Preparation, characterization and use of 1,3-disulfonic acid imidazolium hydrogen sulfate as an efficient, halogen-free and reusable ionic liquid catalyst for the trimethylsilyl protection of hydroxyl groups and deprotection of the obtained trimethylsilanes
摘要:
Novel 1,3-disulfonic acid imidazolium hydrogen sulfate, a halogen-free ionic liquid, is a recyclable and eco-benign catalyst for the trimethylsilyl protection of hydroxyl groups at room temperature under solvent free conditions to afford trimethylsilanes in excellent yields (92-100%) and in very short reaction times (1-5 min). Deprotection of the resulting trimethylsilanes can also be achieved using the same catalyst in methanol. The catalyst was characterized by IR. H-1 NMR, C-13 NMR and MS studies. All the products were extensively characterized by IR, H-1 NMR, MS, and elemental and melting point analyses. This new method consistently has the advantages of excellent yields and short reaction times. Further, the catalyst can be recovered and reused for several times without loss of activity. The work-up of the reaction consists of a simple separation, followed by concentration of the crude product and purification. (C) 2012 Elsevier B.V. All rights reserved.
Chemoselective and Catalytic Trimethylsilylation of Alcohols and Phenols by 1,1,1,3,3,3-Hexamethyldisilazane and Catalytic Amounts of PhMe3N+Br3−
摘要:
An efficient procedure for the trimethylsilylation of alcohols and phenols is presented The combination of 1,1,1,3,3,3-hexamethyldisilazane and a catalytic amount of phenyltrimethylammonium tribromide ((PhMe3NBr3-)-Br-1) was found to be effective for the trimethylsilylation of alcohols and phenols The protection reaction is very simple and homogenously performed in dichloromethane at room temperature and mild conditions
Cross-Coupling of Aryl/Alkenyl Ethers with Aryl Grignard Reagents through Nickel-Catalyzed CO Activation
作者:Lan-Gui Xie、Zhong-Xia Wang
DOI:10.1002/chem.201003731
日期:2011.4.26
achieved through the cleavage of the sp2 CO bond of aryl/alkenyl ethers catalyzed by a nickel complex, and by using Grignard reagents as nucleophiles (see scheme). This method displays a broad substrate scope and leads to good to excellent yields of the aryl–aryl or alkenyl–aryl cross‐coupling products.
An efficient procedure for the trimethylsilylation of alcohols and phenols is presented The combination of 1,1,1,3,3,3-hexamethyldisilazane and a catalytic amount of phenyltrimethylammonium tribromide ((PhMe3NBr3-)-Br-1) was found to be effective for the trimethylsilylation of alcohols and phenols The protection reaction is very simple and homogenously performed in dichloromethane at room temperature and mild conditions
Preparation, characterization and use of 1,3-disulfonic acid imidazolium hydrogen sulfate as an efficient, halogen-free and reusable ionic liquid catalyst for the trimethylsilyl protection of hydroxyl groups and deprotection of the obtained trimethylsilanes
Novel 1,3-disulfonic acid imidazolium hydrogen sulfate, a halogen-free ionic liquid, is a recyclable and eco-benign catalyst for the trimethylsilyl protection of hydroxyl groups at room temperature under solvent free conditions to afford trimethylsilanes in excellent yields (92-100%) and in very short reaction times (1-5 min). Deprotection of the resulting trimethylsilanes can also be achieved using the same catalyst in methanol. The catalyst was characterized by IR. H-1 NMR, C-13 NMR and MS studies. All the products were extensively characterized by IR, H-1 NMR, MS, and elemental and melting point analyses. This new method consistently has the advantages of excellent yields and short reaction times. Further, the catalyst can be recovered and reused for several times without loss of activity. The work-up of the reaction consists of a simple separation, followed by concentration of the crude product and purification. (C) 2012 Elsevier B.V. All rights reserved.