Solvent-Free, Mechanochemically Scalable Synthesis of 2,3-Dihydroquinazolin-4(1H)-one Using Brønsted Acid Catalyst

Although the synthesis of novel N-heterocyclic molecules is extremely demanding as well as challenging, the involvement of toxic solvents often triggers environmental safety concerns, resulting in process-engineering challenges. Herein, we have demonstrated a rapid, environmentally benign and energy efficient scalable method for the synthesis of 2,3-dihydroquinazolin-4­(1H)-one by grinding in a mortar pestle as well as mechanochemically via ball milling using p-TSA catalyst. The ability to accomplish the reaction in the absence of solvent via grinding or milling with p-TSA catalyst, with an immediate reduction in the cost and operational procedures, features the significant advantages of this protocol. The scalability and significance of the operational parameters during mechanochemical milling in the tubular ball mill were also demonstrated. Excellent yield in short duration, large substrate scope, product scalability, and easy recoverability are the prime features of this mechanochemical solvent-free protocol for the synthesis of 2,3-dihydroquinazolin-4­(1H)-one. The study also demonstrated the significant role of ball diameter to improve the efficiency of the milling operation in this mechanochemical synthesis.