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Search for "thiadiazoles" in Full Text gives 19 result(s) in Beilstein Journal of Organic Chemistry.
Trifluoromethylated hydrazones and acylhydrazones as potent nitrogen-containing fluorinated building blocks
- Zhang Dongxu
Beilstein J. Org. Chem. 2023, 19, 1741–1754, doi:10.3762/bjoc.19.127
- ][52][53][54][55][56][57][58] (Scheme 9). Thioketones, thiochalcones, and tertiary thioamides react as C=S super dipolarophilic agents. Jasiński et al. reported that these thiocarbonyl compounds react with trifluoromethylated hydrazonoyl halides to give trifluoromethylated 1,3,4-thiadiazoles via
Graphical Abstract
Scheme 1: Synthesis of trifluoromethylpyrazoles from trifluoroacetaldehyde hydrazones.
Scheme 2: Synthesis of polysubstituted pyrazolidines and pyrazolines.
Scheme 3: Asymmetric synthesis of 3-trifluoromethyl-1,4-dihydropyridazines reported by Rueping et al. [39].
Scheme 4: Synthesis of 3-trifluoromethyl-1,4-dihydropyridazine with Brønsted acid-assisted Lewis base catalys...
Scheme 5: Synthesis of CF3-pyrazoles and CF3-1,6-dihydropyridazines.
Scheme 6: Asymmetric reactions of trifluoromethylimines with organometallic reagents.
Scheme 7: Mannich-type reaction of trifluoroacetaldehyde hydrazones.
Scheme 8: Synthesis of trifluoromethylated hydrazonoyl halides.
Scheme 9: Early work of trifluoromethylated hydrazonoyl halides.
Scheme 10: [3 + 2]/[3 + 3] Cycloadditions of trifluoromethylated hydrazonoyl halides.
Scheme 11: Substrate scope for [3 + 2] cycloadditions with trifluoroacetonitrile imines reported by Jasiński’s...
Scheme 12: Synthesis of trifluoromethylated 1,2,4-triazole and 1,2,4-triazine derivatives.
Scheme 13: [3 + 2] Cycloadditions of difluoromethylated hydrazonoyl halides.
Scheme 14: Preparation and early applications of trifluoromethylated acylhydrazones.
Scheme 15: 1,2-Nucleophilic addition reactions of trifluoromethylated acylhydrazones.
Scheme 16: Cascade oxidation/cyclization reactions of trifluoromethylated homoallylic acylhydrazines.
Scheme 17: Synthesis of trifluoromethylated cyanohydrazines and 3-trifluoromethyl-1,2,4-triazolines.
Scheme 18: N-Arylation and N-alkylation of trifluoromethyl acylhydrazones.
Scheme 19: [3 + 2]-Cycladditions of trifluoromethyl acylhydrazones.
Eschenmoser coupling reactions starting from primary thioamides. When do they work and when not?
- Lukáš Marek,
- Jiří Váňa,
- Jan Svoboda and
- Jiří Hanusek
Beilstein J. Org. Chem. 2023, 19, 808–819, doi:10.3762/bjoc.19.61
- thiobenzamides [26][27]. The latter authors concluded that the relative occurrence of 1,2,4-thiadiazoles (XV) during the Hantzsch reaction probably depends on the steric demands of the starting α-haloketones/esters II, but the real explanation is probably more complicated. Therefore, we have decided to examine
Graphical Abstract
Scheme 1: Eschenmoser coupling reaction between 3-substituted oxindoles and thioamides.
Scheme 2: Possible reactions of α-haloketones, esters and amides with primary thioamides.
Figure 1: Studied α-bromoamides and α-bromolactams.
Scheme 3: Reaction of 4-bromo-1,1-dimethyl-1,4-dihydroisoquinolin-3(2H)-one (2b) with thiobenzamide and thioa...
Scheme 4: Reaction of 4-bromo-1,1-dimethyl-1,4-dihydroisoquinolin-3(2H)-one (2b) with 4’-substituted thiobenz...
Scheme 5: Reaction of 4-bromoisoquinoline-1,3(2H,4H)-dione (3) with thiobenzamide, thioacetamide, and thioben...
Scheme 6: Reaction of N-phenyl- and N-methyl-2-bromo(phenyl)acetamide (4a,b) with thiobenzamide in acetonitri...
Scheme 7: Transformation of salt 15 under kinetic and thermodynamic control conditions [1].
Figure 2: Comparison of energy profiles (relative Gibbs energies at 298 K in kJ·mol−1 for the ECR (right) and...
A straightforward conversion of 1,4-quinones into polycyclic pyrazoles via [3 + 2]-cycloaddition with fluorinated nitrile imines
- Greta Utecht-Jarzyńska,
- Karolina Nagła,
- Grzegorz Mlostoń,
- Heinz Heimgartner,
- Marcin Palusiak and
- Marcin Jasiński
Beilstein J. Org. Chem. 2021, 17, 1509–1517, doi:10.3762/bjoc.17.108
- -thiadiazoles as the products of [3 + 2]-cycloaddition to the C=S bond [25]. Taking into account that fluorinated heterocycles [31][32][33][34], including pyrazoles [31][35][36], are of great significance for various medicinal and agricultural applications, the development of new methods for the construction of
Graphical Abstract
Figure 1: Structures of exemplary benzo- and heteroaromatic fused 1,4-quinone drugs and natural products.
Scheme 1: First [3 + 2]-cycloaddition of 1,4-naphthoquinone (1a) with intermediate nitrile imine 2, generated...
Scheme 2: Selected applications of trifluoroacetonitrile imines 7 in the synthesis of S-containing 5- and 6-m...
Scheme 3: Synthesis of [3 + 2]-cycloadducts 9a–l derived from CF3-substituted nitrile imines 7a–h and 1,4-qui...
Figure 2: X-ray structure of 3-trifluoromethylpyrazole derivative 9d. The labeling scheme of the asymmetric u...
Scheme 4: Thermal elimination of MeOH from the initial [3 + 2]-cycloadduct of 1d and nitrile imine 7d generat...
Scheme 5: Formation of the thermally stable, initially formed [3 + 2]-cycloadduct 10c obtained from 1e and ni...
Figure 3: Electronic absorption spectra for selected a) naphthoquinone-derived (9c, 9d, 9g) and b) anthraquin...
Regioselective synthesis of heterocyclic N-sulfonyl amidines from heteroaromatic thioamides and sulfonyl azides
- Vladimir Ilkin,
- Vera Berseneva,
- Tetyana Beryozkina,
- Tatiana Glukhareva,
- Lidia Dianova,
- Wim Dehaen,
- Eugenia Seliverstova and
- Vasiliy Bakulev
Beilstein J. Org. Chem. 2020, 16, 2937–2947, doi:10.3762/bjoc.16.243
- interesting building blocks in organic synthesis [17][18][19][20] (Figure 1). An N-sulfonyl amidine was recently found to be a key group in acid–base-induced rearrangements of 1,2,3-triazoles and thiadiazoles [22]. A variety of methods have been developed for the synthesis of N-sulfonyl amidines. The most
Graphical Abstract
Figure 1: Examples of biological activity and interesting chemical reactivity of N-sulfonyl amidines.
