Lewis Acid Promoted Tandem Intermolecular Diels−Alder/Intramolecular Allylation Reactions of Silyl-Substituted 1,3-Butadienes Leading to Multisubstituted 7-Norbornenones and Related Polycyclic Compounds

7-Norbornenones of exo,exo-disubstituted patterns were formed highly selectively in good yields from Lewis acid-promoted tandem intermolecular Diels−Alder/intramolecular allylation reactions. The intermolecular Diels−Alder reaction between 1,4-bis(trimethylsilyl)-1,3-butadienes or 1-trimethylsilyl-1,3-butadienes with maleic anhydride in the presence of newly sublimed AlCl3 afforded their corresponding cycloaddition adducts, which underwent AlCl3-mediated intramolecular allylation of the carbonyl group by the in situ generated allylsilane moiety affording 7-norbornenones of exo,exo-disubstituted patterns.