Cyclocarbonylative Sonogashira Reactions of 1‐Ethynylbenzyl Alcohols: Synthesis of 1‐Carbonylmethylene‐1,3‐Dihydroisobenzofurans

Abstract

Abstract In this work, we present a carbonylative Sonogashira reaction of o ‐ethynyl benzyl alcohols and aryl iodides, followed by a cyclization process to selectively give carbonylmethylene isobenzofurans in high yields and in an atom‐economic fashion. The reaction can be carried out in the absence of CuI, with a small amount of PdCl 2 (PPh 3 ) 2 (0.2–0.5 mol‐%), using aryl iodides bearing both electron‐withdrawing and electron‐donating groups. Of the two possible stereoisomeric products, Z ‐isobenzofuran derivatives were obtained as major products. But, when the reaction was extended to a secondary alcohol, an interesting switch in stereoselectivity was observed.