Synthesis, X-ray Structure, and Properties of a Tetrabenzannelated 1,2,4,5-Cyclophane

Highly strained but thermally stable: Tetrabenzocyclophane 1, which was obtained in a four-step synthesis by two Diels–Alder addition reactions (see scheme) sublimes at high temperature, rather than decomposing. The distorted aromatic rings are more reactive with tetracyanoethylene than those in [2.2]paracyclophane. Another consequence of heightened strain is a bathochromic shift of the cyclophane band to 330 nm, the longest wavelength absorption for this band to date.