Abstract
2, 3-Bis (methoxycarbonyl) -7-oxanorbornadiene, a synthon equivalent to acetylene, reacted efficiently with anthracenes, tropones, cyclohepta [b] furan-2-ones, and cyclohepta [b] pyrrol-2 (1 H) -ones under high-pressure conditions to give cycloadducts. These adducts were thermolyzed to furnish cage-molecules such as dibenzobarrelenes, janusenes, and homobarrelenones. In the cases of cyclohepta [b] furan-2-ones and cyclohepta [b] -pyrrol-2 (1 H) -ones, [4+2] cycloadditions were predominated over [8+2] cycloadditions. The preferred cycloaddition modes were explained by a molecular orbital consideration involving the interactions of not only frontier orbitals but also NHOMO and NLUMO of dienes.
