PERFECTED PROCESS FOR THE PREPARATION OF STABLE NITROXIDE RADICALS

摘要

Process for the preparation of stable nitroxide radicals (I) starting from N-benzylphthalimide in three steps. In the first step, the N-benzylphthalimide is transformed into N-benzyl-1,1,3,3-tetralkylisoindoline by treatment with a Grignard reagent prepared in methyl-tert-butyl ether. In the second step, the N-benzyl-1,1,3,3-tetra­alkylisoindoline is transformed into 1,1,3,3-tetra­alkylisoindoline by hydrogenolysis. In the third step, the 1,1,3,3-tetra-alkyl-isoindoline is transformed into the ni­troxide radical by oxidation with hydrogen peroxide in the presence of a catalyst selected from acids and salts of po­lymolybdic or polytungstic acids.