نتایج جستجو برای: silylation
تعداد نتایج: 439 فیلتر نتایج به سال:
Electrophilic triethylsilylation of diphenylketene leads to exclusive C-silylation giving the diphenyl(triethylsilyl)acetyl cation in the solution phase even though density functional theory calculations at the B3LYP/6-311+G* level indicate that the O-silylation of diphenylketene is preferred over C-silylation by 5.4 kcal/mol in the gas phase. On the other hand, in the case of the parent ketene...
A single clean, good-yielding, environment-friendly microwave-assisted procedure for O-silylation of uridine with tert-butyldimethylsilyl chloride (TBDMSCl), 1,8-Diazabicyclo(5.4.0)undec-7-ene (DBU) and potassium nitrate as catalyst under solvent-free conditions is reported. Subsequent silyl ether deprotection accomplished a reusable acidic resin via microwave irradiation. Both the silylation d...
In the presence of magnesium and hexamethylphosphorictriamide, HMPT, trimethylchlorosilane, TMS-C1, reacts with cyanoepoxides to give related compounds. Ring cleavage at ? - position of cyanoepoxide, 1, followed by the addition of two trimethylsilyl groups leads to 2 then substitution of OSiMei by trimethylsilyl or H takes place to give ?, ? - bis (trimethylsilyl) nitrile or ? - trimethyls...
A GC/MS method suitable to conduct practical toxicological analyses of unspecified opiates including hydrocodone or hydromorphone is presented. Silylation can be a convenient reaction to derivatize unknown analytes in toxicological samples. However, silylation of drugs with tautomeric keto/enol groups in molecular structure can cause analytical problems due to poor reproducibility. After using ...
metalloporphirins; cu(tpp), mn(tpp)cl, co(tpp), fe(tpp)cl, zn(tpp) and mn(obp)cl catalyze region and chemoselective silylation of hydroxyl groups with hmds. fe(tpp)cl is the most effective catalyst and silylation occurs immediately in its presence at room temperature.
Dehydrogenative silylation, which produces vinyl silanes, was generally regarded as a side reaction in hydrosilylation of alkenes. However, due to utility transition-metal catalyzed dehydrogenative silylations have been developed. This mini-review focuses on recent developments manganese-catalyzed selective silylation
A theoretical investigation of the reductive oxo-group silylation reaction of the uranyl dication held in a Pacman macrocylic environment has been carried out. The effect of the modeling of the Pacman ligand on the reaction profiles is found to be important, with the dipotassiation of a single oxo group identified as a key component in promoting the reaction between the Si-X and uranium-oxo bon...
Metalloporphirins; Cu(TPP), Mn(TPP)Cl, CO(TPP), Fe(TPP)Cl, zn(TPP) and Mn(OBP)Cl catalyze region and chemoselective silylation of hydroxyl groups with HMDS. Fe(TPP)Cl is the most effective catalyst and silylation occurs immediately in its presence at room temperature.
Silylation is an effective means of cellulose modification. However, the condensation reaction process between hydrolysis products silane coupling agent and cellulose, as well structure coating, which both have a strong influence on wettability, are still controversial. In this paper, reactions different methyltriethoxysilane with were simulated via density functional theory method. The activit...
Treatment of thiol ester with bis(iodozincio)alkane in the presence of palladium catalyst followed by silylation affords Z-silyl enol ether chemo-, regio- and stereoselectively.
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