نتایج جستجو برای: silylation
تعداد نتایج: 439 فیلتر نتایج به سال:
Conventional Suzuki–Miyaura arylations use halogenated compounds as electrophilic coupling partners. Although the catalytic activation of organohalides is well established, these substrates are seldom naturally abundant and questions exist to their metabolic environmental friendliness. Owing existence readily available chemical feedstocks, alcohols highly desirable cross-coupling partners, alth...
In this research, different alcohols and phenols are subjected to the reaction with HMDS in the presence of ionic liquid and silica-supported catalysts. Silylation was accomplished under mild reaction conditions at room temperature in short reaction times and good to excellent yields.
Silyl triflate-promoted rearrangement of cis-2,3-epoxycycloalkanols A, prepared by epoxidation of the cyclic allylic alcohol and then silylation, afforded good yields ( approximately 70-75%) of the cis-2-alkyl-3-silyloxycycloalkanones B, presumably via the intermediates C and D, even with quite large alpha-substituents, e.g., tert-butyl. Finally, it has been shown that the stereochemistry of th...
The use of derivatization in the analysis of food additivies by chromatographic means has been reviewed. The large majority of these derivatization techniques are employed to facilitate the gas-liquid chromatographic quantitation of various food additives. Silylation, alkylation, acylation, as well as transesterification, saponification, and chemical decomposition techniques are discussed. The ...
The tert-butyl hydroperoxide (TBHP) promoted sequential silylation and aromatisation of isonitriles was developed, where the silyl group was regioselectively installed at the 6-position of phenanthridines. This procedure tolerates a series of functional groups, such as fluoro, chloro, acetyl, methoxy carbonyl, cyano and trifluoromethyl. The addition of a silyl radical to the isonitrile followed...
Variable-temperature hyperpolarized (HP) 129Xe NMR spectroscopy has been employed to characterize surface properties of mesoporous MCM-41 modified by silylation treatment. The characteristic chemical shifts responsible for Xe-surface interactions exhibit strong correlations with both the surface coverage and chain length of the grafted alkylsilanes. Consequently, the deshielding medium contribu...
A chiral auxilliary-based direct aldol reaction is reported. The reactions are catalytic in magnesium salts and are facilitated by silylation with chlorotrimethylsilane. The adducts isolated are in high diastereoselectivity (up to 32:1 dr) and favor the anti-aldol diastereomer B. Reactions are operationally simple and can be run under ambient atmosphere without rigorous exclusion of water. Many...
The chemical waste generated in today’s microelectronic fabrication processes has driven the need to develop a more environmentally benign process. Silicone fluids are linear methyl siloxanes that are non-toxic, not ozonedepleting and can be easily recycled. They are used as environmentally friendly alternatives in this study to develop conventional photoresists. After silylation, two conventio...
A gas chromatograph-mass spectrometer was used in an attempt to achieve rapid separation and accurate identification of benzo(a)pyrene and its synthesized derivatives. All derivatives, after being trimethylsilylated, were developed on Dexsil-300 and OV-1 columns. The seven diols and four stereoisomeric 7,8,9,10-tetraols studied were separated successfully. The separation of the 12 phenols was u...
We recently reported a new method for the direct dehydrogenative C-H silylation of heteroaromatics utilizing Earth-abundant potassium tert-butoxide. Herein we report a systematic experimental and computational mechanistic investigation of this transformation. Our experimental results are consistent with a radical chain mechanism. A trialkylsilyl radical may be initially generated by homolytic c...
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