Nitrile Cycloaddition Research Articles

An efficient synthesis of 5-substituted 1H-tetrazoles via B(C6F5)3 catalyzed [3+2] cycloaddition of nitriles and sodium azide

A simple and efficient protocol is developed for the synthesis of 5-substituted 1H-tetrazole derivatives from various nitriles and sodium azide (NaN3) via [3+2] cycloaddition reaction using B(C6F5)3 as a catalyst. The present synthetic method displayed significant advantages such as low catalyst loading, mild reaction conditions, low toxicity, easy work-up, high yields, and compatibility with other functional groups.

AgNO3 catalyzed synthesis of 5-substituted-1H-tetrazole via [3+2] cycloaddition of nitriles and sodium azide

An efficient one-pot, convenient catalysis for the synthesis of 5-substituted-1H-tetrazoles is reported. The [3+2] cycloaddition involves various nitriles, sodium azide in refluxing DMF and AgNO3 as catalyst to give corresponding 5-substituted-1H-tetrazoles in good to excellent yields. It is expected that the reaction proceeds via in situ formation of a silver azide species, which participates in coordination of nitrile moiety followed by cycloaddition of azide ion to give tetrazole.

Copper-organic frameworks assembled from in situ generated 5-(4-pyridyl)tetrazole building blocks: synthesis, structural features, topological analysis and catalytic oxidation of alcohols.

Two new metal-organic compounds {[Cu3(μ3-4-ptz)4(μ2-N3)2(DMF)2](DMF)2}n (1) and {[Cu(4-ptz)2(H2O)2]}n (2) {4-ptz = 5-(4-pyridyl)tetrazolate} with 3D and 2D coordination networks, respectively, have been synthesized while studying the effect of reaction conditions on the coordination modes of 4-pytz by employing the [2 + 3] cycloaddition as a tool for generating in situ the 5-substituted tetrazole ligands from 4-pyridinecarbonitrile and NaN3 in the presence of a copper(ii) salt. The obtained compounds have been structurally characterized and the topological analysis of 1 discloses a topologically unique trinodal 3,5,6-connected 3D network which, upon further simplification, results in a uninodal 8-connected underlying net with the bcu (body centred cubic) topology driven by the [Cu3(μ2-N3)2] cluster nodes and μ3-4-ptz linkers. In contrast, the 2D metal-organic network in 2 has been classified as a uninodal 4-connected underlying net with the sql [Shubnikov tetragonal plane net] topology assembled from the Cu nodes and μ2-4-ptz linkers. The catalytic investigations disclosed that 1 and 2 act as active catalyst precursors towards the microwave-assisted homogeneous oxidation of secondary alcohols (1-phenylethanol, cyclohexanol, 2-hexanol, 3-hexanol, 2-octanol and 3-octanol) with tert-butylhydroperoxide, leading to the yields of the corresponding ketones up to 86% (TOF = 430 h(-1)) and 58% (TOF = 290 h(-1)) in the oxidation of 1-phenylethanol and cyclohexanol, respectively, after 1 h under low power (10 W) microwave irradiation, and in the absence of any added solvent or additive.

An efficient synthesis of 5-substituted 1H-tetrazoles catalyzed by graphene

We report an efficient method of synthesis of 5-substituted 1H-tetrazoles by [2+3] cycloaddition of nitriles and sodium azide with graphene as nonmetal catalyst. Under optimized conditions, moderate to good yields (60–70 %) are obtained. The catalyst can be easily separated by centrifugation.

ChemInform Abstract: Amberlyst‐15 Catalyzed Synthesis of 5‐Substituted 1‐H‐Tetrazole via [3 + 2] Cycloaddition of Nitriles and Sodium Azide.

Abstract A mild and efficient method for the preparation of 5-substituted 1- H -tetrazole derivatives is reported using solid acidic resin Amberlyst-15 as an effective heterogeneous catalyst. This method is advantageous because of non-toxicity and stability of catalyst, high product yield, simple methodology, and easy work up. The catalyst was recovered by simple filtration and reused several times delivering moderate to good product yield.

