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     

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.     

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.     

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.     

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.     

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.     

New photochromic 1,1,3-trimethylspiro[benzo[<Emphasis Type="Italic">e</Emphasis>]indoline-2,3′-[3<Emphasis Type="Italic">H</Emphasis>]-pyrano[3,2-<Emphasis Type="Italic">f</Emphasis>]quinoline]

A new photochromic spiropyran of the benzoindoline series containing the quinoline moiety was synthesized. Its structure was determined by IR and ¹H NMR spectroscopy. The crystal structure of the new compound was established by X-ray diffraction. The photochromic properties of the synthesized spiropyran were investigated.     

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.     

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.     

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.     

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.     

<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.     

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.     

Basicity of Highly Substituted β-Octaalkyl-<Emphasis Type="Italic">meso</Emphasis>-aryl- and -<Emphasis Type="Italic">meso</Emphasis>-thienyl Porphyrins

5-Phenyl-, 5,15-diphenyl-5,15-di(thiophen-2-yl)-, and 5,10,15,20-tetraphenyloctaalkyl-21H,23H-porphyrins in benzene–acetic acid mixtures are moderate bases (pK–0.27 to–2.48). There is no simple correlation between the basicity constants and any electronic or geometric structure parameter of their molecules due to the contributions of three factors to the basicity: distortion of the planar structure in highly substituted macrocycles and their protonated forms, positive charge delocalization over the conjugated bond system, and electronic effects of substituents.     

Novel <Emphasis Type="Italic">β</Emphasis>-<Emphasis Type="Italic">N</Emphasis>-acetylglucosaminidases from <Emphasis Type="Italic">Vibrio harveyi 650</Emphasis>: Cloning,expression, enzymatic properties,and subsite identification

Background  

Since chitin is a highly abundant natural biopolymer, many attempts have been made to convert this insoluble polysaccharide into commercially valuable products using chitinases and β-N-acetylglucosaminidases (GlcNAcases). We have previously reported the structure and function of chitinase A from Vibrio harveyi 650. This study t reports the identification of two GlcNAcases from the same organism and their detailed functional characterization.     

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.     

Production and Accumulation of 4-<Emphasis Type="Italic">O</Emphasis>-Methyl-α-<Emphasis Type="SmallCaps">d</Emphasis>-Glucuronosyl-Xylotriose by Growing Culture of Thermophilic <Emphasis Type="Italic">Anoxybacillus</Emphasis> sp. Strain JT-12

A thermophilic Anoxybacillus sp. strain JT-12, isolated from soil, produced acidic xylotriose, 4-O-methyl-α-d-glucuronosyl-xylotriose (MeGlcAX₃), as a main product from birchwood xylan and accumulated them in the culture under optimum conditions at pH 7.0 and 55 °C using 0.75% (w/v) birchwood xylan as a carbon source for 42–72 h. The acidic xylotriose was purified by ethanol precipitation and high-performance liquid chromatography using NH₂ Lichosher® 100 column. The results of electrospray ionization mass spectrometry, mass to charge ratio (m/z) 603.23, confirmed that the purified sample was acidic xylotriose that had benefits and applications in many fields.