焦脱镁叶绿酸-a甲酯衍生物的合成及其结构与光谱性能关系研究

以焦脱镁叶绿酸-a甲酯(MPP-a, 1)为起始原料,通过乙二醇对E-环羰基进行保护,选用四氧化锇和高碘酸钠将3-位碳碳双键氧化,生成131-二氧环戊基-131-去氧焦脱镁叶绿酸-d甲酯(2),经Grignard反应将3-甲酰基转换成羟烷基得仲醇3,再通过高钌酸四乙基胺和N-甲基吗啡啉N-氧化物将其氧化成酮4,脱去保护基生成3-烷酰基3-去乙烯基焦脱镁叶绿酸-a甲酯(6).焦脱镁叶绿酸-d (MPP-d)7与过量重氮甲烷发生加成和重排反应,生成6a及3-烷酰甲基3-去乙烯焦脱镁叶绿酸甲酯衍生物8和9,7的3-位醛基经过Wittig和氧化反应得到3-苯乙二酰基焦脱镁叶绿酸甲酯11.所合成的新卟吩衍生物均经UV,IR,¹H NMR及元素分析证明其结构,并且讨论了周边取代羰基对核磁共振光谱和最大可见光吸收的影响.

Synthesis of 3-Alkyloyl-3-devinyl-methyl Pyropheophorbide-a and the Effect of the Peripheral Carbonyl Groups on the 1H NMR and the Visible Spectra

Methyl pyropheophorbide-a (MPP-a) was used as starting material for the synthesis of new chlorin derivatives. Under the protection of the carbonyl group at 13 1-position with glycol, the carbon-carbon double bond at 3-position was oxidized by OsO 4 and NaIO 4 to give methyl pyropheophorbide-d (MPP-d) derivative 2. The formyl group was converted into the hydroxyalkyl group by the Grignard reaction giving the secondary alcohol 3 which was oxidized with TPAP and N-methyl morphline N-oxide to afford ketone 4. After deprotection 3-alkyloyl derivatives of methyl pyropheophorbide-a 6 were obtained. The addition and rearrangement reactions of MPP-d 7 with excess diazomethane generated rearranged products 6a, 8 and 9. 3-Phenyloxalyl methyl pyropheophorbide-a 11 was obtained by the Wittig and oxidation reactions of 3-formyl group. The structures of these compounds were characterized by elemental analysis, UV, IR and 1H NMR spectra, and the effect of the peripheral carbonyl groups on the 1H NMR and the visible spectra was discussed.