Synthesis of heterocycles from arylation products of unsaturated compounds: XVIII. 5-Arylfuran-2-carboxylic acids and their application in the synthesis of 1,2,4-thiadiazole, 1,3,4-oxadiazole,and [1,2,4]triazolo[3,4-<Emphasis Type="Italic">b</Emphasis>][1,3,4]thiadiazole derivatives

Arylation of furan-2-carboxylic acid or its methyl ester with arenediazonium chlorides in the presence of copper(II) chloride gave the corresponding 5-arylfuran-2-carboxylic acids or methyl 5-arylfuran-2-carboxylates. 5-Arylfuran-2-carbonyl chlorides reacted with potassium thiocyanate and then with 5-methyl-1,2-oxazol-3-amine to give 5-aryl-N-[3-(2-oxopropyl)-1,2,4-thiadiazol-5-yl]furan-2-carboxamides as a result of recyclization of intermediate isoxazolylthiourea derivatives. The reactions of 5-arylfuran-2-carbonyl chlorides with 5-(2-furyl)-1H-tetrazole involved opening of the tetrazole ring with elimination of nitrogen molecule and led to the formation of 2-(5-arylfuran-2-yl)-5-(2-furyl)-1,3,4-oxadiazoles. 3-Substituted 6-(5-arylfuran-2-yl)-[1,2,4]triazolo[3,4-b][1,3,4]thiadiazoles were obtained by condensation of 5-arylfuran-2-carboxylic acids with 5-substituted 4-amino-4H-1,2,4-triazole-3-thiols in phosphoryl chloride.     

Synthesis of polyazaheterocycles containing linearly bound 1,2,4-thiadiazole using enaminones

A reaction of N-substituted 5-amino-3-(2-oxopropyl)-1,2,4-thiadiazoles with dimethylformamide dimethyl acetal gave 3-(5-amino-1,2,4-thiadiazol-3-yl)-4-(dimethylamino)but-3en-2-ones, whose cyclization with hydrazine, guanidine, 1H-pyrazol-5-amines and 6-aminopyrimidin-4(3H)-ones led to 3-methyl-1H-pyrazole, 4-methylpyrimidin-2-amine, 5-methyl3-arylpyrazolo[1,5-a]pyrimidines, and 5-methyl-2-R-pyrido[2,3-d]pyrimidin-4(3H)-ones containing a 5-amino-1,2,4-thiadiazole fragment linearly bound at position 3.     

Synthesis and X-ray study of 6<Emphasis Type="Italic">H</Emphasis>-chromeno[3,4-<Emphasis Type="Italic">e</Emphasis>][1,3,4]triazolo[2,3-<Emphasis Type="Italic">a</Emphasis>]pyrimidine

2-Dimethylamino methylenechromanone 1 reacted with 4H-1,2,4-triazol-3-amine in acetic acid to give only one isolated product which was identified by X-ray study as 6H-chromeno[3,4-e][1,3,4]triazolo[2,3-a]-pyrimidine. The molecular structure of 3, C₁₂H₈N₄O, was determined to be monoclinic, P2₁/c, a = 16.3875(5), b = 8.8378(3), c = 13.8392(5) Å, β = 101.190(1)°, V = 1966.22(11) ų, Z = 8.     

Synthesis and Structure of 4-Indolyl-5-(thieno[3,2-<Emphasis Type="Italic">b</Emphasis>]pyrrol-6-yl)imidazoles

A procedure was proposed for regioselective acylation of methyl 2-methyl-4H-thieno[3,2-b]-pyrrole-5-carboxylate with 2-(3-indolyl)-2-oxoacetyl chloride. Reactions of the resulting methyl 6-[2-(3-indolyl)-1,2-dioxoethyl]-2-methyl-4H-thieno[3,2-b]pyrrole-5-carboxylate with aromatic aldehydes and ammonium acetate in acetic acid afforded the corresponding methyl 6-[2-aryl-4-(3-indolyl)imidazol-5-yl]-2-methyl-4H-thieno[3,2-b]pyrrole-5-carboxylates. The structure of methyl 6-[2-(4-chlorophenyl)-4-(3-indolyl)imidazol-5-yl]-2-methyl-4H-thieno[3,2-b]pyrrole-5-carboxylate was studied by X-ray analysis.     

