Facile synthesis of 4-quinolone derivatives via one-pot cascade reaction under transition-metal-free conditions
摘要:
A practical and efficient strategy has been described for the preparation of 4-quinolone derivatives. Using commercially available diethyl acetylenedicarboxylate and aromatic amines as starting materials, the synthetic protocol has been achieved and afforded the product via hydroamination at room temperature followed by PPA-catalyzed intramolecular ring closure. The products can be easily obtained in high yields. Conditions and mechanism of the reaction have also been investigated. This protocol is environmentally friendly and transition-metal-free, with advantages including short reaction time, convenient operation, and mild reaction conditions. (C) 2015 Elsevier Ltd. All rights reserved.