Synthesis and a UV and IR spectral study of some 2-aryl-Δ-2-1,3,4-oxadiazoline-5-thiones

Twenty four 2-Aryl-Δ-²-1,3,4-oxadiazoline-5-thione derivatives 2 were synthesized and their uv and ir spectra were studied. Correlation between σ-Hammett constants of aryl substituents and the differences in absorption maxima (Δv = v₁-v₂ in kK) of the electronic spectra of the deprotonated species were also evaluated. A new method for the synthesis of the 2-(amino)aryl derivatives 2v,w,x is also reported.     

Direction of alkylation of 5-aryl-1,3,4-oxadiazoline-2-thiones

The reaction of potassium salt of 5-(2,4-dichlorophenyl)-1,3,4-oxadiazoline-2-thione with dimethyl sulfate was carried out in water and HMPT. It was shown that the nature of the solvent affects the ratio of the formed products of S- and N-methylation. The alkylation of 5-aryl-1,3,4-oxadiazoline-2-thiones with isomeric butyl chlorides showed that the reaction takes place only with n-butyl chloride with the formation of the corresponding S-butyl-substituted derivative.Institute of the Chemistry of Vegetable Substances, Academy of Sciences of the Republic of Uzbekistan, Tashkent 700170. Translated from Khimiya Geterotsikliheskikh Soedinenii, No. 9, pp. 1268–1270, September, 1997.     

5-Aryl-1,3,4-oxadiazoline-2(3H)-thiones in reactions with alkyl haloacetates

The reaction of 5-aryl-1,3,4-oxadiazoline-2(3H)-thiones with alkyl haloacetates has been studied. It was shown that the reaction proceeds to give S-substituted products. The effect of the nature of the substituents in the molecules of both the thiones and the haloacetates on the reaction route and yields has been examined.     

Interaction of 5-Aryl-1,3,4-oxadiazoline-2(3H)-thiones wth N-Substituted Chloroacetamides

The reactions of some 5-aryl-1,3,4-oxadiazoline-2(3H)-thiones (aryl = phenyl, 4-bromophenyl, 4-methylphenyl, 2,4-dichlorophenyl) with N-alkyl- and N-arylchloroacetamides has been studied. The nature of the substituents in the molecules of the thiones and the chloroacetamides does not affect the direction of the reaction but does affect the yield of the desired products.     

The synthesis and reactivity of some 2-amino-5-bromo-],1,3,4-thiadiazoles and the corresponding Δ2-1,3,4-thiadiazolines

The synthesis of some 2-amino-5-bromo-1,3,4-thiadiazoles is reported; these substrates are found to behave as ambidenl nucleophiles in alkylation, aeylation and nitrosation reactions, giving thiadiazoliens along with thiadiazole derivatives. This finding suggests amine-imine tautomerism between these compounds and the corresponding Δ²-1,3,4-thiadiazolines.     

Synthesis of polyamides from active 4,4′-diacylbis-2-aryl-1,3,4-oxadiazoline-5-thiones and -ones and diamines under mild conditions

New active bisamides, 4,4′ -diacylbis-2-aryl-1,3,4-oxadiazoline-5-thiones and -ones having various electron accepting groups in the oxadiazoline units were synthesized, and their reactivities toward diamines were investigated. The polycondensation reactions of the bisamides derived from 2-aryl-1,3,4-oxadiazoline-5-thiones with both aliphatic and aromatic diamines occurred rapidly even at room temperature to form high-molecular-weight polyamides in quantitative yields. The reactivities of the bisamides having electron accepting groups such as p-chloro and p-nitro groups, particularly p-nitro groups, toward diamines were much higher than that of the corresponding bisamide having no such group. It was also found that reaction conditions such as solvent, monomer concentration, and temperature had a strong influence on the molecular weight of the resulting polyamides. Aminolysis of several benzoyl derivatives of 2-aryl-1,3,4-oxadiazoline-5-thiones and -ones was also carried out as a model reaction, and the effect of electron accepting groups on the reactivity of these compounds was discussed.     

Hydrazidoyl halides in synthesis of Δ2-1,3,4-selenadiazolin-5-ones

Reaction of hydrazidoyl halides 1-5 with potassium selenocyanate in ethanol produces the corresponding 2,4-disubstituted-5-iminoδ²-1,3,4-selenadiazolines, 9-13 respectively. Nitrosation of the latter yields the N-nitroso derivatives 14-17 , which decompose upon refluxing in xylene to give 2,4-disubstituted Δ²-1,3,4-selenadiazolin-5-ones in good yield. Compounds 9-13 give the respective N-acetyl derivatives 22-26 and N-benzoyl derivatives 27-31 with acetic anhydride and benzoyl chloride in pyridine.     

