Studies on the chemical constituents of rutaceous plants. LV. The development of a versatile method for the synthesis of antitumor-active benzo(c)phenanthridine alkaloids. 5. A new method for quaternization of the benzo(c)phenanthridine nucleus.
作者:HISASHI ISHII、TSUTOMU ISHIKAWA、YUHICHIRO ICHIKAWA、MITSUGI SAKAMOTO、MUNEKAZU ISHIKAWA、TSUTOMU TAKAHASHI
DOI:10.1248/cpb.32.2984
日期:——
A versatile method of synthesis of the quaternary benzo [c] phenanthridine alkaloid (1), having a tertiary benzo [c] phenanthridine skeleton, from the norbase (3) is described. Treatment of the norbase (3) with sodium borohydride in formic or in acetic acid gave the N-methyl-(5) or the N-ethyl-(7) dihydrobase, respectively, in good yield. The N-methyldihydrobase (5) could also be prepared by treatment of the norbase (3) with sodium borohydride and dimethyl sulfate in hexamethylphosphoric triamide. The dihydrobases (5 and 7) were readily convertible to the corresponding quaternary benzo [c] phenanthridine alkaloids by oxidation with Jones reagent or with 2, 3-dichloro-5, 6-dicyano-1, 4-benzoquinone (DDQ) in good yields. In addition, we found that the air-oxidation of the carbanions derived from the ψ-cyanides (11) of the quaternary bases (1) gave the corresponding oxybases (10) in excellent yields.
本文介绍了一种从硼酸基(3)合成具有三级苯并[c]菲啶骨架的四级苯并[c]菲啶生物碱(1)的通用方法。用硼氢化钠在甲酸或乙酸中处理去甲基 (3),可分别得到 N-甲基-(5)或 N-乙基-(7)二氢化酶,收率很高。在六甲基磷酸三酰胺中用硼氢化钠和硫酸二甲酯处理硼氢化钠碱(3),也可以制备出 N-甲基二氢化酶(5)。用琼斯试剂或 2,3-二氯-5,6-二氰基-1,4-苯醌(DDQ)进行氧化,二氢化酶(5 和 7)很容易转化为相应的季苯并[c]菲啶生物碱,而且收率很高。此外,我们还发现,通过空气氧化从季铵盐碱(1)的ψ-氰化物(11)中得到的碳离子,可以得到相应的氧碱(10),而且收率极高。