Synthesis of Isoquinolines via the [4+2] Cycloaddition Reaction of Oxazoles and Arynes

Abstract

AbstractHerein, we report our investigations on the reaction of a variety of substituted oxazoles with o‐(trimethylsilyl)aryl triflates promoted by potassium fluoride and 18‐crown‐6‐ether. Several functionalized isoquinoline compounds were obtained in moderate to good yields when the transformation was carried out at room temperature, followed by acidic workup, presumably via a [4+2] cycloaddition‐ring‐opening reaction pathway. Alternatively, bicyclic ethers were produced in reasonable yields when performing the transformation at 60 °C via a sequence of [4+2] cycloaddition, retro‐Diels‐Alder, and [4+2] cycloaddition reactions.