Amberlyst-15 catalyzed synthesis of 5-substituted 1-H-tetrazole via [3+2] cycloaddition of nitriles and sodium azide

A mild and efficient method for the preparation of 5-substituted 1-H-tetrazole derivatives is reported using solid acidic resin Amberlyst-15 as an effective heterogeneous catalyst. This method is advantageous because of non-toxicity and stability of catalyst, high product yield, simple methodology, and easy work up. The catalyst was recovered by simple filtration and reused several times delivering moderate to good product yield.

ChemInform Abstract: Phosphomolybdic Acid (H3Mo12O40P) as a Reusable Heterogeneous Catalyst for the Synthesis of 5‐Substituted 1H‐Tetrazoles via [2 + 3] Cycloaddition of Nitriles and Sodium Azide.

AbstractThe applied catalyst can be reused several times.

ChemInform Abstract: Intramolecular 1,3‐Dipolar Cycloaddition of Nitrile N‐Oxide Accompanied by Dearomatization.

AbstractAn easy approach to partially dearomatized cis‐dihydrobenzoisoxazole frameworks is presented.

Reaction-temperature-dependent supramolecular isomerism of copper(I) coordination polymers with incorporated thiocyanate and in situ generated 5-methyltetrazolate ligands

The hydrothermal reaction of NaN3, acetonitrile and KSCN in the presence of [Cu(CH3CN)4]ClO4 yields two new d10 coordination polymers, [Cu2(μ3-SCN)(μ4-mtta)]n (1) and its supramolecular isomer [Cu2(μ4-SCN)(μ4-mtta)]n (2) (mtta=5-methyl tetrazolate), involving in situ formation of the 5-methyltetrazolate ligand by cycloaddition of nitrile and azide. Compounds 1 and 2 were both found to crystallize in the orthorhombic Pbam system, with different unit cells, exhibiting interesting examples of supramolecular polymorphism. Both compounds are built by [Cu2mtta]+n ribbons connected by thiocyanate anions which act as μ3- and μ4-ligands in 1 and 2, leading to 2D and 3D coordination polymers, respectively. Short Cu(I)⋯Cu(I) distances were found in 1 and 2, which may be attributed to metallophilic Cu⋯Cu interactions. Thermogravimetric analyses indicate that compounds 1 and 2 are stable up to 265 and 340°C, respectively.

Phosphomolybdic Acid (H3Mo12O40P) as a Reusable Heterogeneous Catalyst for the Synthesis of 5-Substituted 1H-Tetrazoles via [2 + 3] Cycloaddition of Nitriles and Sodium Azide

An efficient and practical protocol for the preparation of 5-substituted 1H-tetrazole derivatives is reported using phosphomolybdic acid as an effective heterogeneous catalyst. Good yields, simple methodology, and easy workup make this protocol more attractive for the diversity-oriented synthesis of these heterocycle libraries. The catalyst can be recycled three times with good yields.

Ammonium acetate mediated synthesis of 5-substituted 1H-tetrazoles

Synthesis of 5-substituted 1H-tetrazoles was achieved by [3+2] cycloaddition of nitriles and sodium azide in the presence of ammonium acetate. The reaction proceeds in situ formation of ammonium azide. Present protocol has advantage of good to excellent yields, short reaction times and simple isolation of products than reported methods.

Improved Synthesis of 5-Substituted 1H-Tetrazoles via the [3+2] Cycloaddition of Nitriles and Sodium Azide Catalyzed by Silica Sulfuric Acid

A silica supported sulfuric acid catalyzed [3+2] cycloaddition of nitriles and sodium azide to form 5-substituted 1H-tetrazoles is described. The protocol can provide a series of 5-substituted 1H-tetrazoles using silica sulfuric acid from nitriles and sodium azide in DMF in 72%–95% yield.

Intramolecular 1,3-Dipolar Cycloaddition of Nitrile N-Oxide Accompanied by Dearomatization

Intramolecular 1,3-dipolar cycloaddition of 2-phenoxybenzonitrile N-oxides to benzene rings, accompanied by dearomatization, formed the corresponding isoxazolines in high yields. The X-ray single-crystal structure analysis revealed that the reaction formed the cis-adduct as a single isomer. The substituents on the benzene rings markedly affected the reaction rate, yield, and structure of the final product.

ChemInform Abstract: Synthesis of the Pyridine Core of Cyclothiazomycin.

AbstractKey step is the regioselective [2 + 2 + 2] cycloaddition of nitrile (II) to the diyne (I).

