An Efficient Protocol for the Synthesis of 2-Phenylquinazolines Catalyzed by Ceric Ammonium Nitrate (CAN)

Abstract

A facile and efficient method for the synthesis of 2-phenylquinazolines has been developed from 2-aminobenzophenones and benzylamines catalyzed by ceric ammonium nitrate (CAN)-TBHP in acetonitrile. The corresponding 2-phenylquinazolines were obtained in good to excellent yields.

Key words

2-aminobenzophenones - benzylamines - ceric ammonium nitrate - tert-butyl hydroperoxide - acetonitrile

References and Notes

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10

All chemicals were purchased from Sigma-Aldrich with purity not less than 99.9%. Analytical TLC was carried out by using silica gel 60 F254 pre-coated plates. Visualization was accomplished with UV lamp of I₂ stain. All products were characterized by their NMR and Mass spectra. ^¹H NMR and ^¹³C NMR were recorded at 200 MHz or 300 MHz, in CDCl₃ using TMS as the internal standard, chemical shifts are reported in ppm (δ) downfield from the TMS.
Typical Experimental Procedure for the Synthesis of 2-Phenylquinazolines: To a magnetically stirred 2-aminobenzophenone/2-aminoacetophenone (1.0 mmol) in MeCN (10 mL), benzylamine (2.5 mmol), CAN (10 mol%), and TBHP (7.0 mmol of 70% aq solution) were added and heated to reflux under nitrogen atmosphere at 80-85 ˚C until the reaction was completed (as indicated by TLC). After completion of the reaction, the mixture was concentrated to remove MeCN. After evaporation of the solvent under reduced pressure, the crude residue was extracted with EtOAc and the combined organic layers were washed with brine solution, dried over anhyd Na₂SO₄, evaporated to get crude product and purified by column chromatography by using hexane and EtOAc as eluent to give the titled compound, 2-phenylquinazoline. All the products were characterized by ^¹H NMR, ^¹³C NMR and mass spectroscopy and compared with the authentic samples known in literature.