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Search for "[bmim][Br]" in Full Text gives 4 result(s) in Beilstein Journal of Organic Chemistry.
Synthesis of heterocycles based on azomethine ylides from α-amino acids (or amines) and carbonyl compounds
- Ekaterina V. Berezhnaya,
- Alexander I. Ponyaev,
- Vitali M. Boitsov and
- Alexander V. Stepakov
Beilstein J. Org. Chem. 2026, 22, 705–741, doi:10.3762/bjoc.22.55
Graphical Abstract
Scheme 1: Strategies for the preparation of pyrrolidine derivatives by (3 + 2) cycloaddition of azomethine yl...
Scheme 2: (3 + 2) Cycloaddition of iminoesters to dimethylmaleate.
Scheme 3: Cycloaddition of 1 with various dipolarophiles catalyzed by Ag(I)-L1.
Scheme 4: Cycloaddition of 1 with tert-butyl acrylate catalyzed by Ag(I)-L2.
Scheme 5: Cycloaddition of 1 with dimethyl maleate catalyzed by Cu(I)-L3.
Scheme 6: Cycloaddition of 1 with alkenes catalyzed by Zn(II)-t-Bu-BOX (L4).
Scheme 7: (3 + 2) Cycloaddition of iminoesters to acrylates.
Scheme 8: Catalytic double (3 + 2) cycloaddition to form pyrrolizidine derivatives.
Scheme 9: (3 + 2) Cycloaddition of iminoethers to vinyl phenyl sulfone.
Scheme 10: Regiodivergent and enantioselective synthesis of pyrrolidines 16 and 17.
Scheme 11: Substrate-controlled regioreversible "normal" and "incomplete" 1,3-dipolar cycloaddition.
Scheme 12: Enantioselective synthesis of exo-/endo-pyrrolidines.
Scheme 13: (3 + 2) Cycloaddition of iminoethers 21 to dipolarophiles 22–24.
Scheme 14: Synthesis of bicyclic pyrrolidines 29 from cyclopentene-1,3-diones.
Scheme 15: (3 + 2) Cycloaddition of aldimine esters and allyl alcohols using copper-ruthenium catalysis.
Scheme 16: Synthesis of 3,3-difluoro- and 3,3,4-trifluoropyrrolidine derivatives.
Scheme 17: Use of iminoesters from natural compounds and pharmaceuticals for reactions with 1,1-difluoro- and ...
Scheme 18: Reaction of iminoesters with 1,3-enynes.
Scheme 19: Synthesis of pyrrolidines from iminoesters and vinyl(hetero)arenes.
Scheme 20: Synthesis of exo-pyrrolidines 42 and 43.
Scheme 21: Enantioselective synthesis of heteroarylpyrrolidines 45 and 46.
Scheme 22: Catalytic reaction of (3 + 2) cycloaddition of imines 12 to benzofulvenes 47.
Scheme 23: Fullerene as a dipolarophile in (3 + 2) cycloaddition reactions.
Scheme 24: Asymmetric synthesis of optically active tetrasubstituted pyrrolidines 54.
Scheme 25: (3 + 2) Cycloaddition reaction of imines 55 and α,β-unsaturated aldehydes.
Scheme 26: Probable mechanism of enantioselective (3 + 2) cycloaddition of azomethine ylides to α,β-unsaturate...
Scheme 27: Cycloaddition between iminoesters 12 and sulfinylimines 58.
Scheme 28: (3 + 2) Cycloaddition between triarylideneacetylacetone and azomethine ylides in the presence of ti...
Scheme 29: Stereoselective synthesis of decahydropyrrolo[2,1,5-cd]indolizine 66.
Scheme 30: Synthesis of policyclic derivatives 71 and 72.
Scheme 31: Catalytic аsymmetric (3 + 2) сycloaddition of 2-pyridylimines with N-methylmaleimide.
Scheme 32: Catalytic аsymmetric (3 + 2) сycloaddition of 2-pyridylimines 1 with other dipolarophiles.
