Studies in the Cycloproparene Series: Attempted Cycloadditions With Tricyclo-[5.4.1.0^3,5]dodeca-2,5,7,9,11-pentaene

Abstract

4,4-Dichlorotricyclo[5.4.1.0^3,5]dodeca-7,9,11-triene (18a) undergoes cycloaddition with 4-phenyl-1,2,4 triazoline-3,5-dione via its norcaradiene valence-bond isomer (18b) to give adduct (21)in 86% yield. By comparison the aromatic tricyclo [5.4.1.0^3,5]dodeca-2,5,7,9,11-pentaene (6)and its 12-chloro stereoisomer (20) fail to react; this contrasts with the behaviour of other 1,6-methano[10] annulene derivatives.