Comparative study of the vicinal functionalization of olefins with 2:1 bromide/bromate and iodide/iodate reagents
作者:Manoj K. Agrawal、Subbarayappa Adimurthy、Bishwajit Ganguly、Pushpito K. Ghosh
DOI:10.1016/j.tet.2009.01.095
日期:2009.4
halohydrins, halo methyl ethers, and halo acetates from olefins using 2:1 Br−/BrO3− and I−/IO3− reagents. In many cases both reagents afforded products selectively in high yields. The highest halogen atom efficiencies attained were 97% and 93% for Br−/BrO3− and I−/IO3−, respectively. Of the two reagents, I−/IO3− was established to be the preferred reagent for vicinal functionalization of linear alkenes and
A convenient procedure was developed for the synthesis of vicinal iodoperoxyalkanes by the reaction of alkenes with iodine and hydroperoxides. The best results were achieved with the use of excess iodine. The replacement of one iodine atom by hydroperoxides in vicinal diiodoalkanes was discovered. A suggestion was made about the reaction mechanism.
The reaction of epoxides with lithiumhalides was efficiently promoted on the surface of silica gel in the absence of any solvent to give the corresponding β-halohydrins. The reactivity of lithiumhalides was shown to follow the order LiI> LiBr>> LiCl, and the reactivity of LiCl was dramatically increased by adding an equivalent amount of water to this system. On the other hand, a similar reaction
A simple efficient, stereoselective, and regioselective method for the synthesis of beta-chlorohydrins, beta-bromohydrins, and beta-iodohydrins by the direct opening of 1,2-epoxides with the corresponding ammonium halide in acetonitrile, in the presence of metal salts. is described. This new method appears to be of general use and competitive with the other methods previously reported.