نتایج جستجو برای: ring opeing of epoxides

تعداد نتایج: 21176018  

  This study represents a highly efficient and regioselective ring-opening of epoxides with acetic anhydride in the presence of NaOAc<span style="font-size: 10.0pt; font-family: 'Times ...

1999
Li-Xin Dai Xue-Long Hou Yong-Gui Zhou

Three types of small ring compounds (epoxides, aziridines and cyclopropanes) can be synthesized stereoselectively via ylide route. Among them, the stereochemistry of vinyloxiranes, vinylaziridines, cyclopropylesters, amides and ketones can be tuned by the choice of reaction conditions and ylides with varying heteroatoms and ligands. Optically active epoxides and acetylenylaziridines can be prep...

An environmentally benign procedure for the synthesis of vicinal nitrohydrins via the regioselective ring opening reaction of epoxides with nitrite anion using silica-bound 3-{2-[poly(ethylene glycol)]ethyl}-substituted 1-methyl-1H-imidazol-3-ium bromide as an effective heterogeneous phase transfer catalyst was described. Short reaction time, high yield of products, simple work-up proc...

2006
T. J. Slaga G. L. Gleason G. Mills L. Ewald P. P. Fu H. M. Lee R. G. Harvey N. Shyamasundar

†̃ †̃bay-region' â€d̃iol-epoxides of PAH are important in their car cinogenic activity. A bay region occurs in PAH when an angu larly fused benzo ring is present (Chart 1). There is now direct evidence from tumorigenicity studies that bay-region diol epoxides of B(a)P (2, 14, 15, 22, 23) and BA (18, 25, 26) are ultimate carcinogenic metabolites. In addition, recent studies have shown that cert...

Journal: :The journal of physical chemistry. A 2010
Nathan C Eddingsaas David G VanderVelde Paul O Wennberg

Epoxydiols are produced in the gas phase from the photo-oxidation of isoprene in the absence of significant mixing ratios of nitrogen oxides (NO(x)). The reactive uptake of these compounds onto acidic aerosols has been shown to produce secondary organic aerosol (SOA). To better characterize the fate of isoprene epoxydiols in the aerosol phase, the kinetics and products of the acid-catalyzed rin...

Journal: :Chemistry 2014
Xiao Shen Qinghe Liu Tao Luo Jinbo Hu

Unlike the facile synthesis of β-monofluoromethyl alcohols by nucleophilic monofluoromethylation of epoxides, the synthesis of β-difluoromethyl alcohols by nucleophilic difluoromethylation of epoxides still remains a challenge. Herein, studies on tackling this problem with PhSO(NTBS)CF2H (2; TBS=tert-butyldimethylsilyl) are reported. The preorganization of 2 and epoxides with BF3⋅Et2O was found...

H3PW12O40 (PW12) was immobilized over mesoporous alumina through the reaction of mesoporous alumina functionalized 3-aminopropyl triethoxy silane (3-APTES) and PW12. The surface properties of the functionalized nanocomposite was analyzed by a series of characterization techniques like elemental analysis, FTIR and XRD. XRD and adsorption–desorption analysis shows that the mesostructure of silica...

2001
Mauricio Gomes Constantino Valdemar Lacerda Valquiria Aragão

Epoxide ring opening is a frequently required transformation in Organic Synthesis. In this paper we describe the application of NbCl5 for this purpose using three different substrates. Chlorohydrins, 1,2-diols, products containing solvent residues as well as rearrangement products are obtained, depending on both the substrate structure and reaction conditions. Rationalizations to account for so...

B. Tamami H. Allahyari R. Teymoori S. Ghasemi

Poly (vinylpyrrolidone)-grafted silica as an organic-inorganic hybrid material was used as an effective heterogeneous polymeric cosolvent catalyst in organic reactions. This modified silica catalyzed nucleophilic displacement of alkyl halides for easy preparation of alkyl thiocyanates, alkyl cyanides, alkyl azides and alkyl aryl ethers. Furthermore, the catalyst was applied for the conversion o...

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