Synthesis of 1,2,4- and 1,3,4-oxadiazoles from 1-aryl-5-methyl-1<Emphasis Type="Italic">H</Emphasis>-1,2,3-triazole-4-carbonyl chlorides

5-Substituted 2-(1-aryl-5-methyl-1H-1,2,3-triazol-4-yl)-1,3,4-oxadiazoles were synthesized by reaction of 1-aryl-5-methyl-1H-1,2,3-triazole-4-carbonyl chlorides with the corresponding 5-substituted 1H-tetrazoles. 5-Methyl-1-phenyl-1H-1,2,3-triazole-4-carbonyl chloride reacted with N′-hydroxybenzimidamides to give 3-aryl-5-(5-methyl-1-phenyl-1H-1,2,3-triazol-4-yl)-1,2,4-oxadiazoles. Reactions of 4-(5-methyl-1H-1,2,3-triazol-1-yl)benzoic acid with N′-hydroxybenzimidamides resulted in the formation of 3-aryl-5-[4-(5-methyl-1H-1,2,3-triazol-1-yl)phenyl]-1,2,4-oxadiazoles.     

Synthesis and properties of ethyl 1-aryl-5-methyl-4-[1-(phenylhydrazinylidene)ethyl]-1<Emphasis Type="Italic">H</Emphasis>-pyrazole-3-carboxylates

Ethyl 1-aryl-4-acetyl-5-methyl-1H-pyrazole-3-carboxylates reacted with phenylhydrazine to give the corresponding hydrazones, ethyl 1-aryl-5-methyl-4-[1-(phenylhydrazinylidene)ethyl]-1H-pyrazole-3-carboxylates, which were converted to ethyl 1′-aryl-4-formyl-5′-methyl-1-phenyl-1H,1′H-3,4′-bipyrazole-3′-carboxylates by treatment with the Vilsmeier–Haack reagent. No indole derivatives were formed from the same hydrazones under the Fischer reaction conditions, but cyclization to 2-aryl-3,4-dimethyl-6-phenyl-2,6-dihydro-7H-pyrazolo[3,4-d]pyridazin-7-ones was observed.     

Functionalization of methyl 3-acetyl-5-[(methoxycarbonyl)amino]-2-methyl-1<Emphasis Type="Italic">H</Emphasis>-indole-1-carboxylate

Oxidative heterocyclization of methyl 3-{1-[2-(carbamoylhydrazinylidene)]ethyl}-2-methyl-5-[(methoxycarbonyl)amino]-1H-indole-1-carboxylate by the action of selenium dioxide in acetic acid and heating of the corresponding thiosemicarbazone in boiling acetic anhydride gave 1,2,3-selenadiazole and 2,3-dihydro-1,3,4-thiadiazole derivatives, respectively. Methyl 3-acetyl-2-methyl-5-[(methoxycarbonyl)amino]-1H-indole-1-carboxylate reacted with selenium dioxide in dioxane–water (30: 1) at 80?90°C to form methyl 5-[(methoxycarbonyl)amino]-2-methyl-3-(2-oxoacetyl)-1H-indole-1-carboxylate whose condensation with o-phenylenediamine afforded methyl 2-methyl-5-[(methoxycarbonyl)amino]-3-(quinoxalin-2-yl)-1H-indole-1-carboxylate.     

Synthesis of N-aryl- and <Emphasis Type="Italic">N</Emphasis>,<Emphasis Type="Italic">N</Emphasis>-diethyl-9-methyl-11-sulfanylidene-8-oxa-10,12-diazatricyclo[7.3.1.0<Superscript>2,7</Superscript>]trideca-2,4,6-triene-13-carboxamides

Three-component condensation of N-aryl- and N,N-diethyl-3-oxobutanamides with salicylaldehyde and thiourea in ethanol in the presence of sodium hydrogen sulfate afforded N-aryl- and N,N-diethyl-9-methyl-11-sulfanylidene-8-oxa-10,12-diazatricyclo[7.3.1.0^2,7]trideca-2,4,6-triene-13-carboxamides. Reaction of the same compounds in the absence of a catalyst under solvent-free conditions gave N-aryl-6-(2-hydroxyphenyl)-4-methyl-2-sulfanylidene-1,2,3,6-tetrahydropyrimidine-5-carboxamides.     