Scheme 33: Enantioselective (3 + 2) cycloaddition of silylimine with various dipolarophiles.
Scheme 34: Proposed mechanism of formation of pyrrolidines 78.
Scheme 35: Synthesis of polyheterocyclic pyrrolidines 82–91.
Scheme 36: Synthesis of spirocyclic (95) and fused (96) pyrrolidines.
Scheme 37: (3 + 2) Cycloaddition involving aromatic aldehydes 97, N-propargylmaleimide (98) and α-amino acids ...
Scheme 38: Synthesis of pyrrolizidines 106 and by-product 107.
Scheme 39: Iridium-catalyzed three-component cascade (3 + 2) cycloaddition.
Scheme 40: Intramolecular (3 + 2) cycloaddition of N-alkenylpyrrole-2-carbaldehyde 110 and α-amino acids.
Scheme 41: Three-component (3 + 2) cycloaddition involving fullerene.
Scheme 42: Four-component stereoselective one-pot synthesis of spiro-cycloadducts 119–122.
Scheme 43: Reactions of azomethine ylide 123 with cyclopropenes.
Scheme 44: Three-component reactions involving ninhydrin, cyclopropenes and acyclic α-amino acids.
Scheme 45: Reaction of cyclopropenes 138 with the N-protonated form of Ruhemann purple 137.
Scheme 46: Enantioselective (3 + 2) cycloaddition of azomethine ylides generated in situ from isatins and amin...
Scheme 47: (3 + 2) Cycloaddition of cyclohexenone 143, isatins 140 and aminomalonic diesters 141, catalyzed by...
Scheme 48: Enantioselective (3 + 2) cycloaddition of azomethine ylides generated in situ from isatins and amin...
Scheme 49: Enantioselective (3 + 2) cycloaddition of azomethine ylides generated in situ from isatins and benz...
Scheme 50: (3 + 2) Cycloaddition involving isatins, azetidine-2-carboxylic acid, maleimides or itaconimides.
Scheme 51: (3 + 2) Cycloaddition involving isatins, amino acids and tetraethylvinylidenebis(phosphonate).
Scheme 52: Synthesis of spirooxindoles 156 from triarylideneacetylacetones 155.
Scheme 53: Synthesis of spirooxindole derivatives 157–160.
Scheme 54: Synthesis of hybrid spiro-heterocycles 164–166.
Scheme 55: Formation of azomethine ylide from isatin and sarcosine.
Scheme 56: (3 + 2) Cycloaddition involving isatins, amino acids and trans-3-benzoylacrylic acid.
Scheme 57: Regioselective synthesis of spirooxindoles 170.
Scheme 58: Synthesis of hybrid spiro-heterocycles 86.
Scheme 59: (3 + 2) Cycloaddition involving acenaphthenequinones, amino acids and cyclopropenes.
Scheme 60: Synthesis of hybrid glyco-3-nitrochromane cycloadducts 179.
Scheme 61: Synthesis of spiro[indenoquinoxaline-(thia)pyrrolizidines] 90a.
Scheme 62: Three-component reactions of cyclopropenes, 11H-indeno[1,2-b]quinoxalin-11-onesand α-amino acids, s...
Scheme 63: Synthesis of hybrid glyco-3-nitrochromane cycloadducts 92.
Scheme 64: (3 + 2) Cycloaddition of 11H-benzo[4,5]imidazo[1,2-a]indol-11-one (189) with cyclopropenes and male...
Scheme 65: Diastereoselective synthesis of spiro derivatives of barbituric acid from alloxan 193, α-amino acid...
Scheme 66: Probable mechanism of formation of azomethine ylide from alloxan and ʟ-proline.
Scheme 67: Three-component reactions involving tryptanthrin 196, α-amino acids and cyclopropenes.
