Synthesis and Extended Activity of Triazole‐Containing Macrocyclic Protease Inhibitors

Peptide‐derived protease inhibitors are an important class of compounds with the potential to treat a wide range of diseases. Herein, we describe the synthesis of a series of triazole‐containing macrocyclic protease inhibitors pre‐organized into a β‐strand conformation and an evaluation of their activity against a panel of proteases. Acyclic azido–alkyne‐based aldehydes are also evaluated for comparison. The macrocyclic peptidomimetics showed considerable activity towards calpain II, cathepsin L and S, and the 20S proteasome chymotrypsin‐like activity. Some of the first examples of highly potent macrocyclic inhibitors of cathepsin S were identified. These adopt a well‐defined β‐strand geometry as shown by NMR spectroscopy, X‐ray analysis, and molecular docking studies.     

Synthesis of proton‐ionizable acyclic,macrocyclic and macrobicyclic compounds containing one or two triazole groups

New acyclic, macrocyclic and macrobicyclic compounds containing one or two proton‐ionizable triazole groups are prepared and characterized. The series includes six podands, a macrocycle with one triazole and one pyridine unit in the ring, a bis‐triazolo macrocycle with four pentafluorobenzyl substitutents, and two bis(crown ethers) with a triazolo group connecting the two polyether rings. The solid‐state structure and solubility in supercritical carbon dioxide are determined for the bis‐triazolo macrocycle with pendant pentafluorobenzyl groups.     

Synthesis of novel benzo‐substituted macrocyclic schiff bases containing two triazole rings

A synthesis of a series of novel macrocyclic Schiff bases containing two triazole rings 10a,b, 11a,b, 34‐37 in good yields by heating the appropriate bis‐amines 1f, 6a,b, 31 with the corresponding bis‐aldehydes 2, 9a,b, 29 in refluxing acetic acid under high dilution conditions was described. Attempts to synthesize macrocyclic Schiff bases containing pyridine and two triazole rings were also described.     

Regioselective synthesis of spiropyrrolidine/spiropyrrolizidine/spirothiazolidine-grafted macrocycles through 1,3-dipolar cycloaddition methodology

Synthesis of 13- and 16-membered macrocyclic enone with alkyl ether and triazole as a linker was achieved using intramolecular aldol condensation. The newly synthesized macrocyclic enone was successfully utilized as a dipolarophile in 1,3-dipolar cycloaddition (1,3-DC). The dipole generated from isatin/acenaphthenequinone with various secondary amino acids (sarcosine, l-proline, and thiazolidine-4-carboxylic acid) were reacted with macrocyclic enone to give a new class of spiropyrrolidine-grafted macrocycles in good yield (>85%). The structures were assigned by 2D NMR spectra and the regio- and stereochemical outcome of the cycloadducts were established by a single crystal X-ray analysis.     

Silver Salt and Derivatives of 5‐Azido‐1H‐1, 2, 4‐triazole‐3‐­carbonitrile

This study features the preparation of three new energetic C‐azido‐1, 2, 4‐triazoles, with the anion of one being a new binary C–N compound. 5‐Azido‐1H‐1, 2, 4‐triazole‐3‐carbonitrile ( 1 ) was prepared from 5‐amino‐1H‐1, 2, 4‐triazole‐3‐carbonitrile and further derivatized to 5‐azido‐1H‐1, 2, 4‐triazole‐3‐carbohydroximoyl chloride ( 5 ) with 3‐azido‐1H‐1, 2, 4‐triazole‐5‐carboxamidoxime ( 3 ) as an intermediate. The ability of 1 and 3 for salt formation was shown with the respective silver salts 2 and 4 . All compounds were well characterized by various means, including IR and multinuclear NMR spectroscopy, mass spectrometry, and DSC. The molecular structures of 1 , 3 , and 5 in the solid state were determined by single‐crystal X‐ray diffraction. The sensitivities towards various outer stimuli (impact, friction, electrostatic discharge) were determined according to BAM standards. The silver salts were additionally tested for their potential as primary explosives.     

A kinetic study of the thermolysis of N‐crotyl substituted 1,2,4‐triazoles

A kinetic study of the thermolysis of 4‐crotyl‐3,5‐diphenyl‐4H‐1,2,4‐triazole ( 1 ) in a melt of the neat compound was performed at temperatures in the range of 260–350 °C. The main products formed were 1‐crotyl‐3,5‐diphenyl‐1H‐1,2,4‐triazole (3) and 1‐(1‐methylallyl)‐3,5‐diphenyl‐1H‐1,2,4‐triazole ( 4 ) together with 3‐methyl‐2,6‐diphenylpyridine ( 2 ) and 3,5‐diphenyl‐1,2,4‐triazole ( 5 ). Products 2 and 5 were both formed preferentially from 3 and 4 . In the melt was observed first order kinetics. Activation parameters for formation of 3 and 4 were determined. Product 3 : E_a = 95 kJ/mole. Product 4 : E_a= 145 kJ/mole.     

