Background: Porphyrins are highly conjugated heterocyclic compounds and are found as the backbone of many natural products such as heme and chlorophyll. To improve its biological and optical properties, the functionalization of porphyrin at its β- and meso-position has gained importance in recent years. Objective: The purpose of this review is to describe the Pictet-Spengler method for the incorporation of nitrogenous and biologically important heterocyclic scaffolds such as pyrrolo-/indolo[1,2-a]quinoxaline, pyrrolo[1,2-a]pyrazine, and quinoline at the β- and meso-positions of the porphyrins to increase π-conjugation and improve their biological, optical, and electrochemical properties. Conclusion: This review provides a comprehensive overview of the synthesis of N-heterocyclic ex-tended porphyrins and metalloporphyrins via a modified Pictet-Spengler approach. The synthesized porphyrins were found to be highly conjugated and exhibited improved photophysical properties com-pared to their parent analogues. Moreover, the review article provided a brief overview of the Pictet-Spengler procedure, including product yields, reaction conditions, photophysical properties of the synthesized products, and potential applications in a variety of fields.

中文翻译：

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N-杂芳族扩展卟啉的 Pictet-Spengler 合成

背景：卟啉是高度共轭的杂环化合物，被发现是血红素和叶绿素等许多天然产物的主链。为了改善其生物和光学特性，近年来，卟啉β-和内消旋位的功能化变得越来越重要。目的：本综述的目的是描述用于掺入含氮和生物学上重要的杂环支架的 Pictet-Spengler 方法，例如吡咯并/吲哚并[1,2-a]喹喔啉、吡咯并[1,2-a]吡嗪、和喹啉在卟啉的β-和中间位，以增加π-共轭并改善其生物、光学和电化学性质。结论：本综述全面概述了通过改进的 Pictet-Spengler 方法合成 N-杂环扩展卟啉和金属卟啉。发现合成的卟啉是高度共轭的，并且与其母体类似物相比表现出改善的光物理性质。此外，综述文章还对 Pictet-Spengler 程序进行了简要概述，包括产物收率、反应条件、合成产物的光物理性质以及在各个领域的潜在应用。