Anionic spirocyclization of 3-nitro-4-(2-hydroxyphenoxy)-2H-1-benzopyran-2-one: Formation of stabilized Meisenheimer-type salts

Article abstract of DOI:10.1016/S0040-4020(01)89009-8

The interaction of 3-nitro- and 3,6-dinitro-4-(2-hydroxy-4,5-R₂-phenoxy)-2H-1-benzopyran-2-ones 4a-d with triethylamine leads to the formation of triethylammonium salts of corresponding anionic spirocyclic compounds 5a-d as a result of intramol