Copper-mediated synthesis of 1,2,3-triazoles from N-tosylhydrazones and anilines

Product Control in Alkene Trifluoromethylation: Hydrotrifluoromethylation, Vinylic Trifluoromethylation, and Iodotrifluoromethylation using Togni Reagent

Hydrotrifluoromethylation, vinylic trifluoromethylation, and iodotrifluoromethylation of simple alkenes have been achieved by using Togni reagent in the absence of any transition metal catalyst. These reactions were readily controllable by selection of appropriate salts and solvents. The addition of K2CO3 afforded the hydrotrifluoromethylation product, with DMF acting not only as a solvent, but also as the hydrogen source. In contrast, the use of tetra-n-butylammonium iodide (TBAI) in 1,4-dioxane resulted in vinylic trifluoromethylation, while the use of KI afforded the iodotrifluoromethylation product. The vinylic trifluoromethylation product was obtained by treatment of the iodotrifluoromethylation product with ammonium 2-iodobenzoate, indicating that it was formed through an elimination reaction of the in-situ-generated iodotrifluoromethylation product, and the solubility of the resulting 2-iodobenzoate salt plays a key role in the product switching. A radical-clock experiment showed that these reactions proceed via radical intermediates.

I₂-TBHP-catalyzed oxidative cross-coupling of N-sulfonyl hydrazones and isocyanides to 5-aminopyrazoles

I2-TBHP-catalyzed oxidative cross coupling of N-sulfonyl hydrazones with isocyanides has been realized for the synthesis of 5-aminopyrazoles through formal [4 + 1] annulation via in situ azoalkene formation. Notable features are the metal/alkyne-free strategy, C-C and C-N bond formation, atom economy, catalytic I2, broad functional group tolerance, good reaction yields, shorter time, and also applicability to one-pot methodology.

Synthesis, crystal structure and properties of sandwich type compounds based on {AsW9} and a hexa-nuclear unit with three supporting TM–triazole complexes

Tree {AsW₉}-based sandwich compounds exhibit good electrocatalytic activity, antiferromagnetic interactions, and inhibitory effect on proliferation of HeLa cells.

Direct access to 1,4-disubstituted 1,2,3-triazoles through organocatalytic 1,3-dipolar cycloaddition reaction of α,β-unsaturated esters with azides

DBU-catalyzed organocatalytic 1,3-dipolar cycloaddition reactions of α,β-unsaturated esters with azides have been developed. This strategy generates 1,4-disubstituted 1,2,3-triazoles in high yields with high regioselectivities.

Synthesis of α-enamino esters via Cu(ii)-promoted dehydrogenation of α-amino acid esters: application to the synthesis of polysubstituted pyrroles

α-Enamino esters are synthesized from α-amino acid esters using Cu(ii)-promoted dehydrogenation. Application of the α-enamino esters to the synthesis of polysubstituted pyrroles is achieved through oxidative coupling with alkynes under Cu(ii)-promoted conditions.

A straightforward synthesis of alkyl 1H-tetrazol-5-yl thioethers via a one-pot reaction of aldehydes and 1H-tetrazole-5-thiols mediated by N-tosylhydrazones

A method for the straightforward synthesis of alkyl 1H-tetrazol-5-yl thioethers from aldehydes and 1H-tetrazole-5-thiols through a one-pot procedure is presented.

Azide–acetonitrile “click” reaction triggered by Cs2CO3: the atom-economic, high-yielding synthesis of 5-amino-1,2,3-triazoles

Medicinally important 5-amino-1,2,3-triazoles were synthesized using a novel Cs₂CO₃-catalyzed azide–acetonitrile [3 + 2]-cycloaddition. Aryl azides and aryl acetonitriles were employed in this transformation resulting in excellent yields with high regioselectivity.

NIS/CHP-mediated reaction of isocyanides with hydrazones: access to aminopyrazoles

A NIS/CHP-mediated reaction of isocyanides with hydrazones to construct aminopyrazoles has been developed.

Synthesis of pyrazolo[5,1-a]isoquinolines via a silver(i)-catalyzed reaction of (1-arylethylidene)hydrazides with N′-(2-alkynylbenzylidene)hydrazides

A silver(i)-catalyzed reaction of (1-arylethylidene)hydrazides with N′-(2-alkynylbenzylidene)hydrazides via [3 + 2] cycloaddition and intramolecular rearrangement is reported, which proceeds through azo-alkene and isoquinolinium-2-yl amide intermediates.

