Regioselective Synthesis of Fluorenones via the Consecutive In-Mediated Barbier Reaction, Pd-Catalyzed Cyclization, and Friedel-Crafts Reaction Starting from Baylis-Hillman Adducts

摘要

Recently, various kinds of aromatic compounds have been synthesized from Baylis-Hillman adducts including benzenes, naphthalenes, pyridines, quinolines, pyrroles, and furans. During our continuous efforts on the synthesis of regioselectively-substituted aromatic compounds from Baylis-Hillman adducts, we decided to develop an efficient synthetic approach of fluorenone derivatives. Our synthetic approach of benzo[b]fiuoren-11-one (4a) is schematically depicted in Scheme 1, as a representative example.