 2020, 16, 15–21, doi:10.3762/bjoc.16.3
- -phosphonoacrylates; α-phosphonopropionates; imidazo[1,2-a]pyridine; microwave-assisted reaction; Mizoroki–Heck reaction; Introduction In the last few decades, the Mizoroki–Heck reaction has become one of the main tools in organic synthesis. Its use for the functionalization of a wide range of compounds cannot be
Graphical Abstract
Figure 1: Substrates used for the Mizoroki–Heck reaction in this study.
Figure 2: Structures of the identified side products 4 and 5.
Scheme 1: Scope of the method for analogs derived from 1 and 2. The ratio of isomers is given (E/Z or β/α) in...
Scheme 2: Dealkylation of fluorinated analog 23 under the Mizoroki–Heck reaction conditions.
Mechanochemical Friedel–Crafts acylations
- Mateja Đud,
- Anamarija Briš,
- Iva Jušinski,
- Davor Gracin and
- Davor Margetić
Beilstein J. Org. Chem. 2019, 15, 1313–1320, doi:10.3762/bjoc.15.130
- mixture of 19 and 18 (3:2 ratio), accompanied with a small amount of 22. As a substitute for dianthracene 19, thermally more stable substrate, anthracene-N-methyl maleimide adduct 25 [54] was prepared by Diels–Alder reaction under high pressure conditions as well as by microwave-assisted reaction and
Graphical Abstract
Scheme 1: FCR of pyrene and phthalic anhydride.
Scheme 2: Scope of acylation reagents in FCR under mechanochemical activation conditions and comparison with ...
Scheme 3: Scope of aromatic substrates in FCR under mechanochemical activation conditions. aIsolated yields.
Scheme 4: Mechanochemical regiodirected FCR of anthracene dimer and succinic anhydride.
Scheme 5: Regioselectivity direction by protection of 9,10-anthracene ring positions.
Scheme 6: Double FCR of phthaloyl chloride and aromatics.
Figure 1: In situ Raman monitoring of reaction of phthalic anhydride with p-xylene.
5-Aminopyrazole as precursor in design and synthesis of fused pyrazoloazines
- Ranjana Aggarwal and
- Suresh Kumar
Beilstein J. Org. Chem. 2018, 14, 203–242, doi:10.3762/bjoc.14.15
- assistance (Scheme 24). The microwave-assisted reaction provided better yields of pyrazolo[3,4-b]pyridine derivatives 88 as compared to reactions under conventional heating conditions in short time. Hill et al. [72][73] reported the synthesis of pyrazolo[3,4-b]pyridines 89 from the reaction β-ketonitriles 15
Graphical Abstract
Figure 1: Selected examples of drugs with fused pyrazole rings.
Figure 2: Typical structures of some fused pyrazoloazines from 5-aminopyrazoles.
Scheme 1: Regiospecific synthesis of 4 and 6-trifluoromethyl-1H-pyrazolo[3,4-b]pyridines.
Scheme 2: Synthesis of pyrazolo[3,4-b]pyridine-6-carboxylates.
Scheme 3: Synthesis of 1,4,6-triaryl-1H-pyrazolo[3,4-b]pyridines with ionic liquid .
Scheme 4: Synthesis of coumarin-based isomeric tetracyclic pyrazolo[3,4-b]pyridines.
Scheme 5: Synthesis of 6-substituted pyrazolo[3,4-b]pyridines under Heck conditions.
Scheme 6: Microwave-assisted palladium-catalyzed synthesis of pyrazolo[3,4-b]pyridines.
Scheme 7: Acid-catalyzed synthesis of pyrazolo[3,4-b]pyridines via enaminones.
Scheme 8: Synthesis of pyrazolo[3,4-b]pyridines via aza-Diels–Alder reaction.
Scheme 9: Synthesis of macrocyclane fused pyrazolo[3,4-b]pyridine derivatives.
Scheme 10: Three-component synthesis of 4,7-dihydro-1H-pyrazolo[3,4-b]pyridine derivatives.
Scheme 11: Ultrasonicated synthesis of spiro[indoline-3,4'-pyrazolo[3,4-b]pyridine]-2,6'(1'H)-diones.
Scheme 12: Synthesis of spiro[indoline-3,4'-pyrazolo[3,4-b]pyridine] derivatives under conventional heating co...
Scheme 13: Nanoparticle-catalyzed synthesis of pyrazolo[3,4-b]pyridine-spiroindolinones.
Scheme 14: Microwave-assisted multicomponent synthesis of spiropyrazolo[3,4-b]pyridines.
