Several 2, 8-dioxo-1, 7-cycloerythrinan drivatives (bearing a 6β-ethoxycarbonyl or 6β-hydrogen substituent) were prepared in good yields from the reported 2, 8-dioxo-7β or 7α-hydroxyerythrinan derivatives by a base-catalyzed intramolecular alkylation of the corresponding O-mesylates, and they were shown to be useful intermediates for synthesizing natural erythrinan alkaloids. The C-1 of these compounds has been suitably protected for further manipulation at C-3 and the cyclopropane ring can be readily cleaved in a reductive or a non-reductive manner to give C-1 methylene or C-1 olefin derivatives. The latter process is discussed in detail with reference to several examples of ionic and radical opening. The reactivity of the carboxylate ester group on the cyclopropane ring bearing an electro-negative substituent was unusually high.
通过碱催化相应 O-
甲磺酸酯的分子内烷基化反应,从已报道的 2,8-二氧代-1,7-环红花楠衍
生物中制备出了几种 2,8-二氧代-1,7-环红花楠二价化合物(带有 6β- 乙氧基羰基或 6β- 氢取代基),并证明它们是合成天然红花楠
生物碱的有用中间体。这些化合物的 C-1 已被适当保护,可在 C-3 处进一步操作,
环丙烷环可以很容易地以还原或非还原方式裂解,得到 C-1 亚甲基或 C-1 烯烃衍
生物。我们将参照离子开环和自由基开环的几个实例详细讨论后一种工艺。
环丙烷环上带有负电取代基的
羧酸酯基团的反应活性异常高。