Recent Advancements in Pyrrole Synthesis

Abstract

AbstractThis 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 Introduction2 From π-Systems2.1 Alkenes2.2 1,6-Dienes2.3 Allenes2.4 Alkynes2.5 Propargylic Groups2.6 Homopropargylic Amines3 From Carbonyl Compounds3.1 Aldehydes3.2 Ketones3.3 Cyanides and Isocyanides3.4 Formamides3.5 β-Enamines3.6 Dicarbonyl Compounds4 From Polar Compounds4.1 Aminols4.2 Diols4.3 Organonitro Compounds5 From Heterocycles5.1 Münchnones5.2 Isoxazoles5.3 Carbohydrates5.4 trans-4-Hydroxy-l-prolines5.5 Pyrrolines6 Summary