Bioinspired Total Synthesis of Eighteen <i>Pallavicinia</i> Diterpenoids with Three Distinct Skeletons

The total synthesis of eighteen structurally complex pallavicinia diterpenoids with three distinct carbon skeletons was accomplished from the second‐generation common intermediate 19 employing our bioinspired skeletal diversification strategy. Among these, (±)‐pallavicinolide D ( 4 ), (±)‐pallambins G/H ( 11 / 12 ), (±)‐pallaviambin C ( 13 ), (±)‐pallasubcin A ( 16 ), and (±)‐pallavisubin B ( 44b ) were synthesized prior to the reports of their isolation. The structures of (±)‐pallavicinolide D ( 4 ) and (±)‐pallasubcin A ( 16 ) were revised based on the X‐ray crystallographic and Nuclear Magnetic Resonance (NMR) analyses. The total synthesis of (±)‐pallavicinin A ( 17 ) was achieved for the first time. The synthetic route of (±)‐pallavicinolide A ( 1 ) was the shortest.