Synthesis of Chloro-Substituted 6H-Dibenzo[b,d]pyran-6-one Natural Products, Graphislactone G, and Palmariols A and B

A palladium-mediated intramolecular aryl-aryl coupling reaction was applied to the total synthesis of the bioactive natural products, graphislactone G (1), and palmariols A (2) and B (3), which possess an unusual chloro-subsutituent on the 6H-dibenzo[b,d]pyran-6-one skeleton. Based on the transition state model of the coupling reaction, the mechanistic aspect for the regioselectivity of the aryl-aryl coupling reaction is also discussed.

Three-Step Synthesis of Fluoranthenes through Pd-Catalyzed Inter- and Intramolecular C-H Arylation

A three-step synthetic method for the preparation of fluoranthenes, involving Miura's intermolecular C-H arylation, nonaflation, and intramolecular C-H arylation, has been developed. Various 1-naphthols and haloarenes were successfully used as substrates. Reaction conditions that afford high site selectivity have been developed for the intramolecular C-H arylation step.