Synthesis and properties of diaminothiadiazoles

Refined synthetic procedure for preparation of 3,5-diamino-1,2,4-thiadiazole and 2,5-diamino-1,3,4-thiadiazole based on the reaction of dithiourea or amidinothiourea with hydrogen peroxide is developed. The optimal reagents ratio was found, and monitoring methods were developed. It resulted in the increase of the target product yield and in a shorter reaction time. On the basis of 2,5-diamino-1,3,4-thiadiazole the alkylsubstituted 1,3,4-diaminothiadiazolidines were synthesized. The compounds prepared were characterized by the elemental analysis data, the IR, ¹H NMR, and electronic spectra, and also by mass spectrometry.     

Synthesis of 2<Emphasis Type="Italic">N</Emphasis>-Alkyl-substituted 5-Amino-3-imino-1,2,4-thiadiazolines

Conditions for an efficient and a readily reproducible synthesis of a series of 2N-Alkyl-substituted 5-amino-3-imino-1,2,4-thiadiazolines by the direct alkylation of 3,5-diamino-1,2,4-thiadiazole with alkyl bromides in fairly high yields (up to 76%).     

Synthesis and Physicochemical Properties of Heterocyclic Compounds Based on 5,7-Diimino-2,5,6,7-tetrahydro-1H-cyclopenta[cd]phenalene

N,N'-Bis(7-amino-2,5-dihydro-1H-cyclopenta[cd]phenalen-5-ylidene)-substituted derivatives of 2,5-diamino-1,3,4-thiadiazole, 2,6-diaminopyridine, and 3,5-diamino-1-phenyl-1,2,4-triazole were synthesized. The products are soluble in water, and they attract interest as potential biologically active substances.     

N-Nitroimines: I. Synthesis,Structure, and Properties of 3,5-Diamino-1-nitroamidino-1,2,4-triazole

The reaction of 3,5-diamino-1,2,4-triazole with 2-methyl-1-nitroisothiourea gives 3,5-diamino-1-nitroamidino-1,2,4-triazole instead of the expected 1-[5(3)-amino-1,2,4-triazol-3(5)-yl]-2-nitroguanidine. Almost planar structure of the molecule of 3,5-diamino-1-nitroamidino-1,2,4-triazole gives rise for direct polar conjugation which is responsible for the low basicity of the amino groups.     

Reaction of 3-acetonyl-5-cyano-1,2,4-thiadiazole with phenylhydrazine hydrochlorides: indolization and phenylpyrazolation

Treatment of 3-acetonyl-5-cyano-1,2,4-thiadiazole (1) with 4-methyl or 4-methoxyphenylhydrazine hydrochloride provided 5-cyano-3-(2,5-dimethylindol-3-yl)-1,2,4-thiadiazole (2) or 5-cyano-3-(5-methoxy-2-methylindol-3-yl)-1,2,4-thiadiazole (3) as the sole product, respectively. In contrast, treatment of 1 with phenylhydrazine hydrochloride resulted in the formation of 5-cyano-3-(2-methylindol-3-yl)-1,2,4-thiadiazole (4) and the unexpected 5-cyano-3-(3,5-dimethyl-1-phenylpyrazol-4-yl)-1,2,4-thiadiazole (5). In a similar manner, when 1 was treated with 4-chlorophenylhydrazine hydrochloride, indolization was suppressed by phenylpyrazolation giving rise to 5-cyano-3-(5-chloro-2-methylindol-3-yl)-1,2,4-thiadiazole (6) and 5-cyano-3-[1-(4-chlorophenyl)-3,5-dimethylpyrazol-4-yl]-1,2,4-thia diazole (7). The reaction mechanism is discussed. Compounds 4, 5 and 6 exhibited weak antimicrobial activity against Helicobacter pylori.     

