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Keywords
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Nitrogen-doped graphene, multicomponent reaction, pyridine, solvent-free condition, acid-based catalyst, arylaldehydes.
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Abstract
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Polysubstituted pyridine derivatives were produced with high to excellent yields
in the presence of nitrogen-doped graphene (NDG) as a dual acid-based catalyst. NDG
efficiently catalyzes the multicomponent reaction between arylaldehydes, diethyl-acetylene
dicarboxylates, malononitrile, and ammonium acetate under solvent-free conditions at 80°C
to afford the polysubstituted pyridines in short reaction times. The structures of the synthesized pyridines were established by Ft-IR, 1
H, and 13C NMR spectroscopic analysis. The
advantages of this method include the in-situ oxidation of prepared 1,4-dihydropyridines,
one-pot procedure, solventless system, operational simplicity, and no column chromatography. Additionally, neither toxic solvents nor catalysts are needed, and the procedure can
be very reliable among the reported methodologies. The yields and reaction times in the
presence of four times recycled catalyst are in comparable to the fresh catalyst
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