Description:
<jats:p><jats:bold>Nitro‐ and Allyloxy‐Substituted Helical [2.2]Metacyclophanes: Synthesis, Circular Dichroism and Crystal Structures</jats:bold></jats:p><jats:p>The preparations of the title compound <jats:bold>3a</jats:bold>, intraannularly nitro‐functionalized, of the extraannularly substituted reference compound <jats:bold>3b</jats:bold>, and of the sulfone <jats:bold>4</jats:bold> are described. Enantiomeric resolution of these helical phanes was accomplished on (+)‐PTrMA and cellulose tris(3,5‐dimethylphenyl)carbamate by HPLC. Racemization of the enantiomers of <jats:bold>3b</jats:bold> is faster than that of the previously reported extraannularly substituted phanes. The crystal structure of <jats:bold>3a</jats:bold> as well as that of the allyl ether <jats:bold>3d</jats:bold> show severe distortions of the benzene rings; the CD spectrum of <jats:bold>3a</jats:bold> is pointing at an intramolecular charge‐transfer complex, an effect that cannot be evaluated from the CD spectrum of <jats:bold>3b</jats:bold>.</jats:p>