Figure 2: Data on the synthesis of N′-sulfonylazole-4-carboximidamides.
Scheme 1: Synthesis of 1-alkyl-N-phenyl-N'-(sulfonyl)-1H-1,2,3-triazole-4-carboximidamides 3.
Figure 3: Starting compounds.
Scheme 2: Scope for the reaction of 1-alkyl-1,2,3-triazole-4-carbothioamides 1a–d with azides 2a–f.
Scheme 3: Scope of the reaction of 5-arylamino-1,2,3-triazole-4-carbothioamides 1i–l with azides 2a,c–f.
Scheme 4: Synthesis of 2-aminothiazole-4-N-sulfonyl amidines.
Scheme 5: Synthesis of N-sulfonyl amidines of isoxazolylcarboxylic acid.
Scheme 6: Synthesis of bis(sulfonyl amidines) 3aj–an.
Scheme 7: Plausible mechanism for the reaction of heterocyclic thioamides with sulfonyl azides.
Synthesis of imidazo[1,5-a]pyridines via cyclocondensation of 2-(aminomethyl)pyridines with electrophilically activated nitroalkanes
- Dmitrii A. Aksenov,
- Nikolai A. Arutiunov,
- Vladimir V. Maliuga,
- Alexander V. Aksenov and
- Michael Rubin
Beilstein J. Org. Chem. 2020, 16, 2903–2910, doi:10.3762/bjoc.16.239
- -thiadiazoles 10 [46], respectively (Scheme 1). Finally, it was found that the reaction of 2-hydrazinylpyridine with electrophilically activated nitroalkanes provides the corresponding triazolopyridines 11 (Scheme 1) [47]. These results prompted the desire to implement this general scheme in order to access
Graphical Abstract
Figure 1: Biologically active imidazo[1,5-a]pyridines.
Scheme 1: Activation of nitroalkanes towards nucleophilic attack by amines.
Scheme 2: Mechanistic rationale.
Scheme 3: Reaction of the N-tosylate 17 with electrophilic nitroalkanes.
Scheme 4: Reaction of 2-(aminomethyl)pyridine (12) with electrophilic nitroalkanes.
Scheme 5: Reaction of the 2-(aminomethyl)quinolines 18 with electrophilic nitroalkanes.
Scheme 6: Reactivity of α-nitroacetophenone (1h) and α-nitroacetic ester (1i).
Synthesis of dipolar molecular rotors as linkers for metal-organic frameworks
- Sebastian Hamer,
- Fynn Röhricht,
- Marius Jakoby,
- Ian A. Howard,
- Xianghui Zhang,
- Christian Näther and
- Rainer Herges
Beilstein J. Org. Chem. 2019, 15, 1331–1338, doi:10.3762/bjoc.15.132
- is provided by ethynyl units as rotary joints. Carboxylate groups are terminating the axes on both sides because they are known to form the typical paddle wheel structures in MOFs [36]. Benzo-annelated 2,1,3-thiadiazoles were introduced (2 and 3) to shift absorption and fluorescence into the visible
Graphical Abstract
Figure 1: Interactions of a pair of dipolar rotors in different orientations. The axes of the rotors are para...
Figure 2: Structures of molecular dipolar rotors/linker molecules 1–5.
Scheme 1: General synthetic strategy to prepare the dipolar rotors 1–5.
Scheme 2: Synthesis of 3,3'-(2,3-difluoro-1,4-phenylene)dipropiolic acid (1) starting with diiodination of 1,...
Scheme 3: Synthesis of 3,3'-(5,6-Difluoro-2,1,3-benzothiadiazol-4,7-diyl)dipropiolic acid (2) and 3,3'-(5,6-D...
Scheme 4: Synthesis of 3,3'-(5,6-dicyano-1,3-benzodioxole-4,7-diyl)dipropiolic acid (4) and 3,3'-(6,7-dicyano...
Applications of organocatalysed visible-light photoredox reactions for medicinal chemistry
- Michael K. Bogdos,
- Emmanuel Pinard and
- John A. Murphy
Beilstein J. Org. Chem. 2018, 14, 2035–2064, doi:10.3762/bjoc.14.179
- drugs. The Yadav research group have also published the homocoupling of primary thioamides for the formation of symmetrical 1,2,4-thiadiazoles, using visible light and Eosin Y as the photocatalyst, in air at room temperature (Scheme 19) [64]. The immediately obvious limitation of this reaction is the
Graphical Abstract
Figure 1: Depiction of the energy levels of a typical organic molecule and the photophysical processes it can...
Figure 2: General catalytic cycle of a photocatalyst in a photoredox organocatalysed reaction. [cat] – photoc...
Figure 3: Structures and names of the most common photocatalysts encountered in the reviewed literature.
Figure 4: General example of a reductive quenching catalytic cycle. [cat] – photocatalyst, [cat]* – photocata...
Figure 5: General example of an oxidative quenching catalytic cycle. [cat] – photocatalyst, [cat]* – photocat...
Scheme 1: Oxidative coupling of aldehydes and amines to amides using acridinium salt photocatalysis.
Figure 6: Biologically active molecules containing a benzamide linkage.
Scheme 2: The photocatalytic reduction of amino acids to produce the corresponding free or protected amines.
Scheme 3: The organocatalysed photoredox base-mediated oxidation of thiols to disulfides.
Scheme 4: C-Terminal modification of peptides and proteins using organophotoredox catalysis.
Scheme 5: The reduction and aryl coupling of aryl halides using a doubly excited photocatalyst (PDI).
Figure 7: Mechanism for the coupling of aryl halides using PDI, which is excited sequentially by two photons.
Scheme 6: The arylation of five-membered heteroarenes using arenediazonium salts under organophotoredox condi...
Scheme 7: The C–H (hetero)arylation of five-membered heterocycles under Eosin Y photocatalysis.
Scheme 8: The C–H sulfurisation of imidazoheterocycles using Eosin B-catalyzed photochemical methods.
Scheme 9: The introduction of the thiocyanate group using Eosin Y photocatalysis.
Scheme 10: Sulfonamidation of pyrroles using oxygen as the terminal oxidant.
Scheme 11: DDQ-catalysed C–H amination of arenes and heteroarenes.
Scheme 12: Photoredox-promoted radical Michael addition reactions of allylic or benzylic carbons.
Figure 8: Proposed mechanistic rationale for the observed chemoselectivities.
Scheme 13: The photocatalytic manipulation of C–H bonds adjacent to amine groups.
Scheme 14: The perylene-catalysed organophotoredox tandem difluoromethylation–acetamidation of styrene-type al...
Figure 9: Examples of biologically active molecules containing highly functionalised five membered heterocycl...
