One-pot synthesis of α-bromo- and α-azidoketones from olefins by catalytic oxidation with in situ-generated modified IBX as the key reaction

Simple one-pot protocols for the syntheses of alpha-bromoketones and alpha-azidoketones starting from olefins have been developed by employing catalytic oxidation of the intermediary bromohydrins with in situ generated modified IBX as the key reaction. The improved procedure involves initial formation of bromohydrin by the reaction of olefin with NBS in acetonitrile-water mixture (1:1) at rt followed by oxidation with in situ-generated 3,4,5,6-tetramethyl-2-iodoxybenzoic acid (TetMe-IBX), produced in catalytic amounts from 3,4,5,6-tetramethyl-2-iodobenzoic and Oxone. alpha-Bromoketones are further converted in the same pot to the corresponding alpha-azidoketones using NaN3/NaHCO3. The one-pot conversions are versatile for a variety of olefins that include cyclic as well as acyclic aliphatic olefins and electron-rich and electron-deficient styrenes. Chemoselective bromohydroxylation of electron-rich double bond and subsequent oxidation to the alpha-bromoketone is demonstrated for a substrate that contains both electron-rich and deficient double bonds. (C) 2017 Elsevier Ltd. All rights reserved.