3,4-ِDihydropyrano[c]chromene derivatives were synthesized using sulfonic acid functionalized silica (SiO2-Pr-SO3H) as a highly efficient heterogenous solid acid catalyst via one-pot three-component condensation of aromatic aldehydes with malononitrile and 4-hydroxycoumarin in excellent yields.

Silica boron sulfonic acid [SiO2–B(OSO3H)3] as an inexpensive, reusable, and Lewis and Brønsted acid catalyst was successfully synthesized, and used for the one-pot three-components synthesis of biologically active substituted Hantzsch 1,4-dihydropyridine derivatives  in the absence of solvent at 90ºC. Silica boron sulfonic acid is attractive and efficient, because it plays in two role as a Lew...

      Plants of Asteraceae are used in traditional medicine and phytotherapy. The two main caffeic acid derivatives, chicoric and caftaric acid which are found in many genus of Asteraceae including Echinacea exhibit important biological activities. The level of these acids in E. purpurea is affected by many factors such as growing situations, extraction methods, storage condit...

From the ethyl acetate soluble fraction of a methanol/water extract of the herb Eupatorium perfoliatum L. (Asteraceae) six caffeic acid derivatives have been isolated and identified by 1D- and 2D-NMR spectroscopic data. Besides the common quinic acid derivatives 5-caffeoylquinic acid (chlorogenic acid), 3-caffeoylquinic acid (neochlorogenic acid) and 3,5-dicaffeoylquinic acid, three up to now u...

Surface modification of nanocrystalline TiO(2) particles (45 A) with bidentate benzene derivatives (catechol, pyrogallol, and gallic acid) was found to alter optical properties of nanoparticles. The formation of the inner-sphere charge-transfer complexes results in a red shift of the semiconductor absorption compared to unmodified nanocrystallites. The binding structures were investigated by us...

Silanes, Silylbenzenes, Di(silyl)benzenes. Bromo(silyl)benzenes 1,2-Di(silyl)benzene (3). has been prepared in a three-step process starting with the reac­ tion of 1 ,2-dibromobenzene and /?-tolyl(chloro)silane with magnesium in tetrahydrofuran, which affords l,2-bis(p-tolylsilyl)benzene (1) as a stable high-yield intermediate. Compound 1 has been converted into 1 .2-bis(trifluoromethanesulfona...

plants of asteraceae are used in traditional medicine and phytotherapy. the two main caffeic acid derivatives, chicoric and caftaric acid which are found in many genus of asteraceae including echinacea exhibit important biological activities. the level of these acids in e. purpurea is affected by many factors such as growing situations, extraction methods, storage conditions and plant age. in t...

Stable radical cations of dimeric amino acid derivatives of tryptophan and tyrosine were generated by collision-induced dissociation of [Cu(II)(diethylenetriamine)(amino acid derivative)2]*2+. The yields of the dimer radical cations were dependent on both the auxiliary ligand and the tryptophan or tyrosine derivatives used. Amino acid derivatives with an unmodified carboxylic acid group did not...

a series of novel 2-aminopyrimidine and 2-substituted-4,6-diaminopyrimidine derivatives have been synthesized and their anti platelet aggregation activities were assessed against adp and arachidonic acid- induced platelet aggregation in human plasma using light transmission aggregometry. none of the compounds showed satisfactory activity against the aggregation induced by adp. however, satisfac...

electrochemical oxidation of some selected catechol derivatives, using cyclic voltammetry, in the presence of different 2-aryl-1,3-indandiones as nucleophiles, resulted in electrochemical synthesis of new 1,3- indandione derivatives in an undivided cell in good yield and purity. a michael addition mechanism was proposed for the formation of the analogs based on the reaction conditions which wer...