Scheme 15: The [3 + 2]-cycloaddition leading to the formation of pyrroles, through the reaction of 2H-azirines...
Figure 10: Proposed intermediate that determines the regioselectivity of the reaction.
Figure 11: Comparison of possible pathways of reaction and various intermediates involved.
Scheme 16: The acridinium salt-catalysed formation of oxazoles from aldehydes and 2H-azirines.
Scheme 17: The synthesis of oxazolines and thiazolines from amides and thioamides using organocatalysed photor...
Figure 12: Biologically active molecules on the market containing 1,3,4-oxadiazole moieties.
Scheme 18: The synthesis of 1,3,4-oxadiazoles from aldehyde semicarbazones using Eosin Y organophotocatalysis.
Scheme 19: The dimerization of primary thioamides to 1,2,4-thiadiazoles catalysed by the presence of Eosin Y a...
Scheme 20: The radical cycloaddition of o-methylthioarenediazonium salts and substituted alkynes towards the f...
Scheme 21: The dehydrogenative cascade reaction for the synthesis of 5,6-benzofused heterocyclic systems.
Figure 13: Trifluoromethylated version of compounds which have known biological activities.
Scheme 22: Eosin Y-catalysed photoredox formation of 3-substituted benzimidazoles.
Scheme 23: Oxidation of dihydropyrimidines by atmospheric oxygen using photoredox catalysis.
Scheme 24: Photoredox-organocatalysed transformation of 2-substituted phenolic imines to benzoxazoles.
Scheme 25: Visible light-driven oxidative annulation of arylamidines.
Scheme 26: Methylene blue-photocatalysed direct C–H trifluoromethylation of heterocycles.
Scheme 27: Photoredox hydrotrifluoromethylation of terminal alkenes and alkynes.
Scheme 28: Trifluoromethylation and perfluoroalkylation of aromatics and heteroaromatics.
Scheme 29: The cooperative asymmetric and photoredox catalysis towards the functionalisation of α-amino sp3 C–...
Scheme 30: Organophotoredox-catalysed direct C–H amidation of aromatics.
Scheme 31: Direct C–H alkylation of heterocycles using BF3K salts. CFL – compact fluorescent lamp.
Figure 14: The modification of camptothecin, demonstrating the use of the Molander protocol in LSF.
Scheme 32: Direct C–H amination of aromatics using acridinium salts.
Scheme 33: Photoredox-catalysed nucleophilic aromatic substitution of nucleophiles onto methoxybenzene derivat...
Scheme 34: The direct C–H cyanation of aromatics with a focus on its use for LSF.
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
- of 5-amino-4-cyanopyrazole 208 with N,N-dimethylformamide dimethyl acetal (DMFDMA) in acetonitrile at reflux temperature. Amidines 219 were condensed with appropriate 2-amino-5-subsitituted-1,3,4-thiadiazoles 220 under microwave irradiation in acetic acid for the generation of the desired pyrazolo
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.
Photocatalytic formation of carbon–sulfur bonds
- Alexander Wimmer and
- Burkhard König
Beilstein J. Org. Chem. 2018, 14, 54–83, doi:10.3762/bjoc.14.4
- thiourea derivative giving the Eosin Y radical anion and a thiyl radical. Aerobic oxidation closes the catalytic cycle and after hydrogen atom abstraction of the carbon-centred radical intermediate the final product is formed. Formation of 1,3,4-thiadiazoles In a second article the same concept led to the
- formation of 1,3,4-thiadiazoles (Scheme 34) [69]. Again, the sulfur anion is photooxidized by Eosin Y to produce a thiyl radical intermediate. Aerobic oxidation regenerates the photocatalyst and forms a superoxide radical anion. Subsequent thiyl radical addition to the imine moiety forms the five-membered
Graphical Abstract
Scheme 1: General overview over the sulfur-based substrates and reactive intermediates that are discussed in ...
Scheme 2: Photoredox-catalyzed radical thiol–ene reaction, applying [Ru(bpz)3](PF6)2 as photocatalyst.
Scheme 3: Photoredox-catalyzed thiol–ene reaction of aliphatic thiols with alkenes enabled by aniline derivat...
Scheme 4: Photoredox-catalyzed radical thiol–ene reaction for the postfunctionalization of polymers (a) and n...
Scheme 5: Photoredox-catalyzed thiol–ene reaction enabled by bromotrichloromethane as redox additive.
Scheme 6: Photoredox-catalyzed preparation of β-ketosulfoxides with Eosin Y as organic dye as photoredox cata...
Scheme 7: Greaney’s photocatalytic radical thiol–ene reaction, applying TiO2 nanoparticles as photocatalyst.
Scheme 8: Fadeyi’s photocatalytic radical thiol–ene reaction, applying Bi2O3 as photocatalyst.
Scheme 9: Ananikov’s photocatalytic radical thiol-yne reaction, applying Eosin Y as photocatalyst.
Scheme 10: Organocatalytic visible-light photoinitiated thiol–ene coupling, applying phenylglyoxylic acid as o...
Scheme 11: Xia’s photoredox-catalyzed synthesis of 2,3-disubstituted benzothiophenes, applying 9-mesityl-10-me...
Scheme 12: Wang’s metal-free photoredox-catalyzed radical thiol–ene reaction, applying 9-mesityl-10-methylacri...
Scheme 13: Visible-light benzophenone-catalyzed metal- and oxidant-free radical thiol–ene reaction.
Scheme 14: Visible-light catalyzed C-3 sulfenylation of indole derivatives using Rose Bengal as organic dye.
Scheme 15: Photocatalyzed radical thiol–ene reaction and subsequent aerobic sulfide-oxidation with Rose Bengal...
Scheme 16: Photoredox-catalyzed synthesis of diaryl sulfides.
Scheme 17: Photocatalytic cross-coupling of aryl thiols with aryl diazonium salts, using Eosin Y as photoredox...
Scheme 18: Photocatalyzed cross-coupling of aryl diazonium salts with cysteines in batch and in a microphotore...
Scheme 19: Fu’s [Ir]-catalyzed photoredox arylation of aryl thiols with aryl halides.
Scheme 20: Fu’s photoredox-catalyzed difluoromethylation of aryl thiols.
Scheme 21: C–S cross-coupling of thiols with aryl iodides via [Ir]-photoredox and [Ni]-dual-catalysis.
Scheme 22: C–S cross-coupling of thiols with aryl bromides, applying 3,7-bis-(biphenyl-4-yl)-10-(1-naphthyl)ph...
Scheme 23: Collin’s photochemical dual-catalytic cross-coupling of thiols with bromoalkynes.
Scheme 24: Visible-light-promoted C–S cross-coupling via intermolecular electron donor–acceptor complex format...
Scheme 25: Li’s visible-light photoredox-catalyzed thiocyanation of indole derivatives with Rose Bengal as pho...
Scheme 26: Hajra’s visible-light photoredox-catalyzed thiocyanation of imidazoheterocycles with Eosin Y as pho...
