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1.
A rapid method for the derivatization of phenolic antioxidants using microwave irradiation has been developed. Six antioxidatively active phenolic components of wines and fruits, namely gallic acid, gentisic acid, vanillic acid, caffeic acid, ferulic acid and p-coumaric acid were used in the model study. The solution of phenolic acids was evaporated to dryness on a rotary evaporator followed by further drying under microwave irradiation (600 W, 30 s). The resultant residue was dissolved in pyridene and treated with bis(trimethylsilyl)acetamide while irradiated by microwave using high power for 30 s. Controlled reaction was carried out employing bis(trimethylsilyl)trifluoroacetamide under conventional heating for 30 min. The trimethylsilyl derivatives were identified and quantified on a gas chromatography/mass selective detector. The mass spectral fragmentation patterns of the derivatives obtained by microwave irradiation were identical to those prepared by heating. The yields of microwave-assisted silylation were comparable to those from conventional heating. The rsd were less than 8% for six replicates. The linearity in wine matrix was nearly perfect. This method is a useful protocol to examine the phenolic constituents in wines and agricultural products. 相似文献
2.
Vuthichai Ervithayasuporn Xin Wang Bahadir N. Gacal Yusuke Kawakami 《Journal of organometallic chemistry》2011,696(10):2193-4478
Formation of open-cage oligomeric azidophenylsilsesquioxane was surprisingly discovered in the successive reduction and azidation reactions starting from octa(nitrophenyl)octasilsesquioxane. The mixture of oligomeric products was characterized after end-capping with trimethylsilyl groups. The IR spectra confirmed the introduction of azide function to aromatic moiety, and trimethylsilyl group on silsesquioxane framework. Together with the GPC result, NMR analysis revealed the introduction of different number of trimethylsilyl groups in the structure. Some of them maintained the cage-like silsesquioxane structure characterized by XRD analysis. Their TGA profiles gave a unique pattern with clear two-step mass loss with the first mass loss of about 8-10 wt% from 180 to 225 °C corresponding to a thermal decomposition of azide groups. 相似文献
3.
A one-step method for the conversion of isopropyl protected guaiacols to the corresponding acetates is reported. Treating 6-substituted isopropyl protected guaiacols with trimethylsilyl trifluoromethanesulfonate in a mixture of acetic anhydride and acetonitrile affords 6-substituted guaiacol acetates in yields ranging from 35% to 99%. 相似文献
4.
A new convenient synthetic procedure to obtain various 1,1,1,3,3,3-hexafluoro-2-organyl-propan-2-ols and the corresponding trimethylsilyl ethers has been worked out starting from anhydrides or activated esters of carboxylic acids and trimethyl(trifluoromethyl)silane in the presence of tetramethylammonium fluoride. Conditions for the selective formation of 1,1,1,3,3,3-hexafluoro-2-organyl-propan-2-ols as well as the trimethylsilyl derivatives have been found. 相似文献
5.
《合成通讯》2013,43(21):3653-3660
Abstract Silica chloride (SiO2-Cl), as a heterogeneous reagent, has been used for the efficient dehydration of tertiary alcohols under mild reaction conditions. For comparison, we have also used trimethylsilyl chloride (TMSCl) as a homogeneous reagent for this purpose. We have found that silica chloride is a more efficient reagnet than trimethylsilyl chloride for this purpose. Handling of SiO2-Cl is much safer and easier than TMSCl, especially for large-scale operation. The selectivity of the method is also demonstrated by several competitive reactions. Ether formation, rearranged products, and polymerization have not been observed in the reactions. 相似文献
6.
Dinneswara Reddy GudaTengjiao Wang Hyeon Mo ChoMyong Euy Lee 《Tetrahedron letters》2012,53(39):5238-5242
A mild, convenient, and efficient one-pot synthesis of mercapto-1,2,4-triazoles is described. Various hydrazides efficiently reacted with trimethylsilyl isothiocyanate (TMSNCS) under basic condition to give mercapto-1,2,4-triazoles in high yields. 相似文献
7.
Michał Brokl Ana Cristina Soria Isabel Martínez-Castro Maria Luz Sanz Ana Isabel Ruiz-Matute 《Journal of chromatography. A》2009,1216(22):4689-4692
Gas chromatography (GC) data (linear retention indices and relative areas) and mass spectra (most representative m/z fragments) of 12 reducing trisaccharides as trimethylsilyl oximes (TMSO) and four non-reducing as trimethylsilyl (TMS) ethers have been described for the first time and related to their structural features. Some trends have been observed: earlier elution of non-reducing compounds and fructotrioses; aldotrioses bearing the reducing end with link in position 6 showing the highest retention. Abundance of several fragment ions and their ratios were useful for trisaccharide characterization; some of these features seem to be useful for the characterization of new trisaccharides. 相似文献
8.
LY544344·HCl was efficiently prepared in two steps from LY354740. The key step highlighted the in situ masking of the carboxylic acid groups as trimethylsilyl esters to facilitate an effective acylation reaction. 相似文献
9.
Ujwal Pratim Saikia Diganta BaruahPallab Pahari Manash Jyoti Borah Amrit GoswamiDilip Konwar 《Tetrahedron letters》2014
A mild and efficient methodology has been developed for the synthesis of spiro-1,3-oxazine derivatives by the microwave assisted cyclization of N-2-(1′-cyclohexenyl)ethyl-acetamides/benzamides. The reaction was catalyzed by in situ generated trimethylsilyl iodide and featured by its very short reaction time. The starting materials were easily obtained by the condensation of substituted acetic/benzoic acids with 2-(1′-cyclohexenyl)ethyl amine. 相似文献
10.
