脱镁叶绿酸甲酯的Wittig反应及其红紫素-18酰亚胺衍生物的合成

以脱镁叶绿酸-a甲酯为原料,通过对其3-位乙烯基的氧化,得到3-(2,2-二甲氧基乙基)-去乙烯基脱镁叶绿酸-a甲酯,经过甲酸处理得到3-(2-氧代乙基)-去乙烯基脱镁叶绿酸-a甲酯,选择适当的条件,通过Witting反应合成了对应的3-(2-取代乙基)-去乙烯基脱镁叶绿酸-a甲酯。结合E环的改造,将其转变成酸酐环进而转变成N-取代的酰亚胺环。合成的一系列红紫素-18酰亚胺衍生物具有长波长的紫外吸收。

Wittig Reaction of Methyl Pheophorbide-a and Synthesis of Derivatives Purpurin-18 Imide

A series of novel purpurin-18 imide derivatives with long absorption wavelength were synthesized through Wittig reaction of methyl pheophorbide-a.The 3-(2-Dimethoxyethyl)-3-devinyl methyl pheophorbide- a was prepared through the oxidation of methyl pheophorbide-a with Tl(NO_3)_3 and transformed into the 3-(2- oxo-ethyl)-2-devinyl methyl pheophorbide-a through the treatment with the formic acid.The Wittig reaction of the formyl group at 3-position was carried out and the 3-(2-substituted ethyl)-3-devinyl methyl pheopjorbide-a were given.Under basic conditions the E-ring was converted into the cyclohexanedicarboxylic anhydride through the air-oxidation.The oxidized products were reacted with the hydroxylamine hydrochloride to generate the purpurin-18 imide derivatives.N-acyloxy purpurin-18 imide was obtained with acylation of N-OH.The ti- tle compounds demonstrated a considerable bathochromic shift on the major absorption band.