Clauson–Kaas pyrrole synthesis using diverse catalysts: a transition from conventional to greener approach

Abstract

Pyrrole is an important aromatic heterocyclic scaffold found in many natural products and predominantly used in pharmaceuticals. Continuous efforts are being made to design and synthesize various pyrrole derivatives using different synthetic procedures. Among them, the Clauson–Kaas reaction is a very old and well-known method for synthesizing a large number of N-substituted pyrroles. In recent years, due to global warming and environmental concern, research laboratories and pharmaceutical industries around the world are searching for more environmentally friendly reaction conditions for synthesizing compounds. As a result, this review describes the use of various eco-friendly greener protocols to synthesize N-substituted pyrroles. This synthesis involves the reaction of various aliphatic/aromatic primary amines, and sulfonyl primary amines with 2,5-dimethoxytetrahydrofuran in the presence of numerous acid catalysts and transition metal catalysts. The goal of this review is to summarize the synthesis of various N-substituted pyrrole derivatives using a modified Clauson–Kaas reaction under diverse conventional and greener reaction conditions.

Toward Biomass-Based Organic Electronics: Continuous Flow Synthesis and Electropolymerization of N-Substituted Pyrroles

“…13 The Clauson-Kaas reaction serves as the primary synthetic pathway for 1,4unsubstituted pyrroles. Different protocols for performing this reaction have been reported and recently summarized in a review by Kumar et al 14 The literature contains instances of the Clauson-Kaas protocol being executed without the need for a catalyst. Furthermore, reactions conducted under neat conditions or in water are documented.…”