Naphtho [l, 2, 3-mno] acephenanthrylene (21, a benzannelated derivative of cyclopenta [cd] pyrene not described in the literature, is of interest in biological activity studies because it contains both the cyclopenta-fused ring and bay region features. 21 This compound may be conveniently synthesized from commercially available 1, 2, 3, 6, 7, 8, 11, 12-octahydrobenzo [e] pyrene-9 (lOH)-one (3) by a scheme involving the TTN oxidation of 4-acetylbenzo [e] ...