Copper-catalyzed one-pot synthesis of tetrasubstituted pyrazoles from sulfonyl azides,terminal alkynes,and hydrazonoyl chlorides

Ketenimine intermediates generated by the addition of copper acetylides to sulfonyl azides are trapped by nitrile imines (generated from hydrazonoyl chlorides and triethylamine) to afford tetrasubstituted pyrazoles in moderate to good yields.     

Efficient synthesis of sulfonyl azides from sulfonamides

Triflyl azide serves as an efficient diazo transfer reagent in this first direct synthesis of sulfonyl azides from readily available and stable sulfonamides. The process is experimentally simple, mild, and high-yielding. Sulfonyl azides participate in various catalytic transformations providing rapid access to diversely functionalized sulfonamide derivatives in good yields.     

One-pot synthesis of 5-sulfonamidopyrazole from terminal alkynes, sulfonyl azides and hydrozones

5-Sulfonamidopyrazoles were efficiently synthesized from terminal alkynes, sulfonyl azides and hydrozones. The sequential reaction involves a copper-catalyzed three-component reaction, a Lewis acid-catalyzed electrocyclic reaction and a dehydrogenation.     

Expedient synthesis of sulfinamides from sulfonyl chlorides

Sulfinamides were synthesized from sulfonyl chlorides using a procedure involving in situ reduction of sulfonyl chlorides. The reaction is broad in scope and easy to perform.     

Selective formation of 1,5-substituted sulfonyl triazoles using acetylides and sulfonyl azides

The reaction of acetylides with sulfonyl azides was found to selectively form 1,5-substituted sulfonyl triazoles. This reaction thus provides access to the regioisomeric product as compared to the popular copper-catalyzed azide-alkyne cycloaddition. The reaction is efficient and selective with a variety of alkyne sources and sulfonyl azides and can incorporate an additional electrophile to yield 1,4,5-trisubstituted sulfonyl triazoles.     

Some heterocyclic sulfonyl chlorides and derivatives

The syntheses of 4- and 5-chlorosulfonylfuran-2-carboxylic acid (Ia,IIa), 4-chlorosulfonylfuran-2-carboxamide (Ib), 3,5-dimethylpyrazole and isoxazole-4-sulfonyl chlorides (IIIa,IVa) and 2,4-dimethylthiazole-5-sulfonyl chloride (Va) are described. The sulfonyl chlorides were converted into a range of amides, hydrazides and azides. Condensation of the sulfonohydrazides with β-dicarbonyl compounds, gave the corresponding β-ketohydrazones (VII), which, with the exception of the derivatives (VIIe,f,g,i), were converted to the sulfonylpyrazoles (VIII). The structures and spectral data of these compounds are briefly discussed. The reaction of the sodio derivative of acetylacetone with thiophene-2-sulfonyl chloride (VIc) gave 3-(thiophene-2-sulfonyl)pentane-2,4-dione (XII), which with hydrazine gave 4-(thiophene-2-sulfonyl)-3,5-dimethylpyrazole (XIII). However, the analogous reaction with thiophene-2-sulfonohydrazide (VIa) failed to give the expected 1,4-bisthiophenesulfonylpyrazole.     

Palladium-catalyzed Stille cross-couplings of sulfonyl chlorides and organostannanes

Arene and phenylmethanesulfonyl chlorides can be cross-coupled with aryl, heteroaryl, and alkenylstannanes with desulfitation in the presence of 10 mol % CuBr.Me2S, 1.5 mol % Pd2dba3, and 5 mol % tri-2-furylphosphine in tetrahydrofuran or toluene under reflux. This extension of the Stille cross-coupling reaction realizes a new and economical method for the generation of C-C bonds. The palladium-catalyzed carbonylative Stille cross-coupling reactions of arenesulfonyl chlorides and organostannanes in the presence of CO (60 bar) at 110 degrees C in toluene generate the corresponding ketones. Arenesulfonyl chlorides are more reactive than aryl chlorides and aryl bromides in their Stille cross-coupling with organostannanes but less reactive than aryl iodides. The new methods disclosed for the generation of C-C bonds open new possibilities for medicinal chemistry and material sciences.     

