Total Synthesis of Leptosperol B through Stereocontrolled Intramolecular 1,4-Addition to Construct the Octahydronaphthalene Framework

Leptosperol B, possessing a unique octahydronaphthalene framework and 5-substituted aromatic ring, was isolated from the leaves of Leptospermum scoparium in 2020. The asymmetric total synthesis of leptosperol B was accomplished in 12 steps from (−)-menthone. The efficient synthetic scheme involves regioselective hydration and stereocontrolled intramolecular 1,4-addition to construct the octahydronaphthalene skeleton, followed by the introduction of the 5-substituted aromatic ring.