Base-Promoted Ring Expansion Reactions for the Construction of Cycloheptanones through C—C Bond Cleavage

Abstract

An efficient ring expansion strategy has been developed for the construction of cycloheptanones through C-C bond cleavage. The reactions take place with easily accessible starting materials, good functional group tolerance, and mild reaction conditions in the presence of Cs2CO3 without any metal or oxidant reagent. The transition-metal free insertions of alkynes into carbon-carbon σ-bonds of acenaphthenone initialized through intramolecular nucleophilic addition/ring-opening to furnish multifarious cycloheptanones, which has the potential to be widely utilized in organic synthetic chemistry.