以叶绿素降解产物脱镁叶绿酸-a甲酯为起始原料,利用空气氧化反应在12-位上引进甲酰基,再通过氧化、还原、Grignard、Knoevenagel、Cannizzaro和1,3-偶极环加成等经典反应进行官能团转换,并对五元外接E-环实施结构改造,在C(12)-位上分别建立了能与大环色基形成不同共轭程度的酰基、酯基和取代烃基,完成了一系列未见报道的叶绿素类二氢卟吩衍生物的合成,其化学结构均经UV,IR,^1H NMR及元素分析予以证实,同时也讨论了C(12)-位非甲基化对叶绿素类四吡咯大环分子所形成的各种影响.
Pyropheophorbide-a methyl ester, as a degradation product from chlorophyll-a, was used as a starting material, and the formyl group was introduced at 12-position by allomerization. The transformations of C(12)-functional group, including the structural rebuilding of E-ring, were carried out by classic reactions such as oxygenation, reduction, Grignard reaction, Knoevenagel reaction, Cannizzaro reaction and 1,3-dipolar cyclocaddition. The acyl, ester and substituted alkyl groups, which could conjugated with macrocyclic chromophore at various degrees, were established at 12-position. The synthesis of a series of unreported chlorins related to chlorophyll was accomplished and their chemical structures were characterized by elemental analysis, UV, IR and 1H NMR spectra. The different fluences on the chlorophyllous tetrapyrrole molecule by C(12)- nomethvlation were also discussed.