Regioselective synthesis of polyfluoroalkyl-substituted 7-(1<Emphasis Type="Italic">H</Emphasis>-1,2,3-triazol-1-yl)-6,7-dihydro-1<Emphasis Type="Italic">H</Emphasis>-indazol-4(5<Emphasis Type="Italic">H</Emphasis>)-ones

3-Polyfluoroalkyl-6,6-dimethyl-7-(1H-1,2,3-triazol-1-yl)-6,7-dihydro-1H-indazol-4(5H)-ones were synthesized with high regioselectivity by 1,3-dipolar cycloaddition of terminal alkynes (phenylacetylene, hex- 1-yne, hept-1-yne, and but-3-yn-1-ol) to 7-azido-6,6-dimethyl-3-polyfluoroalkyl-6,7-dihydro-1H-indazol-4(5H)-ones which were prepared by bromination of 6,6-dimethyl-3-polyfluoroalkyl-6,7-dihydro-1H-indazol- 4(5H)-ones with N-bromosuccinimide in anhydrous carbon tetrachloride, followed by treatment of the corresponding 7-bromo derivatives with sodium azide.     

Reaction 5-(Arylmethylidene)pyrimidine-2,4,6(1<Emphasis Type="Italic">H</Emphasis>,3<Emphasis Type="Italic">H</Emphasis>,5<Emphasis Type="Italic">H</Emphasis>)-triones with L-Proline and Aldehydes

Boiling in toluene of 5-(arylmethylidene)pyrimidine-2,4,6(1H,3H,5H)-triones with L-proline and aldehyde led to the formation of previously unknown substituted 1′-arylhexahydro-1H-spiro[pyrimidine-5,2′-pyrrolysine]-2,4,6(1H,3Н,5Н)-triones.     

Synthesis of 3-alkylquinoxalin-2(1<Emphasis Type="Italic">H</Emphasis>)-ones via Grignard reaction

A two-step procedure has been developed for the synthesis of 3-alkylquinoxalin-2(1H)-ones from o-phenylenediamine and ethyl 2-oxoalkanoates prepared by the Grignard reaction of diethyl oxalate with alkyl bromides. Analogous reaction with α,ω-dibromoalkanes instead of alkyl bromides leads to the formation of 3,3′-(alkane-α,ω-diyl)di[quinoxalin-2(1H)-ones].     

Azacycloalkanes: XXXIX. New Syntheses of 1<Emphasis Type="Italic">H</Emphasis>-Pyrrole-1-carboxylic acid and 1,2-dihydropyrrolo-[1,2-<Emphasis Type="Italic">a</Emphasis>]pyrazin-3(4<Emphasis Type="Italic">H</Emphasis>)-one derivatives

New procedures have been developed for the synthesis of α-(2-formyl-1H-pyrrol-1-yl)-substituted carboxylic acids, α-(2-R-aminomethyl-1H-pyrrol-1-yl)-substituted carboxylic acids, and 1,2-dihydropyrrolo-[1,2-a]pyrazin-3(4H)-ones on the basis of furfurol and α-amino acids.     

Synthesis of 4<Emphasis Type="Italic">H</Emphasis>-imidazole-5-carbaldoxime 3-oxides and 4<Emphasis Type="Italic">H</Emphasis>-imidazole-5-carbonitrile 3-oxides

The condensation of 3-hydroxyamino-3-methylbutan-2-one or 3-ethyl-3-hydroxyamino-pentan-2-one with aldehydes and ammonia afforded a series of new 1-hydroxy-4-methyl-2,5-dihydroimidazoles, whose oxidation gave rise to the corresponding 5-methyl-4H-imidazole 3-oxides. The latter, like 1-hydroxy-4-methyl-2,5-dihydroimidazoles, react with PrⁱONO in the presence of bases to form 4H-imidazole-5-carbaldoxime 3-oxides, which are transformed into 4H-imidazole-5-carbonitrile 3-oxides in the reaction with TsCl in the presence of Et₃N. The by-products produced in different steps of the synthesis were isolated and characterized. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp. 1487–1503, July, 2008.     

