Recent Advancements in Pyrrole Synthesis

Abstract

Abstract This review article features selected examples on the synthesis of functionalized pyrroles that were reported between 2014 and 2019. Pyrrole is an important nitrogen-containing aromatic heterocycle that can be found in numerous compounds of biological and material significance. Given its vast importance, pyrrole continues to be an attractive target for the development of new synthetic reactions. The contents of this article are organized by the starting materials, which can be broadly classified into four different types: substrates bearing π-systems, substrates bearing carbonyl and other polar groups, and substrates bearing heterocyclic motifs. Brief discussions on plausible reaction­ mechanisms for most transformations are also presented. 1 Introduction 2 From π-Systems 2.1 Alkenes 2.2 1,6-Dienes 2.3 Allenes 2.4 Alkynes 2.5 Propargylic Groups 2.6 Homopropargylic Amines 3 From Carbonyl Compounds 3.1 Aldehydes 3.2 Ketones 3.3 Cyanides and Isocyanides 3.4 Formamides 3.5 β-Enamines 3.6 Dicarbonyl Compounds 4 From Polar Compounds 4.1 Aminols 4.2 Diols 4.3 Organonitro Compounds 5 From Heterocycles 5.1 Münchnones 5.2 Isoxazoles 5.3 Carbohydrates 5.4 trans-4-Hydroxy-l-prolines 5.5 Pyrrolines 6 Summary

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