Synthesis of five‐ring‐fused azepinone derivatives from bis‐isatins via sequential 6π‐electrocyclic ring closure, ring expansion, and dehydrogenation process

Abstract

Five‐ring‐fused azepinone derivatives were synthesized serendipitously from bis‐isatins via sequential 6π‐electrocyclic ring closure, ring expansion, and dehydrogenation process in moderate yields (34%–47%). The reaction was carried out in diphenyl ether at 230 °C for 4–12 h under O2 balloon atmosphere.

Diastereoselective Synthesis of Dihydrobenzofuran Spirooxindoles and Their Transformation into Benzofuroquinolinones by Ring Expansion of Oxindole Core

“…On the other hand, the ring expansion of oxindoles provides efficient synthetic approaches to creating various polyheterocyclic skeletons such as pyrazoloquinazolinones, pyrroloquinolines, quinazolinoquinazoline, indoloquinolinones, pyridine-fused quinolinones, and azepinone derivatives (Scheme ). However, this strategy for achieving diverse heterocyclic frameworks is still very scarce. In this context, we envision constructing benzofuroquinolinone skeletons by ring expansion of dihydrobenzofuran spirooxindoles, which could be highly appealing.…”