Synthesis and Biological Evaluation of Novel Isonucleosides with 1,2,4‐Triazole‐3‐Carboxamide

Novel 1,2,4‐triazole isonucleosides (1 and 2) were efficiently synthesized starting from D‐ribose and D‐xylose, respectively. The key steps were condensation of cyclic sulfate 8 with methyl‐1,2,4‐triazole‐3‐carboxylate and nucleophilic displacement of the tosylate 15 with methyl‐1,2,4‐triazole‐3‐carboxylate, respectively.     

Histone deacetylase inhibitors: synthesis of cyclic tetrapeptides and their triazole analogs

Synthesis of nine macrocyclic peptide HDAC inhibitors and three triazole derivatives is described. HDAC inhibitory activity of these compounds against HeLa cell lysate is evaluated. The biological data demonstrate that incorporation of a triazole unit improves the HDAC inhibitory activity.     

Studies on the Reaction of α‐Chloroformylarylhydrazine Hydrochloride with Imidazole and 1,2,4‐Triazole

α‐Imidazolformylarylhydrazine 2 and α‐[1,2,4]triazolformylarylhydrazine 3 have been synthesized through the nucleophilic substitution reaction of 1 with imidazole and 1,2,4‐triazole, respectively. 2,2′‐Diaryl‐2H,2′H‐[4,4′]bi[[1,2,4]‐triazolyl]‐3,3′‐dione 4 was obtained from the cycloaddition of α‐chloroformylarylhydrazine hydrochloride 1 with 1,2,4‐triazole at 60 °C and in absence of n‐Bu₃N. The inducing factor for cycloaddition of 1 with 1,2,4‐triazole was ascertained as hydrogen ion by the formation of 4 from the reaction of 3 with hydrochloric acid. 4 was also acquired from the reaction of 3 with 1 and this could confirm the reaction route for cycloaddition of 1 with 1,2,4‐triazole. Some acylation reagents were applied to induce the cyclization reaction of 2 and 3.1 possessing chloroformyl group could induce the cyclization of 2 to give 2‐aryl‐4‐(2‐aryl‐4‐vinyl‐semicarbazide‐4‐yl)‐2,4‐dihydro‐[1,2,4]‐triazol‐3‐one 6. 7 was obtained from the cyclization of 2 induced by some acyl chlorides. Acetic acid anhydride like acetyl chloride also could react with 2 to produce 7D . 5‐Substituted‐3‐aryl‐3H‐[1,3,4]oxadiazol‐2‐one 8 was produced from the cyclization reaction of 3 induced by some acyl chlorides or acetic acid anhydride. The 1,2,4‐triazole group of 3 played a role as a leaving group in the course of cyclization reaction. This was confirmed by the same product 8 which was acquired from the reaction of 1 , possessing a better leaving group: Cl, with some acyl chlorides or acetic acid anhydride.     

Proton-ionizable crown compounds. 4. New macrocyclic polyether ligands containing a triazole subcyclic unit

A series of macrocyclic polyether (crown) ligands containing the proton-ionizable s-triazole subcyclic unit were prepared by reacting the 1-THP blocked 3,5-bis(chloromethyl)-1H-1,2,4-triazole with various oligoethylene glycols. The starting bis(chloromethyl)triazole is a vessicant and must be used with caution. Triazolo-18-crown-6 ( 5 ) formed stable complexes with barium, strontium, copper and benzylammonium cations but not with potassium or lithium. The crystal structure of 5 showed the triazole proton to be on nitrogen 3 which is outside the macroring cavity.     

Mercury(II) Chloride‐Mediated Desulphurization of Amidinothioureas: Synthesis and Antimicrobial Activity of 3‐Amino‐1,2,4‐triazole Derivatives

The synthesis of 3‐amino‐1,2,4‐triazole via mercury(II) chloride‐mediated cyclization of amidinothiourea is described. This procedure offers a general and efficient route to synthesize the title compound by 3 + 2 annulation reaction. On the basis of the literature precedence, the mechanism for the formation of 3‐amino‐1,2,4‐triazole is proposed. When the synthesized compounds were tested for their antimicrobial activity showed promising inhibition against tested microbes.     

