Microwave-Assisted Cobalt-Catalyzed Synthesis of Quinazolinones via Acceptorless Dehydrogenative Coupling under Neat Condition.

Herein, we present a sustainable and atom-economical approach for the synthesis of quinazolinones via acceptorless dehydrogenative coupling (ADC) using earth-abundant Co-salt, (CoCl2) as the catalyst under neat condition. This method is distinguished by its green credentials, like, solvent-free, microwave-assisted heating, cost-effective, use of renewable alcohols, and generating only H2 and water as byproducts. Remarkably, this protocol achieves quinazolinone synthesis without the need for external ligands, oxidants, or additional additives. Two synthetic pathways were developed: one involving the coupling of alcohols with 2-aminobenzamide, and the other with N-phenyl-substituted 2-aminobenzamides and its derivative. The scalability of this method, demonstrated through gram-scale synthesis, highlights its potential for industrial applications. Mechanistic insights were explored through control experiments, intermediate detection by HRMS, and Hammett analysis, shedding light on the plausible reaction pathway.