A tandem palladium-catalyzed Heck-lactonization through the reaction of ortho-iodophenols with beta-substituted acrylates:synthesis of 4,6-substituted coumarins

摘要

Coumarins were obtained in one pot through a palladium-catalyzed Heck-lactonization reaction involving ortho-iodophenols and methyl crotonate or a Z-enoate derived from D-mannitol.These reactions were investigated under different conditions and palladium sources.In the more interesting cases,coumarins were prepared in water,using triethylamine as base and 1 mol % of PdCl2 as catalyst.