叶绿素降解产物的羟(烷)基化及其二氢卟吩衍生物的合成

Hydroxy(alky)lation of Chlorophyllous Degradation Products and Synthesis of Their Chlorin Derivatives

以脱镁叶绿酸-a甲酯为起始原料,利用二氢卟吩大环上的富电子区域的化学反应性对其实施结构修饰,通过外接E环α-氢的空气氧化、C(3)-乙烯基的亲电加成、羰基的亲核加成和20-meso-氢的亲电取代反应,在外接E环、C(3)-,C(12)-β-位和20-meso-位上完成了羟基或者羟烷基的引进,新建羟基的氧化和脱水反应进一步转换成碳氧双键或者碳碳双键.所合成的11个未见报道的叶绿素类二氢卟吩衍生物的化学结构均经UV,1H NMR,IR及元素分析得以证实,对相应的化学反应提出了可能的反应机理.

Methyl pheophorbide-a was used as a starting material, and its modifications were carried out making use of the chemical reactivities of electron-richous regions on the chlorin macrocycle. The introdustions of hydroxyl groups or hy- droxyalkyl groups at exocyclic E-ring, C（3）（C12）-fl-position and 20-meso-position were accomplished by the allomerizations of a-hydrogen of the exocyclic E-ring, the electrophilic addition of C（3）-vinyl group, the nucleophilic addition of the carbonyl groups and electrophilic substitution at C（20）-position. The newly-formed hydroxyl groups were further converted into car- bon-oxygen double bonds or carbon-carbon double bonds by oxidation and dehydration reactions. The chemical structures of 11 unreported chlorin derivatives were characterized by UV, 1H NMR, IR spectra and elemental analysis. The possible mecha- nisms about corresponding reactions were tentatively proposed.