P2O5–SiO2 as an efficient heterogeneous catalyst for the solvent-free synthesis of 1-substituted 1H-1,2,3,4-tetrazoles under conventional and ultrasound irradiation conditions

Applications of alkyl orthoesters as valuable substrates in organic transformations, focusing on reaction media

In this review we focus on applications of alkyl orthoesters as valuable and efficient substrates to perform various classes of two-component and multi-component organic reactions. The article has classified them according to two aspects, which are: (i) a focus on the reaction medium (solvent-free conditions, aqueous media, and organic solvents); and (ii) an examination of product structures. Reaction accomplishment under solvent-free conditions is an eco-friendly process with the absence of volatile toxic solvents, which puts it in line with green chemistry goals. Water is an interesting choice in organic transformations due to its inexpensiveness and safety. The authors hope their assessment will help chemists to attain new approaches for utilizing alkyl orthoesters in various organic synthetic methods. The review covers the corresponding literature up to the beginning of 2020.

In this review we focus on applications of alkyl orthoesters as valuable and efficient substrates to perform various classes of two-component and multi-component organic reactions.

Isocyanide based multicomponent click reactions: a green and improved synthesis of 1-substituted 1H-1,2,3,4-tetrazoles

An improved synthesis of 1-substituted 1H-1,2,3,4-tetrazoles via a novel isocyanide based multicomponent click reaction under ultrasound assisted mild, solvent, catalyst and column-free conditions has been developed.

One-pot synthesis of 1-substituted 1H-1,2,3,4-tetrazoles from 2aminothiazoles using tributylmethylammonium chloride as a catalyst

Reaction between substituted thiazolylamine or oxazolylamine, triethyl orthoformate and sodium azide in the presence of tributylmethylammonium chloride in DMSO furnishes 1-substituted 1

High Catalytic Activity of Peptide Nanofibres Decorated with Ni and Cu Nanoparticles for the Synthesis of 5-Substituted 1H-Tetrazoles and N-Arylation of Amines

A rapid development of a new methodology for decarboxylative N-arylation of carboxylic acids and the preparation of 5-substituted 1H-tetrazoles catalysed by peptide nanofibres decorated with Cu and Ni nanoparticles is presented. Compared with conventional aryl halides, benzoic acids are extremely interesting and environmentally friendly options for the synthesis of secondary aryl amines.

Trifluoromethanesulfonimide catalysed synthesis of 1-substituted-1H-1,2,3,4-tetrazoles using glycerol as green solvent at room temperature

A direct synthetic protocol is developed for the synthesis of 1-substituted-1 H-1,2,3,4-tetrazoles via a three-component condensation of primary amines, triethyl orthoformate and sodium azide in the presence of 5 mol% of trifluoromethanesulfonimide (HNTf2) in glycerol at room temperature with good to excellent yields.

A comparative study between heterogeneous stannous chloride loaded silica nanoparticles and a homogeneous stannous chloride catalyst in the synthesis of 5-substituted 1H-tetrazole

Heterogeneous SnCl₂–nano-SiO₂efficiently catalyzed 5-substituted 1H-tetrazole synthesis with excellent yield. It is widely applicable on aliphatic, aromatic, heteroaromatic and sterically hindered nitriles with five times recyclability. ​

Ultrasound-promoted one-pot three component synthesis of tetrazoles catalyzed by zinc sulfide nanoparticles as a recyclable heterogeneous catalyst

Ultrasound irradiation was applied for the appropriate and rapid synthesis of 1-substituted tetrazoles through cyclization reaction of various primary amines, sodium azide and triethyl orthoformate. This reaction was effectively catalyzed by ZnS nanoparticles as an efficient, recoverable and reusable catalyst. Compared with conventional methods, this method has the considerable advantages such as shorter reaction times, easier work-up, purer products with high yields and mild conditions. The ZnS nanoparticles catalyst is an excellent instance to replace Brønsted acids for the preparation of 1-substituted tetrazole derivatives in very short reaction times with excellent yields. The catalyst can be recovered and reused several times without significant loss of its catalytic activity.

