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

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%).