A convenient preparation of 3, 4-bismethylenecyclopentanone ethylene ketal, a new valuable diene for Diels-Alder reaction, designed to produce functionalized [6.5] ring systems, is described. A formal synthesis of gibberellic acd GA3 using as starting materials two cycloadducts derived from the title compound demonstrates the value and the applicability of this methodology for the construction of functionalized hydrindane systems.
![(3aR,6S,8aS)-6-((2-methoxyethoxy)methoxy)-5-methyleneoctahydrospiro[3a,6-methanoazulene-2,2'-[1,3]dioxolane] Structure](https://image.chemsrc.com/caspic/021/69843-47-6.png)
