Preparation of highly functionalized 1,5-disubstituted tetrazoles via palladium-catalyzed Suzuki coupling

The preparation of a range of 1,5-disubstituted tetrazoles has been achieved through palladium-catalyzed Suzuki coupling. Using appropriately substituted 5-p-toluenesulfonyltetrazoles as substrates (obtained by cycloaddition of a substituted azide with p-toluenesulfonyl cyanide), this methodology provides access to a variety of highly substituted tetrazoles that would be difficult to access otherwise. The procedure is compatible with functional groups commonly found in drug-like molecules, and has been used to generate a number of compounds of potential biological interest.     

On the discrimination of tetrazole regioisomers by NOE difference spectroscopy

Summary The unambiguous discrimination between 1-substituted and 2-substituted tetrazoles as well as between 1,5- and 2,5-disubstituted tetrazoles by means of homonuclear NOE difference spectroscopy is described.

---

Zur Unterscheidung regioisomerer Tetrazole mittels NOE Differenzspektroskopie

Zusammenfassung Die Unterscheidung zwischen 1-substituierten und 2-substituierten bzw. zwischen 1,5- und 2,5-disubstituierten Tetrazolen mittels NOE Differenzspektroskopie wird beschrieben.

     

Selective synthesis of ureas and tetrazoles from amides controlled by experimental conditions using conventional and microwave irradiation

An efficient synthetic procedure has been achieved for selective synthesis of 1,5-disubstituted tetrazoles and diaryl ureas from secondary amides in situ in the presence of NaN₃ and POCl₃ as solvent, both by conventional and microwave methods. The reaction conditions were optimized to yield selectively either tetrazoles or urea derivatives from reasonable to excellent yields. These conversions have been tested and verified with various secondary amide precursors. The synthesized compounds were characterized by ¹H NMR, ¹³C NMR and ESI-MS spectroscopic techniques.     

Tetrazoles from N-(4-dimethylaminophenyl)nitrones and hydrogen azide

The reaction of N-(4-dimethylaminophenyl)nitrones, 1 , with hydrogen azide proceeds via three distinct pathways to give a mixture of two tetrazoles, 5 and 9 , and a 2-azido-4-dimethyl-aminoaniline derivative, 6 . The proportions largely depend on the electron-withdrawing force resident in the function R attached to nitrone carbon. The formation of 5 constitutes a new synthetic approach to 1,5-disubstituted tetrazoles.     

Metal triflate catalyzed reactions of alkenes, NBS, nitriles, and TMSN3: synthesis of 1,5-disubstituted tetrazoles

A versatile and highly efficient protocol for the synthesis of 1,5-disubstituted tetrazoles has been developed by metal triflate catalyzed one-pot reaction of alkenes, NBS, nitriles, and TMSN3. Among the metal triflates, Zn(OTf)2 was found to be the best catalyst. Use of different combinations of alkenes and nitriles generate a variety of 1,5-disubstituted tetrazoles containing an additional alpha-bromo functionality of the N1-alkyl substituent.     

Synthesis of New Tetrazole Derivatives and Their Biological Evaluation

Russian Journal of General Chemistry - An operationally simple and efficient method of synthesis of novel 1,5-disubstituted tetrazoles with high yields from easily accessible...     

1-Isocyanomethylbenzotriazole and 2,2,4,4-tetramethylbutylisocyanide—cleavable isocyanides useful for the preparation of α-aminomethyl tetrazoles

1-Isocyanomethylbenzotriazole and 2,2,4,4-tetramethylbutylisocyanide smoothly undergo Ugi type reaction toward 1,5-disubstituted aminomethyl tetrazoles and can be subsequently cleaved under acidic conditions yielding substituted α-aminomethyl tetrazoles.     

Improved conditions for converting sterically hindered amides to 1,5-disubstituted tetrazoles

Improved conditions for converting amides into 1,5-disubstituted tetrazoles are described. The optimum reaction conditions [diisopropyl azodicarboxylate (DIAD), diphenylphosphoryl azide (DPPA), and diphenyl-2-pyridyl phosphine in THF at 45 °C] converted sterically hindered amides to their corresponding tetrazoles in good yield.     

