B. S. Drach

Synthesis of New 5-Mercapto-1,3-oxazole Derivatives on the Basis of 2-Acylamino-3,3-dichloroacrylonitriles and Their Analogs

Enamides of the general formula Cl2CÍC(X)NHCOR1, where X = CN, COOAlk, CONH2, P(O)(OEt)2, P(O)Ph2, +PPh3 Cl-, were treated in succession with alkane- or arenethiols and silver carbonate to obtain 5-alkyl(aryl)thio-2-R1-4-X-1,3-oxazoles with high selectivity. The latter were converted into the corresponding sulfonyl derivatives. Unlike 2-acylamino-3,3-dichloroacrylonitriles which react with sodium hydrogen sulfide in a nonselective fashion, reactions of derivatives like Cl(ArS)CÍC(CN)NHCOR1 with NaHS lead to hitherto unknown 5-arylthio-4-thiocarbamoyl-2-R1-1,3-oxazoles whose structure was confirmed both by spectral methods and by cyclocondensation with bromoacetophenone according to Hantzsch. Heating of some 2-aryl-5-mercapto-4-X-1,3-oxazoles with benzenethiols results in recyclization into the corresponding 2,4-disubstituted 5-arylthio-1,3-thiazoles, presumably due to prototropic tautomerism in the 5-mercaptooxazole fragment.

Reaction of 1-Aryl-1,3,4,4-tetrachloro-2-azabuta-1,3-dienes with aminoazoles

Reactions of polychlorinated 2-aza-1,3-dienes of the general formuls ArCCl=NCCl=CCl2 with 3(5)-aminopyrazoles, 3(5)-amino-1,2,4-triazoles, and 5-aminotetrazole led to the formation of substituted pyrazolo[1,5-a][1,3,5]triazines, [1,2,4]triazolo[1,5-a][1,3,5]triazines, and 2-azido-1,3,5-triazine derivatives whose structure was reliably established by spectral methods and X-ray analysis.

Reaction of 2-aryl-4-dichloromethylidene-1,3-oxazol-5(4H)-ones with 2-aminopyridine

Reactions of multicenter electrophilic substrates, 2-aryl-4-dichloromethylidene-1,3-oxazol-5(4H)-ones, with 2-aminopyridine, involved cleavage of the dihydrooxazole ring by the primary amino group of nucleophilic reagent and subsequent cyclization to imidazopyridine derivatives. The latter reacted with morpholine and its analogs via recyclization with formation of 5-amino-2-aryl-N-(pyridin-2-yl)-1,3-oxazole-4-carboxamides.

Synthesis of new 2,5-diamino-1,3-thiazole and 2-thiohydantoin derivatives by condensation of N-(2-Aryl-1-chloro-2-oxoethyl) carboxamides with thioureas

N-(2-Aryl-1-chloro-2-oxoethyl) carboxamides react under mild conditions with thiourea, N-alkyl-and N-arylthioureas, and various N,N′-disubstituted thioureas, following the Hantzsch reaction scheme. The reactions are selective, and the resulting 2,5-diamino-1,3-thiazole derivatives undergo recyclization acid followed by hydrolysis to give substituted 2-thiohydantoins on heating with hydrochloric acid in ethanol.

New transformations of 5-Hydrazino-2-phenyl-1,3-oxazole-4-carbonitrile

Treatment of 5-hydrazino-2-phenyl-1,3-oxazole-4-carbonitrile with acetylacetone lead to the formation of a substituted pyrazole residue on C5, which enhanced the electrophilicity of the cyano group in position 4 so that it became capable of reacting with hydrogen sulfide, sodium azide, and hydroxylamine. As a result, the corresponding azole fragments were introduced into position 4 of the 5-(1H-pyrazol-1-yl)-1,3-oxazole system.

Cyclocondensation of 1-Tosyl-2,2-dichloroethenyl Isothiocyanate with O-, S-, N-, and C-Nucleophiles

Treatment of 1-tosyl-2,2-dichloroethenyl isothiocyanate with alcohols, thiols, primary and secondary amines, hydrazine and its derivatives, and phosphonium ylides results in addition of the O-, S-, N-, or C-nucleophilic center to the isothiocyanate group, followed by cyclocondensation with elimination of hydrogen chloride and formation of the corresponding 2-functionally substituted 4-tosyl-5-chloro-1,3-thiazoles. Further transformations of these compounds were studied, and a series of previously unknown types of 3-functionally substituted 1,3-thiazole derivatives were prepared.

2-aryl-5-arylsulfanyl-1,3-oxazole-4-carboxylic acids and their derivatives

A convenient preparative procedure has been developed for the synthesis of previously unknown 2-aryl-5-arylsulfanyl-1,3-oxazole-4-carboxylic acids and their functional derivatives from accessible multicenter substrates of the general formula Cl2C=C(NHCOR)C(O)OMe. The products turned out to be suitable for various subsequent transformations. Some oxazole-4-carboxylic acid hydrazide derivatives containing a substituted oxazol-5-yl fragment at the N2 atom in the hydrazine moiety underwent recyclization on heating in acetic acid; as a result, one oxazole ring was converted into 1,3,4-oxadiazole.

Reactions of N-(1-chloro-2-oxo-2-phenylethyl) carboxamides with thiosemicarbazide and its derivatives

N-(1-Chloro-2-oxo-2-phenylethyl)acet-, -benz-, and -4-methylbenzamides reacted with thiosemicarbazides and aromatic aldehyde thiosemicarbazones to give derivatives of 5-amino-2-hydrazino-1,3-thiazole. The latter underwent recyclization and acid hydrolysis on heating with hydrochloric acid to produce substituted 3-amino-2-thiohydantoins.

Synthesis of new derivatives of 5-amino-1,3-oxazole basing on 3-benzoylamino-3,3-dichloroacrylonitrile

DOI: 10.1134/S1070363207070250 It was shown previously that 2-benzoylamino-3,3dichloroacrylonitrile (I) and its analogs are valuable reagents for heterocyclizations leading to derivatives of mononuclear and condensed heterocycles [1 7]. In our systematic research on such cyclizations we have found two simple transformation sequences I II IV and III III V leading to new derivatives of 5-amino-1,3-oxazole (see scheme).

Syntheses of functionalized thieno[3,4-d]imidazoles and thieno[3,2-d]pyrimidines from chlorine-containing enamidonitriles

Enamidonitriles of the general formula Cl(X)C=C(CN)NHCOR readily react with methyl sulfanylacetate to give tri-or tetra-substituted thiophenes, which can be converted into new functional derivatives of thieno[3,2-d]pyrimidine and thieno[3,4-d]imidazole.