Recyclable, Graphite-Catalyzed, Four-Component Synthesis of Functionalized Pyrroles

Abstract

A facile, convenient, and multicomponent coupling strategy for the synthesis of highly functionalized pyrroles is developed using graphite as a catalyst, but devoid of moisture-sensitive metal catalysts and corrosive acidic reagents. This method involves four-component coupling reactions of ethyl acetoacetate compound or diethyl acetylene dicarboxylate, amines, aromatic aldehydes, and nitromethane without an inert atmosphere. This approach provides easy access to highly substituted pyrroles in good yields via one-pot tandem reaction. The method is very simple, straightforward, and environmentally friendly compared to the existing methods.

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GRAPHICAL ABSTRACT

Keywords:

• Carbon catalyst
• graphite
• multicomponent reaction
• Paal–Knorr synthesis
• pyrroles

Notes

^aAll reaction were carried out using aldehyde (1mmol), amine (1.5mmol), ethyl acetoacetate (1mmol), and (Table 1, entries 1–6) nitromethane (3mmol) and (Table 1, entries 7–12) nitromethane (1.5ml).

^b Yield obtained after column chromatography.

^aReaction time 4–6h.

^bPurified by column chromatography.