Strategies for constructing seven-membered rings: Applications in natural product synthesis

The seven-membered ring motifs are found in bioactive pharmaceuticals and a wide range of natural products, including alkaloids and terpenoids, which hold significant importance in synthetic chemistry and has garnered considerable attention from both academia and industry. Despite the challenges faced in the past decade, the total synthesis of natural products incorporating the non-aromatic cycloheptane skeletons remains a compelling pursuit. Recently, numerous elegant strategies for constructing the seven-membered ring system have been successfully developed. This review focuses on the recent advancements in this field from 2017 to April 2023, highlighting key transformations utilized to construct the non-aromatic cycloheptane core structures and serves as a valuable guide for synthetic chemists engaged in the total synthesis of natural products containing seven-membered ring motifs.