Herein, we report the catalytic activity of nebivolol nanoparticles a novel organocatalyst for the synthesis of DHPMs and DHPM-5-carboxamides. The nanoparticles are confirmed by DSC, TEM, AFM, and IR spectroscopy. The catalyst can be readily recovered and reused for the next four runs without any significant impact on the yields of the products. The products are fully characterized by FTIR, 1H NMR, 13C NMR, and distortionless enhanced polarization transfer (DEPT) NMR. The methodology adopted here offers several advantages such as solvent-free reaction, low loading of catalyst, short reaction times, and quantifiable yields.
A variety of 4-substituted 5-acetyl- and 5-carboethoxy-2-oxo-1,2,3,4-tetrahydropyrimidines were oxidized under UV irradiation in the presence or absence of benzoyl peroxide. The nature of the substituents on the 4- and 5-positions of the heterocyclic ring affects the rate of photo-oxidation, and irradiation of these compounds in the presence of benzoyl peroxide decreases the time of reaction drastically. Removal of 4-H by a benzoyloxy radical under formation of a trihydropyrimidinoyl radical intermediate occurs in the rate-determining step. The stability of this benzylic and allylic radical intermediate is affected by the nature and the position of the additional substituent on the phenyl group located at C-4.