Scheme 15: Unexpected synthesis of naphthoic acid-substituted pyrazolo[3,4-b]pyridines.
Scheme 16: Multicomponent synthesis of variously substituted pyrazolo[3,4-b]pyridine derivatives.
Scheme 17: Three-component synthesis of 4,7-dihydropyrazolo[3,4-b]pyridines and pyrazolo[3,4-b]pyridines.
Scheme 18: Synthesis of pyrazolo[3,4-b]pyridine-5-spirocycloalkanediones.
Scheme 19: Ultrasound-mediated three-component synthesis of pyrazolo[3,4-b]pyridines.
Scheme 20: Multicomponent synthesis of 4-aryl-3-methyl-1-phenyl-4,6,8,9-tetrahydropyrazolo [3,4-b]thiopyrano[4...
Scheme 21: Synthesis of 2,3-dihydrochromeno[4,3-d]pyrazolo[3,4-b]pyridine-1,6-diones.
Scheme 22: FeCl3-catalyzed synthesis of o-hydroxyphenylpyrazolo[3,4-b]pyridine derivatives.
Scheme 23: Ionic liquid-mediated synthesis of pyrazolo[3,4-b]pyridines.
Scheme 24: Microwave-assisted synthesis of pyrazolo[3,4-b]pyridines.
Scheme 25: Multicomponent synthesis of pyrazolo[3,4-b]pyridine-5-carbonitriles.
Scheme 26: Unusual domino synthesis of 4,7-dihydropyrazolo[3,4-b]pyridine-5-nitriles.
Scheme 27: Synthesis of 4,5,6,7-tetrahydro-4H-pyrazolo[3,4-b]pyridines under conventional heating and ultrasou...
Scheme 28: L-Proline-catalyzed synthesis of of pyrazolo[3,4-b]pyridine.
Scheme 29: Microwave-assisted synthesis of 5-aminoarylpyrazolo[3,4-b]pyridines.
Scheme 30: Microwave-assisted multi-component synthesis of pyrazolo[3,4-e]indolizines.
Scheme 31: Synthesis of fluoropropynyl and fluoroalkyl substituted pyrazolo[1,5-a]pyrimidine.
Scheme 32: Acid-catalyzed synthesis of pyrazolo[1,5-a]pyrimidine derivatives.
Scheme 33: Chemoselective and regiospecific synthesis of 2-(3-methylpyrazol-1’-yl)-5-methylpyrazolo[1,5-a]pyri...
Scheme 34: Regioselective synthesis of 7-trifluoromethylpyrazolo[1,5-a]pyrimidines.
Scheme 35: Microwave-assisted synthesis of 7-trifluoromethylpyrazolo[1,5-a]pyrimidine carboxylates.
Scheme 36: Microwave and ultrasound-assisted synthesis of 7-trifluoromethylpyrazolo[1,5-a]pyrimidines.
Scheme 37: Base-catalyzed unprecedented synthesis of pyrazolo[1,5-a]pyrimidines via C–C bond cleavage.
Scheme 38: Synthesis of aminobenzothiazole/piperazine linked pyrazolo[1,5-a]pyrimidines.
Scheme 39: Synthesis of aminoalkylpyrazolo[1,5-a]pyrimidine-7-amines.
Scheme 40: Synthesis of pyrazolo[1,5-a]pyrimidines from condensation of 5-aminopyrazole 126 and ethyl acetoace...
Scheme 41: Synthesis of 7-aminopyrazolo[1,5-a]pyrimidines.
Scheme 42: Unexpected synthesis of 7-aminopyrazolo[1,5-a]pyrimidines under solvent free and solvent-mediated c...
Scheme 43: Synthesis of N-(4-aminophenyl)-7-aryloxypyrazolo[1,5-a]pyrimidin-5-amines.
Scheme 44: Base-catalyzed synthesis of 5,7-diarylpyrazolo[1,5-a]pyrimidines.
Scheme 45: Synthesis of 6,7-dihydropyrazolo[1,5-a]pyrimidines in PEG-400.
Scheme 46: Synthesis of 7-heteroarylpyrazolo[1,5-a]pyrimidine-3-carboxamides.
Scheme 47: Synthesis of 7-heteroarylpyrazolo[1,5-a]pyrimidine derivatives under conventional heating and micro...
Scheme 48: Synthesis of N-aroylpyrazolo[1,5-a]pyrimidine-5-amines.
Scheme 49: Regioselective synthesis of ethyl pyrazolo[1,5-a]pyrimidine-7-carboxylate.
