Highly Substituted Acephenanthrylenes and Their π-Extended Derivatives: Syntheses, Structural Analyses, and Properties.

This investigation demonstrates that a series of (highly) substituted acephenanthrylenes (APs) 2 , benzo[ l ]acephenanthrylene 3 , and dicyclopenta[ cd , mn ]pyrene 4 are easily prepared by palladium-catalyzed cycloaromatization of 2,3-diethynylbiphenyls 1 . The first nonpyrolysis synthesis of 4 by two-fold cycloaromatization was achieved in a high yield. This synthetic protocol has two crucial advantages: facile introduction of various substituents and efficient extension of the AP backbone.