Chemistry Letters, Vol.31, No.3, 280-281, 2002
Synthesis of benzocyclooctene derivatives via thermal ring expansion of dienylbenzocyclobutenes
Dienylbenzocyclobutenes, readily available by the cycloaddition of benzyne and ketene silyl actetal followed by addition of dienyllithium, underwent thermal four-carbon ring expansion to give benzocyclooctenone derivatives in high yields. In some cases, acid treatment of the thermal product gave tricyclic ketones via transannular bond formation.