Hydrophobically Directed, Catalyst‐Free, Multi‐Component Synthesis of Functionalized 3,4‐Dihydroquinazolin‐2(1H)‐ones.

A one-pot three-component reaction of o-formyl carbamate, a primary amine, a nucleophile (1H-indole or 2-napthol) in water generated a variety of functionalised 3,4-dihydroquinazolin-2(1H)-one derivatives. The reaction operated under catalyst-free conditions involves a Mannich type reaction followed by intramolecular cyclization and produced good to excellent yields of the products with a wide range of substrates. The environmentally benign multi-component reaction is a sustainable approach to the library of 3,4-dihydroquinazolin-2(1H)-one derivatives under completely neutral conditions. All the newly synthesized compounds were evaluated for their antimicrobial activity against Gram positive bacteria and Gram negative bacteria. Nineteen compounds exhibited good antibacterial activity against both Gram positive pathogens and Gram negative species.