The stereochemistry of overcrowded homomerous bistricyclic aromatic enes with alkylidene bridges
Abstract
The objective of the research was to study the effects of alkylidene bridges on the conformations and the conformational behaviour of overcrowded homomerous bistricyclic aromatic ethenes (1). The isopropylidene-bridged bistricyclic ethene 2 and 3 were synthesized by a reductive “dimerization” of 7, using TiCl4–Zn–C9′ bond in 2 was essentially planar. A short C9
⋯
C10 distance of 2.81 Å in 2 indicated an intramolecular overcrowding effect in the highly folded bistricyclic