Modification of the Fries Type Rearrangement of the<i>O</i>-Enol Acyl Group Using<i>N</i>,<i>N</i>-Dicyclohexyl-carbodiimide and 4-Dimethylaminopyridine

Abstract

3-Acyl-5,6-dihydro-4-hydroxy-2-pyrones are prepared in one step from carboxylic acids and β-keto-δ-valerolactones using N,N-dicyclohexylcarbodiimide and 4-dimethylaminopyridine. This reaction includes O-acylation and Fries type rearrangement of O-enol acyl group toward adjacent carbon atom. This method is also extended to the preparation of 3-acyl-4-hydroxy-2-pyrones, 2-acyl-3-hydroxy-2-cyclohexen-1-ones and 5-acyl-2,2-dimethyl-1,3-dioxane-4,6-diones.