An Expeditious Synthesis of N-substituted Pyrroles via Microwave-Induced Iodine-Catalyzed Reactions under Solventless Conditions

Abstract

An expeditious synthesis of N-substituted pyrroles has been developed by reacting 2,5-dimethoxy tetrahydrofuran and several amines using a microwave-induced molecular iodine-catalyzed reaction under solventless conditions.

Dihydropyridines as Calcium Channel Blockers: An Overview

“…Several heterocyclic compounds (both synthetic and natural) are widely known and many of them possess significant biological activities [1][2][3][4][5]. In 2013, four out of top six and nine out of top twenty one highest selling drugs were small molecule heterocyclic compounds [6].…”

Microwaves in Heterocyclic Chemistry

“…The formation of the N-substituted pyrroles in high yields (∼94%) may be explained by the formation of an azomethine ylide via decarboxylation and a subsequent 1,5-proton shift to give the more stable zwitterions, which can be easily transformed to the more stable product to gain aromatic character [4]. Banik and co-workers demonstrated that a solvent-free mixture of 2,5-dimethoxytetrahydrofuran and an amine with iodine (5 mol%) in an automated microwave oven afforded in short reaction time (∼5 min) N-substituted pyrroles in good yields (75-98%) [5]. A microwave process is highly beneficial in a small-scale parallel synthesis of 2-aminothiophenes by the Gewald reaction [6].…”

“…A catalytic enantioselective synthesis of 4-substituted-4,5-dihydro-1H- [1,5]benzodiazepin-2(3H)-ones employing an efficient hydrogenation protocol was developed by Rueping et al [142]. The target products were obtained in good yields (69-95%) with excellent enantioselectivities (83-99% ee) and broad functional group tolerance.…”

“…The s-triazine ring is a remarkable system for producing supramolecular structures because it easily forms hydrogen bonds and coordinates to transition metals. Recently, de la Hoz and co-workers showed that the reaction of 6-chloro-N,Nbispyrazolyl [1,3,5]triazine-2,4-diamines with 4-aminobenzylamine under microwave irradiation produced bistriazines in excellent yields [157]. The use of a diamine bearing amino groups with different reactivities allowed the reaction to be carried out in two steps and gave selectively the monotriazines (80 • C, 15-45 min) in 84-96% yield, the bistriazines (140 • C, 10 min) with identical substituents, and different substituted triazines.…”

Molecular Iodine: Mild, Green, and Nontoxic Lewis Acid Catalyst for the Synthesis of Heterocyclic Compounds

“…Pyrrole derivatives have also been reported as antimicrobial and antioxidant [15,16], anti-HIV [17], anticancer [18,19], antagonists of 5-HT7 receptor [20], antihepatitis [21], and as antifungal agents [22] as well as cognition enhancers [23] Banik et al [24] reported an expeditious synthesis of N-substituted pyrroles 1 by reacting 2,5-dimethoxy tetrahydrofuran and several amines under microwave irradiation using iodine as a catalyst. 2-Azetidinones and pyrroles are two highly important classes of molecules in organic and medicinal chemistry.…”