A simple, economical, and environmentally benign protocol for the synthesis of [1,2,4]triazolo[5,1-b]quinazolin-8(4H)-one and hexahydro[4,5]benzimidazolo[2,1-b]quinazolinone derivatives

An efficient synthesis of [1,2,4]triazolo[5,1-b]quinazolin-8(4H)-one and hexahydro[4,5]benzimidazolo[2,1-b]quinazolinone derivatives with good yields is described. This method involves three-component reaction between aldehydes, dimedone, and 3-amino-1,2,4-triazole or 2-aminobenzimidazole in acetic acid as reaction medium at 60 A degrees C. We have found that the use of acetic acid as reaction medium results in a remarkable beneficial effect on the reaction, allowing it to be performed without the need of incorporating a catalyst, which is the case in other similarly reported methodologies. The notable advantages of this protocol are excellent yields, short reaction time, mild reaction conditions, more readily available and inexpensive materials, more environmentally friendly, no need for column chromatography, and simple work-up procedure.