α-Amino nitriles are synthesized by the three-component coupling reaction of aldehydes, amines and trimethylsilyl cyanide using sulfamic acid as a heterogeneous solid acid catalyst, under solvent-free conditions in excellent yields. The catalyst was recovered by simple filtration and was recycled in subsequent reactions. 相似文献
11.
A straightforward and general method has been developed for the synthesis of α-aminonitriles by simply combining aldehydes or ketones, amines, and trimethylsilyl cyanides in the presence of a catalytic amount of molecular iodine at room temperature. 相似文献
12.
Trimethylsilyl fluorosulfonyldifluoroacetate (TFDA): a new, highly efficient difluorocarbene reagent
William R Dolbier Jr. Feng Tian An-Rong Li Olivia Bautista J Marshall Baker Pauline Anselme Aneta Modzelewska Merle A Battiste 《Journal of fluorine chemistry》2004,125(3):459-469
TFDA is readily prepared from the reaction of fluorosulfonyldifluoroacetic acid with trimethylsilyl chloride, and it is a very effective and efficient source of difluorocarbene for use in addition reactions to alkenes of a broad scope of reactivities. Acid-sensitive substrates may require an additional purification step involving treatment of the distilled TFDA with sufficient Et3N to remove the acid impurity. Other trialkylsilyl fluorosulfonyldifluoroacetates can also be prepared, and they have been found to have reactivities similar to TFDA. The triethyl derivative, TEFDA is more convenient to prepare in a pure state and has similar reactivity to TFDA. Thus, it may prove to be a superior reagent. 相似文献
13.
《Tetrahedron letters》2014,55(50):6795-6798
A new protocol for the synthesis of 2-allylindole and 2-allylbenzofuran derivatives has been developed from readily accessible starting material, 2-((trimethylsilyl)ethynyl)arenes via Pd-catalysis. The presence of trimethylsilyl group in the alkyne is vital for this reaction. Stereoselectivity of 2-allylindole derivatives is controlled by the use of different nitrogen-protecting groups for 2-((trimethylsilyl)ethynyl)aniline. The CO2Me protection gives Z-isomers, whereas acetyl protection gives E-isomers. 相似文献
14.
《Journal of carbohydrate chemistry》2013,32(6):453-470
Glycosylation of 2-(trimethylsilyl)ethanol with various ethyl 1-thioglycosides, which were activated with N-iodosuccinimide and silver triflate, was studied. The starting thioglycosides, some prepared for the first time, were obtained conventionally from the corresponding α-1-acetates. When β-1-acetates were more readily available, these were converted to the α-anomers by anomerization, prior to the glycosylation. Using ethyl 1-thioglycosides as glycosyl donors, especially those bearing a pivaloyl or a nonparticipating group at O-2, the corresponding 2-(trimethylsilyl)ethyl α-d-mannopyranosides were obtained in excellent yields. 相似文献
15.
Santos Fustero Sonia Flores Diego Jiménez Jorge Bueno 《Journal of fluorine chemistry》2007,128(10):1248-1254
A new synthesis of fluorinated allylamines through the reaction of 2-(trimethylsilyl)ethyl sulfones and sulfoxides (as vinyl anion equivalents) with imines and imino esters has been described. The process includes a TBAF-mediated fragmentation of 2-(trimethylsilyl)ethyl sulfones to afford the desired allylic amines. When the reaction is performed with the corresponding sulfoxides, the fragmentation takes place under the addition conditions, affording the final products in a single step. 相似文献
16.
Rozbeh Yousefi 《Journal of organometallic chemistry》2005,690(1):76-78
A practical and efficient method for the synthesis of α-aminonitriles of ferrocene by one-pot three-component reaction of ferrocenecarboxaldehyde, trimethylsilyl cyanide and amines catalyzed by lithium perchlorate suspend in CH2Cl2 is reported under mild and neutral reaction conditions in high yields and short reactions times. 相似文献
17.
A new diphenylphosphinite ionic liquid (IL-OPPh2) is introduced. This ionic liquid is used as both a reagent and a solvent to convert alcohols and trimethylsilyl and tetrahydropyranyl (THP) ethers into their corresponding alkyl bromides, thiocyanates or isothiocyanates in the presence of Br2 and SCN− at 80 °C. In this ionic liquid, bromination and thiocyanation of alcohols occurs highly selectively in the presence of trimethylsilyl and THP-ethers and also between different classes of alcohols. The use of this ionic liquid allows easy separation of the desired products from the phosphinate by-product. 相似文献
18.
Hai-Tao Zhu Ting-Ting Luo Shi-Hui Shi Ni-Ni Zhou Si-Si Ning Chen Zhang Yu-Gang Xiao Ming-Jin Fan De-Suo Yang 《Tetrahedron letters》2017,58(43):4137-4140
An effective and concise electrophilic cyclization of 1,4-butynediols, 4-aminobut-2-yn-1-ols, pent-2-yne-1,5-diols, 2-propynolphenols and 2-propynolanilines with N-halo succinimides and trimethylsilyl halides opens a one-pot synthetic access to five- and six-membered dihalogenated heterocycles in moderate to good yields. The optimized cyclization conditions are tolerated with many functional groups. 相似文献
19.
20.
Potassium phthalimide was found to be a highly effective and easily accessible organocatalyst for the cyanosilylation of various carbonyl compounds under extremely mild conditions. The corresponding cyanohydrin trimethylsilyl ethers were obtained in high to quantitative yields in solvent-free conditions at room temperature using 2.5 mol% catalyst loading. 相似文献