Mild method for Ullmann reaction of 2-chlorobenzoic acids and aminothiazoles or aminobenzothiazoles under ultrasonic irradiation

One-pot syntheses of 5H-[1,3] thiazolo[2,3-b] quinazolin-5-one, 12H-[1,3]benzothiazolo-[2,3-b] quinazolin-12-one, and corresponding derivatives were developed using the copper-catalyzed Ullmann condensation. The use of ultrasonic irradiation enhanced yields and reduced the reaction time to minutes.