Scheme 27: Wang’s photoredox-catalyzed thiocyanation reaction of indoles, applying heterogeneous TiO2/MoS2 nan...
Scheme 28: Yadav’s photoredox-catalyzed α-C(sp3)–H thiocyanation reaction for tertiary amines, applying Eosin ...
Scheme 29: Yadav’s photoredox-catalyzed synthesis of 5-aryl-2-imino-1,3-oxathiolanes.
Scheme 30: Yadav’s photoredox-catalyzed synthesis of 1,3-oxathiolane-2-thiones.
Scheme 31: Li’s photoredox catalysis for the preparation of 2-substituted benzothiazoles, applying [Ru(bpy)3](...
Scheme 32: Lei’s external oxidant-free synthesis of 2-substituted benzothiazoles by merging photoredox and tra...
Scheme 33: Metal-free photocatalyzed synthesis of 2-aminobenzothiazoles, applying Eosin Y as photocatalyst.
Scheme 34: Metal-free photocatalyzed synthesis of 1,3,4-thiadiazoles, using Eosin Y as photocatalyst.
Scheme 35: Visible-light photoredox-catalyzed preparation of benzothiophenes with Eosin Y.
Scheme 36: Visible-light-induced KOH/DMSO superbase-promoted preparation of benzothiophenes.
Scheme 37: Jacobi von Wangelin’s photocatalytic approach for the synthesis of aryl sulfides, applying Eosin Y ...
Scheme 38: Visible-light photosensitized α-C(sp3)–H thiolation of aliphatic ethers.
Scheme 39: Visible-light photocatalyzed cross-coupling of alkyl and aryl thiosulfates with aryl diazonium salt...
Scheme 40: Visible-light photocatalyzed, controllable sulfenylation and sulfoxidation with organic thiosulfate...
Scheme 41: Rastogi’s photoredox-catalyzed methylsulfoxidation of aryl diazonium salts, using [Ru(bpy)3]Cl2 as ...
Scheme 42: a) Visible-light metal-free Eosin Y-catalyzed procedure for the preparation of vinyl sulfones from ...
Scheme 43: Visible-light photocatalyzed cross-coupling of sodium sulfinates with secondary enamides.
Scheme 44: Wang’s photocatalyzed oxidative cyclization of phenyl propiolates with sulfinic acids, applying Eos...
Scheme 45: Lei’s sacrificial oxidant-free synthesis of allyl sulfones by merging photoredox and transition met...
Scheme 46: Photocatalyzed Markovnikov-selective radical/radical cross-coupling of aryl sulfinic acids and term...
Scheme 47: Visible-light Eosin Y induced cross-coupling of aryl sulfinic acids and styrene derivatives, afford...
Scheme 48: Photoredox-catalyzed bicyclization of 1,7-enynes with sulfinic acids, applying Eosin Y as photocata...
Scheme 49: Visible-light-accelerated C–H-sulfinylation of arenes and heteroarenes.
Scheme 50: Visible-light photoredox-catalyzed β-selenosulfonylation of electron-rich olefins, applying [Ru(bpy)...
Scheme 51: Photocatalyzed preparation of β-chlorosulfones from the respective olefins and p-toluenesulfonyl ch...
Scheme 52: a) Photocatalyzed preparation of β-amidovinyl sulfones from sulfonyl chlorides. b) Preparation of β...
Scheme 53: Visible-light photocatalyzed sulfonylation of aliphatic tertiary amines, applying [Ru(bpy)3](PF6)2 ...
Scheme 54: Reiser’s visible-light photoredox-catalyzed preparation of β-hydroxysulfones from sulfonyl chloride...
Scheme 55: a) Sun’s visible-light-catalyzed approach for the preparation of isoquinolinonediones, applying [fac...
Scheme 56: Visible-light photocatalyzed sulfonylation/cyclization of vinyl azides, applying [Ru(bpy)3]Cl2 as p...
Scheme 57: Visible-light photocatalyzed procedure for the formation of β-ketosulfones from aryl sulfonyl chlor...
Scheme 58: Zheng’s method for the sulfenylation of indole derivatives, applying sulfonyl chlorides via visible...
Scheme 59: Cai’s visible-light induced synthesis of β-ketosulfones from sulfonyl hydrazines and alkynes.
Scheme 60: Photoredox-catalyzed approach for the preparation of vinyl sulfones from sulfonyl hydrazines and ci...
Scheme 61: Jacobi von Wangelin’s visible-light photocatalyzed chlorosulfonylation of anilines.
Scheme 62: Three-component photoredox-catalyzed synthesis of N-amino sulfonamides, applying PDI as organic dye....
Scheme 63: Visible-light induced preparation of complex sulfones from oximes, silyl enol ethers and SO2.
CF3SO2X (X = Na, Cl) as reagents for trifluoromethylation, trifluoromethylsulfenyl-, -sulfinyl- and -sulfonylation. Part 1: Use of CF3SO2Na
- Hélène Guyon,
- Hélène Chachignon and
- Dominique Cahard
Beilstein J. Org. Chem. 2017, 13, 2764–2799, doi:10.3762/bjoc.13.272
- metals found in Langlois’ reagent could be responsible for reaction initiation. The scope was evaluated on pyridines, pyrroles, indoles, pyrimidines, pyrazines, phthalazines, quinoxalines, deazapurine, thiadiazoles, uracils, xanthenes and pyrazolino-pyrimidines (Scheme 35). The combination of previous
Graphical Abstract
Scheme 1: Trifluoromethylation of enol acetates by Langlois.
Scheme 2: Trifluoromethylation of (het)aryl enol acetates.
Scheme 3: Mechanism for the trifluoromethylation of enol acetates.
Scheme 4: Oxidative trifluoromethylation of unactivated olefins and mechanistic pathway.
Scheme 5: Oxidative trifluoromethylation of acetylenic substrates.
Scheme 6: Metal free trifluoromethylation of styrenes.
Scheme 7: Synthesis of α-trifluoromethylated ketones by oxytrifluoromethylation of heteroatom-functionalised ...
Scheme 8: Catalysed photoredox trifluoromethylation of vinyl azides.
Scheme 9: Oxidative difunctionalisation of alkenyl MIDA boronates.
Scheme 10: Synthesis of β-trifluoromethyl ketones from cyclopropanols.
Scheme 11: Aryltrifluoromethylation of allylic alcohols.
Scheme 12: Cascade multicomponent synthesis of nitrogen heterocycles via azotrifluoromethylation of alkenes.
Scheme 13: Photocatalytic azotrifluoromethylation of alkenes with aryldiazonium salts and CF3SO2Na.
Scheme 14: Copper-promoted intramolecular aminotrifluoromethylation of alkenes with CF3SO2Na.
Scheme 15: Oxytrifluoromethylation of alkenes with CF3SO2Na and hydroxamic acid.
Scheme 16: Manganese-catalysed oxytrifluoromethylation of styrene derivatives.
