Ring transformation of isoxazoles into furan and pyran derivatives
Abstract
A ring transformation of isoxazole into 3,5-dicyano-4H-pyran-2-amines (4) and N-arylidenefuran-2-amines (7) is reported. It involves a ring opening of the isoxazole ring in the presence of an aromatic aldehyde, leading to 2-arylidene-3-oxopropanenitrile (2), followed by nucleophilic attack by either cyanide or propanedinitrile and then heterocyclization. The reaction can also be applied to 5-substituted isoxazoles.