Synthesis of 2-Mono- and 2,2-Bis[2-(1<Emphasis Type="Italic">H</Emphasis>-tetrazol-5-yl)ethyl] Derivatives of Dipterocarpol

The azidation of 2,2-bis(2-cyanoethyl)-20-hydroxydammar-24-en-3-one afforded new tetrazole derivatives of natural dipterocarpol, 2-(2-cyanoethyl)-2-[2-(1H-tetrazol-5-yl)ethyl]-20-hydroxydammar-24-en- 3-ones, 2,2-bis[2-(1H-tetrazol-5-yl)ethyl]-20-hydroxydammar-24-en-3-one, and 2,2-bis[2-(1H-tetrazol-5-yl)- ethyl]-3-oxo-25,26,27-trinordammaran-(20S),24-olide. The structure of the final and intermediate products was determined by NMR spectroscopy and X-ray analysis.     

Fused pyrimidine systems: XVI. Electrophilic intramolecular cyclization of 2-(alkenylsulfanyl)pteridin-4(3<Emphasis Type="Italic">H</Emphasis>)-ones

2-[Allyl(but-3-en-1-yl, pent-4-en-1-yl)sulfanyl]pteridin-4(3Н)-ones at heating in polyphosphoric acid undergo an intramolecular cyclization affording respectively 9-methyl-8,9-dihydro-5H-[1,3]thiazolo[3,2-a] pteridin-5-one and 10-methyl(ethyl)-9,10-dihydro-5Н,8Н-[1,3]thiazino[3,2-a]pteridin-5-ones of angular structure. The cyclization of 2-(alkenylsulfanyl)pteridin-4(3Н)-ones under the action of iodine or arylsulfenyl chlorides afforded iodo(arylsulfanyl) derivatives of angularly fuzed thiazolo- and thiazinopteridines.     

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.     

Terminal bis-acetylenes derived from 1,2-bis(1<Emphasis Type="Italic">H</Emphasis>-tetrazol-5-yl)ethane

The N(1)—N(1), N(2)—N(2), and N(1)—N(2) regioisomers of 1,2-bis[(prop-2-yn-1-yl)-1H-tetrazol-5-yl]ethane were first synthesized by alkylation of 1,2-bis(1H-tetrazol-5-yl)ethane with propargyl bromide. The peculiarities of the crystal structure of 1,2-bis[1-(prop-2-yn-1-yl)-1H-tetrazol-5-yl]ethane were evaluated by X-ray diffraction analysis. This compound is readily underwent Cu-catalyzed [3+2] cycloaddition with p-tolyl azide, p-nitrophenyl azide, and benzyl azide to give heterocyclic assembles bearing 1,2,3-triazole and tetrazole cycles. Catalyst-free [3+2] cycloadditions of 1,2-bis[1-(prop-2-yn-1-yl)-1H-tetrazol-5-yl]ethane and the mixtures of the N(1)—N(1), N(2)—N(2), N(1)—N(2) regioisomers with poly(glycidyl azide) oligomers resulted in 1,2,3-triazole cycles and crosslinking of the polymer chains.     

Synthesis,Structure, and Antiproliferative Activity of <Emphasis Type="Italic">trans</Emphasis>-Palladium(II) Complexes with Tetrazol-2-ylacetic Acid Derivatives

A series of trans-palladium(II) complexes (trans-[PdCl₂L₂], L = ethyl 5-R-2H-tetrazol-2-ylacetate, 5-R-2H-tetrazol-2-ylacetamides, R = Me, Ph) has been synthesized, and their structure has been proved by ¹H and ¹³C–{¹H} NMR and high-resolution mass spectra and X-ray analysis. Antiproliferative activity of the synthesized complexes has been determined, and the mechanism of their interaction with DNA has been studied by UV and CD spectroscopy.     

<Emphasis Type="Italic">N</Emphasis>-acylimino-substituted 2-oxa-7-azaspiro[4.4]nona-3,6,8-trienes in the synthesis of 3-(1<Emphasis Type="Italic">H</Emphasis>-1,2,4-triazol-3-yl)-3<Emphasis Type="Italic">H</Emphasis>-pyrrole-4-carbonitriles

Reaction with phenylhydrazine of 3Н-pyrroles spirobound to a furan ring, N-acylimino-substituted 2-oxa-7-azaspiro[4.4]nona-3,6,8-trienes, occurs with a diasteroselective formation of previously unknown derivatives of 1,2,4-triazole: 5-amino-3-(5-alkyl-1-phenyl-1H-1,2,4-triazol-3-yl)-2-morpholin-4-yl-3H-pyrrole-4-carbonitriles.     