Application of a functionalized mesoporous silica catalyst to the synthesis of tetrazoles

Highly ordered MCM-41 was synthesized and functionalized with benzylic groups. The solid catalyst was used in the synthesis of aryl tetrazoles.

Fabrication of silica nanoparticle based polymer nanocomposites via a combination of mussel inspired chemistry and SET-LRP

A facile and efficient strategy combination of mussel inspired chemistry and SET-LRP has been developed for the surface modification of silica nanoparticles.

Green synthesis, characterization and catalytic activity of natural bentonite-supported copper nanoparticles for the solvent-free synthesis of 1-substituted 1H-1,2,3,4-tetrazoles and reduction of 4-nitrophenol

In this study, Cu nanoparticles were immobilized on the surface of natural bentonite using Thymus vulgaris extract as a reducing and stabilizing agent. The natural bentonite-supported copper nanoparticles (Cu NPs/bentonite) were characterized by FTIR spectroscopy, X-ray diffraction (XRD), X-ray fluorescence (XRF), field emission scanning electron microscopy (FE-SEM), energy dispersive X-ray spectroscopy (EDS), transmission electron microscopy (TEM), selected area electron diffraction (SAED) and Brunauer-Emmett-Teller (BET) analysis. Afterward, the catalytic performance of the prepared catalyst was investigated for the solvent-free synthesis of 1-substituted 1H -1,2,3,4-tetrazoles and reduction of 4-nitrophenol (4-NP) in water. It was found that the Cu NPs/bentonite is a highly active and recyclable catalyst for related reactions.

Copper Iodide Nanoparticles-Catalysed Cyanation of Aryl Halides Using Non-Toxic K4[Fe(CN)6] in the Presence of 1,2-Bis(5-Tetrazolyl)Benzene as an Efficient Ligand

Cyanation of aryl bromides were carried out with K4[Fe(CN)6] in the presence of catalytic amounts of a copper salt and 1,2-bis(5-tetrazolyl)benzene as a ligand under thermal conditions. This method has the advantages of high yields, simple methodology and easy work up.

Copper Complex-catalysed C–N Coupling Reaction of Aryl Iodides with Nitrogen-containing Heterocycles

An efficient method for the copper-catalysed arylation of nitrogen-containing heterocycles is reported using 3-(diphenylphosphino) propanoic acid as a ligand in combination of CuCl. The C–N coupling reactions afford various N-arylated products in good to excellent yields.

CoFe2O4 Nanoparticles as a Magnetically Recoverable and Reusable Catalyst for the Synthesis of Arylaminotetrazoles and 5-aryloxytetrazoles

An efficient and direct method is described for the synthesis of 5-arylamino-1 H-tetrazoles (Isomer A) or 1-aryl-5-amino-1 H-tetrazoles (Isomer B) and 5-aryloxytetrazoles from arylcyanamides or cynates with nano CoFe2O4 as a reusable and efficient heterogeneous catalyst. Isomer A was obtained from arylcyanamides carrying electron-withdrawing substituents on the aryl ring, while isomer B was produced with electron-releasing groups. The significant advantages of this methodology are high yields, elimination of dangerous and harmful hydrazoic acid, simple work-up procedure and the recovery and reusability of the catalyst.

Electrochemical and DFT study on the inhibition of 316L stainless steel corrosion in acidic medium by 1-(4-nitrophenyl)-5-amino-1H-tetrazole

This article describes the best corrosion inhibition behavior and adsorption of newly synthesized amino tetrazole using electrochemical and computational methods.

Ultrasound-promoted green approach for the synthesis of sulfonamides using natural, stable and reusable Natrolite nanozeolite catalyst at room temperature

Natural Natrolite nanozeolite has been investigated as an efficient and reusable catalyst for the N-sulfonylation of amines under ultrasound irradiation at room temperature. Compared with traditional methods, the significant advantages for method are green solvent, milder and cleaner conditions, higher purity and yields, shorter reaction time, easier work-up procedure and the lower generation of waste or pollutions. The catalyst can be recovered and reused several times without significant loss of its catalytic activity.