Sonogashira Reactions with Propyne: Facile Synthesis of 4-Hydroxy-2-methylbenzofurans from Iodoresorcinols

The Sonogashira reaction of terminal alkynes and ortho-halophenols with subsequent cyclization is a well-precedented method for the synthesis of substituted benzofurans. Here we describe the extension of this method to the coupling of 2-iodoresorcinols and terminal alkynes, including propyne, to give 4-hydroxy-2-substituted benzofurans. In particular, we describe the screening, method development, and scaleup of the reaction with propyne using standard hydrogenation equipment.