Recyclization of 1,3-dialkyl-6-nitro-1<Emphasis Type="Italic">H</Emphasis>-imidazo[4,5-<Emphasis Type="Italic">b</Emphasis>]pyridine-2,5(3<Emphasis Type="Italic">H</Emphasis>,4<Emphasis Type="Italic">H</Emphasis>)-diones into imidazole derivatives

Treatment of 5-amino-1,3-dialkyl-2,3-dihydro-1H-imidazo[4,5-b]pyridin-2-ones with sodium nitrite in aqueous HCl gave 1,3-dialkyl-1H-imidazo[4,5-b]pyridine-2,5(3H,4H)-diones which were nitrated with potassium nitrate in sulfuric acid to 6-nitro derivatives, and the latter underwent recyclization into 4-amino-1,3-dialkyl-5-(1H-pyrazol-5-yl)-2,3-dihydro-1H-imidazol-2-ones by the action of hydrazine hydrate.     

Reaction of acetylenedicarboxylic acids esters with 4,5-dihydro-1<Emphasis Type="Italic">H</Emphasis>-pyrazole-1-carbothioamides and 3,4,5,6-tetrahydro-2<Emphasis Type="Italic">H</Emphasis>-1,2,4-triazepine-3-thiones

The reactions of dimethyl acetylenecarboxylate with 3,4,5,6-tetrahydro-2H-1,2,4-triazepine-3-thiones and 4,5-dihydro-1H-pyrazole-1-carbothioamides are convenient methods for the synthesis of 7,8-dihydrothiazolo[3,2-b][1,2,4]triazepin-3-ones derivatives and methyl esters of (2Z)-[2-(4,5-dihydro-1H-pyrazol-1-yl)-4-oxo-1,3-thiazol-5(4H)-ylidene]acetic acids, respectively. The reaction of methyl propynoates with 4,5-dihydro-1H-pyrazole-1-carbothioamides or with 5,5,7-trimethyl-2,4,5,6-tetrahydro-3H-1,2,4-triazepine-3-thione gives 2-(4,5-dihydro-1H-pyrazol-1-yl)-4H-1,3-thiazin-4-ones.     

Reaction of 5-arylfuran-2(3<Emphasis Type="Italic">H</Emphasis>)-ones with amines

5-(4-Chlorophenyl)- and 5-phenylfuran-2(3H)-ones reacted with guanidine carbonate at the methylene group in the unsaturated lactone molecule, leading to the formation of 4-(2-aryl-5-oxo-2,5-dihydrofuran-2-yl)-5-aryltetrahydrofuran-2-ones, while 5-(4-methylphenyl)furan-2(3H)-one under analogous conditions gave rise to N,N′-bis[4-(4-methylphenyl)-4-oxobutanoyl]guanidine. The reactions of 5-arylfuran-2(3H)- ones with thioacetamide afforded 4-aryl-N-{1-[5-aryl-2-oxo-2,3-dihydrofuran-3-ylidene]ethyl}-4-oxobutanamides. The corresponding N-(4-aryl-4-oxobutanoyl)thioureas were obtained by heating 5-arylfuran-2(3H)-ones with thiourea.     

Alkylation of 2-(hydroxyimino)-5<Emphasis Type="Italic">H</Emphasis>-[1,3]thiazolo[3,2-<Emphasis Type="Italic">a</Emphasis>]-pyrimidin-3(2<Emphasis Type="Italic">H</Emphasis>)-ones

Alkylation products were obtained from ethyl 2-(hydroxyimino)-7-methyl-3-oxo-5-aryl-2,3- dihydro-5H-[1,3]thiazolo[3,2-a]pyrimidin-6-carboxylates at the treatment with alkyl halides, dimethyl sulfate, and diazomethane. Diazomethane alkylated the initial substrate at the oxygen atom of the carbonyl group of the thiazolidine fragment, the other reagents, at the oxygen atom of the hydroxyimino group.     