Synthesis and antimicrobial activity of novel fused [1,2,4]triazino[5,6-<Emphasis Type="Italic">b</Emphasis>]indole derivatives

Synthesis of new fused systems of triazino[5,6-b]indole starting with preparation of 3-amino[1,2,4]-triazino[5,6-b]indole 1 by reaction of isatin with 2-aminoguanidinium carbonate in boiling acetic acid is presented [1]. Intermediate compound 1 reacted with aldehyde, ethyl chloroformate, triethyl orthoformate, and ninhydrine and gave new heterotetracyclic nitrogen systems, such as 3-(N ²-guanidinylimino)indole-2(1H)-one 2, 3-(N-ethoxycarbonylamino)-4H-[1,2,4]triazino[5,6-b]indole 3, 3-(N-ethoxymethyleneamino)-4H-[1,2,4]-triazino[5,6-b]indole 4, 3-(hydrazinothiocarbonylamino)-4H-[1,2,4]triazino[5,6-b]indole 5, respectively. N-(1,3-dioxoindene-2-ylidene)-4H-[1,2,4]triazino[5,6-b]indol-3-amine 6 was synthesized by reaction of compound 1 with aldehyde, ethyl chloroformate, triethyl orthoformate, and ninhydrine. New fused indole systems, pyrimido[2′,1′:3,4][1,2,4]triazino[5,6-b]indol-3(4H)-one 8, 9, 11, 12 and 1H-imidazo[2′,1′:3,4][1,2,4]triazino-[5,6-b]indol-2(3H)-one 10, were synthesized in the reaction of the intermediate 1 with bifunctional compounds. Structures of the products were elucidated from their elemental analysis and spectral data (IR, ¹H and ¹³C NMR and mass spectra). Antimicrobial activity of some synthesized compounds was tested.     

Synthesis and Study of Macroheterocyclic Compounds Based on 2,6-Dihydro-1<Emphasis Type="Italic">H</Emphasis>-cyclopenta[<Emphasis Type="Italic">cd</Emphasis>]phenalene-5,7-diimine

Previously unknown macroheterocyclic compounds containing cyclopenta[cd]phenalene and 1-phenyl-1,2,4-triazole, 1,3,4-thiadiazole, or pyridine fragments were synthesized by reaction of 2,6-dihydro-1H-cyclopenta[cd]phenalene-5,7-diimine with heteroaromatic diamines.     

Synthesis of bifunctional thieno[3,2-c]pyrazole,pyrazolothieno[2,3-d]pyrimidin derivatives and their antimicrobial activities

A simple and convenient route was performed for the synthesis of some new heterocyclic compounds based on thieno[3,2-c]pyrazole derivative for antimicrobial evaluation. The key intermediate, 5-amino-3-methyl-1-phenyl-1H-thieno[3,2-c]pyrazole-6-carbohydrazide 3, was prepared by Gewald’s synthesis of Ethyl 5-amino-3-methyl-1-phenyl-1H-thieno[3,2-c]pyrazole-6-carboxylate 2. This intermediate reacted with various reagents to afford different fused and polyfunctional substituted. The structures of these compounds were confirmed by elemental analysis, IR, ¹H NMR, ¹³C NMR and mass spectral data. All the new synthesized compounds were screened for various microorganisms such as Aspergillus fumigatus; Geotrichum candidum; Syncephalastrum racemosum (Fungus); Candida albicans (Yeast fungus); Staphylococcus aureus; Bacillus subtilis (as Gram-positive bacteria); Pseudomonas aeruginosa and Escherichia coli (as Gram-negative bacteria) by the disc diffusion method. In general, the novel synthesized compounds possessed moderate to high antimicrobial activity against the previously mentioned microorganisms.     