Ring-opening reaction of 1,3,4-oxadiazolone and 1,3,4-oxadiazolinethione: Reaction of 2-phenyl-1,3,4-oxadiazolin-5-one and 2-phenyl-1,3,4-oxadiazoline-5-thione with amines

The ring-opening abilities of amines toward 1,3,4-oxadiazolines, 2-phenyl-1,3,4-oxadiazolin-5-one ( 1a ) and 2-phenyl-1,3,4-oxadiazoline-5-thione ( 1b ), were investigated with relation to their basicities or pK_b values. Oxadiazolines 1a and 1b were easily reacted with amines such as benzylamine and aniline, but not with p-nitroaniline, to form the corresponding ring-opening adducts. The reactions of both 1a and 1b with o-phenylenediamine produced benzodiazoles with the liberation of benzoylhydrazide, whereas the reactions with o-aminobenzamide furnished quinazolines with the liberation of ammonia. o-Aminophenol and o-aminothiophenol were also reacted with 1a and 1b both of them giving 1,5-dibenzoylcarbohydrazide from 1a and 1,2-dibenzoylhydrazine from 1b. From the conditions affording the corresponding ring-opening adducts or reaction products, the ring-opening abilities of the amines toward 1a and 1b are in good correlation with the strength of their basicities or pK_b values. The ring-opening of oxadiazolines were proved to occur with anilines. Therefore, the other reactions are also supposed to proceed via the ring-opening steps.     

A facile synthesis of 2-substituted-4-(substituted)phenyl-Δ2-1,3,4-oxadiazolin-5-ones

The title compounds, 3, are formed at ambient temperature from 4,4-dimethyl-2-(substituted)-phenylsemicarbazides (1) and carboxylic acid chlorides in the presence of triethylamine. 2-Dimethylamino-4-(substiluted)phenyl-Δ²-1,3,4-oxadiazolin-5-ones are formed from 1 and dialkyl-carbamoyl chlorides at elevated temperature (about 15° ). Acylation of 1 with carboxylic acid anhydrides, also at elevated temperature, is accompanied by loss of dimethylamine from the intermediate l-acyl-4,4-dimethyl-2-(substituted)phenylsemicarbazides, 2, to give 3.     

The azomethine nitrene. I. Pyrolysis and photolysis of Δ2 1,2,4-oxadiazoline-5-ones

Both photolytic and pyrolytic fragmentation of the oxadiazolone ring produces carbon dioxide and a residue which may exist in part as an intermediate azomethine nitrene and may react with or without rearrangement and/or further fragmentation. Rearrangement produces carbodiimides 2 and cyanamides 6. Thermal and photo-isornerization of carbodiimides into cyanamides provides a key step in an explanation for the formation of the latter from an oxadiazolone. A highly selective cyclization produces a benzimidazole 3 when a suitable aryl subsliluent is at nitrogen. The formation of N-phenylbenzamidine 7a from 3-phenyl-4-benzyloxadiazolone 5c requires a 1,4-migration from carbon to nitrogen followed by hydrolysis. The same or similar migration of hydrogen and subsequent ring-closure with dehydrogenation provides the formation of 2-phenyl-quinazoline 8. Products which require no rearrangement of the residue include amidines 7 and triazoles 10. A portion of each triazole corresponds to a nitrile, in turn a product along with a simple nitrene;, of more extensive fragmentation of the; oxadiazolone ring. Phenyl, benzyl, and cyclohexyl nitrenes are respectively detected by the isolation of aniline, benzaldehyde and cyclohexanone. Other recombination reactions bring about the formation of triphenyltriazine 13 and triphenylimidazole 14.     

The Route of Alkylation of 5-Substituted 1,3,4-Thiadiazoline-2-thiones

The reaction of 5-anilino(toluidino-, morpholino)-1,3,4-thiadiazoline-2-thiones at 80°C with allyl bromide and benzyl chloride in alcohol, acetonitrile or DMF in the presence of KOH and also with phenoxymethyloxirane in alcohol in the absence of base gives the corresponding novel allyl-, benzyl-, and 2-hydroxy-3-phenoxypropyl products substituted at the exocyclic S atom. Alkylation of the indicated thiones with benzyl chloride at 150-153°C in DMF in the presence of KOH occurs similarly. Under these conditions, allyl bromide forms alkylation products at the endocyclic N(3) atom as a result of an SN thio-Claisen rearrangement of the initially formed product which is allyl substituted at the exocyclic S atom.     

Synthesis of 5-aroylamino-3H-1,3,4-thiadiazole-2-thiones and their tautomerism

5-Aroylamino-3H-1,3,4-thiadiazole-2-thiones 2 have been synthesized by acylation of 5-amino-3H-1,3,4-thiadiazole-2-thione 1 . 5-Aroylamino-3H-1,3,4-thiadiazole-2-thiones can exist in two tautomeric forms — a thiol form and a thione form. On the basis of the ¹³C nmr spectra and additional experimental information, it has been established that the thione form is the stable form in which these compounds exist.     

