Synthetic Transformations of Higher Terpenoids. 36. * Synthesis of 13-(Oxazol-5-Yl)-15,16-Bisnorisopimaranes

The conditions for oxidizing methyl isopimarate to the 15-oxo-15,16-dihydroisopimarate were studied. The latter was used for one-pot syntheses of 13-(oxazol-5-yl)-15,16-bisnorisopimarates that included formation of the 16-oxoaldehyde isopimarate and its condensation with α-amino acids. The structures of the synthesized compounds were confirmed by IR, UV, and NMR spectral data and an XSA.