Porphyrins with exocyclic rings. Part 21: Influence of pyrrolic and carbocyclic ring alkyl substituents on the synthesis of porphyrins bearing six-membered exocyclic rings
作者:Craig M. Shiner、Timothy D. Lash
DOI:10.1016/j.tet.2005.10.019
日期:2005.12
cyclohexanones with phenylhydrazones derived from esters of acetoacetic acid under Knorr-type reaction conditions. Related 6,6-dimethyltetrahydroindoles were also prepared by reacting dimedone with oximes by the Knorr pyrrole syntheses, followed by selective reduction of the remaining ketone moiety with diborane. The substituted tetrahydroindoles were regioselectively oxidized with lead tetraacetate to give
通过使4-取代的环己酮与衍生自乙酰乙酸酯的苯hydr在Knorr型反应条件下反应,制备了一系列5-取代的4,5,6,7-四氢吲哚。相关的6,6-二甲基四氢吲哚也可以通过用克诺尔吡咯合成法使二甲酮与肟反应,然后用乙硼烷选择性还原剩余的酮部分来制备。用四乙酸铅将取代的四氢吲哚区域选择性地氧化,得到相关的7-乙酰氧基衍生物,并使它们与5-未取代的吡咯酯反应,得到吡咯基四氢吲哚。在一种情况下,使用溴取代基保护吡咯反应物的β-位。在Pd / C上用氢裂解苄基酯保护基,这也除去了溴保护基,得到四种二吡咯羧酸。使用MacDonald'2 + 2'缩合将其与二吡咯基甲烷二醛缩合,得到具有六元环外环的取代卟啉。这些结构可用于与富含有机物的沉积物(如油页岩和石油)中的卟啉样品进行比较。四氢吲哚前体在六元环上存在甲基取代基会稍微降低卟啉合成的收率,并且当系统由于相邻吡咯环上存在乙基而变得空间更拥挤时,这种作用会