Regioselectivity in the reactions of <Emphasis Type="Italic">N</Emphasis>-(polychloroethylidene)-sulfonamides with 1<Emphasis Type="Italic">H</Emphasis>-pyrrole and 1-methyl-1<Emphasis Type="Italic">H</Emphasis>-pyrrole

N-(2,2,2-Trichloroethylidene)arenesulfonamides react with 1H-pyrrole and 1-methyl-1H-pyrrole to give the corresponding N-[2,2,2-trichloro-1-(1H-pyrrol-2-yl)ethyl]arenesulfonamides. The reaction of N-(2,2,2-trichloroethylidene)trifluoromethanesulfonamide with pyrrole leads to a mixture of 2-mono-and 2,5-disubstituted pyrroles, whereas in the reaction with 1-methyl-1H-pyrrole only the 2-substituted compound is formed. N-(2,2-Dichloro-2-phenylethylidene)-4-methylbenzenesulfonamide reacts with 1H-pyrrole to form N-[2,2-dichloro-2-phenyl-1-(1H-pyrrol-2-yl)ethyl]-4-methylbenzenesulfonamide, and its reaction with 1-methyl-1H-pyrrole gives a mixture of 2-and 3-monosubstituted derivatives. The results of quantum-chemical calculations of the initial reactants and products indicate that the process is orbital-controlled. A good agreement is observed between the experimental data and theoretical conclusions concerning the dependence of the reaction regioselectivity on the nature of substituents in the electrophile molecule.     

The Unusual Transformation of an Aromatic 1<Emphasis Type="Italic">H</Emphasis>-Imidazole into a Non-Aromatic 2<Emphasis Type="Italic">H</Emphasis>-Imidazole

2H-Imidazole derivative 5 has been synthesized and characterized by the X-ray diffraction (XRD) method. The compound crystallizes in the monoclinic space group Cc with cell parameters a = 19.398(1), b = 8.890(1), c = 10.247(1), β = 110.76(1), Z = 4. The molecules are inter-linked through C–H⋅sO and C–H⋅sπ interactions forming infinite chains.     

Regioselective Reaction of <Emphasis Type="Italic">N</Emphasis><Superscript>1</Superscript>-Benzyl-<Emphasis Type="Italic">N</Emphasis><Superscript>2</Superscript>-(4-nitrophenyl)ethanediamide and Acetylenic Esters

Summary. The regioselective reaction of N¹-benzyl-N²-(4-nitrophenyl)ethanediamide with dialkyl acetylenedicarboxylates or alkyl propiolates in the presence of triphenylphosphine leads to dialkyl 4-benzylamino-1-(4-nitrophenyl)-5-oxo-2,5-dihydro-1H-pyrrole-2,3-dicarboxylates or alkyl 4-benzylamino-1-(4-nitrophenyl)-2-oxo-5-pyrrolidinecarboxylates in good yields.     

Synthesis and structures of benzo[<Emphasis Type="Italic">cd</Emphasis>]furo[2,3-<Emphasis Type="Italic">f</Emphasis>]indol-4(5<Emphasis Type="Italic">H</Emphasis>)-one derivatives

A procedure was developed for the synthesis of derivatives of the new heterocyclic system, benzo[cd]furo[2,3-f]indole, based on the cyclodehydration of 6-acylmethyloxy-1-alkyl-benzo[cd]indol-2(1H)-ones. Either 7- or 8-aryl derivatives of benzo[cd]furo[2,3-f]indol-4(5H)-ones can be prepared depending on the reaction conditions. The molecular and crystal structures of 7- and 8-phenylbenzo[cd]furo[2,3-f]indol-4(5H)-ones were established by X-ray diffraction.     

Synthesis of (<Emphasis Type="Italic">S</Emphasis>)-(+)-6-aryl-3-acetyl-6-trifluoromethyl-5,6-dihydropyridin-2(1<Emphasis Type="Italic">H</Emphasis>)-ones

(S)-(+)-4-Amino-4-aryl-5,5,5-trifluoropentan-2-ones reacted with ethyl acetoacetate and ethyl trifluoroacetoacetate to give (S)-(+)-6-aryl-3-acetyl(or trifluoroacetyl)-6-trifluoromethyl-5,6-dihydropyridin-2(1H)-ones.     

Synthesis of substituted 3,4-dihydropyrimidin-2(1<Emphasis Type="Italic">H</Emphasis>)-ones and pyrimidin-2(1<Emphasis Type="Italic">H</Emphasis>)-ones by the Biginelli reaction with 3,5-Di-<Emphasis Type="Italic">tert</Emphasis>-butyl-4-hydroxybenzaldehyde

Three-component acid-catalyzed cyclocondensation of 3,5-di-tret-butyl-4-hydroxybenzaldehyde with urea and ethyl acetoacetate or α-nitroacetophenone (Biginelli reaction) under homogeneous conditions gave the corresponding 5-substituted 3,4-dihydropyrimidin-2(1H)-ones having in position 4 of the heteroring an aryl substituent with sterically shielded hydroxy group. The condensation catalyzed by inorganic salts (Fe³⁺, Co²⁺, Zn²⁺, Li⁺) was successful only with ethyl acetoacetate as initial methylene-active component. Under analogous conditions, acetophenone and 4-fluoroacetophenone gave rise to 4,6-diarylpyrimidin-2(1H)-ones which are capable of undergoing phenol-quinonemethide tautomerism.     