Synthesis and Structure Determination of Some New N‐Glycosides of 4,5‐Disubstituted‐1,2,4‐Triazole‐3‐Thiones

Some new N‐glycosides of 4‐(2‐phenylethyl)‐5‐pyridyl‐1,2,4‐triazole‐3‐thiones were synthesised by the coupling reaction of halo sugar with 4,5‐disubstituted 3H‐1,2,4‐triazole‐3‐thiones in the presence of mercuric cyanide and dry nitromethane as solvent, followed by deprotection using dry ammonia in methanol. All of the above compounds were fully characterized by means of infrared, ¹H NMR spectroscopy, mass spectroscopy and elemental analysis.     

Design,Synthesis and Antitumor Activity of Asymmetric Bis(s‐triazole Schiff‐base)s Bearing Functionalized Side‐Chain

1‐Amino‐2‐pyrid‐3‐yl‐5‐(2‐benzoylethylthio)‐s‐triazole ( 1 ) was condensed with 1‐amino‐3‐mercapto‐5‐ [(un)substituted phenyl]‐s‐triazoles and subsequently substituted with chloroacetic acid to afford bis‐s‐triazole sulfanylacetic acid mono‐Schiff bases ( 3a – 3e ), which were condensed with 9‐formylanthracene to produce asymmetric bis(s‐triazole Schiff base) sulfanylacetic acids ( 4a – 4e ). The structures of new synthesized compounds were characterized by elemental analysis and spectral data, and their in vitro antitumor activity against L1210, CHO and HL60 cell lines was evaluted via the respective IC₅₀ values by methylthiazole trazolium (MTT) assay.     

A Computational View of PATO and its Tautomers

1, 2, 4‐Triazole and 3‐amino‐1, 2, 4‐triazole are useful starting materials for the synthesis of many 1, 2, 4‐triazole‐based explosives. Electronic properties and Kamlet–Jacobs detonation performances of PATO (3‐picrylamino‐1, 2, 4‐triazole) (a relatively inexpensive, insensitive, and thermally stable explosive) and its 1, 3‐ and 1, 5‐ tautomers are investigated computationally using PM3, HF/6‐31G(d, p), and B3LYP/6‐31G(d, p) methods. The relationships between the thermodynamic and kinetic stabilities and the aromaticities are examined for all structures and their relative sensitivities are compared in terms of bond dissociation energies. The use of both PM3 and isodesmic methods in the calculation of heat of formation of PATO is discussed.     

New diazadi(and tri)thia‐21‐crown‐7 ethers containing 8‐hydroxyquinoline side arms

A series of macrocyclic diazadi(and tri)thiacrown ethers containing two 5‐substituent‐8‐hydroxyquinoline side arms have been synthesized from the corresponding macrocyclic diazadi(and tri)thiacrown ethers. The crown ethers were obtained by reduction of the proper macrocyclic di(and tri)thiadiamides by borane‐tetrahydrofuran or by sodium borohydride‐boron trifluoride ethyl etherate‐tetrahydrofuran. The yields for the reduction of diamides by sodium borohydride‐boron trifluoride ethyl etherate‐tetrahydrofuran were higher than those by borane‐tetrahydrofuran. The following four methods were used to prepare macrocycles bearing two 8‐hydroxyquinoline side arms: (1) Mannich reaction with 8‐hydroxyquinoline; (2) Reductive animation with 8‐hydroxyquinoline‐2‐carboxaldehyde using sodium triacetoxyborohydride as the reducing agent; (3) Cyclization of N,N'‐bis(8‐hydroxyquinolin‐2‐ylmethyl)‐1,2‐bis(2‐aminoethoxy)ethane (38) with bis(α‐chloroamide) 5 ; and ( 4 ) A step‐by‐step process wherein macrocyclic trithiadiamide 11 was reduced by lithium aluminum hydride‐tetrahydrofuran to the cyclic monoamide 36 , which smoothly reacted with 5‐chloro‐8‐hydroxyquinoline to produce monosubstituted‐macrocyclic monoamide 39 .     

An Efficient Route to Ethyl 5‐Alkyl‐ (Aryl)‐1H‐1,2,4‐triazole‐3‐carboxylates

An efficient general route to the synthesis of 5‐substituted 1H‐1,2,4‐triazole‐3‐carboxylates was developed. N‐acylamidrazones were obtained from carboxylic acid hydrazides and ethyl thiooxamate or ethyl 2‐ethoxy‐2‐iminoacetate hydrochloride and then were reacted with chloroanhydride of the same carboxylic acid. As the next step, diacylamidrazones were cyclized to 5‐substituted 1H‐1,2,4‐triazole‐3‐carboxylates one pot in mild conditions.     

