Intramolecular 1,3-dipolar cycloaddition of cyclo-1,3-diene-tethered nitrile oxides

Intramolecular 1,3-dipolar cycloaddition of cyclo-1,3-diene- and -1,3,5-triene-tethered nitrile oxides gave tricyclic isoxazolines as a single stereoisomer in most cases. The relative stereochemistry of tricycle-fused isoxazolines resulting from 1,3-dipolar cycloaddition of cyclo-1,3-diene-tethered nitrile oxides is cis-cis, whereas from cyclohepta-1,3,5-triene-tethered nitrile oxides the cis-trans isomer predominates.     

Novel efficient preparative method for phthalocyanines from phthalimides and phthalic anhydride with HMDS

A convenient synthesis of peripherally substituted or unsubstituted phthalocyanines having a variety of metals is described. Phthalocyanines can be obtained by heating phthalimides or phthalic anhydride with metal salts, hexamethyldisilazane, a catalytic amount of p-TsOH, and DMF at 150 degrees C.     

A new total synthesis of (±)-oestrone

A conceptually new total synthesis of oestrone, based on a novel cascade of radical cyclisations from the iodo aryl vinylcyclopropane 2, via 10, 15, 16 and 17, leading to the intermediate trans,anti,trans-oestradiol derivative 11 in one step, is described. Oxidation of 11, followed by demethylation of the resulting aryl methyl ether 18 then gives (±)-oestrone 1.     

Synthesis and antimicrobial activity of N-(substituted)-N'-(2,3-dihydro-2-oxido-5-benzoyl-1H-1,3,2-benzodiazaphosphol-2-yl) ureas

N-(substituted)-N'-(2,3-dihydro-5-benzoyl-2-oxido-1H-1,3,2-benzodiazaphosphol-2-yl) ureas were synthesized by reacting 3,4-diaminobenzophenone (4) with different chlorides of carbamidophosphoric acids (3) in the presence of triethylamine at 40-45 degrees C. Their 1H-, 13C- and 31P-NMR spectral data are discussed. The title compounds were screened for antifungal and antibacterial activity against the fungi Aspergillus niger and Fusarium solani and bacteria Escherichia coli and Staphylococcus aureus. These compounds showed higher antibacterial activity when compared with antifungal activity.     

Gallium(III) halide-catalyzed coupling of indoles with phenylacetylene: synthesis of bis(indolyl)phenylethanes

Indoles undergo smooth coupling with phenylacetylene in the presence of 10 mol % of gallium(III) chloride or gallium(III) bromide under mild conditions to afford the corresponding 1,1-bis(1H-3-indolyl)-1-phenylethanes in high yields and with high selectivity.     

Potassium 3-phenylmethyldithiocarbazate as substoichiometric reagent: Determination of silver

An accurate and rapid radiochemical method has been developed for the determination of silver based on the substoichiometric extraction of its complex with potassium 3-phenylmethyldithiocarbazate into chloroform from pH 5.5 acetate buffer. Microgram amounts of silver could be determined with an average error of ±1.1% and the effect of diverse metal ions was critically examined. The method developed was applied to evaluate the silver content of photofilm washings.     

Catalysis of thiophene hydrogenolysis by bimetallic sulfide catalysts of different compositions

The activity of sulfide catalysts M_I/SiO₂, M_I/WS₂, (M_I,W)/SiO₂ and (Ni,M_II)/SiO₂ (M_I is a first row transition metal, and M_II=Nb, Mo, W or Re) in the thiophene hydrogenolysis reaction has been studied. Activities of mono- and bimetallic catalysts are found to change in the same manner depending upon the nature of M_I. The formation of a sulfide bimetallic species (SBMS) is suggested.

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M_I/SiO₂, M_I/WS₂, (M_I,W)/SiO₂ (Ni, M_II)/SiO₂, M_I — , M_II–Nb, Mo, W, Re. - M_I. .

     

Identification of inhibitors of DNA topoisomerase II from a synthetic library of glycoconjugates

A library of 24 glycoconjugates related to glycosylated beta-amino acid derivative (I) was been prepared and screened against DNA topoisomerase-II of the filarial parasite S. cervi. Among these, compound 6 was found to be a potent inhibitor of DNA topoisomerase-II with 95% inhibition at 1.09 microM. Furthermore, compound 6 was at least three times more potent than the lead compound, glycosylated beta-amino acid derivative I.     

Palladium-catalyzed addition of hydroxylamine derivatives to Baylis-Hillman acetate adducts

The first use of hydroxylamine derivatives as the aminoxy equivalent of nucleophiles in palladium catalyzed addition to Baylis-Hillman acetate adducts is described. The reaction proceeds smoothly to give the substituted allyloxy amines in good yield and selectivity.