نتایج جستجو برای: regioselective
تعداد نتایج: 2974 فیلتر نتایج به سال:
Discrimination among equals: A catalytic method for the selective oxidation of unprotected glycosides, both monosaccharides and disaccharides, has been developed. The resulting ketosaccharides are isolated in moderate to excellent yields. This approach provides a basis for protecting-group-free synthetic transformations of carbohydrates.
Selective modification of unprotected carbohydrates is difficult due to the similar reactivity of the hydroxyl groups. In carbohydrate synthesis, therefore, even straightforward transformations often require multiple synthetic steps. The development of selective methods for carbohydrate modification is consequently highly desired. This review describes the methods for the regio- and chemoselect...
Haloarenes undergo direct borylation using amine : BCl3 : AlCl3 in the ratio of 1 : 1 : 2. After esterification the pinacol boronate esters are isolated in good yield with regioselectivity controlled by steric and electronic effects.
The first highly regioselective and general osmium-catalyzed hydroformylation of olefins to aldehydes is reported. The combination of Os3(CO)12 and imidazoyl-substituted phosphine ligands allows n-selective (up to 99%) hydroformylation of bulk aliphatic as well as functional alkenes in good yields (64-87%).
this study represents a highly efficient and regioselective ring-opening of epoxides with acetic anhydride in the presence of naoac·3h2o at solvent-free conditions. the ring-opening of different classes of epoxides were carried in oil bath (70-80 °c) to afford 1,2-diacetates in high to excellent yields
A simple, mild and efficient method for the regioselective nitration of various aromatic compounds usingpoly(4-vinylpyridinium nitrate) (P4VPyN) in the presence of melamine trisulfonic acid (MTSA), is reported.This method provides several advantages such as good selectiveity between ortho and para positions ofaromatic compounds, clean procedure, simple work-up, short reaction times, solvent-fre...
An efficient and simple method for the preparation of Si-Imidazole-HSO4 functionalized magnetic Fe3O4 nanoparticles (Si-Im-HSO4 MNPs) and used as an efficient and reusable magnetic catalysts for the regioselective ring opening of epoxides under green conditions in water. This catalyst was used for the ring opening of epoxide corresponding to the thiocyanohydrins and azidohydrines. Compared to t...
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