One-pot synthesis of alkyl 3-aryl-2-(4-phenyl-1<Emphasis Type="Italic">H</Emphasis>-1,2,3-triazol-1-yl)propanoates

Reaction of 3-aryl-2-bromopropanoic acids esters, products of the Meerwein arylation, with sodium azide afforded alkyl 2-azido-3-arylpropanoates. The latter react with ethyl acetoacetate and phenylacetylene to form 1,2,3-triazole derivatives. A one-pot method for the synthesis of 3-aryl-2-(4-phenyl-1H-1,2,3-triazol-1-yl)-propanoic acid esters via a tricomponent reaction of alkyl 2-bromo-3-arylpropanoates, sodium azide, and phenylacetylene in the presence of CuI was developed.     

Synthesis and transformations of 3-acetylpyridine-2(1<Emphasis Type="Italic">H</Emphasis>)-thiones

Reactions of substituted 3-cyanopyridine-2(1H)-thiones with methyllithium gave 3-acetylpyridine-2(1H)-thiones. The best results were achieved by adding a solid-state thione to a solution of methyllithium in ether (thione: MeLi = 1: 3). The compounds obtained and their 3-pentanoyl analogs were used to synthesize a number of fused heterocyclic systems. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp. 1504–1507, July, 2008.     

One step synthesis of 14-alkyl- or aryl-14<Emphasis Type="Italic">H</Emphasis>-dibenzo[<Emphasis Type="Italic">a</Emphasis>,<Emphasis Type="Italic">j</Emphasis>]xanthenes using sodium hydrogen sulfate as catalyst

A simple and environmentally benign procedure for the synthesis of 14-alkyl- or aryl-14H-dibenzo[a,j]xanthenes is described through a one-pot condensation of 2-naphthol with aryl or alkyl aldehydes in the presence of sodium hydrogen sulfate as a catalyst under solvent-free conditions. Correspondence: Mohammed M. Hashemi, Department of Chemistry, Sharif University of Technology, P.O. Box 11365-9516, Tehran, Iran.     

Five-membered 2,3-dioxo heterocycles: LXXVII. [4 + 2]-Cycloaddition of alkyl vinyl ethers to 3-aroylpyrrolo[2,1-<Emphasis Type="Italic">c</Emphasis>][1,4]benzoxazine-1,2,4(4<Emphasis Type="Italic">H</Emphasis>)-triones

[4 + 2]-Cycloaddition of 3-aroylpyrrolo[2,1-c][1,4]benzoxazine-1,2,4(4H)-triones to alkyl vinyl ethers gave substituted stereoisomeric (1R*,16R*)- and (1S*,16R*)-16-alkoxy-14-aryl-3,15-dioxa-10-azatetracyclo[8.7.0.0^{1, 13}.0^{4, 9}]heptadeca-4,6,8,13-tetraene-2,11,12-triones.     

Halocyclization of 2-(2-{4-[allylamino(thioxo)methyl]piperazin-1-yl}ethyl)-1<Emphasis Type="Italic">H</Emphasis>-benzo[<Emphasis Type="Italic">de</Emphasis>]isoquinoline-1,3(2<Emphasis Type="Italic">H</Emphasis>)-dione

Cyclization of 2-(2-{4-[allylamino(thioxo)methyl]piperazin-1-yl}ethyl)-1H-benzo[de]isoquinoline-1,3(2H)-dione by the action of iodine, bromine, or sulfuryl chloride gave 2-(2-{4-[4,5-dihydro-5-(halomethyl)-thiazol-2-yl]piperazin-1-yl}ethyl)-1H-benzo[de]isoquinoline-1,3(2H)-dione hydrohalides which were converted into 2-{2-[4-(5-methylthiazol-2-yl)piperazin-1-yl]ethyl}-1H-benzo[de]isoquinoline-1,3(2H)-dione.