Recyclable reagents and Catalytic systems based on hypervalent iodine Chemistry

Abstract

Hofmann rearrangement of carboxamides to carbamates using Oxone® as an oxidant can be efficiently catalyzed by iodobenzene. This reaction involves hypervalent Iodine species generated in situ from catalytic amounts of PhI and Oxone® in the presence of 1,1,1,3,3,3-hexafluoroisopropanol (HFIP) in aqueous methanol solutions. Under these conditions, Hofmann rearrangement of various carboxamides affords the corresponding carbamates in high yields. Aziridination of alkenes to aziridines using catalytic amounts of tetrabutylammonium iodide, meta-Chloroperoxybenzoic acid (mCPBA) and PhthNH2 can be run under metal-free conditions. This reaction involves an oxidized iodine species generated in situ from Bu4NI and mCPBA. Under optimized conditions, Conversion of various alkenes to the corresponding aziridine products proceeds in comparable yields to previous by reported procedures. A green, recyclable and efficient catalytic oxidative system based on SiO2-supported RuCl3 and 3-(dichloroiodo)benzoic acid for the oxidation of alcohols and sulfides in water is developed. This catalytic oxidative system effects clean and efficient oxidation of a wide range of alcohols to the corresponding aldehydes and ketones, or sulfides to sulfoxides in high conversions with excellent chemoselectivity, under mild conditions. Furthermore, the SiO2-RuCl3 catalyst can be recovered by simple filtration and recycled in up to six consecutive runs without significant loss of activity. The reduced form of 3-(dichloroiodo)benzoic acid, 3-iodobenzoic acid, can be easily separated from reaction mixtures and converted back to 3-(dichloroiodo)benzoic acid by treatment with NaOCl and aqueous HCl in about 90% overall yield.