Regioselective Preparation of 7-Oxanorborna-2,5-diene-2,3-dicarboxylic Acid Derivatives by the Diels-Alder Reaction: A Selective Access to Furans by Retro-Diels-Alder Reaction
1-substituted 7-oxanorborna-2,5-diene-2,3-dicarboxylates occurred regioselectively at the ester group in the 3-position to give monocarboxylic acids from which diesters containing two different alkoxy groups and amido esters were selectively prepared. Hydrogenation of these oxanorbornadiene derivatives followed by a retro-Diels–Alder reaction gave the corresponding furans as single regioisomers. Hydrolysis