Resourceful synthesis of pyrazolo[1,5-a]pyrimidines under ultrasound irradiation

• A series of 7-trifluoromethyl-pyrazolo[1,5-a]pyrimidines under ultrasound irradiation was synthesized.
• Ultrasound irradiation method was more efficient than conventional thermal heating.
• The reaction was in ethanol and free of catalyst.
• Products were obtained with excellent yields.

Pyrazolo[1,5-a]pyrimidines were synthesized via the ultrasonic sonochemical method using the cyclocondensation reaction of 4-alkoxy-1,1,1-trifluoro-3-alken-2-ones [CF3C(O)CH = C(R)(OMe) – where R = Me, Bu, i-Bu, Ph, 4-Me–C6H4, 4-F–C6H4, 4-Cl–C6H4, 4-Br–C6H4, naphth-2-yl and biphen-4-yl] – with 3-amino-5-methyl-1H-pyrazole in the presence of EtOH for 5 min. This methodology has several advantages, for example, it is a simple procedure, it has an easy work-up, mild conditions, short reaction times (5 min) and produces satisfactory yields (61–98%).

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