Synthesis and Reactions of Novel Pyrimido[4,5-<Emphasis Type="Italic">c</Emphasis>]pyridazine and <Emphasis Type="Italic">s</Emphasis>-Triazolo[3′,4′:2,3]pyrimido[4,5-<Emphasis Type="Italic">c</Emphasis>]pyridazine Derivatives

Summary. The reaction of 3-chloro-5,6-diphenylpyridazine-4-carbonitrile with potassium thiocyanate gave the corresponding isothiocyanate derivative. This was reacted with aromatic amines in ethanol to afford pyrimido[4,5-c]pyridazine derivatives. The reaction of the latter compounds with hydrazine hydrate led to the formation of 6-hydrazino derivatives. One hydrazino compound was reacted with a variety of reagents to produce other new pyrimidopyridazines as well as a number of s-triazolo derivatives.     

Synthesis of imidazo[4,5-<Emphasis Type="Italic">e</Emphasis>]benzo[1,2-<Emphasis Type="Italic">c</Emphasis>;3,4-<Emphasis Type="Italic">c</Emphasis>´]difuroxanes

A method for the synthesis of imidazo[4,5-e]benzo[1,2-c;3,4-c´]difuroxanes, potential nitric oxide donors, has been developed. The synthesized compounds were characterized by IR and NMR spectroscopy, high resolution mass spectrometry, and elemental analysis.     

Synthesis of New Thieno[2,3-<Emphasis Type="Italic">b</Emphasis>:5,4-<Emphasis Type="Italic">c</Emphasis>′]dipyridines

Summary. We describe the formation of thieno[2,3-b:5,4-c]dipyridines from 5,6-dihydropyridine-2(1H)-thiones. The two-step reaction mechanism was revealed by isolation of an intermediate. The oxo and thioxo groups of the obtained tricyclic compounds were hydrogenated selectively. The structures of all new compounds were elucidated by NMR experiments.Received December 17, 2002; accepted December 20, 2002 Published online June 2, 2003     

The synthesis of substituted 5-aminopyrido[3′,2′:4,5]thieno[3,2-<Emphasis Type="Italic">c</Emphasis>]isoquinolines and their sulfinyl and sulfonyl derivatives

5-Aminopyrido[3′,2′:4,5]thieno[3,2-c]isoquinolines were synthesized via alkylation of 3-cyanopyridine-2(1H)-thiones with 2-(chloromethyl)benzonitrile followed by treatment of the products with potassium tert-butoxide. The oxidation of the alkylated products to corresponding sulfoxides or sulfones followed by treatment with potassium tert-butoxide provided the corresponding 11-oxides or 11,11-dioxides.     

Derivatives of Condensed Thienopyrimidines. 22. Synthesis of 2-Substituted 4-Thioxopyrano[4′,3′:4,5]thieno[2,3-<Emphasis Type="Italic">d</Emphasis>]pyrimidines

A method has been developed for the synthesis of 4-thioxopyrano[4,3: 4,5]thieno[2,3-d]pyrimidines from the corresponding acyl derivatives of 2-amino-3-cyanothieno[2,3-c]pyran.__________Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, 267–269, February, 2005.     

A convenient synthesis of pyrrolo[2,3-<Emphasis Type="Italic">b</Emphasis>]pyridines and pyrido[2′,3′:5,4]pyrrolo[2,3-<Emphasis Type="Italic">d</Emphasis>]pyrimidines

2-Chloro-6-ethoxy-4-phenylpyridine-3,5-dicarbonitrile was taken as versatile building block that allows the synthesis of 1H-pyrrolo[2,3-b]pyridine, thieno[2,3-b]pyridine and pyrido[2′,3′:5,4]pyrrolo[2,3-b]pyrimidine systems. Some of the synthesized compounds were screened as antibacterial agents. Correspondence: Shawkat A. Abdel-Mohsen, Chemistry Department, Faculty of Science, Assiut University, Assiut 71516, Egypt.     

Hetero-Diels–Alder reaction of 3-aroylpyrrolo[2,1-<Emphasis Type="Italic">c</Emphasis>][1,4]benzoxazines with styrene. Synthesis of pyrano[4′,3′: 2,3]pyrrolo[2,1-<Emphasis Type="Italic">c</Emphasis>][1,4]benzoxazines

The hetero-Diels–Alder reaction of 3-aroylpyrrolo[2,1-c][1,4]benzoxazine-1,2,4-triones with styrene afforded mixtures of diastereoisomeric (10R*,11aR*)- and (10S*,11aR*)-8-aryl-10-phenyl-10,11-dihydropyrano[4′,3′: 2,3]pyrrolo[2,1-c][1,4]benzoxazine-6,7,12-triones.     

