Synthesis of dihydrosilanaphthoindolizines and dihydrosilaazaaceanthrelenes

New heterocyclic systems, dihydrosilanaphthoindolizines and dihydrosilaazaaceanthrelenes, have been synthesized starting from 9,10-dihydro-9-sila-3-azaanthracenes. Substituted 6,11-dihydro-6-silanaphtho[2,3-g]indolizines were obtained as a result of 1,3-dipolar cycloaddition reaction of dimethylacetylenedicarboxylate with the quaternary salts of dihydrosilaazaanthracenes having a N-phenacyl group. In a similar manner, substituted 3H,6H-6-sila-3-azaaceanthrelenes, a new pseudoazulene system, have been synthesized from N-benzyl (methyl) quaternary salts. Dihydrosilanaphthoindolizine, having a linear linkage of the dihydrosilanaphtholene and the indolizine cycles has been synthesized from the corresponding dihydrosilaazaanthracene quaternary salt using the Tschitschibabin method.     

Synthesis and properties of polymers containing aromatic amino groups in the main chain and their glass-forming model compounds

Polymers containing di(carbazol-3-yl)phenylamine and N,N^′-di(carbazol-3-yl)-N,N^′-diphenyl-1,4-phenylenediamine units in the main chain have been synthesized by a modified Ullmann condensation as a key step. The number-average molecular weights of the polymers synthesized were in the range of 2300-4800 with a molecular weight distribution of 1.42-2.25. Well defined model compounds of the title polymers were synthesized by stepwise reactions. All the materials exhibit high thermal stability with the initial weight loss temperatures exceeding 320 °C and form glasses. Their glass transition temperatures range from 102 to 216 °C as characterised by differential scanning calorimetry. The electron photoemission spectra of thin films of the synthesized compounds have been recorded and the ionisation potentials of 5.0-5.1 eV have been established.     

Synthesis,characterization and biological activities of some azo derivatives of aminothiadiazole derived from nicotinic and isonicotinic acids

In this study we synthesized the new compounds containing bis-1,3,4-thiadiazole 3(A–D)_n from many reaction steps (cyclization, diazotization and etherification respectively). The compounds have been characterized by melting point, FT-IR and ¹H NMR data. All the synthesized compounds have been evaluated in vitro for their antimicrobial activities against several microbes like: Escherichia coli, Klebsiellia pneumonia, Pseudomonas aeruginosa, Serratia marscens and Staphylococcus aureus and show that some of these compounds have very good antibacterial activity.     

Synthesis of novel rhodium phosphite catalysts for efficient and selective isomerization-hydroformylation reactions

New modular H₈-BINOL-based phosphite ligands have been synthesized. High activity and regioselectivity has been achieved in the rhodium-catalyzed isomerization-hydroformylation of internal olefins. The active catalysts have been characterized by insitu NMR studies.     

Stereochemistry of the tin—carbon bond: I. Synthesis and characterization by 13C and 119Sn NMR of a series of exo- and endo-2-triorganostannylnorbornanes

A series of endo- and exo-2-triorganostannylnorbornanes have been synthesized by various methods, some of them leading to pure stereoisomers. The 2-triorganostannylnorbornanes have been characterized by their ¹³C and ¹¹⁹Sn NMR spectra.     

Synthesis of cesium selective pyridyl azocalix[n]arenes

A series of pyridylazo calix[n]arenes (n=4, 6, 8) including the first examples of mixed hetroaryl azocalix(n)arenes have been synthesized by coupling calix[n]arenes with diazonium salts derived from amino pyridines. It has been observed that the coupling reaction of diazonium salt obtained from 3-aminopyridine with calix[n]arene gives tetrakis-, hexakis- and octakis (pyridylazo)calix[n]arenes (n=4,6,8) while those derived from 4-aminopyridine give partially substituted (4-pyridylazo)calix[n]arene analogs. There is no reaction of calix(n)arenes with diazonium salts derived from 2-aminopyridine under identical conditions of experiments. The conformational analysis of synthesized compounds have been ascertained by detailed spectral measurements and single crystal X-ray analysis of 5-(3′-pyridylazo)-25,26,27,28-tetrahydroxycalix[4]arene. A rational explanation for the observed partial and exhaustive coupling reaction in the synthesis of heteroaryl azocalix(n)arenes has been suggested. Preliminary evaluation of synthesized derivatives as molecular receptors for metal ions indicates that they have good potential to function as selective ionic filters for cesium ions.     

