Recent advances in total synthesis of illisimonin A

Illicium sesquiterpenes are a large class of highly oxygenated and sterically congested sesquiterpenoids isolated from the genus Illicium. Illisimonin A stands out as one of the most structurally intricate members of this family, featuring a novel bridged tricyclo[5.2.1.0^1,5]decane carbon framework designated as the "illisimonane" skeleton. This core ring system is further embellished by additional bridging via a γ-lactone and a γ-lactol ring, resulting in a caged pentacyclic scaffold with a 5/5/5/5/5 ring arrangement. The compound demonstrates neuroprotective activity by mitigating oxygen-glucose deprivation-induced cell injury in SH-SY5Y cells. Since its isolation in 2017, illisimonin A has garnered significant interest from the synthetic chemistry community. To date, five research groups have accomplished the total synthesis of illisimonin A. This review offers a comprehensive overview of its isolation, proposed biosynthetic pathway and the synthetic strategies employed in its total synthesis.