Synthesis of 6-Acyl-7-aryl-4,7-dihydrotetrazolo[1,5-<Emphasis Type="Italic">a</Emphasis>]pyrimidine-5-carboxylic acids and their methyl esters

6-Acyl-7-aryl-4,7-dihydrotetrazolo[1,5-a]pyrimidine-5-carboxylic acids and methyl 6-acyl-7-aryl-4,7-dihydrotetrazolo[1,5-a]pyrimidine-5-carboxylates were synthesized by fusion of 4-aryl-2,4-dioxobutanoic acids and their methyl esters, respectively, with 1H-tetrazol-5-amine and aromatic aldehydes. The reaction of methyl 2,4-dioxopentanoate with 1H-tetrazol-5-amine and 2-fluorobenzaldehyde in boiling acetic acid gave methyl 6-acetyl-5-hydroxy-7-(2-fluorophenyl)-4,5,6,7-tetrahydrotetrazolo[1,5-a]pyrimidine-5-carboxylate.     

Thermolysis of 1-(methylideneamino)-1<Emphasis Type="Italic">H</Emphasis>-pyrrole-2,3-diones. Formation of pyrazolodioxazines at [4+2]-cycloaddition of azomethinimines to arylcarbaldehydes

4-Acyl-1-[(diphenylmethylidene)amino]-5-methoxycarbonyl-1Н-pyrrole-2,3-diones generate at the thermolysis 4-acyl-3-(methoxycarbonyl)-1-(diphenylmethylidene)-1H-pyrazol-1-ium-5-olates that react with aromatic aldehydes to form methyl 2-aryl-8-acyl-4,4-diphenyl-4H-pyrazolo[5,1-d][1,3,5]dioxazine-7-carboxylates whose structure is proved by X-ray diffraction analysis.     

Synthesis of new dyes containing double tetrazole groups for sensitization of TiO<Subscript>2</Subscript> nanoparticles in dye-sensitized solar cells

Di(1H-tetrazol-5-yl)methane is employed as a new electron acceptor group in the synthesis of two metal-free organic dyes containing triphenylamine donor group. Dye-sensitized nanocrystalline TiO₂ solar cell (DSSC) applying these novel dyes is constructed for consideration of their photovoltaic properties. The electronic properties of the dyes are also considered with the aid of theoretical calculations. The DSSC constructed from 4-(2,2-di(1H-tetrazol-5-yl)vinyl)-N,N-diphenylaniline (T1) shows a short-circuit photocurrent density of 13.38 mA cm^?2, an open circuit voltage of 578 mV, and a fill factor of 0.54, with a resulted solar energy-to-electricity conversion efficiency of 4.18% under simulated 1 sun irradiation (100 mW cm^?2). This result reveals that the dye with the di(1H-tetrazol-5-yl)methane anchoring group injects more electrons to the conduction band of TiO₂ in comparison with its analogs with single tetrazole ring in their anchoring group. It is found that in spite of a red-shift of the absorption spectrum resulted from the lengthening of the molecule, the dye with two di(1H-tetrazol-5-yl)methane groups gives lower performance than the dye with a single electron acceptor.     

Synthesis of 1-substituted 5-alkyl(aryl)-1,3-dihydro-2<Emphasis Type="Italic">H</Emphasis>-pyrrol-2-ones. Azocoupling with diazonium salts

Reactions of 5-alkyl- and 5-aryl-3H-furan-2-ones with 1,3- and 1,4-binucleophiles of aromatic series were carried out for the first time under various conditions. In the presence of a base the reaction resulted in 1-R-1,3-dihydro-2Н-pyrrol-2-ones, under milder conditions intermediates were isolated, 4-aryl-4-oxobutanamides. The structure of the latter was proved by spectral methods. By an example of 1-R-1,3-dihydro-2Н-pyrrol-2-ones the possibility was demonstrated of their functionalization via introducing an aryldiazenyl fragment.     