Heterocycles with a bridging nitrogen atom. 15. The novel recyclization of dipyrido[1,2-<Emphasis Type="Italic">a</Emphasis>:1′,2′-<Emphasis Type="Italic">c</Emphasis>]-imidazolium salts to pyrido[1,2-<Emphasis Type="Italic">a</Emphasis>]-benzimidazole-8-carboxaldehydes

A previously unknown recyclization of an 11-acyldipyrido[1,2-a:1,2-c]imidazolium cation to 8-formyl-9-methyl(aryl)pyrido[1,2-a]benzimidazoles has been discovered. The proposed reaction mechanism includes a selective opening of one of the pyridinium rings and the formation of a benzaldehyde fragment via condensation of the intermediate with the participation of the acyl group.__________Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 1, pp. 135–139, January, 2005.     

Fused pyridothienopyrimidine heterocycles. 2*. A facile and efficient synthesis of the annelated pyrido[3′,2′:4,5]thieno-[2,3-<Emphasis Type="Italic">e</Emphasis>]pyrimido[3,2-<Emphasis Type="Italic">c</Emphasis>]pyrimidones

The cyclocondensation reactions of 4-aminopyridothienopyrimidine with malonates and their acetylation were studied. All structures were determined by ¹H NMR and mass spectra techniques.     

Polynitromethyl derivatives of furazano[3,4-<Emphasis Type="Italic">e</Emphasis>]di([1,2,4]triazolo)-[4,3-<Emphasis Type="Italic">a</Emphasis>:3′,4′-<Emphasis Type="Italic">c</Emphasis>]pyrazine as components of solid composite propellants

The energetic potential of solid composite propellants (SCP) with furazano[3,4-e]di([1,2,4]- triazolo)[4,3-a:3′,4′-c]pyrazine including trinitromethyl (C(NO₂)₃), fluorodinitromethyl (CF(NO₂)₂), and (difluoroamino)dinitromethyl (C(NF₂)(NO₂)₂) groups was estimated based on thermochemical calculations. It was shown that C(NO₂)₃ and C(NF₂)(NO₂)₂ derivatives can constitute the basis of metal-free compositions of SCP with a specific impulse from 251 to 263 s, i.e., comparable or superior in efficiency to HMX-based propellants.     

Determination of the <Emphasis Type="Italic">R</Emphasis> ⇄ <Emphasis Type="Italic">S</Emphasis> enantiomerization barrier in 5,6-dihydrobenzoimidazo[1,2-<Emphasis Type="Italic">c</Emphasis>]quinazolines

Chiral imidazoquinazolines undergoing thermally induced reversible R ⇄ S enantiomerization have been synthesized by the interaction of 2-(o-aminophenyl)benzimidazoles with aldehydes and ketones. The benzimidazole fragment has been used for the first time as an indicator group in temperature-dependent ¹H NMR spectra for determining the energy barrier of this rearrangement. The effects of nearby substituents on the kinetic and activation parameters, and on the recyclization mechanism have been investigated.     

Synthesis of Pyrano[4′,3′:2,3]pyrrolo[1,2-<Emphasis Type="Italic">a</Emphasis>]quinoxalines by Reaction of Aroylpyrroloquinoxalines with Alkyl Vinyl Ethers

Thermally induced [4 + 2]-cycloaddition of 3-aroylpyrrolo[1,2-a]quinoxaline-1,2,4(5H)-triones with alkyl vinyl ethers afforded mixtures of diastereoisomeric (5S*,6aR*)- and (5R*,6aR*)-5-alkoxy-3-aryl-5,6-dihydropyrano[ 4′,3′: 2,3]pyrrolo[1,2-a]quinoxaline-1,2,7(8H)-triones.     

Synthesis and structure of a new heterocyclic system – 7,8-dihydroimidazo- [1,2-<Emphasis Type="Italic">c</Emphasis>][1,3]thiazolo[4,5-<Emphasis Type="Italic">e</Emphasis>]pyrimidine

The purpose-directed synthesis of a new heterocyclic system, 7,8-dihydroimidazo[1,2-c][1,3]thia- zolo[4,5-e]pyrimidine has been carried out based on the successive interaction of available 2-(aroyl- aminocyanomethylene)imidazolidines with hydrogen sulfide and triethyl orthoformate with subsequent intramolecular cyclocondensation of the obtained 8-aroylamino-7-thioxo-1,2,3,7-tetrahydroimidazo- [1,2-c]pyrimidines under the action of phosphorus pentasulfide or polyphosphoric acid.     