Scheme 17: Oxytrifluoromethylation of alkenes with NMP/O2 and CF3SO2Na.
Scheme 18: Intramolecular oxytrifluoromethylation of alkenes.
Scheme 19: Hydrotrifluoromethylation of styrenyl alkenes and unactivated aliphatic alkenes.
Scheme 20: Hydrotrifluoromethylation of electron-deficient alkenes.
Scheme 21: Hydrotrifluoromethylation of alkenes by iridium photoredox catalysis.
Scheme 22: Iodo- and bromotrifluoromethylation of alkenes by CF3SO2Na/I2O5 or CF3SO2Na / NaBrO3.
Scheme 23: N-methyl-9-mesityl acridinium and visible-light-induced chloro-, bromo- and SCF3 trifluoromethylati...
Scheme 24: Carbotrifluoromethylation of N-arylacrylamides with CF3SO2Na / TBHP by Lipshutz.
Scheme 25: Carbotrifluoromethylation of N-arylacrylamides with CF3SO2Na/TBHP reported by Lei.
Scheme 26: Carbotrifluoromethylation of N-arylacrylamides with CF3SO2Na/(NH4)2S2O8.
Scheme 27: Metal-free carbotrifluoromethylation of N-arylacrylamides with CF3SO2Na/K2S2O8 reported by Wang.
Scheme 28: Metal-free carbotrifluoromethylation of N-arylacrylamides with CF3SO2Na/PIDA reported by Fu.
Scheme 29: Metal-free cascade trifluoromethylation/cyclisation of N-arylmethacrylamides (a) and enynes (b) wit...
Scheme 30: Trifluoromethylation/cyclisation of N-arylcinnamamides: Synthesis of 3,4-disubstituted dihydroquino...
Scheme 31: Trifluoromethylation/cyclisation of aromatic-containing unsaturated ketones.
Scheme 32: Chemo- and regioselective cascade trifluoromethylation/heteroaryl ipso-migration of unactivated alk...
Scheme 33: Copper-mediated 1,2-bis(trifluoromethylation) of alkenes.
Scheme 34: Trifluoromethylation of aromatics with CF3SO2Na reported by Langlois.
Scheme 35: Baran’s oxidative C–H trifluoromethylation of heterocycles.
Scheme 36: Trifluoromethylation of acetanilides and anilines.
Scheme 37: Trifluoromethylation of heterocycles in water.
Scheme 38: Trifluoromethylation of coumarins in a continuous-flow reactor.
Scheme 39: Oxidative trifluoromethylation of coumarins, quinolines and pyrimidinones.
Scheme 40: Oxidative trifluoromethylation of pyrimidinones and pyridinones.
Scheme 41: Phosphovanadomolybdic acid-catalysed direct C−H trifluoromethylation.
Scheme 42: Oxidative trifluoromethylation of imidazopyridines and imidazoheterocycles.
Scheme 43: Oxidative trifluoromethylation of imidazoheterocycles and imidazoles in ionic liquid/water.
Scheme 44: Oxidative trifluoromethylation of 8-aminoquinolines.
Scheme 45: Oxidative trifluoromethylation of various 8-aminoquinolines using the supported catalyst CS@Cu(OAc)2...
Scheme 46: Oxidative trifluoromethylation of the naphthylamide 70.
Scheme 47: Oxidative trifluoromethylation of various arenes in the presence of CF3SO2Na and sodium persulfate.
Scheme 48: Trifluoromethylation of electron-rich arenes and unsymmetrical biaryls with CF3SO2Na in the presenc...
Figure 1: Trifluoromethylated coumarin and flavone.
Scheme 49: Metal-free trifluoromethylation catalysed by a photoredox organocatalyst.
Scheme 50: Quinone-mediated trifluoromethylation of arenes and heteroarenes.
Scheme 51: Metal- and oxidant-free photochemical trifluoromethylation of arenes.
Scheme 52: Copper-mediated trifluoromethylation of arenediazonium tetrafluoroborates.
Scheme 53: Oxidative trifluoromethylation of aryl- and heteroarylboronic acids.
Scheme 54: Oxidative trifluoromethylation of aryl- and vinylboronic acids.
Scheme 55: Oxidative trifluoromethylation of unsaturated potassium organotrifluoroborates.
Scheme 56: Oxidative trifluoromethylation of (hetero)aryl- and vinyltrifluoroborates.
Scheme 57: Copper−catalysed decarboxylative trifluoromethylation of cinnamic acids.
Scheme 58: Iron-mediated decarboxylative trifluoromethylation of α,β-unsaturated carboxylic acids.
Scheme 59: Cu/Ag-catalysed decarboxylative trifluoromethylation of cinnamic acids.
Scheme 60: I2O5-Promoted decarboxylative trifluoromethylation of cinnamic acids.
Scheme 61: Silver(I)-catalysed denitrative trifluoromethylation of β-nitrostyrenes.
Scheme 62: Copper-catalysed direct trifluoromethylation of styrene derivatives.
Scheme 63: Transition-metal-free synthesis of β-trifluoromethylated enamines.
Scheme 64: I2O5-mediated iodotrifluoromethylation of alkynes.
Scheme 65: Silver-catalysed tandem trifluoromethylation/cyclisation of aryl isonitriles.
Scheme 66: Photoredox trifluoromethylation of 2-isocyanobiphenyls.
Scheme 67: Trifluoromethylation of potassium alkynyltrifluoroborates with CF3SO2Na.
Scheme 68: N-trifluoromethylation of nitrosoarenes with CF3SO2Na (SQ: semiquinone).
Scheme 69: Trifluoromethylation of disulfides with CF3SO2Na.
Scheme 70: Trifluoromethylation of thiols with CF3SO2Na/I2O5.
Scheme 71: Electrophilic trifluoromethylsulfenylation by means of CF3SO2Na/(EtO)2P(O)H/CuCl/DMSO.
Scheme 72: Electrophilic trifluoromethylsulfenylation by means of CF3SO2Na/(EtO)2P(O)H/TMSCl.
Scheme 73: Electrophilic trifluoromethylsulfenylation by means of CF3SO2Na/PPh3/N-chlorophthalimide.
Scheme 74: Electrophilic trifluoromethylsulfenylation by means of CF3SO2Na/PCl3.
Scheme 75: Electrophilic trifluoromethylsulfenylation by means of CF3SO2Na/PCl3.
Scheme 76: Trifluoromethylsulfenylation of aryl iodides with in situ generated CuSCF3 (DMI: 1,3-dimethyl-2-imi...
Scheme 77: Pioneering trifluoromethylsulfinylation of N, O, and C-nucleophiles.
Scheme 78: Trifluoromethylsulfinylation of (1R,2S)-ephedrine (Im: imidazole; DIEA: N,N-diisopropylethylamine).
Scheme 79: Trifluoromethylsulfinylation of substituted benzenes with CF3SO2Na/CF3SO3H.
