Heterocycles from substituted amides,V.. 1,2,3,5-Oxathiadiazolin-4-one 2-oxides from thionyl chloride and N-hydroxyureas

The reaction of certain N-hydroxy-N-methyl-N′-aryl ureas, 2 , with thionyl chloride are shown to give a new heterocycle, 1,2,3,5-oxathiadiazolin-4-one 2-oxides, 3 , in a synthesis that appears to have more severe structural requirements than the previously reported ring closures from α-hydroxyacylanilides and thionyl chloride. Isolable amounts of 3 are obtained only if the aryl group contains deactivating substituents, and the hydroxy group is attached to the N-alkyl nitrogen; otherwise, resin formation or ring chlorination are found to occur. The assigned structure as 3 was verified by a full three dimensional X-ray analysis of a representative example, 3a , 3-(4-bromophenyl)-5-methyl-1,2,3,5-oxathiadiazolin-4-one.     

Heterocycles from substituted amides III. 1,2,3-Oxathiazolidin-4-one 2-oxides from thionyl chloride and α-hydroxyacylanilides

A new heterocyclic series was synthesized for the first time, from reaction of thionyl chloride with α-hydroxyacylanilides (1). Structural features of the resulting 1,2,3-oxathiazolidin-4-one 2-oxides (2) are discussed with particular reference to their spectral properties, and are compared with the previously reported 1,2,3-oxathiazolidine 2-oxides (3).     

Synthesis of (±) -2,3,5-trichloro-4, 4-dimetoxycyclopent-2-en-1-one

At 20 °C, (±)-1,3,4-trichloro-2-isobornyloxy-5,5-dimethoxyclopentadine slowly decomposes to give (±)-2,3,5-trichloro-4,4-dimethoxycylopent-2-en-1-one.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp.2799–2800, November,1996     

Halogen-substituted pyridines 4. 2,3,5-trichloropyridines substituted at position 6

Addition of alkyl(aryl)trichlorornethylketones to acrylonitrile in the presence of copper(I) chloride gave chlorine-substituted -oxonitriles. Cyclization of the latter was effected by the action of dry hydrogen chloride yielding the corresponding chlorine-containing tetrahydropyridines and pyridines.For Communication 3, see [3].A. N. Kosygin Moscow State Textile Academy Moscow pc117918. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 652–656, May, 1994. Original article submitted March 1, 1994.     

Heterocycles from substituted amides. VII Oxazoles from 2-isocyanoacetamides

Certain heretofore unknown tertiary α-isocyanacetanilides 1 are reported for the first time, prepared by methods necessarily different from those employed to prepare the previously cited aliphatic α-isocyano-acetamides 2 . Like 2, 1 has been shown to readily undergo dialkylation with alkyl halides. Moreover, 1 also gives rise to oxazole and oxazoline derivatives upon reaction with acyl halides and aldehydes, respectively, resembling the similarly activated α-isocyano esters and sulfones. Further, in a demonstrable ring-chain tautomeric equilibration, apparently restricted to tertiary amides, 1 readily cyclizes, providing the only known synthesis of 5-amino-2,4-unsubstituted oxazoles 3 . In other examples 4-chloro and 4-alkyl-5-amino-oxazoles are produced. The materials and reactions are characterized, and compared with previous related studies.     

Preparation of substituted semicarbazides from corresponding amines and hydrazines via phenyl carbamates

A simple synthetic procedure for the conversion of amines and hydrazines into substituted semicarbazides was developed. The initial condensation between the desired amine and phenyl chloroformate into phenyl carbamate is followed by the addition of hydrazine under basic conditions. The reaction is tolerable to a variety of functional groups, with mild conditions and high percent yields.     

Regioselective Synthesis of Heterocycles from 3-Cyclohex-2-enyl-4-hydroxy-1-methylquinolin-2-(1H)-one

3-Cyclohex-2-enyl-4-hydroxy-1-methylquinolin-2(1H)-one (5) reacts with pyridine hydrotribromide in CH₂Cl₂ at 0–5°C for 0.75h to give a furo fused heterocycle 6 in 96% yield. Product 6 on treatment with KOH-EtOH eliminates HBr to give compound 8 which on treatement with Pd-C in refluxing diphenyl ether for 0.5h furnishes benzofuro[3,2-c]quinolone 9 in 90% yield. Substrate 5 on sequential treatment with Ac₂O-AcONa and Br₂/AcOH followed by KOH-EtOH, however produces bicyclic product 7 in excllent overall yield. Substrate 5 reacts with 1 equivalent of m-chloroperbenzoic acid in refluxing benzene to furnish bicyclic heterocycle 12 in 80% yield and with cold conc. H₂SO₄ at 0–5°C for 2h generates the bicyclic heterocycle 14 in 90% yield.     

Synthesis of amino substituted 4-oxo-1,2,3,4-tetrahydropyridines from arylhydrazones and methyl acrylate

Arylhydrazones react with methyl acrylate in the presence of aluminium chloride to afford amino substituted 4-oxo-1,2,3,4-tetrahydropyridines.     

