Organocatalytic asymmetric synthesis of cornolactones A and B, and formal synthesis of brasoside and littoralisone

The asymmetric total synthesis of cornolactones A and B as well as the formal asymmetric synthesis of brasoside and littoralisone were accomplished in short steps, from simple starting materials. The key features of the synthesis include an efficient organocatalytic access to cyclopentenal 15, an intramolecular Michael addition reaction and an intramolecular oxa-Diels–Alder reaction.