Scheme 50: Sodium methoxide-catalyzed synthesis of 3-cyano-6,7-diarylpyrazolo[1,5-a]pyrimidines.
Scheme 51: Synthesis of various pyrazolo[3,4-d]pyrimidine derivatives.
Scheme 52: Synthesis of hydrazinopyrazolo[3,4-d]pyrimidine derivatives.
Scheme 53: Synthesis of N-arylidinepyrazolo[3,4-d]pyrimidin-5-amines.
Scheme 54: Synthesis of pyrazolo[3,4-d]pyrimidinyl-4-amines.
Scheme 55: Iodine-catalyzed synthesis of pyrazolo[3,4-d]pyrimidinones.
Scheme 56: Synthesis of ethyl 6-amino-2H-pyrazolo[3,4-d]pyrimidine-4-carboxylate.
Scheme 57: Synthesis of 4-substituted-(3,6-dihydropyran-4-yl)-1H-pyrazolo[3,4-d]pyrimidines.
Scheme 58: Synthesis of 1-(2,4-dichlorophenyl)pyrazolo[3,4-d]pyrimidin-4-yl carboxamides.
Scheme 59: Synthesis of 5-(1,3,4-thidiazol-2-yl)pyrazolo[3,4-d]pyrimidine.
Scheme 60: One pot POCl3-catalyzed synthesis of 1-arylpyrazolo[3,4-d]pyrimidin-4-ones.
Scheme 61: Synthesis of 4-amino-N1,C3-dialkylpyrazolo[3,4-d]pyrimidines under Suzuki conditions.
Scheme 62: Microwave-assisted synthesis of pyrazolo[3,4-b]pyrazines.
Scheme 63: Synthesis and derivatization of pyrazolo[3,4-b]pyrazine-5-carbonitriles.
Scheme 64: Synthesis of 2-thioxo-pyrazolo[1,5-a][1,3,5]triazin-4-ones.
Scheme 65: Synthesis of 2,3-dihydropyrazolo[1,5-a][1,3,5]triazin-4(1H)-one.
Scheme 66: Synthesis of pyrazolo[1,5-a][1,3,5]triazine-8-carboxylic acid ethyl ester.
Scheme 67: Microwave-assisted synthesis of 4,7-dihetarylpyrazolo[1,5-a][1,3,5]triazines.
Scheme 68: Alternative synthetic route to 4,7-diheteroarylpyrazolo[1,5-a][1,3,5]triazines.
Scheme 69: Synthesis of 4-aryl-2-ethylthio-7-methylpyrazolo[1,5-a][1,3,5]triazines.
Scheme 70: Microwave-assisted synthesis of 4-aminopyrazolo[1,5-a][1,3,5]triazine.
Scheme 71: Synthesis of pyrazolo[3,4-d][1,2,3]triazines from pyrazol-5-yl diazonium salts.
Scheme 72: Synthesis of 2,5-dihydropyrazolo[3,4-e][1,2,4]triazines.
Scheme 73: Synthesis of pyrazolo[5,1-c][1,2,4]triazines via diazopyrazolylenaminones.
Scheme 74: Synthesis of pyrazolo[5,1-c][1,2,4]triazines in presence of sodium acetate.
Scheme 75: Synthesis of various 7-diazopyrazolo[5,1-c][1,2,4]triazine derivatives.
Scheme 76: One pot synthesis of pyrazolo[5,1-c][1,2,4]triazines.
Scheme 77: Synthesis of 4-amino-3,7,8-trinitropyrazolo-[5,1-c][1,2,4]triazines.
Scheme 78: Synthesis of tricyclic pyrazolo[5,1-c][1,2,4]triazines by azocoupling reaction.
New bio-nanocomposites based on iron oxides and polysaccharides applied to oxidation and alkylation reactions
- Daily Rodríguez-Padrón,
- Alina M. Balu,
- Antonio A. Romero and
- Rafael Luque
Beilstein J. Org. Chem. 2017, 13, 1982–1993, doi:10.3762/bjoc.13.194
- alkylation of toluene with benzyl chloride, either via microwave-assisted or with conventional heating (60 °C). For the microwave-assisted reaction (Scheme 2), after three minutes, the conversion was higher than 99% for all of the three materials (Figure 6). For the Fe2O3-PS4-MNP nanocatalyst, even after
- and 25 mg of catalyst were used. The microwave-assisted reaction was conducted for 1, 2 and 3 min, while the reaction under conventional heating was carried out for 30 min until the maximum conversion was reached. The temperature in both cases was kept at around 60 °C. The conversion and selectivity
- -assisted reaction during 3 min (Table 7, Figure 7). Reusability studies prove the high inherent stability and activity of Fe2O3-PS4-MNP and TiO2-Fe2O3-PS4 nanomaterials (Figure 8). However, the Fe2O3-PS4 nanocatalyst loses its activity after the first use, which can be due to the loss of residual acidity
Graphical Abstract
Figure 1: Overview of the preparation of the nanocomposites based on iron oxide and polysaccharide.