Zeolite and sulfated zirconia as catalysts for the synthesis of 5-substituted 1H-tetrazoles via [2+3] cycloaddition of nitriles and sodium azide

The [2+3] cycloaddition between various nitriles and sodium azide proceeds smoothly in the presence of zeolite and sulfated zirconia as effective catalysts, in water and DMF/MeOH, to give the corresponding 5-substituted 1H-tetrazoles in good to high yields. The reaction most probably proceeds through the in situ formation of catalyst azide species, followed by a successive [2+3] cycloaddition with the nitriles. This method has the advantages of high yields, simple methodology and easy work-up. The catalyst can be recovered by simple filtration and reused with good yields.

Aluminum(III) Hydrogensulfate: An Efficient Solid Acid Catalyst for the Preparation of 5-Substituted 1H–Tetrazoles

An efficient method for preparation of 5-substituted 1H-tetrazoles via [2 + 3] cycloaddition of nitriles and sodium azide is reported using aluminum(III) hydrogensulfate as an effective solid acid. This method has the advantages of good yields, simple methodology, and easy workup.

ChemInform Abstract: Fe3O4/ZnS Hollow Nanospheres: A Highly Efficient Magnetic Heterogeneous Catalyst for Synthesis of 5‐Substituted 1H‐Tetrazoles from Nitriles and Sodium Azide.

AbstractAn efficient route for the synthesis of 5‐substituted 1H‐tetrazoles (II) via [2+3] cycloaddition of nitriles and sodium azide is reported using ZnS‐Fe3O4 hollow nanospheres as magnetic heterogeneous catalyst.

Oxadiazoline and Ketoimine Palladium(II) Complexes as Highly Efficient Catalysts for Suzuki–Miyaura Cross‐Coupling Reactions in Supercritical Carbon Dioxide

AbstractThe [2+3] cycloaddition of nitriles (RCN) with 2,2‐dimethyl‐3,4‐dihydro‐2H‐pyrrole 1‐oxide, in the presence of palladium dichloride (PdCl2) gives the corresponding 2,3‐dihydro[1.2.4]oxadiazole (Δ4‐1,2,4‐oxadiazoline) palladium(II) complexes 1–4 in good yields. However, the Pd(II)‐assisted reaction of pentafluorobenzonitrile with the same pyrroline N‐oxide gives a mixture of oxadiazoline 5, ketoimine 6 and pyrrolylbenzamide‐ketoimine 7 Pd(II) complexes, which affords upon heating in refluxing acetone the unprecedented fused tricyclic ketoimine complex 8 as the exclusive product. Under heating, compounds 5 and 7 transform to 6, the latter undergoing intramolecular cyclization by nucleophilic attack of the amino moiety to the ortho carbon of the pentafluorophenyl ring leading ultimately to 8. The compounds were characterized by IR, 1H and 13C NMR, ESI+‐MS, elemental analyses and, in the cases of 3, 6, 7 and 8, also by X‐ray diffraction analyses. The catalytic properties of the Pd complexes were evaluated in Suzuki–Miyaura cross‐coupling reactions, using supercritical carbon dioxide (scCO2) as a green solvent. Cross‐couplings of aryl halides with phenylboronic acid give the desired biaryl products in quantitative yields, in a short reaction time, for substrate‐to‐catalyst molar ratios as high as 4.0⋅104.

ChemInform Abstract: A Versatile and an Efficient Synthesis of 5‐Substituted‐1H‐tetrazoles

Abstract[via Zr‐catalyzed [3 + 2] cycloaddition of nitriles with NaN3].

Ferric Hydrogensulfate [Fe(HSO4)3] As a Reusable Heterogeneous Catalyst for the Synthesis of 5-Substituted-1H-Tetrazoles and Amides.

Ferric hydrogensulfate catalyzed the synthesis of 5-substituted 1H-tetrazoles via [2 + 3] cycloaddition of nitriles and sodium azide. This method has the advantages of high yields, simple methodology, and easy workup. The catalyst can be recovered by simple filtration and reused delivering good yields. Also, ferric hydrogensulfate catalyzed the hydrolysis of nitriles to primary amides under aqueous conditions. Various aliphatic and aromatic nitriles converted to the corresponding amides in good yields without any contamination with carboxylic acids.