Efficient synthesis of arylaminotetrazoles in water

Arylaminotetrazole derivatives are synthesized efficiently by the reaction of arylcyanamides and sodium azide in the presence of ZnCl₂ under aqueous conditions at reflux. Generally, isomer of 5-arylamino-1H-tetrazole can be obtained from arylcyanamides carrying electron-withdrawing substituent on aryl ring and as the electropositivity of substituent is increased, the product is shifted toward the isomer of 1-aryl-5-amino-1H-tetrazole.     

FeCl3-SiO2 as a reusable heterogeneous catalyst for the synthesis of 5-substituted 1H-tetrazoles via [2+3] cycloaddition of nitriles and sodium azide

An efficient method for the preparation of 5-substituted 1H-tetrazole derivatives is reported using FeCl₃-SiO₂ as an effective heterogeneous catalyst. This method has the advantages of high yields, simple methodology, and easy work-up. The catalyst can be recovered by simple filtration and reused delivering good yields.     

AlCl3 as an Effective Lewis Acid for the Synthesis of Arylaminotetrazoles

An efficient method for preparation of the arylaminotetrazoles derivatives is reported using aluminium chloride as an effective Lewis acid. Generally, 5-arylamino-1H-tetrazole isomer can be obtained from arylcyanamides carrying electron-withdrawing substituents on the aryl ring. As the electropositivity of the substituent is increased, the product is shifted toward the formation of 1-aryl-5-amino-1H-tetrazole isomer.     

Silica-Supported Ferric Chloride (FeCl3-SiO2): An Efficient and Recyclable Heterogeneous Catalyst for the Preparation of Arylaminotetrazoles

An efficient method for preparation of 5-arylamino-1H-tetrazole and 1-aryl-5-amino-1H-tetrazole derivatives is reported using FeCl₃-SiO₂ as an effective heterogeneous catalyst. Generally, when the substituent in arylcyanamide is a strongly electron-withdrawing group, the position of the equilibrium would shift toward 5-arylamino-1H-tetrazole, whereas with an electron-releasing substituent, the position of the equilibrium would shift toward 1-aryl-5-amino-1H-tetrazole.     

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.     

Synthesis of 5-substituted 1H-tetrazoles catalyzed by ceric ammonium nitrate supported HY-zeolite

In this Letter we wish to report a simple and efficient synthetic protocol for the synthesis of 5-substituted 1H-tetrazole derivatives through the [2+3] cycloaddition of nitriles with sodium azide using ceric ammonium nitrate supported HY-zeolite as a novel catalyst. Excellent yields of the corresponding tetrazoles were obtained through this cost-effective protocol under aerobic conditions with shorter reaction time under mild reaction conditions.     

Alternatives to 1-H-tetrazole in the preparation of phosphonate diesters and phosphonamidates from phosphonyl dichlorides

5-Ethylthio-1-H-tetrazole (SET) and 4,5-dicyanoimidazole (DCI) were examined as alternatives to 1-H-tetrazole to mediate the synthesis of phosphonate diesters and phosphonamidates from phosphonyl dichlorides through a two-step one-pot reaction in various organic solvents. SET and DCI were comparable to 1-H-tetrazole for catalyzing these reactions. SET afforded slightly greater yields than DCI while benzene was universally the best solvent for this reaction.     

Synthesis and structure of new ditopic ligands containing tetrazole and 3-nitro-1,2,4-triazole fragments

Alkylation of 3-nitro-1,2,4-triazole with haloalkyltetrazoles has afforded in high yields previously unknown 1-[2-(3-nitro-1H-1,2,4-triazol-1-yl)ethyl]-1H-tetrazole and 2-tert-butyl-5-(3-nitro-1H-1,2,4-triazol-1-ylmethyl)-2H-tetrazole. The molecular and crystal structure of these compounds has been established by X-ray diffraction analysis (XRD).     

Distereoselective one-pot synthesis of pyrimidopyrimidines using sulfated tin oxide as a reusable catalyst： An extension of Biginelli-type reaction

The Biginelli-type compounds 4,5,8a-triarylhexahydropyrimido[4,5-d]pyrimidine-2,7（1H,3H）-diones were synthesized by a one-pot three-component reaction using sulfated tin oxide as a reusable catalyst. This method has the advantages of high yields, short reaction time, simple starting materials and reusability of catalyst for several times.     

One pot three-component synthesis of 5-substituted 1H-tetrazole from aldehyde

A versatile, robust and efficient strategy for the synthesis of vast range of highly functionalized 5-substituted 1H-tetrazole derivatives by using one pot three-component synthesis from various aldehydes, hydroxylamine hydrochloride and sodium azide in presence of a catalytic amount of ceric ammonium sulphate, a non toxic, easily available, inexpensive, unexplored and reusable catalyst is reported. This one-pot synthesis has several advantages such as mild reaction conditions, shorter reaction time, low catalyst loading, good to moderate yields and functional group tolerance making this methodology practically feasible. The synthesized compounds were characterized by ¹H NMR, ¹³C NMR and HRMS.     

Solvent-free preparation of arylaminotetrazole derivatives using aluminum(Ⅲ) hydrogensulfate as an effective catalyst

<正>An efficient and simple method for the preparation of 5-arylamino-1H-tetrazole and 1-aryl-5-amino-1H-tetrazole derivatives is reported using aluminum(Ⅲ) hydrogensulfate(Al(HSO_4)_3) as an effective heterogeneous catalyst from secondary arylcyanamides. Generally,when the substitution in arylcyanamide is strongly electron-withdrawing the position of equilibrium would shift toward the isomer of 1-aryl-5-amino-1H-tetrazole(B) and as the electron-donating of substituent increased,the position of equilibrium is shifted toward the isomer of 5-arylamino-1H-tetrazole(A).The present methodology offers several advantages,such as excellent yields,short reaction times,easy work-up and greener conditions.     

