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     

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.     

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 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.     

Carbo[3 + 3] cyclocondensation reactions. A new method for the synthesis of tetrahydropyrazolo[1,5-<Emphasis Type="Italic">b</Emphasis>]quinazolines and tetrahydropyrazolo[4,5-<Emphasis Type="Italic">b</Emphasis>]quinolines

The cyclocondensation of substituted 5-aminopyrazoles with benzylidene acetone leads to the regioselective synthesis of dihydropyrazolo[1,5-a]pyrimidines and dihydropyrazolo[3,4-b]pyridines containing a methyl group in the six-membered heterocycle. Compounds of both these groups readily undergo carbo[3 + 3] cyclo-condensation with chalcones in butanol under alkaline catalysis conditions and upon heating to give aryl-substituted tetrahydropyrazolo[1,5-b]quinazolines and tetrahydropyrazolo[4,5-b]quinolines. Ultrasonic initiation of these reactions leads to enhanced rate and higher yield of the desired products.     

Alkyl <Emphasis Type="Italic">β</Emphasis>-<Emphasis Type="SmallCaps">d</Emphasis>-cellulosides: non-reducing cellulose mimics

Non-reducing cellulose mimics, termed alkyl β-d-cellulosides, were successfully prepared by two efficient multi-step syntheses starting from commercially available microcrystalline cellulose or cellulose triacetate. Introduction of the alkoxy moiety and degradation of the cellulose backbone was carried out in the presence of a Lewis acid, on one hand. On the other hand, cellulose hydrolysis mediated by mineral acids was combined with β-glycosidation performed in the presence of silver salts. The samples obtained possess a number-average degree of polymerization from 5 to 25, determined by size-exclusion chromatography, elemental analyses, NMR spectroscopy, and MALDI-TOF mass spectrometry. Samples in multi-gram quantities were available. Selective formation of a β-glycosidic bond between the C-1 atom of the reducing end group and alkoxy moieties was confirmed by a combination of 2D NMR spectroscopic and MALDI-TOF MS techniques. Due to the blocking of the aldehyde function, the cellulosides described are very useful mimics for the investigation of polysaccharide interactions with other complex molecules such as proteins or to determine polymer properties in solution or in solid state.     

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 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.     

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.     

<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.     

Synthesis of hydrogenated 2,7-dimethylpyrrolo[3,4-<Emphasis Type="Italic">b</Emphasis>]indoles – analogs of dimebon

A schemes have been proposed for the synthesis of novel 4-substituted 2,7-dimethyl-3,4-dihydro-1H- and previously unknown 2,7-dimethyl-cis-1,2,3,3a,4,8b-hexahydropyrrolo[3,4-b]indoles. In the case of the Dimebon structural analog 2,7-dimethyl-4-[2-(6-methylpyridin-3-yl)ethyl]-3,4-dihydro-1H-pyrrolo-[3,4-b]indole a broad spectrum of pharmacological activity was found in the hydrogenated pyrroloindoles suitable for the development of medicines via the “magic bullet” concept. A strong dependence of the antagonist relationship of the synthesized compounds towards histamine H₁ and serotonin 5-HT₆ receptors with the nature of the substituent in the 4 position and the degree of hydrogenation of the pyrrolo[3,4-b]indoles was demonstrated.     

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.     

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.     

Enhanced Production of an Extracellular β-<Emphasis Type="SmallCaps">d</Emphasis>-Fructofuranosidase Fructohydrolase from a 2-Deoxy-<Emphasis Type="SmallCaps">d</Emphasis>-glucose Stabilized Mutant of <Emphasis Type="Italic">Candida utilis</Emphasis>