Scheme 80: Trifluoromethylsulfinylation of indoles with CF3SO2Na/P(O)Cl3.
Scheme 81: Trifluoromethylsulfinylation of indoles with CF3SO2Na/PCl3.
Scheme 82: Formation of triflones from benzyl bromides (DMA: dimethylacetamide).
Scheme 83: Formation of α-trifluoromethylsulfonyl ketones, esters, and amides.
Scheme 84: Allylic trifluoromethanesulfonylation of aromatic allylic alcohols.
Scheme 85: Copper-catalysed couplings of aryl iodonium salts with CF3SO2Na.
Scheme 86: Palladium-catalysed trifluoromethanesulfonylation of aryl triflates and chlorides with CF3SO2Na.
Scheme 87: Copper-catalysed coupling of arenediazonium tetrafluoroborates with CF3SO2Na.
Scheme 88: Synthesis of phenyltriflone via coupling of benzyne with CF3SO2Na.
Scheme 89: Synthesis of 1-trifluoromethanesulfonylcyclopentenes from 1-alkynyl-λ3-bromanes and CF3SO2Na.
Scheme 90: One-pot synthesis of functionalised vinyl triflones.
Scheme 91: Regioselective synthesis of vinyltriflones from styrenes.
Scheme 92: Trifluoromethanesulfonylation of alkynyl(phenyl) iodonium tosylates by CF3SO2Na.
Scheme 93: Synthesis of thio- and selenotrifluoromethanesulfonates.
New tricks of well-known aminoazoles in isocyanide-based multicomponent reactions and antibacterial activity of the compounds synthesized
- Maryna V. Murlykina,
- Maryna N. Kornet,
- Sergey M. Desenko,
- Svetlana V. Shishkina,
- Oleg V. Shishkin,
- Aleksander A. Brazhko,
- Vladimir I. Musatov,
- Erik V. Van der Eycken and
- Valentin A. Chebanov
Beilstein J. Org. Chem. 2017, 13, 1050–1063, doi:10.3762/bjoc.13.104
- with 2-amino-1,3,4-thiadiazoles [71][83][84][89][90], 2-aminoimidazoles [71][72][91][92], 2-aminoxazoles [71] and 1,2,5-oxadiazole-3,4-diamine [93] with the formation of imidazoazoles. Among the pyrazoles only 5-amino-3-methylpyrazole, 5-aminopyrazole-4-carbonitrile and ethyl 5-aminopyrazole-4
Graphical Abstract
Scheme 1: Aminoazoles in GBB-3CR and Ugi-4CR.
Scheme 2: Reactivity of 5-amino-N-aryl-1H-pyrazole-4-carboxamide and 3-amino-5-methylisoxazole in GBB-3CR and...
Figure 1: Alternative structures A and B for compounds 4 and 6.
Figure 2: Selected data of HSQC and HMBC experiments for compound 4a.
Figure 3: Molecular structure of 3-(tert-butylamino)-2-(4-chlorophenyl)-N-(4-fluorophenyl)-1H-imidazo[1,2-b]p...
Figure 4: Selected data of NOE and HSQC experiments for compound 9d.
Figure 5: Molecular structure of N-(2-(tert-butylamino)-1-(4-chlorophenyl)-2-oxoethyl)-N-(5-methylisoxazol-3-...
Dimerization reactions of aryl selenophen-2-yl-substituted thiocarbonyl S-methanides as diradical processes: a computational study
- Michael L. McKee,
- Grzegorz Mlostoń,
- Katarzyna Urbaniak and
- Heinz Heimgartner
Beilstein J. Org. Chem. 2017, 13, 410–416, doi:10.3762/bjoc.13.44
- -methanides 1 belong to the class of S-centered 1,3-dipolar species, which were identified by Huisgen as reactive intermediates formed via nitrogen extrusion from 2,5-dihydro-1,3,4-thiadiazoles 2 [1][2]. In spite of the fact that several methods are reported for the preparation of these precursors, the most
- convenient access comprises the treatment of a C=S substrate with diazomethane or its derivatives. Depending on the substitution pattern, 2,5-dihydro-1,3,4-thiadiazoles 2 display different thermal stability. Whereas sterically bulky aliphatic substituents increase the temperature required for the
Graphical Abstract
Scheme 1: Generation and typical reactions of the reactive dialkyl and diaryl thiocarbonyl S-methanides 1.
Figure 1: Structures of the reactive intermediates as a diradical 6 or a zwitterion 7 in the course of the di...
Scheme 2: The in situ generation of phenyl selenophen-2-yl S-methanide (8) and its competitive reactions: 1,3...
Figure 2: Potential 1,3-dipolar electrocyclization of thiocabonyl S-methanide 8A. Computed enthalpies (free e...
Figure 3: Stepwise radical dimerization of the reactive thiocarbonyl S-methanide 8. Computed enthalpies (free...
Figure 4: Potential competitive cyclization reactions of the intermediate diradical 12.
Figure 5: a) Spin densities in the conformers 12F and 12G of diradical 12. b) Heteroatom effect on the magnit...
Synthesis of ferrocenyl-substituted 1,3-dithiolanes via [3 + 2]-cycloadditions of ferrocenyl hetaryl thioketones with thiocarbonyl S-methanides
- Grzegorz Mlostoń,
- Róża Hamera-Fałdyga,
- Anthony Linden and
- Heinz Heimgartner
Beilstein J. Org. Chem. 2016, 12, 1421–1427, doi:10.3762/bjoc.12.136
- ‘superdienophiles’ [3]. The reactive thiocarbonyl S-methanides of type 2 can conveniently be generated by thermal elimination of N2 from 1,3,4-thiadiazoles 3 at ca. −45 °C in the case of 2,2-diaryl derivatives 3a,b or upon gentle heating of cycloaliphatic precursors 3c,d in THF solution to ca. +45 °C [4][5]. The [3
Graphical Abstract
Scheme 1: Reactions of aromatic thiocarbonyl S-methanides 2a,b with ferrocenyl thioketones 1 (Table 1).
Figure 1: ORTEP Plot [16] of the molecular structures of the ferrocenyl-substituted 1,3-dithiolanes 5b and 5f (wi...
Scheme 2: Reactions of cycloaliphatic thiocarbonyl S-methanides with ferrocenyl hetaryl thioketones 1 (Table 1).
Scheme 3: Reaction of 3c with ferrocenyl methyl thioketone 1e.
Scheme 4: Mesomeric stabilization of the 1,5-diradical intermediate in the reaction of aromatic thiocarbonyl S...
