Metal-Free Synthesis of Furocoumarins: An Approach via Iodine-Promoted One-Pot Cyclization between 4-Hydroxycoumarins and Acetophenones

摘要

A transition metal-free approach was developed to achieve substituted furocoumarins via an iodine-promoted onepot cyclization between 4-hydroxycoumarins and acetophenones. High yields of furocoumarins were achieved in the presence of NH_4OAc as an additive, while neither acidic nor basic additives were effective. The reaction would proceed via a 5- exo-tet cyclization but not an O-alkylation. The fact that commercially available starting materials could be used without the need of a transition metal catalyst could be a significant advantage.