Chemical transformation of protoberberines. XV. A novel and efficient method for the introduction of alkyl groups on the C-13 position in the protoberberine skeleton.
作者:Miyoji HANAOKA、Shuji YOSHIDA、Chisato MUKAI
DOI:10.1248/cpb.37.3264
日期:——
The Wittig reaction of 8, 14-cycloberbin-13-ones (4), derived from the corresponding protoberberine alkaloids (2), with methylenetriphenylphosphorane afforded 13-methylene-8, 14-cycloberbines (5). Irradiation of 5 with a 100 W high pressure mercury lamp effected photochemically-induced electrocyclic fission of the aziridine ring to yield 13-methylberberine (1a), dehydrocorydaline (1b), and corysamine (1c) in high yield. Introduction of ethyl and propyl groups on the C-13 position in 2 was also conveniently achieved via photochemical reaction of the corresponding alkylidene derivatives (8 and 9, respectively).
8, 14-环贝尔本-13-酮(4)通过与甲烯三苯基膦的维蒂格反应,来自相应的原贝尔巴林生物碱(2),得到13-亚甲基-8, 14-环贝尔本(5)。使用100 W高压汞灯对5进行辐照,促进了光化学诱导的电环裂解,生成高产率的13-甲基贝尔巴林(1a)、去氢可可碱(1b)和可可酸(1c)。通过相应烷基烯烃衍生物(8和9)进行光化学反应,还方便地在2的C-13位引入了乙基和丙基取代基。