Efficient synthesis of 4-substituted-ortho-phthalaldehyde analogues: toward the emergence of new building blocks
- Clémence Moitessier,
- Ahmad Rifai,
- Pierre-Edouard Danjou,
- Isabelle Mallard and
- Francine Cazier-Dennin
Beilstein J. Org. Chem. 2019, 15, 721–726, doi:10.3762/bjoc.15.67
- chloride/N,N-dimethylformamide in the presence of a catalytic amount of p-toluenesulfonic acid ended up with only the formation of OPA. Regeneration of phenols from methyl ethers have also been tested by Boovanahalli et al. [26] by using an ionic liquid such as 1-butyl-3-methylimidazolium bromide ([Bmim]Br
- key intermediate 4,5-dihydroisobenzofuran-5-ol (3) before reaching the oxidation step. The methoxy protecting group and the DDQ oxidation reagent were found to be the most efficient. Moreover, deprotection of 4-methoxy-ortho-phthalaldehyde (5b) was successfully achieved using [Bmim]Br and p-TsOH on
- compound 5b (200 mg, 1.2 mmol), p-TsOH (1.68g, 9.8 mmol) and [Bmim]Br (4.0 g, 18.3 mmol) was placed in a sealed vial and irradiated under microwave irradiation for 30 minutes at 150 °C under strong agitation. After cooling, the mixture was vigorously extracted with Et2O overnight. The ether layer was
Graphical Abstract
Scheme 1: Synthesis of 4,5-dihydroisobenzofuran-5-ol (3).
Scheme 2: Protection strategy of 4,5-dihydroisobenzofuran-5-ol (3).
Scheme 3: Oxidation of 5-substituted-4,5-dihydroisobenzofuran-5-ol in presence of SeO2 or DDQ.
Scheme 4: Synthesis of 4-hydroxy-ortho-phthalaldehyde (6) through MAOS demethylation of 4-methoxy-ortho-phtha...
Bi-mediated allylation of aldehydes in [bmim][Br]: a mechanistic investigation
- Mrunesh Koli,
- Sucheta Chatterjee,
- Subrata Chattopadhyay and
- Dibakar Goswami
Beilstein J. Org. Chem. 2018, 14, 2198–2203, doi:10.3762/bjoc.14.193
- temperature ionic liquid (RTIL), [bmim][Br] has been found to be a superior medium for the Bi-mediated Barbier-type allylation of aldehydes compared to other conventional solvents. It plays the dual role of a solvent and a metal activator enabling higher yields of the products in a shorter reaction time using
- stoichiometric/near-stoichiometric amounts of reagents. Plausibly, [bmim][Br] activates Bi metal by a charge transfer mechanism. The 1H VT-NMR studies suggested that both the allylating species, allylbismuth dibromide and diallylbismuth bromide, are generated in situ. Keywords: allylation; bismuth; [bmim][Br
- ineffective (Table 1, entry 15). True to our expectation, the reaction was very fast in [bmim][Br] and furnished 2a in 88% yield. Notably, the reaction proceeded to completion with almost stoichiometric amounts of allyl bromide (1.2 equiv) and Bi (1.0 equiv) in absence of any additional metal activator (Table
Graphical Abstract
Scheme 1: Bi-mediated allylation of aldehydes.
Figure 1: Partial 1H NMR spectra (recorded at two temperatures) of the reaction mixture of allyl bromide and ...
Figure 2: Structures of all the possible allylbismuth species.
Scheme 2: Probable reaction mechanism.
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
- ) and α,β-unsaturated ketones 24 (Scheme 3) in the ionic solvent [bmim]Br at 90 °C with excellent yield. Variation of the aryl substituents on the α,β-unsaturated ketones 24 has no significant effect on the reaction. The reaction was proposed to occur through a sequence of Michael addition, cyclization
- -aminopyrazole 16 and aldehydes 47 in various organic solvents and ionic liquids to synthesize pyrazolo[3,4-b]pyridine derivative 87 (Scheme 23). Ionic liquids provided high yields of 87 in very short time with the best results obtained in [bmim]Br whereas organic solvents resulted in low yields and took longer
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.
