Background:
Nanoscale metal oxide catalysts have been extensively employed in organic reactions because they have been
found to influence the chemical and physical properties of the bulk material. The chromene (benzopyran) nucleus constitutes the core structure in a major class of many biologically active compounds, and interest in their chemistry consequently continues because of their numerous biological activities. The xanthene (dibenzopyran) derivatives are classified as highly significant compounds which display a number of
various bioactive properties. Pyrimidinones have also gained interest due to their remarkable biological utilization such as antiviral, antibacterial, antihypertensive, antitumor and calcium blockers effects.
Objective:
Our aim in the work presented herein was to prepare activated carbon/MoO3 nanocomposite and explore its role as a green and
recyclable catalyst for the synthesis of chromeno[d]pyrimidinediones and xanthenones under ethanol-drop grinding at room temperature.
Methods:
The activated carbon/MoO3 nanocomposite was prepared successfully via a simple route in which carbonization of gums as new
natural precursors was used for the synthesis of activated carbon. This nanocomposite was then effectively used in a reaction of 3,4-
methylenedioxyphenol, aromatic aldehydes and active methylene compounds including 1,3-dimethylbarbituric acid and dimedone to synthesize a series of chromeno[d]pyrimidinediones and xanthenones in high yields. The synthesized catalyst was characterized by Fourier
transform infrared spectroscopy (FT-IR), Powder x-ray diffractometry (XRD), Scanning electron microscope (SEM), Raman spectroscopy,
and also by TGA analysis. Confirmation of the structures of compounds 5(a-g) and 6(a-g) were also established with IR, 1
H NMR and 13C
NMR spectroscopic data and also by elemental analyses.
Results:
A number of 6,8-dimethyl-10-phenyl-6,10-dihydro-7H-[1,3]dioxolo[4΄,5΄:6,7]chromeno[2,3-d]pyrimidine-7,9(8H)-diones and 7,7-
dimethyl-10-(4-methylphenyl)-6,7,8,10-tetrahydro-9H-[1,3]dioxolo[4,5-b]xanthen-9-ones were effectively synthesized using activated carbon/MoO3 nanocomposite (0.05 gr) as catalyst under ethanol-drop grinding at room temperature. The desired products were obtained in
high yields (93-97%) within short reaction times (15-20 min).
Conclusion:
This paper investigates the catalytic potential of the synthesized activated carbon/MoO3 nanocomposite for the prepataion of
chromeno[d]pyrimidinediones and xanthenones under ethanol-drop grinding procedure. The mildness of the reaction conditions, high yields
of products, short reaction times, experimental simplicity, and avoid the use of harmful solvents or reagents makes this procedure preferable
for the synthesis of these compounds.
Trifluoroacetic Acid as an Efficient Catalyst for the Room Temperature Synthesis of 2-Aryl-1-arylmethyl-1H-1,3-benzimidazoles in Aqueous Media