Synthesis of substituted 4-oxo-2-thioxo-1,2,3,4-tetrahydroquinazolines and 4-oxo-3,4-dihydroquinazoline-2-thioles

We have developed a liquid-phase synthesis of combinatorial libraries of new disubstituted 4-oxo-2-thioxo-1,2,3,4-tetrahydroquinazolines and trisubstituted 4-oxo-3,4-dihydroquinazoline-2-thioles. The former were prepared using two general procedures: (i) cyclization of substituted methyl anthranilates with isothiocyanates, or (ii) cyclization of substituted 2-(methylcarboxy)benzeneisothiocyanates with primary amines or hydrazines. 4-Oxo-3,4-dihydroquinazoline-2-thioles were prepared by S-alkylation of disubstituted 4-oxo-2-thioxo-1,2,3,4-tetrahydroquinazolines with alkyl or aryl halides. The hydrolysis of methyl benzimidazo[1,2-c]quinazoline-6(5H)-thione-3-carboxylate led to the corresponding acid. This acid was utilized in the synthesis of new benzimidazo[1,2-c]quinazoline-6(5H)-thione-3-carboxamide and S-substituted 6-mecaptobenzimidazo[1,2-c]quinazoline-3-carboxamide libraries.     

Synthesis of 1-triphenylgermylpropiono-4-substituted semicarbazides,thiosemicarbazides and their heterocyclic derivatives

Twenty-one new organogermanium compounds with the formulae Ph₃GeCHR¹CH₂CONHNHC(X)NHR² (1) (R¹=H, Ph; = Ph, p-CH₃Ph, O -CH₃Ph, p-ClPh, COPh, X = S, O) and (R¹ = H, Ph; R² = Ph, p-CH₃Ph, o-CH₃Ph, p-ClPh; X=S, O) were synthesized and characterized by elemental analysis, ¹H NMR, IR, MS and X-ray diffraction techniques. Compounds l were prepared by the reactions of Ph₃GeCHR¹CH₂CONHNH₂ with R²NCX in chloroform in 77-94% yields, and 2 were obtained by refluxing l with sodium hydroxide (8%) with yields of 55-94%.     

Reaction of cis- and trans-4-alkoxycarbonylamino-3-hydroxythiophans with thionyl chloride

The reaction of cis- and trans-4-alkoxycarbonylamino-3-hydroxythiophans with thionyl chloride gives chlorosulfites. trans-4-Alkoxycarbonylamino-3-chlorosulfito-thiophans are converted to cis-3a,4,6,6a-tetrahydrothieno[3,4-d]oxazolidone by heating or by treatment with pyridine. cis-4-Carboalkoxyamino-3-hydroxythiophans form 3-carboalkoxy-3a,4,6,6a-tetrahydrothieno[3,4-d]oxathiazolidones.     

Novel Fused Heterocycles: Synthesis and Activity of 5,6-Dihydro-7-thia-1,3,3a,5-tetraazainden-4-one and 1-Thia-3,4a,9-triazafluoren-4-one Derivatives

 Thiatetraazaindenone derivatives were synthesized by reaction of 3-substituted 1,2,4-triazole-5-thiols with N-substituted N-chloromethyl carbamoyl chlorides. A series of thiatriazafluorenone derivatives were also prepared by reaction of benzimidazole derivatives with the same substrate. Some of the new compounds show fungicidal, herbicidal, and insecticidal activity.     

Novel Fused Heterocycles: Synthesis and Activity of 5,6-Dihydro-7-thia-1,3,3a,5-tetraazainden-4-one and 1-Thia-3,4a,9-triazafluoren-4-one Derivatives

Summary.  Thiatetraazaindenone derivatives were synthesized by reaction of 3-substituted 1,2,4-triazole-5-thiols with N-substituted N-chloromethyl carbamoyl chlorides. A series of thiatriazafluorenone derivatives were also prepared by reaction of benzimidazole derivatives with the same substrate. Some of the new compounds show fungicidal, herbicidal, and insecticidal activity. Received February 14, 2000. Accepted (revised) April 11, 2000     

Synthesis of substituted 5-oxo-1-thiocarbamoyl-3-pyrazoline-4-alkanoic acid derivatives

Cyclization of the 4-methyl-3-thiosemicarbazone of diethyl acetylsuccinate (1a) by the action of ammonium hydroxide followed by acidification afforded ethyl 3-methyl-1-methylthiocarbamoyl-5-oxo-3-pyrazoline-4-acetate (11a). Pmr spectral analyses using shift reagent, Eu(fod)₃, in deuteriochloroform indicated the presence also of approximately 15% of a second tautomer, ethyl 5-hydroxy-3-methyl-1-(methylthiocarbamoyl)pyrazole-4-acetate (11a'). 3-Methyl-1-methyl-thiocarbamoyl-5-oxo-pyrazoline-4-acetamide (11b) was prepared by extending the reaction time of 1a with ammonium hydroxide. Alkaline hydrolysis of 11a provided the corresponding acid 3-methyl-1-methylthiocarbamoyl-5-oxo-3-pyrazoline-4-acetie acid (11c). Regeneration of 11a was achieved by the reaction of ethyl 3-methyl-5-oxo-3-pyrazoline-4-acetate (IV) with methyl isothiocyanate. The latter reaction provided confirmation of structure for 11a. The preparation of other pyrazolin-5-ones by cyclization of thiosemicarbazones of ethyl formylsuccinate and ethyl acetylglutarate also is presented. All spectra are in accord with the proposed structures.