AgNO2-mediated cleavage of the N–N bond of sulfonylhydrazones and oxygen transfer: access to fulleroisoxazolines via radical cyclization with [60]fullerene

The first example involving cleavage of the N–N bond of sulfonylhydrazones is presented, and a new methodology for the synthesis of fulleroisoxazolines is developed.

Regioselective synthesis of triazoles via base-promoted oxidative cycloaddition of chalcones with azides in aqueous solution

A base-promoted oxidative cycloaddition of chalcones with azides was developed for the regioselective synthesis of trisubstituted triazoles under transition-metal-free conditions.

One-pot three-component synthesis of 1,2,3-triazoles using magnetic NiFe2O4–glutamate–Cu as an efficient heterogeneous catalyst in water

A magnetic NiFe₂O₄ supported glutamate–copper catalyst is prepared and applied for the synthesis of a wide variety of 1,2,3-triazoles in water at room temperature.

Organopromoted direct synthesis of 6-iodo-3-methylthioimidazo[1,2-a]pyridines via convergent integration of three self-sorting domino sequences

An NH₂CN-promoted convergent integration of three self-sorting domino sequences is described for the construction of 6-iodo-3-methylthioimidazo[1,2-a]pyridines from aryl methyl ketones and 2-aminopyridines.

Metal-free C-N- and N-N-bond formation: synthesis of 1,2,3-triazoles from ketones, N-tosylhydrazines, and amines in one pot

A novel synthetic approach toward 1,4-disubstituted 1,2,3-triazoles by C-N- and N-N-bond formation has been established under transition-metal-free conditions. Complete control of the regioselectivity was successfully achieved. Commercially available anilines, ketones, and N-tosylhydrazine were treated with molecular iodine in one pot to allow the regioselective generation of 1,4-disubstituted 1,2,3-triazoles in high yields without the use of azides.

p-Toluenesulfonic acid mediated 1,3-dipolar cycloaddition of nitroolefins with NaN3 for synthesis of 4-aryl-NH-1,2,3-triazoles

A p-TsOH-mediated 1,3-dipolar cycloaddition of nitroolefins and sodium azide for the synthesis of 4-aryl-NH-1,2,3-triazoles has been developed. p-TsOH was discovered as a vital additive in this type of 1,3-dipolar cycloaddition. This novel cycloaddition reaction is a good method for the rapid synthesis of valuable 4-aryl-NH-1,2,3-triazoles in high yields.

I2/TBPB mediated oxidative reaction of N-tosylhydrazones with anilines: practical construction of 1,4-disubstituted 1,2,3-triazoles under metal-free and azide-free conditions

An efficient I2 (20 mol %)/TBPB mediated oxidative formal [4 + 1] cycloaddition of N-tosylhydrazones with anilines via C-N/N-N bond formation and S-N cleavage has been developed. This protocol represents a simple, general, and efficient approach for the construction of 1,2,3-triazoles under metal-free and azide-free conditions by utilizing a catalytic amount of I2.

An organocatalytic azide-aldehyde [3+2] cycloaddition: high-yielding regioselective synthesis of 1,4-disubstituted 1,2,3-triazoles

An organocatalytic azide-aldehyde [3+2] cycloaddition (organo-click) reaction of a variety of enolizable aldehydes is reported. The organo-click reaction is characterized by a high rate and regioselectivity, mild reaction conditions, easily available substrates with simple operation, and excellent yields with a broad spectrum of substrates. It constitutes an alternative to the previously known CuAAC, RuAAC, and IrAAC click reactions.

Practical synthesis of pyrazoles via a copper-catalyzed relay oxidation strategy

An efficient Cu-catalyzed cascade reaction involving N–O bond cleavage and C–C/C–N/N–N bond formations is developed to afford various 1,3- and 1,3,4-substituted pyrazoles.

Efficient access to 1H-indazoles via copper-catalyzed cross-coupling/cyclization of 2-bromoaryl oxime acetates and amines

A novel synthesis of 1H-indazoles via copper-catalyzed cross-coupling/cyclization of 2-bromoaryl oxime acetates and amines is reported.