A facile approach to polysubstituted pyrazoles from hydrazonyl chlorides and vinyl azides

A novel and facile approach to polysubstituted pyrazoles from readily synthesized hydrazonyl chlorides and vinyl azides was developed. The reaction was regiospecific and proceeded under mild conditions in the presence of base.     

On the tautomerism of 5-aminotetrazole

In order to study the connection between the structure of sulfanilamides and their antibacterial action, sulfanilamide derivatives of 1- and 2-methyl-5-aminotetrazoles and of 1,3-dimethyl-5-iminotetrazole have been synthesized. A study of their IR spectra has shown that 1-methyl-5-sulfanilimidotetrazole has the imide structure in the crystalline state and 2-methyl-5-sulfanilamidotetrazole the amide structure. The sulfanilamide derivatives of 1- and 2-methyl-5-aminotetrazoles possess a considerable antibacterial activity, while 1, 3-dimethyl-5-sulfanilimidotetrazole is inactive.For communication V, see [1].     

Palladium-catalyzed Suzuki-Miyaura cross-couplings of sulfonyl chlorides and boronic acids

[reaction: see text] R = tolyl, phenyl, 4-halophenyl, 1-naphthyl, 2-nitrophenyl, benzyl, methallyl, r1 = aryl, heteroaryl, alkenyl. Arene-, arylmethane, and alk-2-ene-1-sulfonyl chlorides undergo Suzuki-Miyaura cross-coupling with arene-, heteroarene-, and alkeneboronic acids in THF at reflux. The reactivity order is ArI > ArSO(2)Cl > ArBr > ArCl.     

The tautomerism of 5-aminotetrazole

In the reaction of 5-amino-1-methyltetrazole and 5-amino-2-methyltetrazole with carboxylic acid anhydrides or chlorides, diacylamides are obtained in addition to monoacyl derivatives. The results of independent synthesis and a study of IR and PMR spectra have shown that in the diacylamides considered both acyl groups are attached to the same (the exocyclic) nitrogen atom.For part VI, see [1].     

A new, mild preparation of sulfonyl chlorides

A new method was developed for the preparation of sulfonyl chlorides from sulfonic acids under neutral conditions using 2,4,6-trichloro-1,3,5-triazine as chlorinating agent.     

Amido acids of norbornene series in reactions with sulfonyl azides

In reaction of amido acids from the norbornene series with arenesunfonyl azides alongside the expected N,N-dialkyl-5-oxo-exo-2-arylsulfonylamino-4-oxatricyclo[4.2.1.0^3,7]nonane-endo-9-carboxamides (oxabrendanones) the formation of zwitter-ions with a structure of 5-(N,N-dialkyliminio)-exo-2-arylsulfonylamino-4-oxatricyclo[4.2.1.0^3,7]nonane-endo-9-carboxylates came as a surprise. The structure of compounds obtained was confirmed by the analysis of their IR and ¹H NMR spectra. The molecular structure of one among the zwitterions was established by XRD analysis.     

One-pot synthesis of 2,6-diamino-4-sulfonamidopyrimidines from sulfonyl azides, terminal alkynes and cyanoguanidine

Ketenimine intermediates, generated in situ by the addition of copper acetylides to aryl- or alkylsulfonyl azides, are trapped by cyanoguanidine to yield 2,6-diamino-4-sulfonamidopyrimidine derivatives in moderate to good yields.     

Thermal analysis of laser-controlled 5-aminotetrazole propellant

Resorting to the continuous assistance of external laser radiation, laser augmented chemical propulsion (LACP) reveals superior combustion performance. However, the corresponding combustion theories have still to be ascertained for this innovative propulsion technique. Thermal characteristics of 5-aminotetrazole (5-ATZ) propellant are studied for LACP. In nitrogen environment, unique structures of burning surface are formed under laser ablation in bare samples of 5-ATZ propellant pressed powders. Resorting to an outer tube, a thermocouple is inserted in 5-ATZ propellant samples to obtain the temperature trace during combustion. In analogy with the burning surface structure reconstructed by micro computed tomography (MicroCT), the temperatures values of three significant regions were obtained. The experimental dependences of the measured temperatures on environment pressure and laser power are discussed.