The enzyme β-d-fructofuranosidase fructohydrolase (FFH) cleaves the α-1,4 glycosidic linkage between α-d-glucose and β-d-fructose molecules of sucrose, releasing monosaccharides by hydrolysis. In the present study, FFH production in Candida utilis GC-46, a lipolytic wild yeast strain was improved by exposure to N-methyl N-nitro N-nitroso guanidine (NG) and 2-deoxy-d-glucose (2dg) at various levels. The mutant strain NG-5 was obtained after exposure to 0.06 mg/ml of NG for 20 min. NG-5 offers improved extracellular FFH production (34 ± 2.6 U/ml/min) when compared to the wild strain (1.15 ± 0.01 U/ml/min). A 40-fold increase of FFH (45.65 ± 2.0 U/ml/min) was achieved when the process parameters, including incubation period (48 h), sucrose concentration (5.0 g/l), initial pH (6.0), inoculum size (2.0% v/v, 16 h old), and urea concentration (0.2%, w/v) were identified using Plackett–Burman design. The kinetic parameters viz. Q _p (0.723 U/g/h), Y _p/s (2.036 U/g), and q _p (0.091 U/g yeast cells/h) indicate that NG-5 is a hyperproducer of extracellular FFH with a concomitant increase in growth rate. The volumetric productivity of NG-5 was over sixfold improved over the parental strain. The enzyme production improvement is highly significant (HS, LSD 0.042, p ≤ 0.05), indicating commercial utility.     

Hydrothermal synthesis and crystal structure of a new 3<Emphasis Type="Italic">d</Emphasis>–4<Emphasis Type="Italic">f</Emphasis> complex generated from the IDA ligand

An interesting 3d–4f complex [CeCo(HIDA)(IDA)₂] _n (I) (IDA = iminodiacetic acid) was synthesized under hydrothermal conditions and characterized by IR, TG, and single-crystal X-ray diffraction analysis. Complex I crystallizes in the monoclinic system, space group C2/c with a = 9.7033(19), b = 24.141(5), c = 8.5810(17) Å, β = 115.01(3)°, V = 1821.6(6) ų, Z = 4, ρ _c = 2.152 g/cm³, F(000) = 1148. Crystallographic data for I were collected at 293 K with a Rigaku R-axis Rapid IP diffractometer using graphite monochromatic MoK _α radiation (λ = 0.71073 Å) and IP technique, GOOF = 0.994, the final R = 0.0245 and wR = 0.0763 (I > 2σ(I)). Complex I is a two-dimensional layer structure, in which the Ce(III) center is surrounded by ten oxygen atoms from different IDA ligands. The Co(II) center is six-coordinated by four oxygen atoms and two nitrogen atoms from two different IDA ligands. The carboxylic oxygen atom connected such units along the z axis to form a one-dimensional chain-like structure. The IDA ligand connects neighboring chains to form a two-dimensional layer structure.     

Preparation of surfactant-free nanoparticles of methoxy poly(ethylene glycol)-<Emphasis Type="Italic">b</Emphasis>-poly(D,L-lactide-<Emphasis Type="Italic">co</Emphasis>-glycolide-<Emphasis Type="Italic">co</Emphasis>-ɛ-caprolactone)

Surfactant-free nanoparticles of methoxy poly(ethylene glycol)-b-poly(D,L-lactide-co-glycolide-co-ɛ-caprolactone) diblock copolymers (MPEG-b-PDLLGCL) with different DLL:G:CL ratios were prepared by modified-spontaneous emulsification solvent diffusion method. Sizes of resulted colloidal nanoparticles obtained from light-scattering analysis were in the range of 121–132 nm with narrow size distribution. The nanoparticle sizes depended on the composition of the PDLLGCL block. Scanning electron microscopy demonstrated that the nanoparticles were aggregated after drying process, suggested they were soft nanoparticles. However, their initial aggregates can be observed and it was shown that the nanoparticles have spherical shape with smooth surface. The text was submitted by the authors in English.     

Transition metal-free synthesis of quinolino[2′,3′:3,4]pyrazolo[5,1-<Emphasis Type="Italic">b</Emphasis>]quinazolin-8(6<Emphasis Type="Italic">H</Emphasis>)-ones via cascade dehydrogenation and intramolecular <Emphasis Type="Italic">N</Emphasis>-arylation

2-(2-Chloroquinolin-3-yl)-3-(arylamino)-2,3-dihydroquinazolin-4(1H)-one was converted to quinolino[2′,3′:3,4]pyrazolo[5,1-b]quinazolin-8(6H)-ones in the presence of KOtBu in DMSO at room temperature. The present method has the advantages of easy conditions, construction of highly novel five heterocycles, transition metal-free conditions, cascade dehydrogenation and intramolecular N-arylation and good to high yield of products.