On the preparation and chemical reactivity of 2-benzopyrylium-4-olate
Abstract
An efficient route to 1-acetoxy-1H-2-benzopyran-4(3H)-one is described. This acetate readily liberates the title compound 2-benzopyrylium-4-olate (3) under thermal or base-catalysed conditions. The 1,3-dipole (3) undergoes cycloadditions with a wide range of dipolarophiles and the regioselectivity of these processes follows frontier molecular orbital predictions.