Azoltrifluormethylschwefeldifluoride

Azoltrifluoromethylsulfurdifluorides From CF₃SF₃ and the silylated azoles N‐trimethylsilylpyrazole, N‐trimethylsilylimidazole, and 1‐trimethylsilyl‐1,2,4‐triazole the corresponding azole trifluoromethyl sulfurdifluorides Az–SF₂–CF₃ were prepared in 30–40% yield (Az = pyrazole, imidazole, 1,2,4‐triazole). The X‐ray structure of the pyrazole derivative was determined.     

Synthesis and antibacterial activity of some novel N2‐hydroxymethyl and N2‐aminomethyl derivatives of 4‐aryl‐5‐(3‐chlorophenyl)‐2,4‐dihydro‐3H‐1,2,4‐triazole‐3‐thione

In this investigation, several novel N2‐hydroxymethyl and N2‐aminomethyl derivatives of 5‐(3‐chlorophenyl)‐4‐(4‐methylphenyl)‐2,4‐dihydro‐ 3H‐1,2,4‐triazole‐3‐thione and 4‐(4‐bromophenyl)‐ 5‐(3‐chlorophenyl)‐2,4‐dihydro‐3H‐1,2,4‐triazole‐3‐ thione were prepared. All synthesized compounds were screened for their antibacterial activity against six Gram‐positive and four Gram‐negative bacterial strains. © 2011 Wiley Periodicals, Inc. Heteroatom Chem 22:737–743, 2011; View this article online at wileyonlinelibrary.com . DOI 10.1002/hc.20737     

An Efficient Synthesis of Some New Isolated and Fused Triazole Derivatives

A facile and efficient route to 5‐hydrazinyl‐3‐phenyl‐3H‐[1,2,4]triazole 2 from the reaction of triazol‐3‐one 1 and hydrazine hydrate is described. In addition, the formation of isolated and fused triazole derivatives was prepared via reaction of 2 with some selected electrophilic reagents in basic medium.     

Multicomponent solid forms of the uric acid reabsorption inhibitor lesinurad and cocrystal polymorphs with urea: DFT simulation and solubility study

Lesinurad (systematic name: 2‐{[5‐bromo‐4‐(4‐cyclopropylnaphthalen‐1‐yl)‐4H‐1,2,4‐triazol‐3‐yl]sulfanyl}acetic acid, C₁₇H₁₄BrN₃O₂S) is a selective uric acid reabsorption inhibitor related to gout, which exhibits poor aqueous solubility. High‐throughput solid‐form screening was performed to screen for new solid forms with improved pharmaceutically relevant properties. During polymorph screening, we obtained two solvates with methanol (CH₃OH) and ethanol (C₂H₅OH). Binary systems with caffeine (systematic name: 3,7‐dihydro‐1,3,7‐trimethyl‐1H‐purine‐2,6‐dione, C₈H₁₀N₄O₂) and nicotinamide (C₆H₆N₂O), polymorphs with urea (CH₄N₂O) and eutectics with similar drugs, like allopurinol and febuxostat, were prepared using the crystal engineering approach. All these novel solid forms were confirmed by XRD, DSC and FT–IR. The crystal structures were solved by single‐crystal and powder X‐ray diffraction. The crystal structures indicate that the lesinurad molecule is highly flexible and the triazole moiety, along with the rotatable thioacetic acid (side chain) and cyclopropane ring, is almost perpendicular to the planar naphthalene moiety. The carboxylic acid–triazole heterosynthon in the drug is interrupted by the presence of methanol and ethanol molecules in their crystal structures and forms intermolecular macrocyclic rings. The caffeine cocrystal maintains the consistency of the acid–triazole heterosynthons as in the drug and, in addition, they are bound by several auxiliary interactions. In the binary system of nicotinamide and urea, the acid–triazole heterosynthon is replaced by an acid–amide synthon. Among the urea cocrystal polymorphs, Form I (P, 1:1) consists of an acid–amide (urea) heterodimer, whereas in Form II (P2₁/c, 2:2), both acid–amide heterosynthons and urea–urea dimers co‐exist. Density functional theory (DFT) calculations further support the experimentally observed synthon hierarchies in the cocrystals. Aqueous solubility experiments of lesinurad and its binary solids in pH 5 acetate buffer medium indicate the apparent solubility order lesinurad–urea Form I (43‐fold) > lesinurad–caffeine (20‐fold) > lesinurad–allopurinol (12‐fold) ? lesinurad–nicotinamide (11‐fold) > lesinurad, and this order is correlated with the crystal structures.