Synthesis of highly substituted γ-hydroxybutenolides through the annulation of keto acids with alkynes and subsequent hydroxyl transposition

An efficient synthesis of highly functionalized gamma-hydroxybutenolides through BF3-catalyzed annulation of keto acids with alkynes is described. Many advantages such as the use of routine reagents, easy operation, and a 100% atom efficiency are demonstrated in the method. The reaction can be readily scaled up to gram quantities, offering good practicality.