Synthesis and in vitro antiproliferative activity of novel androst-5-ene triazolyl and tetrazolyl derivatives

A straightforward and reliable method for the regioselective synthesis of steroidal 1,4-disubstituted triazoles and 1,5-disubstituted tetrazoles via copper(I)-catalyzed cycloadditions is reported. Heterocycle moieties were efficiently introduced onto the starting azide compound 3β-acetoxy-16β-azidomethylandrost-5-en-17β-ol through use of the "click" chemistry approach. The antiproliferative activities of the newly-synthesized triazoles were determined in vitro on three human gynecological cell lines (HeLa, MCF7 and A2780) using the microculture tetrazolium assay.     

Efficient Uncatalyzed Conversion of Primary and Secondary Thioamides into 1-Substituted, 5-Substituted, 1, 5-Disubstituted and Annulated Tetrazoles

Abstract

Unprecedented high-yield simple and mild conversion of primary aliphatic and aromatic thioamides into 5-substituted tetrazoles on treatment with a combination of tetrachlorosilane and sodium azide in refluxing acetonitrile has been achieved. Secondary acyclic, cyclic, and heterocyclic thioamides could also be transformed in high yields into 1-substituted, 1,5-disubstituted, or annulated tetrazoles under the same reaction condition.

GRAPHICAL ABSTRACT      

Concise route to a series of novel 3-(tetrazol-5-yl)quinoxalin-2(1H)-ones

This report presents a novel three step solution phase protocol to synthesize 3-(tetrazol-5-yl)quinoxalin-2(1H)-ones. The strategy utilizes ethyl glyoxalate and mono-N-Boc-protected-o-phenylenediamine derivatives in the Ugi-Azide multi-component reaction (MCR) to generate a unique 1,5-disubstituted tetrazole. Subsequent acid treatment stimulates a simultaneous Boc deprotection and intramolecular cyclization leading to bis-3,4-dihydroquinoxalinone tetrazoles. Direct oxidation using a stable solid-phase radical catalyst (2,2,6,6-tetramethylpiperidin-1-yl)oxyl (TEMPO) with ceric ammonium nitrate (CAN) in catalytic fashion initiating aerobic oxidation, completes the entire procedure to generate a series of original unique bis-quinoxalinone tetrazoles. The method was also expanded to produce a bis-benzodiazepine tetrazole.     

A two-step synthesis of 1,5-disubstituted tetrazoles containing a siloxy or sulfonamide group

A simple two-step route to the synthesis of 1,5-disubstituted tetrazoles containing a β-siloxy or β-sulfonamide group is presented. The synthesis takes place via an isocyanide-based multicomponent reaction and allows incorporation of a wide variety of substitution patterns starting from commercially available reagents. This is followed by cyclization of the ketenimines with trimethylsilyl azide without using any catalyst or activation.     

Exhaustive N-tert-butylation of tetrazoles in thet-BuOH-HBF4 system

Tetrazole and its N-monosubstituted and C,N-disubstituted derivatives in a 48% HBF₄ medium react with tertbutyl alcohol, forming the corresponding tetrazolium salts. In this case, tert-burylation of 2-monosubstituted and 2,5-disubstituted tetrazoles occurs at the N₍₄₎ atom, as in the case of other allcylating agents; the 1-substituted isomers, in contrast, are quaternized preferentially at the less basic atom N₍₃₎, while the 1,5-disubstituted isomers are quaternized exclusively at the N₍₃₎ atom.Scientific-Research Institute of Physicochemical Problems, Belorussian State University, Minsk 220080. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 915–921, July, 1995. Original article submitted December 30, 1994; revised, June 13, 1995.     

Mechanism of the monomolecular thermal decomposition of 1,5- and 2,5-disubstituted tetrazoles

The kinetic parameters of the thermal decomposition of several pairs of 1(2)-R-5-R-disubstituted tetrazoles have been determined using the manometric method. The isomers differ only by the position of the substituents linked with the heterocyclic nitrogen atom. The activation entropies are equal to ca. +8 cal mol^–1 K^–1, the activation energies range from 39 to 48 kcal mol^–1. A linear correlation between the logarithms of the rate constants of decomposition of the isomers has been established. The limiting stages of the stepwise mechanism of the monomolecular decomposition, which determines the experimental rates of nitrogen evolution, include the reversible formation followed by decomposition of intermediate azidoazomethines in the case of 1,5-disubstituted tetrazoles and azodiazo compounds for isomeric 2,5-disubstituted tetrazoles. The enthalpies of formation of R(N₃)C=NR (R = Me, Ph), C₂H₃(N₃)C=NMe and increments _f H°[C_d–(C)(N₃)], _f H°[C_d-(C_b)(N₃)], and _f H°[C_d–(C_d)(N₃)] have been estimated.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 2209–2215, September, 1996.     

