Abstract

Background: Pyrroles are organic cyclic compounds with an extensive and fascinating chemistry. These compounds have a wide structural variety and they are an important basis in technological development as they can be used as drugs, dyes, catalysts, pesticides, etc. Therefore, the production of these heterocyclic compounds by efficient clean methodologies is a great achievement in contemporary chemistry. In this paper, we show recent green procedures in the synthesis of pyrrole derivatives such as Hantzsch, Knorr and Paal- Knorr syntheses, as well as new eco-friendly synthetic procedures with high efficiency and low environmental impact.

Objective: This work focusses on the recent advances in the pyrrole synthesis using clean techniques like ultrasound (US), microwaves (MW), high speed vibration milling (HSVM), catalysts use, solvent replace and other methodologies applied to common reactions to obtain the pyrrole core which follow the green chemistry principles.

Conclusion: The main challenge of Green Chemistry is to gradually eliminate the generation of hazardous or harmful materials or replace them with less toxic and safer ones. However, this process must be driven by scientific developments. Its application in the synthesis of heterocyclic compounds such as pyrrole derivatives involves multiple economic and social benefits due to the biological importance of these compounds and their direct impact on the pharmaceutical industry. Although many processes are still under investigation using novel methodologies of green activation such as microwaves, ultrasound and HSVM, as well as synthetic processes in continuous flow and processes at room temperature, promising results such as cost and waste reduction and greater efficiency are achieved.

Keywords: Pyrrole, green synthesis, heterocyclic compounds, Hantzsch synthesis, Knorr synthesis, Paal-Knorr synthesis.

Graphical Abstract