A one-pot multistep cyclization yielding thiadiazoloimidazole derivatives
- Debabrata Samanta,
- Anup Rana,
- Jan W. Bats and
- Michael Schmittel
Beilstein J. Org. Chem. 2014, 10, 2989–2996, doi:10.3762/bjoc.10.317
- Main, Germany 10.3762/bjoc.10.317 Abstract A versatile synthetic procedure is described to prepare the benzimidazole-fused 1,2,4-thiadiazoles 2a–c via a methanesulfonyl chloride initiated multistep cyclization involving the intramolecular reaction of an in-situ generated carbodiimide with a thiourea
- unit. The structure of the intricate heterocycle 2a was confirmed by single-crystal X-ray analysis and its mechanism of formation supported by DFT computations. Keywords: carbodiimide; cyclization; dithiourea; DFT; 1,2,4-thiadiazoles; Introduction Heterocyclic rings are key components in many
- bioactive compounds. For instance, thiadiazole containing heterocycles are known to exhibit important anti-inflammatory, antihypertensive, anti-HIV and antituberculosis activity [1]. Within this family, 1,2,4-thiadiazoles display notable medicinal properties as potent neuroprotectors [2
Graphical Abstract
Scheme 1: Synthesis of tricyclic 1,2,4-thiadiazoles 2a–c.
Figure 1: (a) and (b) representing the solid state structure of 2a with displacement ellipsoids at the 50% pr...
Scheme 2: Possible mechanistic scenarios.
Figure 2: Optimized structures of 3, TS3→5‡ and 5 at B3LYP/6-31+G*. Free energies are reported in kcal mol−1 ...
Scheme 3: DMAP assisted cyclization-I and IIa. Free energies are reported in kcal mol−1 at 25 °C referenced t...
Figure 3: Optimized geometries of 9‡ and 14‡. Distances are shown in angstrom (italics).
Synthesis of new, highly luminescent bis(2,2’-bithiophen-5-yl) substituted 1,3,4-oxadiazole, 1,3,4-thiadiazole and 1,2,4-triazole
- Anastasia S. Kostyuchenko,
- Vyacheslav L.Yurpalov,
- Aleksandra Kurowska,
- Wojciech Domagala,
- Adam Pron and
- Alexander S. Fisyuk
Beilstein J. Org. Chem. 2014, 10, 1596–1602, doi:10.3762/bjoc.10.165
- /electron donating properties [11]. In this article, we are expanding our prior syntheses of alkylbithiophene substituted thiadiazoles [11] to evaluate the effect of other heteroaromatic rings at the central position on the resulting properties of these five-ring compounds. DA compounds with a 1,3,4
- and Discussion Synthetic toolbox There are several approaches to the synthesis of 2,5-bis(2,2 '-bithiophen-5-yl)-1,3,4-oxadiazoles and 1,3,4-thiadiazoles. Transition metal-catalysed cross-coupling reactions, such as Stille, Suzuki etc. are typically used for the formation of thiophene–thiophene or
Graphical Abstract
Scheme 1: Synthesis of ethyl 3-decyl-2,2'-bithiophene-5-carboxylate (3).
Scheme 2: Synthesis of ethyl 4-(hexyloxy)-2,2'-bithiophene-5-carboxylate (7).
Scheme 3: Hydrolysis and hydrazinolysis of esters 8–10.
Scheme 4: Synthesis of 2,5-bis(2,2'-bithiophen-5-yl)-1,3,4-oxadiazoles 13 and 14 and 1,3,4-thiadiazole 15.
Scheme 5: Synthesis of 3,5-bis(3-decyl-2,2'-bithiophen-5-yl)-4-phenyl-4H-1,2,4-triazole (18).
Figure 1: UV–vis absorption and fluorescence spectra of diluted solutions of a) 13, b) 14, c) 15, and d) 18 i...
Figure 2: Photoluminescence quantum yields measured for 13, 15 and 18 together with their formulae.
Recent advances in transition metal-catalyzed Csp2-monofluoro-, difluoro-, perfluoromethylation and trifluoromethylthiolation
- Grégory Landelle,
- Armen Panossian,
- Sergiy Pazenok,
- Jean-Pierre Vors and
- Frédéric R. Leroux
Beilstein J. Org. Chem. 2013, 9, 2476–2536, doi:10.3762/bjoc.9.287
- [114] as well as of various arenes and heteroarenes (pyridines, pyrimidines, pyrazines, quinolines, pyrroles, thiophenes, furans, pyrazoles, imidazoles, thiazoles, oxazoles, thiadiazoles, triazoles) [115]. The yields were low to excellent, depending on the substrate (Scheme 12 and Figure 20). Iron(II
Graphical Abstract
Scheme 1: Pd-catalyzed monofluoromethylation of pinacol phenylboronate [44].
Scheme 2: Cu-catalyzed monofluoromethylation with 2-PySO2CHFCOR followed by desulfonylation [49].
Scheme 3: Cu-catalyzed difluoromethylation with α-silyldifluoroacetates [57].
Figure 1: Mechanism of the Cu-catalyzed C–CHF2 bond formation of α,β-unsaturated carboxylic acids through dec...
Scheme 4: Fe-catalyzed decarboxylative difluoromethylation of cinnamic acids [62].
Scheme 5: Preliminary experiments for investigation of the mechanism of the C–H trifluoromethylation of N-ary...
Figure 2: Plausible catalytic cycle proposed by Z.-J. Shi et al. for the trifluoromethylation of acetanilides ...
Figure 3: Plausible catalytic cycle proposed by M. S. Sanford et al. for the perfluoroalkylation of simple ar...
Figure 4: Postulated reaction pathway for the Ag/Cu-catalyzed trifluoromethylation of aryl iodides by Z. Q. W...
Figure 5: Postulated reaction mechanism for Cu-catalyzed trifluoromethylation reaction using MTFA as trifluor...
Scheme 6: Formal Heck-type trifluoromethylation of vinyl(het)arenes by M. Sodeoka et al. [83].
Figure 6: Proposed catalytic cycle for the copper-catalyzed trifluoromethylation of (het)arenes in presence o...
Figure 7: Proposed catalytic cycle for the copper-catalyzed trifluoromethylation of N,N-disubstituted (hetero...
Figure 8: Proposed catalytic cycle by Y. Zhang and J. Wang et al. for the copper-catalyzed trifluoromethylati...
Figure 9: Mechanistic rationale for the trifluoromethylation of arenes in presence of Langlois’s reagent and ...
Scheme 7: Trifluoromethylation of 4-acetylpyridine with Langlois’s reagent by P. S. Baran et al. (* Stirring ...
Scheme 8: Catalytic copper-facilitated perfluorobutylation of benzene with C4F9I and benzoyl peroxide [90].
Figure 10: F.-L. Qing et al.’s proposed mechanism for the copper-catalyzed trifluoromethylation of (hetero)are...
Figure 11: Mechanism of the Cu-catalyzed/Ru-photocatalyzed trifluoromethylation and perfluoroalkylation of ary...
Figure 12: Proposed mechanism for the Cu-catalyzed trifluoromethylation of aryl- and vinyl boronic acids with ...
Figure 13: Possible mechanism for the Cu-catalyzed decarboxylative trifluoromethylation of cinnamic acids [62].
Scheme 9: Ruthenium-catalyzed perfluoroalkylation of alkenes and (hetero)arenes with perfluoroalkylsulfonyl c...