Chiral ferrocenyl diphosphines for asymmetric transfer hydrogenation of acetophenone

The synthesis of new optically pure ferrocenyl diphosphines have been realized from (R)-(+)-N,N-dimethylaminoethylferrocene. Particularly, dissymmetric ferrocenyl diphosphines have been synthesized. The diphosphines have been used as ligands in asymmetric transfer hydrogenation of acetophenone in the presence of Ru catalysts.     

Synthesis of hydrazones of anabasinylacetic acid and structure of its isopropylidenehydrazone

Some hydrazones based on N-anabasinylacetic acid hydrazide have been synthesized. Structure of N′-isopropylidenehydrazone of N-anabasinylacetic acid has been studied by X-ray diffraction.     

Synthesis and functional properties of thermosensitive polymer derivatives of proteins

N,N-Diethylacrylamide-N-acryloylphthalimide copolymers have been synthesized. The LCST of the synthesized copolymers decreases with increase in both the molecular mass of the copolymers and the content of more hydrophobic N-acryloylphthalimide units. Through the reaction of the copolymers with the proteinase enzyme inhibitor, ovomucoid, the polymer derivatives of protein have been prepared. It has been shown that the biological activity of ovomucoid and the LCST of polymer derivatives increase with the amount of the immobilized ovomucoid. The effect of biologically active media on the LCST values of polymer derivatives has been studied.     

5-Substituted pyrimidine derivatives

The properties and reactivities of 4-hydroxy- and 2,4-dihydroxy-5-(β-hydroxyethyl)pyrimidines and of the products of their transformations have been studied. 4-Chloro- and 2,4-dichloro-5-(β-chloroethyl)pyrimidines have been obtained. A number of 4-alkyl(aryl)amino-5-(β-chloroethyl)pyrimidines have been synthesized, and they have been converted into derivatives of 5,6-dihydropyrrolo[2,3-d]pyrimidine.     

Green chemical synthesis of fluorinated 1,3,5-triaryl-s-triazines in aqueous medium under microwaves as potential antifungal agents

Reasonable pure fluorinated s-triazines were synthesized in quantitative yield (96-99%) in 2-3 min in aqueous medium under microwaves, by reaction of fluorinated anilines and aqueous formaldehyde. All synthesized compounds have been screened in vitro for their antifungal activity against Rhizoctonia solani, Fusarium oxysporum, and Collectotrichum capsici.     

(N,N-dimethylbenzylamine-2C,N)palladium(II) and -platinium(II) β-diketonates and thio-β-diketonates

(N,N-dimethylbenzylamine-2C,N)palladium(II) and -platinum(II) β-diketonates, DmbaML, have been synthesized by reaction of [DmbaMCl]₂ with the free ligand and KOH, or with the thallium(I) salt of the ligand. The various isomers formed have been investigated by ¹H and ¹⁹F NMR spectroscopy. Infrared and mass spectroscopic studies have also been made on the compounds.     

Synthesis and magnetic properties of CuCr1.5Sb0.5S4 ? x Se x solid solutions

CuCr_1.5Sb_0.5S_{4 ? x} Se _x (x = 0, 0.5, 3.5, 4) metal chalcogenides with spinel structure have been synthesized for the first time. Unit cell parameters have been calculated and magnetic properties have been measured for the samples prepared. These samples are nonuniform antiferromagnets having Neel temperatures of T _N = 21?C30 K.     

