Intramolecular reactivity of a captodative bis-diene

[GRAPHICS] A 1,1-captodative bis-diene (3) has been prepared from crotonaldehyde dieth yl acetal through an elimination-metalation sequence. This compound has bee n reacted with electron-rich and electron-deficient dienophiles. Under both thermal and high-pressure conditions, no intermolecular reaction was obser ved, the fused (4) and bridged (5) intramolecular bicyclic adducts being re covered. The reduction of the central carbonyl group has led to the corresp onding allylic alcohol which, in thermal cycloaddition conditions, also pro vides an intramolecular adduct that aromatizes in the medium.