First stereoselective [4+2] cycloaddition reactions of 3-cyanochromone derivatives with electron-rich dienes: an approach to the ABC tricyclic frame of arisugacin

摘要

Our interest in arisugacin (1), a novel and selective inhibitor of acetylcholine esterase that was isolated fro penicillium sp. Fo-4259, has led us to explore the synthetic potential of γ-pyrones as dienophiles in [4+2] cycloaddition reactions. Particularly, we envisioned that if dienes such as 2 could be used, then such a cycload- formula (ell) dition would lead to a convergent approach for construct- ing not only the tetracyclic frame of arisugacin, but also of other structurally analogous natural products such as pyripyropenes and forskolin.