Synthesis of 7‐Membered Ring Carbocycles via a Palladium‐Catalyzed Intramolecular Allylic Alkylation–Isomerization–Cope Rearrangement Cascade

Abstract

We developed a novel method for synthesizing seven‐membered ring carbocycles via a palladium‐catalyzed intramolecular allylic alkylation–isomerization–Cope rearrangement cascade. Using easily available lactone derivatives as substrates, the target cascade reaction proceeded in the presence of 5 mol‐% of Pd(dba) 2 and 6 mol‐% of 1,3‐diphenylphosphinopropane (dppp) in THF, affording a series of seven‐membered ring carbocycles in 59–88 % yield (11 examples). DFT calculations suggested that, in addition to the reaction cascade including the cis ‐divinylcyclopropane Cope rearrangement, there is another possible pathway based on the palladium‐catalyzed intramolecular allylic substitution to construct the seven‐membered ring through a retro‐cyclopropanation‐mediated oxidative addition.