关键词: 喹唑啉酮, 消旋磷酸, 手性磷酸

N¹-Substituted quinazolinone alkaloids hold significant research value in drug discovery; however, synthetic methods for such alkaloids have rarely been reported. Herein, we present an efficient approach for the synthesis of 1-methyl-2-phenyl-2,3-dihydroquinazolin-4(1H)-one and its derivatives. Using o-methylaminobenzamide and benzaldehyde derivatives as starting materials, racemic phosphoric acid as the catalyst, and 4 Å molecular sieves as a desiccant, the reaction proceeded at 120 °C for 24 h. The final yield of the 26 target products ranged of 57% - 98%. The structures of all compounds were fully characterized by ¹H NMR, ¹³C NMR and high resolution mass spectrum. The structure of the template product was characterized by X-ray single-crystal diffraction. Moreover, the synthesis of chiral target products was achieved when using chiral phosphoric acid as the catalyst. In summary, this method features readily accessible starting materials, cost-effectiveness, high efficiency, and good functional-group tolerance, offering a practical and efficient strategy for synthesizing N¹-substituted quinazolinone alkaloids.

Key words: quinazolinone, racemic phosphoric acid, chiral phosphoric acid