The synthesis of water soluble isoindoline nitroxides and a pronitroxide hydroxylamine hydrochloride UV–VIS probe for free radicals

Abstract

The novel water soluble nitroxides 5-trimethylammonio-1,1,3,3-tetramethylisoindolin-2-yloxyl iodide 8 and 5-carboxy-1,1,3,3-tetramethylisoindolin-2-yloxyl 10 are prepared by nitration of the parent nitroxide 2 and bromination of its amine precursor 1; the stable (t_1/2 > 580 h in MeOH; ca 72 h in physiological saline) pronitroxide 2-hydroxy-1,1,3,3-tetramethylisoindoline hydrochloride 6 was synthesised by treatment of 2 with HCl gas in dry EtOH and reacts with radicals to form 2; the transformation can be followed by UV–VIS spectroscopy.