Figure 14: N. Kamigata et al.’s proposed mechanism for the Ru-catalyzed perfluoroalkylation of alkenes and (he...
Figure 15: Proposed mechanism for the Ru-catalyzed photoredox trifluoromethylation of (hetero)arenes with trif...
Figure 16: Late-stage trifluoromethylation of pharmaceutically relevant molecules with trifluoromethanesulfony...
Figure 17: Proposed mechanism for the trifluoromethylation of alkenes with trifluoromethyl iodide under Ru-bas...
Scheme 10: Formal perfluoroakylation of terminal alkenes by Ru-catalyzed cross-metathesis with perfluoroalkyle...
Figure 18: One-pot Ir-catalyzed borylation/Cu-catalyzed trifluoromethylation of complex small molecules by Q. ...
Figure 19: Mechanistic proposal for the Ni-catalyzed perfluoroalkylation of arenes and heteroarenes with perfl...
Scheme 11: Electrochemical Ni-catalyzed perfluoroalkylation of 2-phenylpyridine (Y. H. Budnikova et al.) [71].
Scheme 12: Fe(II)-catalyzed trifluoromethylation of arenes and heteroarenes with trifluoromethyl iodide (T. Ya...
Figure 20: Mechanistic proposal by T. Yamakawa et al. for the Fe(II)-catalyzed trifluoromethylation of arenes ...
Scheme 13: Ytterbium-catalyzed perfluoroalkylation of dihydropyran with perfluoroalkyl iodide (Y. Ding et al.) ...
Figure 21: Mechanistic proposal by A. Togni et al. for the rhenium-catalyzed trifluoromethylation of arenes an...
Figure 22: Mechanism of the Cu-catalyzed oxidative trifluoromethylthiolation of arylboronic acids with TMSCF3 ...
Scheme 14: Removal of the 8-aminoquinoline auxiliary [136].
Figure 23: Mechanism of the Cu-catalyzed trifluoromethylthiolation of C–H bonds with a trifluoromethanesulfony...
Liquid-crystalline heterodimesogens and ABA-heterotrimesogens comprising a bent 3,5-diphenyl-1,2,4-oxadiazole central unit
- Govindaswamy Shanker,
- Marko Prehm and
- Carsten Tschierske
Beilstein J. Org. Chem. 2012, 8, 472–485, doi:10.3762/bjoc.8.54
- ][82]. Finally, the spacer units of these thiadiazoles are also significantly longer (n = 5, 10) than those used for the related cyanobiphenyl-containing dimesogens (n = 3, 4). As a result, LC phases with a tilted organization of the molecules become dominant. The dimesogen Thia-Ox/5, with the shorter
- thiadiazoles Thia-Ox/n, elongation of the alkylene spacer unit connecting the two mesogenic cores removes the SmC phase, which is contrary to the usually observed effect that elongation of alkyl chains stabilizes smectic phases due to improved segregation. The promotion of nematic phases by elongation of an
Graphical Abstract
Scheme 1: Structures of the investigated ABA-heterotrimesogens CB-Ox-CB/n and heterodimesogens CB-Ox/n, Thia-...
Scheme 2: Synthesis of the ABA-heterotrimesogens CB-Ox-CB/n.
Scheme 3: Synthesis of the dimesogens CB-Ox/n and Thia-Ox/n.
Figure 1: XRD pattern of a (partially) surface-aligned sample of the N phase of compound CB-Ox-CB/4: (a) diff...
Figure 2: Dimesogen CB-Ox/4: (a) DSC traces obtained during initial heating and cooling cycles scanned at a r...
Figure 3: XRD data of the dimesogen CB-Ox/4: (a,b) diffraction patterns of a magnetic-field-aligned sample (t...
Figure 4: Models showing the suggested organizations of dimesogens in the smectic phases and in the preferred...
Figure 5: Dimesogen Thia-Ox/5: (a) DSC traces obtained during first heating and cooling cycles scanned at a r...
Figure 6: XRD data of the SmC phase of the dimesogen Thia-Ox/5: (a) diffraction pattern at T = 160 °C; (b) χ-...
Figure 7: XRD pattern of a magnetic-field-aligned sample of the NcybC phase of the dimesogen Thia-Ox/10: (a) ...
Figure 8: Comparison of the optical textures of distinct types of 1,2,4-oxadiazole based dimesogens as observ...
Low temperature enantiotropic nematic phases from V-shaped, shape-persistent molecules
- Matthias Lehmann and
- Jens Seltmann
Beilstein J. Org. Chem. 2009, 5, No. 73, doi:10.3762/bjoc.5.73
- engineering; thiadiazoles; V-shaped mesogens; Introduction Most molecules forming nematic liquid crystals, the nematogens, are based on rod-shaped (calamitic), anisometric cores with peripheral flexible chains along the molecular long axis [1]. Nematic phases are the simplest liquid crystalline mesophases
- of a series of thiadiazoles of general structure II is presented and the successful approach to low temperature, enantiotropic nematic liquid crystals in the family of bent-shaped oligo(phenylene ethynylenes) will be discussed. Results and Discussion Synthesis The shape-persistent arms of the new
- biaxiality. In contrast, the optical experiments of compound 2c point to the uniaxial nature of its nematic phase. In order to rationalise these two different results, it can be assumed on the bases of the correlation lengths that the thiadiazoles form small aggregates. These aggregates are responsible for
Graphical Abstract
Figure 1: Uniaxial nematic (left) and biaxial nematic (right) phases and their corresponding indicatrices.
Figure 2: Design of V-shaped, shape-persistent oligo(phenylene ethynylene) mesogens of type I and II (R, R′ =...
Scheme 1: Synthesis of arm derivatives 6. Reaction conditions: (i) 1) Pd(PPh3)4, CuI, piperidine, rt; 2) TBAF...
Scheme 2: Two-step synthesis of V-shaped nematogens: symmetric (1) and non-C2-symmetric (2) thiadiazoles. Rea...
Figure 3: Comparison of the mesophase ranges of intermediate hockey stick compounds 3 and symmetric V-shaped ...
Figure 4: Comparison of the thermal behaviour of symmetric and non-symmetric V-shaped molecules. The molecule...
Figure 5: Textures of the nematic phase of 2c. a) Schlieren texture at 173 °C. b) and c) Planar alignment on ...
Figure 6: X-ray study of nematic mesophases from V-shaped mesogens. A: Diffraction pattern of 2c at 70 °C. B:...
Cobalt(II) chloride catalyzed one-pot synthesis of α-aminonitriles
- Surya K. De
Beilstein J. Org. Chem. 2005, 1, No. 8, doi:10.1186/1860-5397-1-8
- α-aminonitriles, which are useful intermediates for the synthesis of amino acids and nitrogen-containing heterocycles such as thiadiazoles, imidazoles, etc [2][3]. They are usually prepared by the nucleophilic addition of cyanide anion to imines. Numerous methods describing the preparation of α
