Development of a Cationic Cascade Trailing into Piancatelli Rearrangement En Route to Skeletally Diverse Polycyclic Frameworks.

The aza-Piancatelli rearrangement represents a powerful strategy for accessing complex cyclopentenones, starting from furan carbinols. We demonstrate herein the use of a noncanonical furan building block and show that this reaction can be effectively combined with an azaoxyallyl cation-centered process. This integration leads to elusive polycyclic scaffolds bearing multiple contiguous stereocenters. The H-bonding clusters of HFIP serve as the sole promoter, highlighting a rapid, diversity-oriented synthesis of cyclopentanoid architectures.