Tandem [4 + 2]/[2 + 2] Cycloaddition Reactions Involving Indene or Benzofurans and Arynes

The reaction of arynes with indene/benzofurans has been developed. The arynes were generated from 2-(trimethylsilyl)­aryl triflates by the fluoride-induced 1,2-elimination react with indene or various benzofurans proceeding via a cascade reaction involving the Diels–Alder reaction and a [2 + 2] cycloaddition reaction. The tandem process afforded functionalized dihydrobenzocyclobutaphenanthrenes in moderate to good yields. Moreover, the method has been utilized for the one-pot synthesis of benzo­[b]­fluoranthene.本研究开发了芳炔（arynes）与茚/苯并呋喃的反应体系。芳炔由2-(三甲基硅基)芳基三氟甲磺酸酯经氟离子诱导的1,2-消除反应生成，随后与茚或多种苯并呋喃发生级联反应，该过程包含狄尔斯-阿尔德（Diels–Alder）反应与[2+2]环加成反应。该级联反应可得到官能化二氢苯并环丁烯并菲类化合物，产率中等至优良。此外，该方法还可用于一锅法合成苯并[b]荧蒽。