N-2-多氟烷基乙基取代1,3,4-噁二唑-2-硫酮及1,2,4-三唑-5-硫酮类化合物的合成和密度泛函理论研究

为改善二唑及三唑类化合物的生物活性, 设计合成了一系列多氟烷基乙基取代的1,3,4-噁二唑-2-硫酮6a～6l及1,2,4-三唑-5-硫酮类化合物9a～9l. ¹H NMR, ¹⁹F NMR, IR和MS谱以及元素分析表征了它们的结构; 实验结果与Materials Studio 3.0中的Dmol3计算模块理论计算表明了唑环上的NH较之CONH中的NH更易进行烷基化反应.     

Studies on the syntheses of azole derivatives. Part III. Syntheses of 1-Phenyl-Δ2-1,2,4-triazolin-5-one and 4-Phenyl-Δ2-1,3,4-oxadiazolin-5-one Derivatives by Fusion of 1-Phenyl-2-acylhydrazine with Urea

Fusion of 1-phenyl-2-acylhydrazine (III) with urea gave Δ²-1,2,4-triazolin-5-one and Δ²-1,3,4-oxadiazolin-5-one derivatives together with various by-products. Furthermore, various derivatives were synthesized for the purpose of examination in a pharmacological screening test.     

Δ3- and Δ4-1,2,4-oxadiazolin-5- and 3-ones

Preparations for 2,3-diphenyl- and 2-benzyI-3-phenyl-Δ³-1,2,4-oxadiazolin-5-ones (3) and (4) and for 2,5-diphenyl-Δ⁴-1,2,4-oxadiazolin-3-one ( 7 ) are reported.     

Rearrangement and complexation of 5-substituted-1,3,4-thiadiazolidine-2-thiones with divalent transition metals

The reactions of a variety of divalent transition metal ions with 3-methyl-5-(2-hydroxypheny)-, 3-methyl-5-(2-thienyl)-and 3-methyl-5-(2-furyl)-1,3,4-thiadiazolidine-2-thiones (htt, ttt and ftt, respectively) are accompanied by opening of the thiadiazolidine ring and rearrangement to the corresponding Schiff base (Hhts, Htts and Hfts, respectively) with the concomitant formation of complexes of the general formulae, [M(hts)] (M=Ni, Cu, Zn or Pd), [M(hts) (py)] (M=Ni, Cu), [Co(Hhts)hts)], and [ML₂] (M=Ni, Cu, Zn or Cd); L=tts or fts). The complexes have been characterised by physico-chemical and spectroscopic methods. The fungitoxicities of the corresponding Schiff base metal complexes have been investigated. TMC 2568     

Carbon-13 NMR Studies of 3-Aryl-4-(5-aryl-Δ 2-1,2,4-oxadiazolin-3-yl)sydnones and 3-Aryl-4-(5-aryl-1,2,4-oxadiazol-3-yl)sydnones

The ¹³C NMR spectra of twelve 3-aryl-4-(5-aryl-Δ²-l,2,4-oxadiazolin-3-yl)sydnones and twelve 3-aryl-4-(5-aryl-l,2,4-oxadiazol-3-yl)sydnones have been measured and assigned by means of proton-noise decoupling and DEPT-experiments. The coupling constants were determined by means of gated decoupling, and NOE effects were observed by comparison of proton-decoupled and inverse-gated decoupled spectra. Differences shown by the oxadiazoline and the oxadiazole rings and the substitution effects are discussed.     

Convenient synthesis of 3-arylazopyrazoles and 2-arylazo-1,3,4-Δ2- thiadiazoline derivatives from 3-nitroformazans

Reactions of 3-nitro-1,5-diarylformazans 1a-c with carbanions of acetylacetone, dibenzoylmethane, aceto-acetanilide, benzoylacetonitrile, ω-benzenesulfonylacetophenone and malononitrile yielded the corresponding 3-arylazopyrazole derivatives 4-9 respectively. Reactions of 1 with nucleophiles result in displacement of the nitro group and the formation of the corresponding 3-substituted formazans 10-13 . Treatment of 1 with potassium thiocyanate gave, however, 5-imino-2-arylazo-1,3,4-Δ²-thiadiazolines 14. Structural assignments have been made on the basis of spectral and elemental analyses, chemical behaviour and alternate synthesis wherever possible.     

Synthesis of isomeric 4- and 5-hydroxylaminothiazolidin-2-thiones

Tsomeric 4- and 5-hydroxylaminothiazolidin-2-thiones were synthesized by the reaction of 1,2-aminosubstituted oximes with CS₂, and of dimeric olefin nitrosochlorides with dithiocarbamate salts. These compounds react with aldehydes and ketones to form the respective nitrones. In contrast to the 5-derivatives, the 4-hydroxylamino derivatives hydrolyze to 4-hydorxythiazolidin-2-thiones.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 549–553, April, 1986.