Molecular Orbital Considerations for Kinetically-Controlled Cycloaddition Reactions of Cyclohepta[<i>b</i>]furan-2-ones to 2,3-Bis(methoxycarbonyl)-7-oxabicyclo[2.2.1]heptadiene, Enamines, and Alkoxyethenes
作者:Guan Rong Tian、Shigeru Sugiyama、Akira Mori、Hitoshi Takeshita、Miwako Higashi、Hiroyuki Yamaguchi
DOI:10.1246/cl.1988.941
日期:1988.6.5
2,3-Bis(methoxycarbonyl)-7-oxabicyclo[2.2.1]heptadiene gave the [4+2] cycloadducts with 8,8-dicyanoheptafulvene and cycloheptaf[b]-furan-2-ones. This mode is different from the [8+2] cycloadduct formations with the previously studied enamines and alkoxyethenes. The results from MNDO calculations were in accord to the observed modes of the cycloadditions. Thermolysis of the cycloadducts gave the methylidene derivatives of “homobarrelenes”.
Superjacent and Subjacent Orbitals Participations for Kinetically-Controlled Cycloaddition Reactions of 2<i>H</i>-Cyclohepta[<i>b</i>]furan-2-ones and 8,8-Dicyanoheptafulvene to 2,3-Bis(methoxycarbonyl)-7-oxabicyclo[2.2.1]heptadiene
作者:Guan Rong Tian、Shigeru Sugiyama、Akira Mori、Hitoshi Takeshita、Miwako Higashi、Hiroyuki Yamaguchi
DOI:10.1246/bcsj.62.1136
日期:1989.4.15
2.1]heptadiene with 2H-cyclohepta[b]furan-2-ones and 8,8-dicyanoheptafulvene gave [4+2]adducts exclusively. This mode is different from the reported [8+2]adduct formations for 2H-cyclohepta[b]furan-2-ones with enamines and alkoxyethenes. A consideration of the superjacent and subjacent orbitals effects of the MO calculations gave a better result in favor of [4+2]adduct formation. Thermolysis of cycloadducts
2,3-双(甲氧基羰基)-7-氧杂双环[2.2.1]庚二烯与2H-环庚[b]呋喃-2-酮和8,8-二氰基七富烯的热环加成反应仅得到[4+2]加合物。这种模式与报道的 2H-环庚 [b]furan-2-ones 与烯胺和烷氧基乙烯的 [8+2] 加合物形成不同。考虑到 MO 计算的上层和下层轨道效应,可以得到更好的结果,有利于 [4+2] 加合物的形成。环加合物的热解得到高巴瑞烯的亚甲基衍生物。