Tricyclic [10]annulenes. Part 4. The effect of benzo-fusion: synthesis, properties, and X-ray structure of 9c-methyl-9cH-cyclopenta[jk]fluorene

Abstract

The effect of benzo-fusion on the tricyclic [10]annulene (1) has been investigated. The benzo-fused annulene (7) was synthesised from the dialdehyde (6) by a bis-Wittig reaction, and has been shown to retain about two-thirds of the ring current of (1). Accurate bond lengths in (7) have been determined by X-ray crystallography. Synthesis of the annulenequinone (5) and the annulenopyridazine (8), and the X-ray structure determination of the dialdehyde (6) are also described.