A facile, regioselective synthesis of novel 3-(N-phenylcarboxamide)pyrazolo[1,5-a]pyrimidine analogs in the presence of KHSO $$_{4}$$ 4 in aqueous media assisted by ultrasound and their antibacterial activities

Abstract

An environmentally benign, simple, efficient, and convenient route is described for the synthesis of novel pyrazolo[1,5-a]pyrimidine derivatives under ultrasound irradiation. Condensation of aminopyrazole 5 with formylated active proton compounds (6, 8, E-G, 12, and 15) furnished pyrazolopyrimidine (7, 9, 10, 13, and 16) in high-to-excellent yields. In comparison with conventional methods, ultrasound irradiation offers several advantages, such as shorter reaction time, higher yields, milder conditions, and environmental friendliness. The reaction is clean with excellent yields and reduces the use of solvents. X-ray crystallographic study of compound 7c confirmed the regioselectivity of the reaction. The antibacterial profile of the newly synthesized compounds was evaluated by cup and saucer method.

New Thiophene Bearing Dimethyl-5-Hydroxy Isophtalate Esters and Their Antimicrobial Activities

“…Aromatic proton peaks of both thiophene and phenyl ring can be seen between 8.62-8.05 ppm for C1, 8.59-7.18 ppm for C2 and 8.34-6.99 ppm for compound 3 as it should be. 13 C-NMR signals of synthesized compounds were in agreement with proposed structures. Aliphatic carbon signals was observed at 52.7 ppm for C1, 52.6 ppm for C2 and 53.2 ppm for C3 compound.…”

“…1 H-NMR and 13 C-NMR spectra were recorded on Bruker DPX FT spectrometer. FT-IR spectra were recorded with Perkin Elmer Spectrum 100 Spectrometer using KBr discs.…”

“…However, consuming excess amount of antibiotics increasing the bacterial resistance and lead to decreasing the number of bacteria killing molecules day by day [1][2][3][4]. Large number of antibiotics have at least one heterocycle like pyridine [5][6][7], furan [8][9][10], pyrrole [11,12], pyrimidine [13,14] etc. In medicinal chemistry, thiophene derivatives have been very well known for their therapeutic applications.…”

Ultrasound assisted synthesis of pyrazolo[1,5-a]pyrimidine-antipyrine hybrids and their anti-inflammatory and anti-cancer activities

“…4-Aminoantipyrine has been used for the protection against oxidative stress as well as prophylactic of some diseases including cancer, and these are found to be important directions in medical applications [22]. In view of these information and in continuation with our research work [23][24][25] on synthesis of pharmacologically important pyrazolo [1,5-a]pyrimidines, it was found worthy to synthesize novel pyrazolo[1,5-a]pyrimidines incorporating the antipyrine moiety to study their biological properties. Ultrasound (US) irradiation has helped researchers tremendously in accomplishing the green goals of chemistry by shortening the reaction time with easy work-up, resulting in high yields of the products and use of readily available solvents and catalysts [26][27][28].…”

A three step one-pot regioselective synthesis of highly substituted pyrazolo[1,5-a]pyrimidines assisted by KHSO4 in aqueous media under ultrasound irradiation

“…Also, pyrazolo [1,5-a]pyrimidine nucleus is an interesting and versatile scaffold for the preparation of various drugs like zaleplon, indiplon and ocinaplon [14][15][16]. Realising the importance of these molecules, we have recently reported [17][18][19][20] a general synthetic strategy and demonstrated the applicability for the synthesis of pyrazolo [1,5-a] pyrimidines. In view of the importance of these molecules we have extended our synthetic strategy for 5methyl-4-phenyl pyrazolo [1,5-a]pyrimidine derivatives and the details are presented herein.…”