Isopagodanes—Precursors of Unusual Cage Ions

Abstract

Isopagodanes like the “square”, D2d-symmetric C20H20 [1.1.1.1] skeleton 1 may serve as precursors to unusual cage ions of very special geometry. The synthetic strategy for pagodanes could not be directly applied to isopagodanes. A detour, in which a [2 + 2] photocycloaddition replaced the unsuccessful [6 + 6] photocycloaddition, was ultimately successful.