Synthesis of Fluorinated 1,2,4-Oxadiazin-6-ones Through ANRORC Rearrangement of 1,2,4-Oxadiazoles

The reaction of 3-ethoxycarbonyl-5-perfluoroalkyl-1,2,4-oxadiazoles with hydroxylamines has been investigated, evidencing the possibility of competitive reaction paths. Nucleophilic addition of hydroxylamine to the electrophilic C(5) of the 1,2,4-oxadiazole ring, followed by ring-opening and ring-closure with enlargement, leads to high yield and in very mild experimental conditions to the formation of 5-hydroxyamino-3-perfluoroalkyl-6H-1,2,4-oxadiazin-6-ones, one of these presenting water gelation ability. In turn, reactions with N-methylhydroxylamine lead the exclusive formation of 4-perfluoroacylamino-2-methyl-2H-1,2,5-oxadiazol-3-ones through the well known Boulton-Katritzky rearrangement. (C) 2009 Elsevier Ltd. All rights reserved.