Novel Protocol for the Synthesis of Organic Ammonium Tribromides and Investigation of 1,1′-(Ethane-1,2-diyl)dipiperidinium Bis(tribromide) in the Silylation of Alcohols and Thiols
作者:Rupa R. Dey、Bappi Paul、Siddhartha S. Dhar、Sushmita Bhattacharjee
DOI:10.1246/cl.140564
日期:2014.10.5
A novel and efficient protocol for the synthesis of organic ammonium tribromides (OATBs) is developed by using inexpensive and eco-friendly periodic acid as an oxidant for the conversion of Br− to Br3−. The method does not use any mineral acid and metal oxidants. The protocol is utilized to synthesize a new bis(tribromide) viz., 1,1′-(ethane-1,2-diyl)dipiperidinium bis(tribromide) (EDPBT). EDPBT is investigated as a catalyst in the silylation of alcohols and thiols by HMDS (hexamethyldisilazane) under solvent-free conditions.
Ketene methyl trialkylsilyl acetals as effective silylating agents for alcohols, carboxylic acids, mercaptans, and amides
作者:Y. Kita、J. Haruta、J. Segawa、Y. Tamura
DOI:10.1016/s0040-4039(01)86575-8
日期:——
Silyl-proton exchange reactions with ketene methyl trialkylsilyl acetals proceeded rapidly and quantitatively under mild conditions. The preparative silylation of alcohols, carboxylic acids, mercaptans, and amides is described.
system of antimonypentachloride, chlorotrimethylsilane and tin(II) iodide, α-substituted cyclic ethers are stereoselectively prepared from lactones by successive treatment with 1-(t-butyldimethylsiloxy)-1-ethoxyethene and silyl nucleophiles such as triethylsilane, allyltrimethylsilane and trimethylsilyl cyanide. These catalysts also promote the reaction of γ-, δ-, and e-trimethylsiloxy carbonyl compounds
β-C-2-Deoxyribofuranosides and β-S-2-deoxyribofuranosides are prepared stereoselectively from 1-O-acetyl-5-O-benzyl-3-O-[2-(methylsulfinyl)ethyl]-2-deoxy-d-erythro-pentofuranose or the corresponding 3-O-(2-pyridyl-methyl)pentofuranose N-oxide by the reaction with silyl enol ethers or trimethlsilyl sulfides in the presence of a Lewis acid.
Sulfur–silicon bond activation catalysed by Cl/Br ions: waste-free synthesis of unsymmetrical thioethers by replacing fluoride catalysis and fluorinated substrates in SNAr reactions
In contrast to conventional activation of NuâSiR3 reagents by F ion attributed to the strong affinity of Si to F, SâSi activation can now be achieved using Cl/Br ions of TBAX as catalysts via formation of weaker XâSi bonds and Me3SiâX. This led to a waste-free synthesis of unsymmetrical thioethers via F-free SNAr reactions of activated (hetero)aryl halides and RSâSiMe3, with recovery of the useful Me3SiâX reagent in high yields.