The directed ortho metalation-palladium catalyzed cross coupling connection.: A general regiospecific route to 9-phenanthrols and phenanthrenes.: Exploratory further metalation

A new general and regiospecific synthesis of 9-phenanthrols (1 + 2 --> 3 --> 4, Scheme 1, Table 1) proceeding by a Directed ortho Metalation (DoM), Suzuki-Miyaura cross coupling, and a new LDA-mediated Directed remote Metalation sequence is described. The facile Pd-catalyzed hydrogenolysis of the phenanthrols 4 into the corresponding phenanthrenes 5 via their triflates 18 translates the original DoM regioselectivity also into a general synthesis of phenanthrenes (Table 2). Further DoM (19 --> 20, 21; 24 --> 25), cross coupling (20c -->23), as well as oxidation - ring contraction (4b, 4f --> 28a, 28b) chemistry of phenanthrene derivatives is reported.