Unprecedented Intra‐ and Intermolecular Palladium‐Catalyzed Coupling Reactions with Methylenecylclopropane‐Type Tetrasubstituted Alkenes

A reaction cascade consisting of a Heck coupling, cyclopropyl ring-opening, and a domino Diels–Alder reaction proceeds in one pot. The palladium-catalyzed coupling of bicyclopylidene (1) with vinyl iodide, even in the presence of dienophile 3, affords dendralene 2, which then reacts smoothly with 3 (R1 = H, CO2Me; R2 = CO2Me) to give bisadducts 4 in satisfactory yields. The key factor in this reaction sequence is that the carbopalladation of the unusual tetrasubstituted alkene 1 proceeds more rapidly than the Heck reaction with the dienophile.