Photocycloaddition of exo,endo-2,7-bis(methoxycarbonyl)-11,12-dioxatetracyclo[6.2.1.13,6.02,7]dodeca-4,9-diene with conjugated enones and p-quinones occurred exclusively at the exo-addition moiety to give [2+2]cycloadducts. From cyclohexenone, all four possible photoadducts were obtained. A single photoadduct from cyclopentenone was a cis-transoid-cis isomer. Upon thermolysis, cyclobutene derivatives were formed from these photoadducts. An acid treatment of oxetane derivatives derived from photoadducts of p-quinones afforded Michael adducts instead of dienone–phenol rearrangement products.
外、内-2,7-双(甲氧基羰基)-11,12-二氧杂四环[6.2.1.13,6.02,7]十二碳-4,9-二烯与共轭烯酮和对醌的光环加成完全发生在外加分子上,生成 [2+2] 环加成物。从
环己酮中得到了所有四种可能的光加成物。从
环戊烯酮中得到的单个光加成物是顺式-反式-顺式异构体。热分解后,这些光加成物形成了
环丁烯衍
生物。对醌的光加成物产生的氧杂
环丁烷衍
生物进行酸处理后,得到了迈克尔加成物,而不是二烯酮-
苯酚重排产物。