Synthesis of liquid crystalline materials based on 1,3,5-triphenylbenzene and 2,4,6-triphenyl-1,3,5-s-triazine

C₃-symmetric alkyloxy/aryloxy polyether dendrimers have been synthesized from 1,3,5-triphenylbenzene and 2,4,6-triphenyl-1,3,5-s-triazine and their liquid crystalline properties have been studied. C₃-symmetric derivatives with n-hexyl and n-dodecyl chains at the periphery show mesophase properties when they are complexed with trinitrofluorenone at different temperatures.     

Synthesis of all 7αH-guaia-4,11-dien-3-one diastereomers from (+)-dihydrocarvone

All four 7αH-guaia-4,11-dien-3-one diastereomers have been synthesized from the common intermediate 1αH,10α-acetoxy-7αH-guaia-4,11-dien-3-one obtained from (+)-dihydrocarvone. The spectral features of the four diasteromers have been correlated and the structure and absolute configuration of 1βH,10βH,7αH-guaia-4,11-dien-3-one isolated from Pleocarphus revolutus has been confirmed.     

Alcohols of the nitrofuran series

By reducing the corresponding aldehydes with sodium borohydride,α-ethyl-β-(5-nitro-2-furyl)allyl alcohol and 5-(5-nitro-2-furyl)penta-2, 4-dienol have been obtained. A number of their esters have been synthesized.     

Total syntheses of cyclitol based natural products from myo-inositol: brahol and pinpollitol

Inositol and their derivatives are important class of biologically active natural products. Among the nine theoretically possible inositols, six are known to occur in nature. Interestingly one or more methyl ethers of these inositols have been isolated from plants and these methyl inositols are presumed to have important functions in plant biology. Brahol and pinpollitol are two naturally occurring methylated inositols reported to have allo-inositol and chiro-inositol configurations, respectively. Adopting our sulfonate inversion strategies for synthesizing protected chiro- and allo-inositols from cheaply available myo-inositol in combination with new methods we have achieved the total syntheses of these methylated inositols. The proposed structure of brahol has been synthesized in six steps from myo-inositol. We have not only disproved the proposed structure of brahol but also established its correct structure. Also, we have efficiently synthesized pinpollitol and its positional isomer from myo-inositol. These works involve several selective protection-deprotection strategies of inositol hydroxyl groups.     

Convenient method for the synthesis of C-phosphorylated N-arylformamidines

C-Phosphorylated (P^V) arylformamidines have been prepared by the reaction of N-arylamidotrichloromethyl derivatives of phosphorus, thiophosphorus, and selenophosphorus acids with secondary amines. Dependence of the reaction on the nature of chalcogene, electronic and steric factors has been studied. By reduction of N-arylformamidinophosphonoselenides the corresponding C-phosphorylated (P^III) arylformamidines have been synthesized.     

Chiral N-phosphonyl imine chemistry: new reagents and their applications for asymmetric reactions

Novel chiral N-phosphonyl imines 2 have been designed and synthesized using chiral N-phosphoramide 1. These N-phosphonyl imines have been successfully utilized for asymmetric aza-Darzens reaction and asymmetric aza-Henry reaction. The C₂-symmetric chiral auxiliary tolerates oxidation, is not sensitive to racemization and can be recycled for large scale synthesis.     

Regioselective synthesis and antioxidant activity of a novel class of mono and C2-symmetric bis-1,2,3-triazole and acridinedione grafted macromolecules

An expedient regioselectivesynthesis of novel mono, C₂-symmetric bis-triazole and acridinedione bridged macromolecules has been achieved in good yields employing intermolecular Cu(I) catalyzed azide and alkyne click reaction. Synthesis of O-propargyl acridinedione was achieved in three good yielding steps starting from dimedone, while the symmetrical aliphatic and aryl bis-azides were derived from appropriate dibromides in the presence of sodium azide in dry DMF. The synthesized mono and C₂-symmetric bis-macromolecules have been elucidated by ¹H, ¹³C, elemental and mass spectroscopic analysis. The antioxidant activity of synthesized compounds has also been investigated.