Dehydrogenation of 1-aryl(hetaryl)-1,2,3,4-tetrahydro-9<Emphasis Type="Italic">H</Emphasis>-β-carboline-3-carboxylic acids and their esters with dimethyl sulfoxide

Oxidative dehydrogenation of 1-aryl(hetaryl)-1,2,3,4-tetrahydro-9Н-β-carboline-3-carboxylic acids derivatives with dimethyl sulfoxide leads to the formation of 1-aryl(hetaryl)-9Н-β-carbolines. Simultaneously with the dehydrogenation decarboxylation occurs. At the oxidation with dimethyl sulfoxide of methyl 1-aryl (hetaryl)-1,2,3,4-tetrahydro-9Н-β-carboline-3-carboxylicates methyl 1-aryl(hetaryl)-9Н-β-carboline-3-carboxylates formed whose hydrolysis afforded the corresponding 1-aryl(hetaryl)-9Н-β-carboline-3-carboxylic acids.     

Synthesis and biologic activity of aryloxyaminopropanoles based on substituted <Emphasis Type="Italic">p</Emphasis>-tolylalkylamines

Reaction of 2,2-dimethyl-2-(p-tolyl)ethyl-, 1-p-tolylcyclopenthylmethyl- and 4-(p-tolyl)tetrahydro-2Н-pyran-4-ylmethylamines with phenoxymethyloxiranes substituted in the aromatic ring afforded new aryloxypropanolamines, some of which show moderate adrenoblocking activity.     

4-(Nitroalkyl- and dinitroalkyl-<Emphasis Type="Italic">ONN</Emphasis>-azoxy)-3-cyanofuroxans and some of their derivatives

Dibromoisocyanurate-mediated reaction of 4-amino-3-cyanofuroxans with pseudonitroles of aliphatic, alicyclic, and heterocyclic series (including pseudonitroles bearing ethylcarboxyl or additional nitro group) resulted in 4-(nitroalkyl- and dinitroalkyl-ONN-azoxy)-3-cyanofuroxans. Subsequent chemical transformations gave 4-(1,3-dinitrooxy-2-nitropropyl-2-ONN-azoxy)-3-cyano- and 4-carbamoylfuroxans, as well as 4-(1,1-dinitroethyl-ONN-azoxy)-3-(1H-tetrazol-5-yl)furoxans.     

Synthesis and intramolecular transformations of 8-substituted 11-nitro-2-phenyl-5,6-dihydro-2H-2,6-methanobenzo[g][1,3,5]oxadiazocin-4(3H)-one diastereomers

The Biginelli reaction between 5-R-salicylic aldehyde (R = H, Me, and Br), α-nitroacetophenone, and urea affords 8-R-11-nitro-2-phenyl-5,6-dihydro-2H-2,6-methanobenzo-[g][1,3,5]oxadiazocin-4(3Н)-ones as mixtures of two diastereomers. The ratio of diastereomers depends on the catalyst (HCl) concentration in the reaction medium. In DMSO and DMF, the resulting compounds undergo oxadiazocine ring opening with establishment of a three-component equilibrium between 4-(2-hydroxy-5-R-phenyl)-5-nitro-6-phenyl-3,4-dihydropyrimidin-2(1Н)-one as the major component and diastereomeric methanobenzoxadiazocines as two minor components. Dilution of these solutions with water favors the oxa-Michael reaction resulting in the reverse transformation of dihydropyrimidinones into the corresponding starting diastereomers.     

The Schiff bases of pyridoxal-5-phosphate and hydrazides of certain pyrazoles: Stability,kinetics of formation,and synthesis

The interaction of pyridoxal-5-phosphate with 3-methyl-1Н-pyrazole-5-carbohydrazide, 2-(3,5-dimethyl-1Н-pyrazol-4-yl)acetohydrazide, and 1Н-pyrazole-3-carbohydrazide has yielded Schiff bases; the products have been characterized by ¹Н NMR and IR spectra. The binding ability of these pyrazoles with respect to pyridoxal-5-phosphate under conditions modeling the living tissues has been evaluated. Rate constants of the formation of the Schiff bases have been determined.     

