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...

Liquid column chromatography, planar chromatography (TLC) on modified and unmodified silica layers, reversed-phase high-pressure liquid chromatography (HPLC), as well as ESI-TOF MS and 1H-NMR have been used for separation, purification and identification of phenolic acids in the barks of Sambucus nigra and Viburnum opulus (Caprifoliaceae). By the use of these procedures three cinnamic acid deri...

β-Cyclodextrin sulfuric acid as a green Lewis acid catalyst has been applied for the preparation of bis(indolyl)methanes, tris(indolyl)methanes and 3,3'-diindolyloxindole derivatives by the condensation of indoles with various carbonyl compounds in aqueous media with high to excellent yields.

Silica-bonded n-propyldiethylenetriamine sulfamic acid (SBPDSA) was found as an efficient solid acid for the synthesis of coumarins. Coumarin derivatives were obtained via the Pechmann condensation reaction of phenols and β-keto-esters at 80 oC under solvent-free conditions. Also, biscoumarins were obtained via the condensation of aldehydes and 4-hydroxycoumarin in water at reflux conditions. T...

Structure-activity relationships are summarized for 87 retinoids, using reversal of keratinization in the hamster tracheal organ culture system to measure biological activity. Classes of compounds evaluated include all-trans-retinoic acid and its esters, ring-modified analogs of all-trans-retinoic acid and its esters, side-chain-modified analogs of all-trans-retinoic acid and its esters, analog...