Total Synthesis of (+)-Pyrenolide D.

An efficient approach to stereoselective construction of a spiro-γ-lactone core structure via BF3-promoted formal [3 + 2] annulation of aldehydo-aldose derivatives with γ-methylene-γ-butyrolactone has been developed. The spiro-γ-lactone derivative was then used in an efficient total synthesis of (+)-pyrenolide D. The developed chemistry paves the way for total synthesis of structurally diverse natural products containing spiro-lactone cores.