Brønsted acidic ionic liquid was found to be an efficient and recyclable catalyst for the synthesis of benzo [4,5]imidazo[1,2-a]pyrimidines and 2,3-dihydroquinazolin-4(1H)-ones. The reactions proceeded smoothly with a broad scope of substrates providing the expected products in good to excellent yields under an atom-economical pathway. The low-cost recyclable catalyst, metal-and solvent-free conditions, and the ease of product isolation are the highlighted advantages in solving the issue of trace metal contamination in synthesized pharmaceuticals. Results and discussion Synthesis of benzo[4,5]imidazo[1,2-a]pyrimidinesPyrimidine derivatives are backbones of various pharmaceutical drugs with various applications including anticancer, 25-29 anti-inammatory, 30-32 antibacterial, 31,33-35 and antifungal activities. [35][36][37] Over the past decade, many approaches have been achieved for the preparation of pyrimidine derivatives. [38][39][40][41][42]