脱镁叶绿酸的硝(烃基)化反应及其叶绿素类二氢卟吩衍生物的合成

Nitration(Nitroalkylation) of Pheophorbide and Synthesis of Chlorophyllous Chlorin Derivatives

以脱镁叶绿酸-a甲酯为起始原料,利用其周环上的活性反应基团进行化学修饰,在N21-N23轴向两端构建了甲酰基、烯酮和邻位二酮结构,通过芳香性大环色基的亲电取代、活性羰基的Henry反应以及外接环上作为不同给受体的β-酮酯和烯酮的Michael加成,分别在3-、12-、20-位和外接环上实施硝化和硝烃基化,完成了一系列未见报道的硝(烷)基取代的叶绿素类二氢卟吩衍生物的合成,其化学结构均经UV-Vis、IR、1H NMR及元素分析予以证实.

Pyropheophorbide-a methyl ester was used as a starting material,and the chemical modification was carried out making use of its active groups attached to the chlorin periphery to establish the formyl group,ketene andα-diketone moieties around the N21-N23 axis.The nitrations or nitroalkylations at 3-,12-,20-position and on the exocyclic ring were performed by the electrophilic substitution on the aromatic macrocyclic chromophore,Henry reaction at the active carbonyl groups,and Michael addition to theβ-keto ester and the ketene structures on the exocyclic ring as different donor-acceptor.A series of unreported nitro(nitroalkyl)substituted chlorins related to chlorophyll were synthesized and their chemical structures were characterized by elemental analysis,UV-Vis,IR and 1 H NMR spectra.