Sulfur-controlled 5-exo selective aryl radical cyclisation of N-vinylic 2-bromobenzamides: synthesis of lennoxamine and chilenine

Abstract

Bu₃SnH-mediated aryl radical cyclisation of N-[2,2-bis(phenylsulfanyl)ethenyl]-2-bromobenzamides 12a–d and 16 takes place in a 5-exo manner to give exclusively the isoindolones 15a–d and 17, respectively. The isoindolone 17 is converted into lennoxamine and a key intermediate 20 for the synthesis of chilenine.