(–)-G-lactone is a bicyclic y-lactone prostaglandin chiral synthon and a building block.{53668,53669} It is a prostaglandin chiral synthon formed from an asymmetric Baeyer-Villiger oxidation reaction.{53668} (–)-G-lactone has also been used as a building block in the synthesis of HIV-1 protease inhibitors.{53669}