Synthesis of new [1,2,3]triazoles and 1H-tetrazoles via reactions of 3,(5)-(Di)chloro-2H-1,4-(benz)oxazin-2-ones with diazocompounds or sodium azide

Treatment of 3,(5)-(di)chloro-2H-1,4-(benz)oxazin-2-ones with diazo compounds or sodium azide yields bi(tri)cyclic compounds which can be converted into [1,2,3]triazoles or 1,5-disubstituted tetrazoles via reactions with nucleophiles as methanol, water and amines.     

Synthesis of Nitrogen Heterocycles from Methyl α‐ and β‐d‐Glucopyranosides

Eight nitrogen heterocycles, mono and disubstituted tetrazoles and oxadiazoles, were synthesized from methyl d‐glucopyranoside anomers. The monosubstituted tetrazoles resulted from the reaction of 6‐cyanoglucopyranoside derivatives with sodium azide. By alkylation of the monosubstituted tetrazoles, the 1,5 and 2,5 disubstituted tetrazoles were obtained. The monosubstituted tetrazoles were reacted with acetic anhydride to give the oxadiazoles.     

Efficient synthesis of 2,5-disubstituted tetrazoles via the Cu2O-catalyzed aerobic oxidative direct cross-coupling of N-H free tetrazoles with boronic acids

We present a new protocol that allows for the synthesis of 2,5-disubstituted tetrazoles via the direct coupling of N-H free tetrazoles and low toxic boronic acids in the presence of only a catalytic amount of Cu(2)O (5 mol%) as catalyst and 1 atm of environmentally benign O(2) as oxidant, without the need for other additives. This method represents a simple, green, and atom-efficient synthesis of 2,5-disubstituted tetrazoles.     

A metal-free route towards 1,5-disubstituted 1,2,3-triazolylmethylene linked disaccharides: Synthesis in a biodegradable hydroxyl-ammonium-based aqueous ionic liquid media

Suitably protected carbohydrates were joined together using 1,5-disubstituted 1,2,3-triazolylmethylene (1,5-DTM) linkers. The DTM linker was built by the 1,3-dipolar cycloaddition reactions of a series of sugar azides with vinyl sulfonylmethylene-modified furanose or pyranose under metal free conditions. Three different biodegradable hydroxylammonium based ionic liquids were studied in water as the reaction media. The N,N-dimethyl ethanolammonium formate-water mixture was found to be the best reaction medium because the reaction time was shortened considerably to generate a dozen new 1,5-DTM-linked disaccharides.     

Darstellung von PdCl2-komplexen substituierter cis,cis-cycloocta-1,5-diene aussachtringen und den entsprechenden substituierten cis-1,2-divinylcyclobutanen. cis,trans-zuordnung 3,4-,3,7- und 3,8-disubstituierter cis,cis-cycloocta-1,5-diene

cis-1,2-Divinylcyclobutanes are transformed with dibenzonitrilepalladium(II) chloride into the corresponding cis,cis-cycloocta-1,5-diene-PdCl₂ complexes. When e.g. the 3-methyl-cis,cis-cycloocta-1,5-diene-PdCl₂ complex is prepared using trans- or cis-3-methyl-cis-1,2-divinylcyclobutane or the corresponding eight-membered ring. two PdCl₂ complexes with the methyl group in the equatorial or axial position are formed in different percentages. With the aid of ¹H NMR spectroscopy the cis- or trans-configurations of 3,4-, 3,7- or 3,8-disubstituted cis,cis-cycloocta-1,5-dienes can be determined unambiguously in PdCl₂ complexes.     

Rhodium(III)-catalyzed ring-opening of strained olefins through C–H activation of O-acetyl ketoximes: an efficient synthesis of trans-functionalized cyclopentenes and spiro[2.4]heptenes

An efficient strategy for the stereoselective synthesis of functionalized cyclopentenes and spiro[2.4]heptenes from strained olefins via C–H activation of aryl ketone O-acetyl ketoximes using [RhCl₂Cp^∗]₂ catalyst is described. The results revealed that a wide range of readily accessible aryl and heteroaryl ketoximes are compatible in this method for the ring opening of bicyclic and spirotricyclic olefins.