Investigation of the Structure of the Complex Oligomeric Mixture Formed During Grignard Tetramethylation of N-benzylphthalimide

Abstract

TMIO or 1,1,3,3-tetramethylisoindolin-2-yloxyl (5, Scheme 1) is one of the most versatile isoindoline nitroxides due to its applications [1, 2] and a variety of important advantages such as thermal stability, low reactivity towards olefins [3], symmetrical nature [4], UV detectability [5] and relative inertness to free radical attack [4][4]. The most common and effective pathway for synthesizing 5 remains the Grignard-based approach in which N-benzylphthalimide 1 is treated with methylmagnesium halide in refluxing toluene, followed by subsequent debenzylation and oxidation of the resulting secondary amine