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M.Z. Kassaee et al. / Chinese Chemical Letters 22 (2011) 1203–1206
benzaldehyde, aniline and cyclohexanone was repeated with the recycled catalyst. The yields obtained (85–78%) for
four consecutive cycles. Reduction of the catalytic activity is attributed to the reduction of its surface activity mainly
through agglomeration of the recycled TiO2 NPs as indicted by its SEM and XRD (available upon request).
2. Conclusion
A versatile method for the synthesis of b-aminocarbonyl compounds is developed using TiO2 NPs under mild
(solvent free, room temperature) conditions. The significant features of this procedure include high yields, good
selectivity, and facile operations, along with the catalyst recyclability.
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[33] General procedure for the synthesis of b-aminocarbonyl compounds (5a): To a mixture of a benzaldehyde (1 mmol), aniline (1 mmol), and
cyclohexanon (3 mmol), TiO2 NPs (0.016 g, 20 mol%) was added at room temperature (23–28 8C), and the mixture was stirred 2 h. After
completion of the reaction (checked by TLC), dichloromethane was added, and the catalyst was removed by filtration. The filtrate was washed
with a saturated aqueous NaHCO3 solution and brine, and dried over anhydrous Na2SO4. The crude mixture was further purified by column
chromatography using hexane:ethyl acetate (8:1) as eluent.