Asymmetric Induction in Intramolecular [5+2] Cycloaddition of 2-(4-Alkenyl)-5-benzoyloxy(or 5-Silyloxy)-4-pyrones Involving Migration of the Pyrone O-5 Group to O-4
Asymmetric Induction in Intramolecular [5+2] Cycloaddition of 2-(4-Alkenyl)-5-benzoyloxy(or 5-Silyloxy)-4-pyrones Involving Migration of the Pyrone O-5 Group to O-4