A modular strategy for meroterpenoid-type marine natural products has been developed from commercially available (+)-sclareolide using a palladium-catalyzed tandem carbene migratory insertion as one of the key steps. Its applicability is showcased by the formal synthesis of (-)-pelorol and 9-epi-pelorol and the concise total synthesis of (+)-yahazunone and (+)-yahazunol. It is worth noting that the formal synthesis of (-)-pelorol and 9-epi-pelorol was achieved by controlling the reaction sequence of hydrogenation and cyclization.