Figure 2: XPS spectra of A: Fe2O3-PS4, B: Fe2O3-PS4-MNP and C: TiO2-Fe2O3-PS4 nanohybrids.
Figure 3: A and B: SEM and TEM images of TiO2-Fe2O3-PS4; C and D: SEM and TEM images of Fe2O3-PS4. E and F: S...
Figure 4: DRIFT spectra of A: TiO2-Fe2O3-PS4 and B: Fe2O3-PS4-MNP nanohybrids.
Scheme 1: Oxidation of benzyl alcohol to benzaldehyde.
Figure 5: Conversion and selectivity of the oxidation of benzyl alcohol for the three catalytic systems.
Scheme 2: Microwave-assisted alkylation of toluene with benzyl chloride.
Figure 6: Conversion and selectivity of the microwave-assisted alkylation of toluene for the three catalytic ...
Scheme 3: Alkylation of toluene with benzyl chloride with conventional heating.
Figure 7: Conversion and selectivity of the alkylation of toluene with conventional heating for the three cat...
Figure 8: Reusability of the iron oxide/polysaccharide nanohybrids.
BODIPY-based fluorescent liposomes with sesquiterpene lactone trilobolide
- Ludmila Škorpilová,
- Silvie Rimpelová,
- Michal Jurášek,
- Miloš Buděšínský,
- Jana Lokajová,
- Roman Effenberg,
- Petr Slepička,
- Tomáš Ruml,
- Eva Kmoníčková,
- Pavel B. Drašar and
- Zdeněk Wimmer
Beilstein J. Org. Chem. 2017, 13, 1316–1324, doi:10.3762/bjoc.13.128
- compound is shown in Scheme 1, part B. Propargyl-ChL [35] was introduced into Huisgen copper-catalyzed 1,3-dipolar cycloaddition [36] (CuAAC) with BODIPY 3. This microwave-assisted reaction catalyzed by CuSO4·5H2O, sodium ascorbate and a catalytic amount of TBTA (tris[(1-benzyl-1H-1,2,3-triazol-4-yl)methyl
Graphical Abstract
Figure 1: Chemical structures of the basic compounds used in this study.
Scheme 1: Synthesis of the BODIPY building block (part A) and construct 6 (part B).
Figure 2: Absorbance and fluorescence spectra of compounds 3–6. UV spectra (part A) were recorded with a conc...
Figure 3: NO production in primary rat macrophages. The cells were treated with Tb, compounds 4, 5, and Tb-co...
Figure 4: Atomic force microscopy images of liposomes, 5 µm area: A) 2D image, B) 3D image (Ra = 2.4 nm); 2 µ...
Figure 5: Panel of images from live-cell fluorescence microscopy: intracellular localization of construct 6 i...
Figure 6: Panel of images from live-cell fluorescence microscopy: intracellular localization of liposomes wit...
Synthesis and properties of fluorescent 4′-azulenyl-functionalized 2,2′:6′,2″-terpyridines
- Adrian E. Ion,
- Liliana Cristian,
- Mariana Voicescu,
- Masroor Bangesh,
- Augustin M. Madalan,
- Daniela Bala,
- Constantin Mihailciuc and
- Simona Nica
Beilstein J. Org. Chem. 2016, 12, 1812–1825, doi:10.3762/bjoc.12.171
- at 110 °C for 10 min in aqueous medium. In both cases, the desired α,β-unsaturated ketone 2 were isolated in similar yields (see Table 1). It is worth mentioning here that the microwave-assisted reaction was performed in aqueous medium, an environmentally benign solvent. The other advantage of this
Graphical Abstract
Scheme 1: Synthesis of 4′-azulenyl substituted terpyridines.
Figure 1: Molecular structure and numbering scheme of 4′-(1-azulenyl)-2,2′:6′,2″-terpyridine (4a, left) and 4...
Figure 2: Packing diagram for 4a showing the π–π stacking and CH–π interactions between the pyridine rings an...