Reaction of <Emphasis Type="Italic">N</Emphasis>-aryl-3-oxobutanethioamides with 2-amino-1,3-thiazole and 2-amino-1,3-benzothiazole

N-Aryl-3-oxobutanethioamides react with 2-amino-1,3-thiazole (2-amino-1,3-benzothiazole) in acetic acid to give mixtures of 7-methyl-5H-[1,3]thiazolo[3,2-a]pyrimidine-5-thione (2-methyl-4H-pyrimido-[2,1-b][1,3]benzothiazole-4-thione) and 5-arylimino-7-methyl-5H-[1,3]thiazolo[3,2-a]pyrimidines (4-arylimino-2-methyl-4H-pyrimido[2,1-b][1,3]benzothiazoles), whose ratio depends on the nature of the aryl substituent in the initial butanethioamide.     

Nitration of 1,3-dihydro-2<Emphasis Type="Italic">H</Emphasis>-imidazo[4,5-<Emphasis Type="Italic">b</Emphasis>]pyridin-2-one derivatives

Nitration of 1,3-dihydro-2H-imidazo[4,5-b]pyridin-2-one and its N-methyl derivatives at 0–5°C and 60°C gives 5-nitro-and 5,6-dinitro-1,3-dihydro-2H-imidazo[4,5-b]pyridin-2-ones, respectively. The latter can also be obtained by nitration of 5-mononitro derivatives under similar conditions. The nitration of 6-chloro-and 6-bromo-1,3-dihydro-2H-imidazo[4,5-b]pyridin-2-ones and their N-methyl-substituted analogs leads to the formation of the corresponding 6-chloro(bromo)-5-nitro compounds. The same products are formed in the nitration of 5,6-dichloro-and 5,6-dibromo-1,3-dihydro-2H-imidazo[4,5-b]pyridin-2-ones. In this case, the process involves replacement of the halogen atom in position 5 of the pyridine fragment by nitro group. The nitration of 6-bromo-5-methyl-1,3-dihydro-2H-imidazo[4,5-b]pyridin-2-one is accompanied by oxidation of the 5-methyl group to carboxy.     

Reactions of 1,3-Dialkyl-5-amino-1,3-dihydro-2<Emphasis Type="Italic">H</Emphasis>-imidazo-[4,5-<Emphasis Type="Italic">b</Emphasis>]pyridin-2-ones with acetylacetone and ethyl acetoacetate

1,3-Dialkyl-5-amino-1,3-dihydro-2H-imidazo[4,5-b]pyridin-2-ones reacted with acetylacetone to give the corresponding 4-(1,3-dialkyl-2-oxo-1,3-dihydro-2H-imidazo[4,5-b]pyridin-5-ylamino)pent-3-en-2-ones which underwent intramolecular cyclization to 1,3-dialkyl-5,7-dimethyl-1,3-dihydro-2H-imidazo[4,5-b]-[1,8]naphthyridin-2-ones on heating in polyphosphoric acid or diphenyl ether. Analogous reaction of 1,3-dialkyl-5-amino-1,3-dihydro-2H-imidazo[4,5-b]pyridin-2-ones with ethyl acetoacetate led to the formation of ethyl 3-(1,3-dialkyl-2-oxo-1,3-dihydro-2H-imidazo[4,5-b]pyridin-5-ylamino)but-2-enoates whose cyclization afforded 1,3-dialkyl-8-hydroxy-7-methyl-1,3-dihydro-2H-imidazo[5,4-b][1,8]naphthyridin-2-ones.     

Features of Reaction of 2-(5-Methyl-2-phenyl-2<Emphasis Type="Italic">H</Emphasis>-1,2,3-diazaphosphol-4-yl)-4<Emphasis Type="Italic">H</Emphasis>-benzo[<Emphasis Type="Italic">e</Emphasis>]-1,3,2-dioxaphosphorin-4-one with 1,2-Dicarbonyl Compounds

2-(5-Methyl-2-phenyl-2H-1,2,3-diazaphosphol-4-yl)-4H-benzo[e]-1,3,2-dioxaphosphorin-4-one reacts with perfluorodiacetyl, 3,6-di(tert-butyl)-1,2-benzoquinone and phenanthrenequinone only with the participation of a three-coordinated phosphorus atom to form spirophosphoranes containing acyclic 5-methyl-2- phenyl-2H-1,2,3-diazaphosphol-4-yl substituent, whereas the interaction with tetrachloro-1,2-benzoquinone proceeds via expanding the six-membered heterocycle to the nine-membered one to form 2-(2-phenyl-2H-1,2,3-diazaphosphol-4-yl)-2,9-dioxo-4,5,6,7-tetrachlorodibenzo[d,h]-1,3,8-trioxaphosphonine.     

