红紫素-18酰亚胺衍生物的合成

以脱镁叶绿酸甲酯为原料, 通过对其3-位乙烯基的氧化, 得到3-(2,2-二甲氧基乙基)-3-去乙烯基脱镁叶绿酸甲酯, 经过甲酸处理得到3-(2-氧代乙基)-3-去乙烯基脱镁叶绿酸甲酯, 选择适当的条件, 通过Grignard 反应合成了对应的3-(2-羟基烷基)-3-去乙烯基脱镁叶绿酸甲酯. 实验结果表明: 3-(2-氧代乙基)-3-去乙烯基脱美叶绿酸甲酯和Grignard试剂的反应, 只要反应条件控制得当, 13²-位的甲氧甲酰基不会脱去. 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. 目标化合物的合成也可以将3-(2,2-二甲氧基乙基)-去乙烯基脱镁叶绿酸甲酯转变成N-取代的酰亚胺后, 再和Grignard试剂反应, 完成目标化合物的合成. 合成的一系列化合物具有长波长的紫外吸收. 化合物的结构变化对紫外吸收的影响作了相应的讨论. 合成的新化合物均由核磁共振、红外光谱、元素分析予以证实.

Synthesis of Purpurin-18 Imide Derivatives

A series of novel purpurin-18 imide derivatives which had long wavelength absorption, were synthesized by modification of methyl pheophorbide-a. The 3-(2,2-dimethoxyethyl)-3-devinyl methyl pheophorbide-a was prepared by oxidation of methyl pheophorbide-a (MPa) with Tl(NO3)3 and transformed to 3-(2-oxo-ethyl)-3-devinyl methyl pheophorbide-a with formic acid. The Grignard reaction of the formyl group at 3-position was carried out to give efficiently the corresponding 3-(2-hydroxylalkyl)-3-devinyl methyl pheophorbide-a. In basic conditions E-ring was converted into the six-membered cyclic anhydride to form purpurin-18 derivatives by the air-oxidation. The experimental results showed that 132-methyloxy- carbonyl group of methyl pheophorbide-a was not destroyed in the process of Grignard reaction. The spec- tral data of H NMR of the compounds showed that there were two methoxy groups in the molecule after 1 Grignard reaction. It was possible to modify 3-vinyl by Grignard reaction and then transform E-ring as long as controlling reaction conditions. The title compounds were synthesized by transforming E-ring to im- ide-ring and then modifing 3-vinyl by Grignard reaction. They demonstrated a considerable bathochromic shift of the major absorption band in the red region of the optical spectrum. The effect on their visible spec- trum by variation of chemical construction was discussed. The structures of all new compounds were char- acterized by elemental analysis, UV, IR and H NMR spectra. 1