Synthesis of Fused Bromofurans via Mg-Mediated Dibromocyclopropanation of Cycloalkanone-Derived Chalcones and Cloke–Wilson Rearrangement

A convenient two-step sequence for the conversion of alkylidenecycloalkanones to bromofurans is reported. The steps involve Mg-mediated diastereoselective dibromocyclopropanation of alkylidenecycloalkanone followed by acidic alumina-mediated regioselective ring expansion of the cyclopropyl ketone. The scope of the reaction was investigated using alkylidenecycloalkanones derived from tetralone, indanone, and benzosuberone to afford 2-aryl-3-bromofurans fused to various benzocycloalkanes. Representative examples of stereoconvergent dibromocyclopropanation and total aromatization of the furobenzocycloalkane are also reported.

本文报道了一条可将亚烷基环烷酮（alkylidenecycloalkanones）转化为溴代呋喃（bromofurans）的便捷两步法反应序列。该反应序列包含两步：首先经镁介导实现亚烷基环烷酮的非对映选择性二溴环丙烷化，随后通过酸性氧化铝介导完成环丙基酮的区域选择性扩环。研究团队以源自四氢萘酮（tetralone）、茚满酮（indanone）及苯并环庚酮（benzosuberone）的亚烷基环烷酮为底物考察了该反应的适用范围，成功合成了与多种苯并环烷烃稠合的2-芳基-3-溴呋喃类化合物。此外，本文还报道了立体汇聚型二溴环丙烷化反应及呋喃并苯并环烷烃完全芳构化的代表性实例。