Construction of Bi‐ and Tricyclic Skeletons by Domino‐Heck–Diels–Alder Reactions

Palladium‐catalyzed intramolecular reactions of 2‐bromo 1,6‐dienes followed by intermolecular [4+2] cycloaddition with suitable dienophiles in one‐pot operations gave hexahydroindenes 8 and 9 in yields of 40–78%, an hexahydro‐s‐indacene derivative 13 could be obtained in up to 25% yield with cyclopent‐2‐en‐1‐one ( 10 ) as a dienophile in the presence of different Lewis acids, and a spirocyclopentane‐hexahydroindenone 18 could be isolated in 72% yield. When in‐situ‐formed iminium salts were used as heterodienophiles, hexahydro‐1H‐[2]pyrindinols 31 could be obtained in a one‐pot two‐step operation in 29–46% yield.