焦脱镁叶绿酸的炔化反应及其叶绿素类二氢卟吩的合成

Alkynylation of Pyropheophorbide-a and Synthesis of Chylorophyllous Chlorin Derivatives

以焦脱镁叶绿酸-a甲酯为起始原料,利用加成和氧化反应将其转化成3-甲酰基或者3-乙酰基取代和E-环保护的反应前体,通过Grignard反应在3-位上引进炔基并构建了叔醇或者仲醇结构,再经脱水和氧化反应生成端位烯炔和炔酮取代的二氢卟吩衍生物.3-甲酰基焦脱镁叶绿酸-a甲酯与癸基溴化镁的Grignard反应、E-保护和C(3)-羟基的氧化反应得到C(3)-长链烷酰基取代的焦脱镁叶绿酸-a甲酯,再经酸催化脱水则得到含有链间烯炔结构的二氢卟吩.首次报道的叶绿素类二氢卟吩衍生物均经UV,IR,1H NMR及元素分析确定其化学结构,对相应的化学反应也提出了可能的反应机理.

Methyl pyropheophorbide-a was used as starting material and convened into 3-formyl or 3-acetyl substituted and E-ring protected reactive precursors. The Grignard reactions of these carbonyl groups introduced alkynyl groups at 3-position to build the tert-alcohol or sec-alcohol structures. Further dehydrations and oxidations produced terminal eneyne and ketyne substituted chlorins, respectively. The pyropheophorbide-a with long chain alkyl group at 3-position was obtained by Grignard reaction with decyl magnesium bromide, protection for E-ring and oxidation of C（3）-hydroxyl group from 3-formylpyropheo- phorbide-a, convened into chlorin containing eneyne moiety in chain by acid-catalyzed dehydration. The structures of all new chlorin derivatives were characterized by elemental analysis, UV, IR and 1H NMR spectra. The possible mechanisms about corresponding reactions were tentatively proposed