An efficient Biginelli one-pot synthesis of new benzoxazole-substituted dihydropyrimidinones and thiones catalysed by alumina-supported trifluoromethane sulfonic acid under solvent free conditions

An efficient synthesis of benzoxazole‐substituted 3,4‐dihydropyrimidinones (DHPMs) using alumina supported trifluoromethane sulfonic acid as the catalyst for the first time from an aldehyde, β‐keto ester, and benzoxazole‐substituted urea and thiourea under solvent‐free conditions is described. When compared with the classical Biginelli reaction conditions, this new method consistently has the advantage of excellent yields (80–93%) and short reaction time (30–120 minutes) at 120°C temperature. J. Heterocyclic Chem., 46, 119 (2009).