Studies on 1-Alkyl-2 (1H)-pyridone Derivatives. X. The Diels-Alder Reaction of 1-Methyl-2 (1H)-pyridone with Maleic Anhydride

The Diels-Alder reaction between 1-methyl-2 (1H)-pyridone (I) and maleic anhydride was successfully carried out in 42% yield. This constitutes a new synthetic route to isoquinuclidine ring. The structure of the adduct (II) so obtained was proved by the synthesis of various derivatives. It was thereby determined that the structure of II is an endo-form IIb, that of dicarboxylic acid (III) is IIIb, that of bromolactone (IV) is IVd, the hydroxy-lactone (V) is Vd, and the dilactone (VI) is VIb.