Synthesis of heterocycles based on arylation products of unsaturated compounds: XVII. Arylation of 2-acetylfuran and synthesis of 3-R-6-(5-aryl-2-furyl)-7<Emphasis Type="Italic">H</Emphasis>-[1,2,4]triazolo[3,4-<Emphasis Type="Italic">b</Emphasis>][1,3,4]thiadiazines

Reaction of 2-acetylfuran with arenediazonium chlorides under Meerwein reaction conditions led to the formation of 5-aryl-2-acetylfurans. The bromination of these compounds gave 2-bromo-1-(5-aryl-2-furyl)-ethanones that reacted with 4-amino-4H-5-R-1,2,4-triazole-3-thiols to form 3-R-6-(5-aryl-2-furyl)-7H-[1,2,4]triazolo[3,4-b][1,3,4]thiadiazines.     

Thermal Rearrangements of 3<Emphasis Type="Italic">H</Emphasis>- and 4<Emphasis Type="Italic">H</Emphasis>-Pyrazoles Prepared by Reactions of 9-Diazofluoren with Methyl Tetrolate and Methyl 3-Phenylpropiolate

9-Diazofluoren adds in Et₂O at 20°C to methyltetrolate in keeping with Auwers rule and nonregioselectively adds to methyl-3-phenylpropiolate with the formation of spirocyclic 3H-pyrazoles. The methyltetrolate adduct at boiling in toluene converts into methyl 3a-methyl-3aH-dibenzo[e,g]indazole-3-carboxylate, at 190°C in benzene, into methyl 3-methyl-2H-dibenzo[e,g]indazole-2-carboxylate, and at 160°C in methanol, into 3-methyl-2H-dibenzo[e,g]indazole. Auwers adduct of methyl 3-phenylpropiolate at boiling in benzene gives cyclopropene derivative and at boiling in methanol isomerizes into methyl 3a-phenyl-3aHdibenzo[e,g]indazole-3-carboxylate. Anti-Auwers adduct at boiling in benzene isomerizes into methyl 2-phenylpyrazolo[1,5-f]phenanthridine-3-carboxylate.     

Synthesis of novel 4<Emphasis Type="Italic">H</Emphasis>-furo[3,2-c]pyran-4-ones and 4<Emphasis Type="Italic">H</Emphasis>-furo[3,2-<Emphasis Type="Italic">c</Emphasis>]chromen-4-ones

It was found that the condensation of two equivalents of 4-hydroxy-6-methyl-2H-pyran-2-one or 4-hydroxycoumarin with arylglyoxals in boiling formic acid leads to 4H-furo[3,2-c]-pyran-4-ones or 4H-furo[3,2-c]chromen-4-ones, respectively.     

Synthesis of 2-Methyl-7-phenyl-5,8-dihydro-4<Emphasis Type="Italic">H</Emphasis>-pyrzylo-[5,1-<Emphasis Type="Italic">d</Emphasis>][1,2,5]triazepin-4-one

An approach is developed to the synthesis of 2-methyl-7-phenyl-5,8-dihydro-4H-pyrazolo[5,1-d]-[1,2,5]triazepin-4-one, based on the recyclization of 2-methyl-6-phenyl-4H-pyrazolo[5,1-c][1,4]oxazin-4-one with hydrazine.     

Synthesis of new aryl(hetaryl)vinyl-substituted benzo[<Emphasis Type="Italic">f</Emphasis>]quinolines and 4,7-phenanthrolines

Previously unknown 1-[2-aryl(quinolin-2-yl)ethenyl]-3-[aryl(quinolin-2-yl)]benzo[f]quinolines and 3-aryl-1-(2-arylethenyl)-4,7-phenanthrolines were synthesized by reactions of 1-methylbenzo[f]quinolines and 1-methyl-4,7-phenanthrolines with substituted N-benzylideneanilines and N-(quinolin-2-ylmethylidene)aniline on heating in dimethylformamide in the presence of potassium hydroxide.