Oxidative azacyclization of 1-monosubstituted thioureas in reaction with [bis(acyloxy)iodo]arenes to form 1,2,4-thiadiazole derivatives

For the first time, derivatives of 1,2,4-thiadiazoles have been obtained by the reaction of [bis(acyloxy)iodo]arenes with 1-monosubstituted thioureas. 1-Acetylthiourea is subject to intermolecular azacyclization to form 3,5-bis-(acetylamino)-1,2,4-thiadiazole in reaction with [bis(acyloxy)iodo]benzene. 1-Phenylthiourea forms 3,5-bis-(phenylamino)-1,2,4-thiadiazole in a single-stage reaction with (diacetoxyiodo)benzene. The reaction of 1-phenylthiourea with [bis(trifluoroacetoxy)iodo]benzene leads to the formation of 5-imino-4-phenyl-3-phenylamino-4H-1,2,4-thiadiazoline.     

Novel Reactions of Tropylium Salts with Heterocyclic Diamines

Russian Journal of General Chemistry - The reactions of tropylium salts with 2,5-diamino-1,3,4-thiadiazol, 3,5-diamino-1,2,4-thiadiazol, and 2,6-diaminopyridine have given novel products of...     

Synthesis of some sym-triazole derivatives

3,5-Di(hydroxyalkyl) derivatives of 4-amino-1,2,4-triazole and the corresponding derivatives of 1,2,4-triazole obtained by diazotizing them are converted by reaction with SOCl₂ into the hydrochlorides of 4-amino-3,5-di(chloroalkyl)-1,2,4-triazoles and 3,5-di(chloroalkyl)-1, 2,4-triazoles. The dinitrate of 3,5-di(hydroxymethyl)-1,2,4-triazole has been prepared. When the cyanohydrazide of glycolic acid is heated with hydrazine hydrate, 4,5-diamino-3-hydroxymethyl-1, 2,4-triazole is formed.     

Preparation of polar group derivative β-cyclodextrin bonded hydride silica chiral stationary phases and their chromatography separation performances

Three new polar group-substituted β-cyclodextrin derivatives were synthetized and they covalent bonded to hydride silica to obtain chiral stationary phases. Their separation results of 35 chiral pyrrolidine compounds were also presented and discussed.     

Synthesis of Partially Hydrogenated 1,2,4-Triazoloquinazolines by Condensation of 3,5-Diamino-1,2,4-triazole with Aromatic Aldehydes and Dimedone

Three-component condensation of 3,5-diamino-1,2,4-triazole with aromatic aldehydes and dimedone in dimethylformamide gives 2-amino-5-aryl-8,8-dimethyl-5,6,7,8,9,10-hexahydro[1,2,4]triazolo[3,2-b]quinazolin-6-ones. The reaction of 3,5-diamino-1,2,4-triazole with dimedone in the absence of aldehyde involves dimethylformamide as one of the carbonyl components to afford 2-amino-8,8-dimethyl-6,7,8,9-tetrahydro[1,2,4]triazolo[2,3-a]quinazolin-6-one.__________Translated from Zhurnal Organicheskoi Khimii, Vol. 41, No. 1, 2005, pp. 115–120.Original Russian Text Copyright © 2005 by Lipson, Desenko, Borodina, Shirobokova, Musatov.     

Regioselective synthesis of alkyl derivatives of 3,5-diamino-1,2,4-triazole

New procedures were suggested for regioselective synthesis of alkyl derivatives of 3,5-diamino-1,2,4-triazole.     

Green synthesis of 1,2,4-thiadizoles from thioamides in water using molecular oxygen as an oxidant

We present here an efficient green process for the synthesis of 1,2,4-thiadiazoles via iodine-catalyzed,oxidative dimerization of thioamides in water using molecular oxygen as a terminal oxidant. Under the optimized reaction conditions, aryl thioamides produced 3,5-diaryl-1,2,4-thiadiazoles in good to excellent yields. Alkyl thioamides and substituted thioureas could also provide corresponding 1,2,4-thiadiazole products.     

