Molecular Synthesis Center and Key Laboratory of Marine Drugs, Ministry of Education, School of Medicine and Pharmacy, Ocean University of China, Qingdao, China.
Laboratory for Marine Drugs and Bioproducts and Open Studio for Druggability Research of Marine Natural Products, Pilot National Laboratory for Marine Science and Technology, Qingdao, China.
Nat Commun. 2021 May 21;12(1):3022. doi: 10.1038/s41467-021-23344-0.
To the best of our knowledge, bridgehead carbon benzofused-bridged ring systems have previously not been accessible to the synthetic community. Here, we describe a formal type-II [4 + 4] cycloaddition approach that provides fully sp-carbon embedded anti-Bredt bicyclo[5.3.1] skeletons through the Rh-catalyzed C-C activation of benzocyclobutenones (BCBs) and their coupling with pedant dienamides. Variously substituted dienamides have been coupled with BCBs to provide a range of complex bicyclo[5.3.1] scaffolds (>20 examples, up to 89% yield). The bridged rings were further converted to polyfused hydroquinoline-containing tetracycles via a serendipitously discovered transannular 1,5-hydride shift/Prins-like cyclization/Schmidt rearrangement cascade.
据我们所知，桥头碳原子苯并稠合桥环体系以前尚未被合成界所获得。在这里，我们描述了一种形式上的 II 型[4+4]环加成方法，该方法通过 Rh 催化的苯并环丁烯酮（BCBs）的 C-C 活化及其与苯并稠合二烯酰胺的偶联，提供了完全 sp-碳嵌入的反-Bredt 双环[5.3.1]骨架。各种取代的二烯酰胺已与 BCB 偶联，提供了一系列复杂的双环[5.3.1]支架（>20 个实例，产率高达 89%）。桥环进一步通过意外发现的反式 1,5-氢化物转移/Prins 型环化/施密特重排级联反应转化为多稠合含氢醌的四元环。
