Synthesis of phenylated phthalimides. The diels‐alder reaction of tetraphenylcyclopentadienone with maleimides

A series of phenylated dihydrophthalimides has been synthesized by the Diels‐Alder reaction of tetraphenylcyclopentadienone with maleimide, N‐phenylmaleimide, and N,N'‐o‐, ‐m‐, and ‐p‐phenylenedimaleimide. Subsequent dehydrogenation of these compounds yielded the corresponding phenylated phthalimides. These phthalimides were also obtained in one step when the initial reactions were carried out in refluxing nitrobenzene.