Synthesis and Structure of 1,2‐Dimethylene[2.10]metacyclophane and Its Conversion into Chiral [10]Benzenometacyclophanes

Bromination of 5,21‐di‐ tert ‐butyl‐8,24‐dimethoxy‐1,2‐dimethyl[2.10]metacyclophan‐1‐ene (MCP‐1‐ene; 1 ) with benzyltrimethylammonium tribromide exclusively afforded 1,2‐bis(bromomethyl)‐5,21‐di‐ tert ‐butyl‐8,24‐dimethoxy[2.10]MCP‐1‐ene ( 2 ). Debromination of 2 with Zn and AcOH in CH 2 Cl 2 solution at room temperature for 24 h produced dimethylene[2.10]MCP 7 in 92 % yield, which is a stable solid compound. Compound 7 was treated with dimethyl acetylenedicarboxylate (DMAD) to provide 1,2‐(3′,6′‐dihydrobenzo)‐5,21‐di‐ tert ‐butyl‐8,24‐dimethoxy[2.10]MCP‐4′,5′‐dimethylcarboxylate ( 8 ) in good yield. Diels–Alder adduct 8 was converted into a novel and inherently chiral areno‐bridged dimethoxy[2.10]MCP‐4′,5′‐dimethylcarboxylate 9 , possessing C 1 symmetry, by aromatization with 2,3‐dichloro‐5,6‐dicyano‐1,4‐benzoquinone (DDQ). A new type of N ‐phenyl‐maleimide substituted 1,2‐(3′,6′‐dihydrobenzo)‐5,21‐di‐ tert ‐butyl‐8,24‐dimethoxy[2.10]MCP‐4′,5′‐ N ‐phenylmaleimide 10 was also synthesized from 7 through treatment with N ‐phenylmaleimide in toluene at 110 °C followed by aromatization with DDQ. Single‐crystal X‐ray analysis of 9 revealed the formation of a syn ‐isomer.