OXACYCLOPHANES BASED ON A META-TERPHENYL FRAMEWORK

m-Terphenyl tetraphenol 4 (Scheme I) and tetrabenzyl alcohol 19 (Scheme IV) were efficiently synthesized from 2,6-dichloroiodobenzene and an appropriate aryl Grignard, using tandem aryne technology. Each tetrol was used to construct bicyclic oxacyclophanes by linking the 3,3" and 5,5" substituents with bis-alkylating or acylating agents. Examples are 7, 14, 15, and 20-24. Only the meta isomer of xylylene dichloride formed a bicyclic oxacyclophane with 4; the ortho and para isomers gave polymers. However all three isomers gave oxacyclophanes (i.e., 10-12) with the diphenol 9 (only one link across the m-terphenyl framework) and bicyclic oxacyclophanes with 19 (i.e., 20-22), where each link contains two additional atoms. Para-linked 12 and 21 show restricted rotation of the p-xylylene rings. Two noninterconvertible conformers were obtained when the m-xylylene linking group contained a vicinal methoxy substituent (i.e., 15uu and 15ud).