Synthesis and spectra of 7‐(o‐ and p‐R‐phenyl)‐10,10‐dimethyl‐8,9,10,11‐tetrahydrobenz[c]acridin‐8‐ones. Structure correction of 1,2,3,4‐tetrahydro‐2,2‐dimethyl‐5‐aryl‐6‐aza‐7,8‐benzophenanthren‐4‐ones