Synthesis of trans,trans,cis-fused tetracyclic skeleton via radical domino cyclization

Abstract Limonoids are characterized by a polycyclic structure and show a wide variety of bioactivities. In particular, mesendanin L, 12-hydroxyamoorastatone, and meliatoosenin F have unique structures containing a trans -A/B/C and cis -C/D-fused tetracyclic skeleton. We synthesized the core structure of these limonoids via Mn(OAc) 3 and Cu(OAc) 2 -mediated radical domino cyclization of an acyclic tetraene precursor having a terminal β-keto ester. To the best of our knowledge, this is the first example of the radical-mediated construction of a 6/6/6/5-membered tetracyclic skeleton.