Thermal transformations of 7-aryl-1,6-diazabicyclo[4.10]heptanes and 6,13-diarylperhydrodipyridazino-[1,2-<Emphasis Type="Italic">a</Emphasis>: 1′,2′-<Emphasis Type="Italic">d</Emphasis>]-1,2,4,5-tetrazines

The thermolysis of 7-aryl-1,6-diazabicyclo[4.1.0]heptanes in the absence of 1,3-dipolarophiles leads to dimers of the initially formed azomethineimines, namely, 6,13-diaryloctahydrodipyridazino[1,2-a:1′,2′ Dedicated to the memory of A. A. Potekhin. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 1062–1070, July, 2008.     

<Emphasis Type="Italic">N</Emphasis>-arylsulfanyl-<Emphasis Type="Italic">N</Emphasis>-arylsulfonyl(acyl)-<Emphasis Type="Italic">N</Emphasis>′-phenylthiourea sodium salts

Reactions of N-arylsulfonyl(acyl)arenesulfenamide sodium salts with phenyl isothiocyanate afforded N-arylsulfanyl-N-arylsulfonyl(acyl)-N-phenylthioura sodium salts which were found to increase thermal stability of finely dispersed poly(vinyl chloride).Translated from Zhurnal Organicheskoi Khimii, Vol. 40, No. 10, 2004, pp. 1532–1535.Original Russian Text Copyright © 2004 by Koval, Oleinik.     

Polymorphism of bimolecular crystals of CL-20 with tris[1,2,5]oxadiazolo[3,4-<Emphasis Type="Italic">b</Emphasis>:3´,4´-<Emphasis Type="Italic">d</Emphasis>:3″,4″-<Emphasis Type="Italic">f</Emphasis>]azepine-7-amine

New bimolecular crystals (BMCs) of 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane (CL-20) with tris[1,2,5]oxadiazolo[3,4-b:3´,4´-d:3″,4″-f]azepine-7-amine (AZ2) were synthesized. Four different crystal structures — two polymorphic modifications with the CL-20: AZ2 ratio of 1: 1 (BMCs 1 and 2) and two polymorphic modifications with the ratio of 1: 2 (BMCs 3 and 4) — were obtained depending on the crystallization conditions. These crystals were studied by X-ray diffraction. The results of quantum chemical calculations indicate that the new η-conformation found in crystal 1 is not a stable conformer of CL-20 and its existence is attributed to the crystal packing effects in structure 1.     

Synthesis and reactivity of 2-(2-furyl)-1,7-dimethyl-1<Emphasis Type="Italic">H</Emphasis>,7<Emphasis Type="Italic">H</Emphasis>-benzo[1,2-<Emphasis Type="Italic">d</Emphasis>: 3,4-<Emphasis Type="Italic">d</Emphasis>′]diimidazole

2-(2-Furyl)-1,7-dimethyl-1H,7H-benzo[1,2-d: 3,4-d′]diimidazole was synthesized by the Weidenhagen reaction followed by N-methylation. Electrophilic substitution reactions of the title compound (nitration, bromination, sulfonation, formylation, and acylation) involved both the furan ring and central benzene fragment.     

Synthesis of thiopyrano[4″,3″:4′,5′]pyrido[3′,2′:4,5]furo[3,2-d]pyrimidines

<正>Reactions of the 6-hydroxy-thiopyrano[3,4-c]pyridine-5-carbonitrile derivative 1 withα-halo-carbonyl compounds gave the ortho-substituted intermediates 2a-c which were converted into furo[2,3-b]thiopyrano[4,3-d]pyridines 3a-c by fusion of a furan moiety under basic conditions.Further cyclization of 3a-c led to a fusion of a pyrimidine ring,yielding the tetracyclic products 6,7 and 8.In addition,condensation of 6 with various aromatic aldehydes afforded the corresponding imines 9a,b.Mannich reaction of 7 gave products 10a,b.     

Synthesis and structures of substituted 5,6-dihydro-spiro(benz[4,5]imidazo[1,2-<Emphasis Type="Italic">c</Emphasis>]quinazoline-6,3′-indolin)-2′-ones

The reactions of 2-(2-aminophenyl)benzimidazole with substituted isatins afforded the corresponding 5,6-dihydrospiro(benz[4,5]imidazo[1,2-c]quinazoline-6,3indolin)-2-ones. The spirocyclic structure of the reaction products was established by NMR spectroscopy and X ray diffraction analysis.Results of the study were presented at the International Conference Modern Trends in Organoelement and Polymer Chemistry dedicated to the 50th anniversary of the A. N. Nesmeyanov Institute of Organoelement Compounds of the Russian Academy of Sciences (May 30–June 4, 2004, Moscow).Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1987–1989, September, 2004.