Highly selective tetrahydropyranylation/dehydropyranylation of alcohols and phenols using porous phenolsulfonic acid-formaldehyde resin catalyst under solvent-free condition
solvent-free chemoselective tetrahydropyranylation/depyranylation of alcohols and phenols is reported herein using mesoporous Phenolsulfonic Acid Formaldehyde Resins as a heterogeneous acidcatalyst. The catalyst successfully performed chemoselective protection and deprotection reactions of a wide range of substrates ranging from primary to secondary and tertiary alcohols and also phenols. The reactions were
Envirocat (K10-MX)–Catalyzed Regioselective Transformation of Alkenes into Iodohydrins and <font>β</font>-Iodo Ethers and Further Conversion of Iodohydrins to Epoxides Using Al<sub>2</sub>O<sub>3</sub>-Na<sub>2</sub>CO<sub>3</sub> Under MWI
作者:Shallu、M. L. Sharma、Jasvinder Singh
DOI:10.1080/00397911.2010.539755
日期:2012.5.1
converted to extremely efficient and environmentally friendly catalyst K10-MX for the preparation of iodohydrins and β-iodo ethers from alkenes (terminal as well as internal) using microwave irradiation. This method was further extended for the conversion of alkenes to epoxides via iodohydrin intermediate in a one-pot reaction system. GRAPHICAL ABSTRACT
Magnetic Fe<sub>3</sub>O<sub>4</sub>@silica sulfuric acid nanoparticles promoted regioselective protection/deprotection of alcohols with dihydropyran under solvent-free conditions
Protection (and deprotection) of hydroxylgroups via tetrahydropyranylation was carried out effectively using a catalytic amount of Fe3O4 supportedsilica sulphuric acid nanoparticles (Fe3O4@SiO2@SO3H) under solvent-free conditions. The synthesized nanocatalyst was characterized by XRD, TEM, FT-IR etc. A wide range of tetrahydropyranylated alcohol derivatives were synthesized using this heterogeneous
在无溶剂条件下,使用催化量的Fe 3 O 4负载的二氧化硅硫酸纳米颗粒(Fe 3 O 4 @SiO 2 @SO 3 H)有效地进行了通过四氢吡喃基化进行的羟基保护(和脱保护)。通过XRD,TEM,FT-IR等对合成的纳米催化剂进行了表征。使用这种多相磁性纳米催化剂,可以在10–20分钟内以高收率合成各种四氢吡喃基化的醇衍生物。另外,也可以使用相同的催化剂在MeOH存在下将四氢吡喃基醚脱保护为母体醇化合物。反应完成后,使用外部磁体很容易将催化剂从反应介质中分离出来,从而改善了整个合成过程。回收催化剂并将其再用于五个连续的反应中,而没有任何明显的活性损失。温和的反应条件,操作简便,无溶剂的条件,高选择性,磁性纳米催化剂的易回收性和高收率可被视为我们程序的优势。
A mild and efficient chemoselective tetrahydropyranylation of primary alcohols using La(NO3)3·6H2O as a catalyst under solvent-free conditions
Primary alcohols undergo selective and efficient tetrahydropyranylation in the presence of a catalytic amount of La(NO3)3·6H2O undersolvent-freeconditions.
The selective cleavage of tetrahydropyranyl (THP), methoxymethyl (MOM), 1-ethoxyethyl (EE), 1-methyl-1-methoxyethyl (MME) and trimethylsilyl (TMS) ether groups with silica-aluminagels prepared by the sol-gel method has been investigated. The deprotection rate follows the order: TMS > MME ⪢ EE > THP ⪢ MOM. The selective deprotection of diol derivatives with mixed protecting groups was achieved efficiently