Improved synthesis of 2-amino-1,2,4-triazolo[1,5-a]pyrimidines

An improved procedure is suggested for preparing 2-amino-1,2,4-triazolo[1,5-a]pyrimidines from 3,5-diamino-1,2,4-triazole and unsaturated aromatic ketones, with acetyl protection of the amino group in the step of oxidation of 2-amino-4,7-dihydro-1,2,4-triazolo[1,5-a]pyrimidines.     

Synthesis of 3-Azido-5-amino-1,2,4-triazole

3-Azido-5-amino-1,2,4-triazole was obtained from 3,5-diamino-1,2,4-triazole in two ways: by partial diazotization-substitution directly in the substrate or at its primarily nitrosation, and also with the use of direct or indirect protection of an amino group with subsequent conversion into azido compound followed by deprotection.     

Acyl and Sulfonyl Derivatives of 3,5-Diamino-1-R-1,2,4-triazoles

3-Acylamino-5-amino-1-R-1,2,4-triazoles are formed regioselectively on acylating 3,5-diamino-1-R-1,2,4-triazoles with an equimolar amount of anhydrides, carboxylic acid chlorides, and sulfonyl chlorides. With an excess of anhydride and carboxylic acid chloride 3,5-diacylamino-1-R-1,2,4-triazoles are formed. 3-Acylamino-5-amino-1-R-1,2,4-triazoles do not interact with sulfonyl chlorides. The higher reactivity of the 3-amino group towards acylating agents is determined by electronic and not steric factors. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 9, pp. 1342–1350, September, 2005.     

Synthesis of 3-amino-5H-pyrrolo[2,3-e]-1,2,4-triazines by Sonogashira/copper(I)-catalyzed heteroannulation

A Sonogashira/copper(I)-catalyzed heteroannulation sequence was developed to convert 3,5-diamino-6-chloro-1,2,4-triazines to the corresponding 3-amino-5H-pyrrolo[2,3-e]-1,2,4-triazine derivatives in good yields.     

1-(N-Arylthiocarbamoyl)amidino-3,5-dimethyl Pyrazoles-Preparation and Use in Heterocycle Synthesis

On reaction with α-haloketones or hydrazine, 1-(N-arylthiocarbamoyl)amidino-3,5-dimethylpyrazoles (1) afford 2,4-diaminothiazoles and 3,5-diamino-1,2,4-triazoles in good yield. A convenient route to 1 is also reported.     

Regioselective single-reactor synthesis of arylsulfonyl derivatives of 3,5-diamino-1,2,4-triazole

Arylsulfonylation of 1-acetyl-3,5-diamino-1,2,4-triazole with arylsulfonyl chlorides in pyridine, with the subsequent hydrolysis of the acetyl group, was studied; a new regioselective method for synthesis of N-(5-amino-1H-1,2,4-triazol-3-yl)arylsulfonamides was developed.     

A one-pot,three-component,microwave-promoted synthesis of 2-amino-substituted 7-amino-1,2,4-triazolo[1,5-a][1,3,5]triazines

A new, efficient, catalyst-free, one-pot, three-component method for the synthesis of 2-amino-substituted 7-amino-1,2,4-triazolo[1,5-a][1,3,5]triazines using 3,5-diamino-1,2,4-triazoles, cyanamide, and triethyl orthoformate is developed. The reaction proceeds smoothly under microwave-assisted heating. Advantages of the method include using easily available reagents, short reaction times, and operational simplicity.     

Macroheterocyclic Compounds with Thiadiazole Fragments. Synthesis and Properties

The reactions of 1-imino-2-phenyl-1H-inden-3-amine with 3,5-diamino-1,2,4- and 2,5-diamino-1,3,4- thiadiazoles were used to synthesize linear 1: 2 and 2: 1 condensation products, as well as symmetrical macroheterocyclic compounds. The synthesized compounds were characterized by IR, UV, and ¹Н NMR spectroscopy.