Direct Synthesis of Pyrroles via Heterogeneous Catalytic Condensation of Anilines with Bioderived Furans

Abstract

Given the wide applications of pyrroles in agriculture, pharmaceuticals, and supramolecular and materials chemistry, a mild and eco-friendly route to produce functionalized pyrroles from bioderived feedstocks is highly desirable. Described herein is a mild and convenient synthesis of pyrroles via direct condensation of an equimolar amount of structurally diverse anilines with biobased furans catalyzed by a simple and efficient solid acid H form zeolite Y catalyst. The protocol tolerates a large variety of functional groups and offers a general and versatile method for scale-up synthesis of a variety of N-substituted pyrrole compounds. Most importantly, the bioactive pyrrole-derived drug pyrvinium, which has lately been confirmed as highly effective in curing colon cancer, can be obtained by this method.

Integrating Biomass into the Organonitrogen Chemical Supply Chain: Production of Pyrrole and d‐Proline from Furfural

“…Considering the amination of furan to pyrrole is promoted by acids, different types of solid acid catalysts, including γ‐Al 2 O 3 , SiO 2 ‐Al 2 O 3 , HZSM‐5, H‐beta and H‐USY, were chosen and combined with Pd@S‐1 to demonstrate the viability of the single‐step conversion strategy. Furan amination required 400–450 °C to occur, [16] but higher temperature (>350 °C) was not suitable for furfural decarbonylation. Almost 40 % carbon was lost when the reaction temperature was 400 °C (Supporting Information, Figure S1).…”

Toward an Integrated Conversion of 5-Hydroxymethylfurfural and Ethylene for the Production of Renewable p-Xylene

“…The involvement of both Lewis and Brö nsted acid sites on t-ZrO 2 for dehydrative aromatization was well supported by the negative effects of titration with 2,6-lutidine or pyridine (Figure S20). 53,54 A major interest arising, then, is how the synergy between such Lewis and Brö nsted acidity could facilitate this t-ZrO 2 -mediated catalysis. Given that the Brö nsted acid sites of t-ZrO 2 originate essentially from the hydroxyl-attached Zr species, 55 a more thoroughly dehydrated sample (denoted as t-ZrO 2 -DH) was prepared and tested under the same conditions as the data in Table S11.…”

Three-component reactions of aromatic amines, 1,3-dicarbonyl compounds, and α-bromoacetaldehyde acetal to access N-(hetero)aryl-4,5-unsubstituted pyrroles

“…Kumar et al [26] developed a proline-catalyzed Mannich reaction-cyclization sequence of succinaldehyde and an in situ-generated arylimine, in which the succinaldehyde contributes three carbon atoms to the pyrrole ring. α,β-Unsaturated aldehydes have also been used as the C 3 donor to construct pyrrole scaffolds [27,28]; (ii) [1 + 4] annulation, in which (hetero)arylamines are reacted with a C 4 donor to form the pyrrole ring; many functional molecules, such as bioderived furans [29], (Z)-enynols [30], 1-vinylpropargyl alcohols [31], doubly activated cyclopropanes [32], and enynals [33], can be used as C 4 counter reagents. The carbon-based 1,4-biselectrophiles, such as the 1,4-dicarbonyl compounds [34,35], γ-car-bonyl tert-butyl peroxides [36], and dihydrofurans [37] have also been reported to construct the pyrrole skeletons through this type of annulation; and (iii) [1 + 2 + 2] annulation, in which (hetero)arylamines are reacted with two different molecules, and each of them contributes two carbon atoms to construct a pyrrole ring [38][39][40][41][42].…”