Synthesis of Some Substituted Pyrazolopyrimidine Derivatives: An Environmentally Benign Approach

Abstract

Pyrazolopyrimidines constitute a medicinally important class of heterocyclic compounds. Herein, we report an efficient and environmentally benign method for the synthesis of pyrazolo[3,4‐d]pyrimidin‐3‐ones from 2,4‐dinitrophenylhydrazine and diethyl malonate under microwave irradiation in 1,3‐dibutylimidazolium bromide ionic liquid. The synthesized compounds were analyzed by elemental analysis and standard spectroscopic techniques. The compounds were screened for their antibacterial and antifungal activities.

Recent developments on microwave-assisted organic synthesis of nitrogen- and oxygen-containing preferred heterocyclic scaffolds

“…Ameta and co-workers reported an efficient and environmentally friendly method to synthesize pyrazolo[3,4- d ]pyrimidine-3-ones using microwave irradiation. 101 The reaction was carried out between 2,4-dinitrophenylhydrazine 104 and diethyl malonate in 1,3-dibutylimidazolium bromide ionic liquid under microwave irradiation for 5–8 min to afford compound 105 which, on further treatment with base and 1,3-dibutylimidazolium bromide ionic liquid under microwave irradiation for 7–8 min, afforded compound 106a–e. The latter, on further reaction with urea under similar conditions, afforded desired compounds 107a–e in moderate-to-good isolated yields (65–85%) ( Scheme 36 ).…”

Efficient Green Protocols for the Preparation of Pyrazolopyrimidines

“…property, ease of recyclability, and reutilization of ionic liquid (Scheme 62). [92] A simplistic and green one-pot synthetic protocol for preparation of 1H-pyrazolo [3,4-d]pyrimidine from various aromatic aldehydes, 5-methyl-2-phenyl-2,4-dihydro-3H-pyrazol-3one and thiourea or urea in ionic liquid with Bronsted acidic properties, 1-butyl-1H-imidazol-1-ium tetrafluoroborate ([HBim] BF 4 ) under ultrasound irradiation at ambient reaction condition was reported by Thummar et al The method provides the advantage of easy preparation, mild reaction conditions, easy isolation of product, higher yields and recyclability of ionic liquid (Scheme 63). [76] Mechanism: The multicomponent reaction involves the formation of an adduct via Knoevenagel condensation of aromatic aldehydes with 5-methyl-2-phenyl-2,4-dihydro-3Hpyrazol-3-one.…”