Synthesis and characterization of 1,3,5-tris((1/2<Emphasis Type="Italic">H</Emphasis>-tetrazol-5-yl)methyl)-1,3,5-triazinane-2,4,6-trione

2,2′,2″-(2,4,6-Trioxo-1,3,5-triazinane-1,3,5-triyl) triacetonitrile (or tris-(cyanomethyl)-isocyanurate) and 1,3,5-tris((1/2H-tetrazol-5-yl)methyl)-1,3,5-triazinane-2,4,6-trione (or tris-(5-tetrazolylmethyl)-isocyanurate) were synthesized with new methods. High yields, simple methodology, and cheapness are advantages of the methods. Furthermore, 1,3,5-tris((1/2H-tetrazol-5-yl)methyl)-1,3,5-triazinane-2,4,6-trione was synthesized in the less hazardous condition. The compounds were characterized by elemental analysis, IR, ¹HNMR, ¹³CNMR and mass spectroscopic analysis. In addition, DSC/TGA measurements were carried out to determine the thermal behavior of the final product.     

Alkenyl derivatives of 5-nitro-2-pyridone: Synthesis and halocyclization

Alkylation of 5-nitro-2-pyridone by alkenyl halides in acetone in the presence of K₂СО₃ proceeds with generation of a mixture of N- and О-derivatives with N-isomer prevailing. 1-Allyl- and 1-methylallyl-5-nitro-2-pyridone react with halogens with the formation of 2-halomethyl-6-nitro-2,3-dihydrooxazolo[3,2-a]-pyridinium halides. 1-Prenyl-5-nitro-2-pyridone reacts with bromine with the formation of 3-bromine-2,2-dimethyl-7-nitro-3,4-dihydro-2Н-pyrido[2,1-b][1,3]oxazinium bromide, and with iodine giving 2,2-dimethyl-7-nitro-3,4-dihydro-2Н-pyrido[2,1-b][1,3]oxazinium triiodide.     

Interaction of 1,5,6,8-tetrahydropyrazolo[3,4-<Emphasis Type="Italic">е</Emphasis>][1,4]diazepine-4,7-diones with some electrophilic reagents

1,5,6,8-Tetrahydropyrazolo[3,4-e][1,4]diazepine-4,7-diones undergo acylation with acetic anhydride and carbamoylation with p-toluensulfonyl isocyanate at the atom N⁵. Interaction with Vilsmeier- Haack reagent occurs at the atom N⁸, it is followed with the opening of the diazepine cycle and leads to the formation of 2-(1Н-pyrazol-4-yl)-1,3-oxazol-5(4Н)-one derivatives.     

Synthesis of 2-amino-5-(2-aryl-2-oxoethylidene)-4-oxo-1<Emphasis Type="Italic">H</Emphasis>-4,5-dihydrofuran-3-carboxylic acids derivatives by recyclization of 5-arylfuran-2,3-diones under the action of cyanoacetic acid derivatives

Recyclization of 5-arylfuran-2,3-diones under the action of ethyl cyanoacetate or of malonic acid dinitrile resulting in the corresponding esters or nitriles of 2-amino-5-(2-aryl-2-oxoethylidene)-4-oxo-1Н-4,5-dihydrofuran-3-carboxylic acids was investigated.     

Synthesis and biotests of 2-aryl-5-arylmethylidene-substituted 1,3-oxazol-5(4<Emphasis Type="Italic">H</Emphasis>)-ones and <Emphasis Type="Italic">N</Emphasis>-methyl-3,5-dihydro-4<Emphasis Type="Italic">H</Emphasis>-imidazol-4-ones as combretastatin A-4 analogs

A series of 2-aryl-5-arylmethylidene-1,3-oxazol-5(4H)-ones and 2-aryl-5-arylmethylidene-N-methyl-3,5-dihydro-4H-imidazol-4-ones was synthesized as structural analogs of combret- astatin A-4 (a compound possessing antitumor activity). (5Z)-5-[(4-Methoxyphenyl)methyl-idene]-3-methyl-2-(4-methylphenyl)-3,5-dihydro-4H-imidazol-4-one was found to exhibit the highest cytotoxicity against cells of human A549 lung carcinoma line (EC₅₀ = 6±0.8 μmol L^?1).