Figure 3: Packing diagram for 4b showing the π–π stacking between the pyridine rings. Hydrogen atoms are omit...
Figure 4: Absorption spectra of the azulene-containing terpyridine, 4a and 4b in CH2Cl2 solution at room temp...
Figure 5: Emission spectra of the azulene-containing terpyridine, 4a and 4b in CH2Cl2 solution (2.59 × 10−5 M...
Figure 6: Selected Kohn–Sham orbitals and orbital energies for 4a and 4b, obtained with three different funct...
Figure 7: DPV-traces (with baseline correction) of 0.5 mM solutions of 4a (solid) and 4b (dash) in DMF, with ...
Figure 8: Absorption spectra of a 4.26 mM solution of 4a in methanol upon titration with an aqueous HgCl2 sol...
Figure 9: Absorption spectra of a 4.26 mM solution of 4a in methanol upon titration with CdCl2 aqueous soluti...
One-pot sequential synthesis of isocyanates and urea derivatives via a microwave-assisted Staudinger–aza-Wittig reaction
- Diego Carnaroglio,
- Katia Martina,
- Giovanni Palmisano,
- Andrea Penoni,
- Claudia Domini and
- Giancarlo Cravotto
Beilstein J. Org. Chem. 2013, 9, 2378–2386, doi:10.3762/bjoc.9.274
- : isocyanates; microwave-assisted reaction; one-pot reaction; tandem Staudinger–aza-Wittig reaction; urea derivatives; Introduction The industrial and commercial impact of isocyanates (R–NCO) is steadily growing. In particular, the polyurethane output has undergone yearly increases of 5% over the last decade
Multistep organic synthesis of modular photosystems
- Naomi Sakai and
- Stefan Matile
Beilstein J. Org. Chem. 2012, 8, 897–904, doi:10.3762/bjoc.8.102
- crude dibromo cNDA 32. Microwave-assisted reaction [15] with amines 14 and 15 gave the mixed cNDI 44 together with the symmetric side products. The obtained mixture of 2,6- and 3,7-regioisomers was not separated throughout the entire synthesis of photosystem 1. Nucleophilic aromatic substitution with
Graphical Abstract
Figure 1: Schematic structure of photosystem 1 on indium tin oxide (ITO, grey) with antiparallel gradients in...
Scheme 1: Synthesis of initiator 2.
Scheme 2: Synthesis of propagators 3 and 4.
Scheme 3: Synthesis of stack exchangers 5 and 6. Compounds 5, 6, 45 and 47 are mixtures of 2,6- and 3,7-regio...
Scheme 4: Synthesis of photosystem 1, self-organizing surface-initiated polymerization (SOSIP). R1 = SH (50) ...
Scheme 5: Synthesis of photosystem 1, stack exchange. R1 = SH or oxidized derivative, R1 = CH2CHCH2. 5 and 6 ...
Scheme 6: Schematic overview over SOSIP and stack exchange.
Solvent-free and time-efficient Suzuki–Miyaura reaction in a ball mill: the solid reagent system KF–Al2O3 under inspection
- Franziska Bernhardt,
- Ronald Trotzki,
- Tony Szuppa,
- Achim Stolle and
- Bernd Ondruschka
Beilstein J. Org. Chem. 2010, 6, No. 7, doi:10.3762/bjoc.6.7
- reaction [33][34][36][37][38][39][40][41][42] were prepared. In combination with alumina, KF seemed to be the best choice, as the reactions with other inorganic bases (for example KOH, NaF, Na2CO3) resulted in lower conversion for microwave-assisted reaction protocols [33][34]. A few literature studies
Graphical Abstract
Scheme 1: Suzuki–Miyaura reaction of phenylboronic acid (1) with aryl bromides 2 yielding substituted biaryls ...
Figure 1: Results of the Suzuki–Miyaura reaction of phenylboronic acid (1) with p-bromoacetophenone (2a; cf. Scheme 1...
Figure 2: Results of the Suzuki–Miyaura reaction according to Scheme 1 assisted by pure aluminas [5 g SRS1–3: cf. Table 2; b...
Figure 3: Influence of Pd(OAc)2 concentration on the results of the Suzuki–Miyaura reaction of phenylboronic ...
Figure 4: Results of the Suzuki–Miyaura reaction according to Scheme 1 assisted by KF-loaded aluminas [5 g SRS1a–4a, ...
Figure 5: Dependence of the yield of Suzuki–Miyaura cross-coupling product (Scheme 1) from water content (Karl-Fische...
