红紫素-18的化学修饰及其叶绿素类二氢卟吩衍生物的合成

Chemical Modifications of Purpurin-18 and Synthesis of Chlorophyllous Chlorins Derivatives

以红紫素-18甲酯及其N-甲氧基二酰亚胺甲酯为起始原料,以氧化苯甲腈或者甲亚胺作为1,3-偶极体,与红紫素-18的3-位乙烯基进行偶极环加成反应,在周环上建立了不同的五元杂环结构;选择芳胺和芳醛缩合而成的含氮二烯与红紫素-18二酰亚胺C(3)-双键实施杂Diels-Alder反应(Povarov反应),得到了3-位芳酰基或者芳烷基取代的开环重排产物;利用20-meso-氢和C(12)-甲基的反应活性,在红紫素-18的二氢卟吩色基上分别完成了亲电取代、空气氧化和类羟醛缩合反应,并在周环的12-和20-位上引进了不同的取代基团,合成了一系列未见报道的叶绿素类二氢卟吩衍生物.其化学结构均经UV,IR,1H NMR,MS及元素分析予以证实.同时,对所涉及的反应机理也进行了相应的讨论.

Purpurin-18 methyl ester and its imid ester were used as starting materials. The cycloaddition of the 3-vinyl group in purpurin-18 with nitril oxide or azomethine as 1,3-dipole was carried up to established different five-membered heterocyclic structures on the chlorin chromophore. Azadiene, prepared from the condensation of arylamine with aromatic aldehyde, with double bond at 3-position of purpurin-18 conducted hetero-Diels-Alder reaction（Povarov reaction） to generate ring-opening rearranged products substituted with aroyl or aralkyl group. The electrophilic substitution, allomerization and like-Aldol reaction were accomplished making use of the reactivity of C（12）-methyl or 20-meso-hydrogen to introduce various substitutes at 12- and 20-position on the periphery of purpurin-18. 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 reaction mechanisms involved were also discussed accordingly.