Synthesis of 5‐substituted 1H‐tetrazoles using a recyclable heterogeneous nanonickel ferrite catalyst

An efficient method was developed for the [2 + 3] cycloaddition of sodium azide with nitriles to afford 5‐substituted 1H‐tetrazoles using nanonickel ferrite (NiFe₂O₄) as an effective heterogeneous catalyst in dimethylformamide. The main advantages of this method are high yields, simple methodology and easy work‐up. The catalyst can be recovered and reused for several cycles with predictable activity. Copyright © 2015 John Wiley & Sons, Ltd.     

Palladium-catalysed direct arylation of heteroaromatics with functionalised bromopyridines

The regioselective 5-arylation of a variety of heteroaromatics with functionalised pyridyl bromides using palladium catalyst gives a simple access to functionalised heteroarylated pyridines. The target products were obtained in moderate to good yields using only 1 mol % PdCl(C₃H₅)(dppb) as the catalyst. Substituents, such as fluoro, acetyl, nitrile, nitro, methoxy or amino on the pyridyl bromide are tolerated. However, the nature of the substituents has an important influence on the yields. Electron-withdrawing substituent favours the reaction; whereas electron-donating are unfavourable.     

Diisopropylethylammonium acetate (DIPEAc): An efficient and recyclable catalyst for the rapid synthesis of 5-substituted-1H-tetrazoles

A simple and efficient protocol developed for the synthesis of 5-substituted 1H-tetrazole derivatives through [2+3] cycloaddition reaction between benzonitriles and sodium azide using diisopropylethylammonium acetate as a recyclable reaction medium is described. The reactions proceed well at 80?°C and provide the corresponding tetrazoles in good to excellent yields (up to 94% yield). Developed method has notable advantages, such as simple and mild conditions, easy workup, reusability with consistent catalytic activity, and safer alternative to hazardous, corrosive conventional Lewis acid catalysts.     

A facile,highly efficient and novel method for synthesis of 5-substituted 1<Emphasis Type="Italic">H</Emphasis>-tetrazoles catalysed by copper(I) chloride

The present study on tetrazole compounds, which have a wide area of application, proposes a new, simple and highly effective method. A series of 5-substituted 1H-tetrazoles were synthesised in DMF via the [3 + 2] cycloaddition reaction, in which different aryl nitriles with sodium azide were used and copper(I) chloride served as a catalyst. Short reaction times, high yields and simple procedures rendered this method attractive and useful for the organic synthesis of 5-substituted 1H-tetrazoles. A further advantage was the use of an environmentally friendly catalyst.     

A hetero-Diels-Alder approach to functionalized 1H-tetrazoles: synthesis of tetrazolyl-1,2-oxazines, -oximes and 5-(1-aminoalkyl)-1H-tetrazoles

This work describes the first and unprecedented examples of inverse electron demand Diels-Alder reactions of 5-(1-nitrosovinyl)-1-phenyl-1H-tetrazole, generated in situ from the corresponding bromooxime, with electron rich alkenes and heterocycles, providing in good overall yields tetrazolyl-1,2-oxazines and -oximes. Upon subsequent reduction these allowed the access to 5-(1-aminoalkyl)-1H-tetrazoles, paving the way for a new entry into this important class of compounds, bioisosteres of α-amino acids.     

A new family of bis-tetrazole (BIZOL) BINOL-type ligands

The synthesis and characterization of 5-(1-(2-(1H-tetrazole-5-yloxy)naphthalen-1-yl)naphthalen-2-yloxy)-1H-tetrazole (BIZOL) as the first bis-tetrazole BINOL-type ligands is described.     

Improved Preparation of 5-Chloro-1-phenyl-1H-tetrazole and Other 5-Chlorotetrazoles.

Reaction of aryldichloroisocyanides 1a–e with sodium azide and a phase transfer agent has provided 5-chloro-1-aryl-1H-tetrazoles 2a–e in good yield. In particular, the widely-used intermediate, 5-chloro-1-phenyl-1H-tetrazole 2a, can be produced conveniently and safely in yields approaching 100%.     

An efficient synthesis of (E)-nitroalkenes catalyzed by recoverable diamino-functionalized mesostructured polymers

A clean, efficient, and simple method has been developed for synthesis of (E)-nitroalkenes using FDU-ED as an efficient catalyst. The reactions proceeded with moderate to high yields (60-96%) under mild conditions. The catalyst FDU-ED is recyclable and can be reused more than seven times without significant loss of activity and selectivity.     

Rearrangement of 2-azanorbornenes to tetrahydrocyclopenta[c]pyridines under the action of activated alkynes – A short pathway for construction of the altemicidin core

A simple approach to a series of 2,4a,7,7a-tetrahydro-1H-cyclopenta[c]pyridines was proposed on the basis of the amino-Claisen rearrangement of readily accessible 2-azabicyclo[2.2.1]hept-5-enes under the action of dialkyl acetylenedicarboxylates, methyl propiolate or propiolamide. The rearrangement is highly diastereoselective and leads to the formation of only one isomer with cis-annulation of the five- and six-membered rings in satisfactory yields. Using the developed method, close analogs of the altemicidin and SB-203207 cores were synthesized.