Copper(I)-catalyzed synthesis of 1-arylpyrazolo[5,1-b]quinazolin-9(1H)-one via intramolecular alkyne hydroamination

Meglumine-based Sustainable Three-component Deep Eutectic Solvent Applicable for the Synthesis of Pyrazolo[5,1-b]quinazoline-3-carboxylates as a Sensing Probe for Cu2+ Ions

An unprecedented meglumine-based three-component deep eutectic solvent (3c-DES) (MegPAc) was synthesized using meglumine, p-toluenesulfonic acid (PTSA), and acetic acid as a renewable, and non-toxic solvent. The exploitation of the MegPAc as an eco-friendly reaction media to construct a selective and sensitive small organic molecular sensing probe, namely, pyrazolo[5,1-b]quinazoline-3-carboxylates (PQCs) was executed. Captivatingly, the MegPAc served the dual role of solvent and catalyst, and it delivered the title components with 69-94 % yields within 67-150 minutes. Furthermore, a UV-visible study unfolds the selective detection of Cu2+ ions with our synthetic probe 4 ba and resulted in hypsochromic shift due to electrostatic interactions. Additionally, 1 H NMR titration study and density functional theory (DFT) calculations were performed to attest the binding mechanism of sensing probe 4 ba and Cu2+ ions. Worthy of mention, this protocol unveils the efficacy of meglumine-based 3c-DES for the first time as a bio-renewable system to synthesize the PQCs.

An efficient synthesis of 16H-dibenzo[2,3:6,7][1,4]oxazepino[5,4-b]quinazolin-16-ones via an Ullmann reaction catalyzed by CuI

CuI functions as a mild Lewis acid catalyst to promote the condensation and cyclization reaction of 2-amino-N-(2-hydroxyphenyl)benzamide and 2-bromobenzaldehyde to build the quinazoline moiety first. With the addition of Cs₂CO₃, it also can catalyse the subsequent intramolecular Ullmann type reaction to give 16H-dibenzo[2,3:6,7][1,4]oxazepino[5,4-b]quinazolin-16-ones in good yields.

An efficient synthesis of 6-arylbenzo[4,5]imidazo[2,1-a]isoquinolines via sequential α-arylation of carbonyl and deacylation catalyzed by CuI

Dibenzoyl methane was found to undergo α-arylation of carbonyl and deacylation reaction with 2-(2-bromophenyl)-1H-benzo[d]imidazoles catalyzed by CuI in the presence of Cs₂CO₃, and provided an efficient synthesis of 6-arylbenzo[4,5]imidazo[2,1-a]isoquinolines.

Ancillary ligand-free copper catalysed hydrohydrazination of terminal alkynes with NH2NH2

An atom-efficient route for the formation of CN bonds containing products from bulk materials and a cheap catalyst.

Copper(II)-Catalyzed Alkoxyhalogenation of Alkynyl Ureas and Amides as a Route to Haloalkylidene-Substituted Heterocycles

A highly effective synthesis of haloalkylidene-substituted heterocycles by copper(II)-catalyzed cyclization of alkynyl ureas and secondary amides has been developed. The reaction, which involves a catalytic amount of CuCl2 and a stoichiometric amount of N-halosuccinimide, occurs selectively through an alkoxyhalogenation process. Alternatively, alkoxychlorination and alkoxybromination reactions can be performed working solely with stoichiometric CuCl2 and CuBr2, respectively.

Pyrazoloquinazolines: Synthetic strategies and bioactivities

Numerous N-heterocycles are indisputably evidenced to exhibit myriad biological activities. In the recent past, attempts made to condense the various heterocycles have resulted in derivatives possessing better bioactivities. Among many such condensed heterocycles, pyrazoloquinazolines have managed to hold the attention of many researchers, owing to the broad spectrum of activities they portray. This review is the first of its kind to congregate the various pyrazoloquinazolines reported until now and categorizes these structurally isomeric classes into eleven different groups based on the fusion pattern of the ring such as [1,5-c], [5,1-b], [4,3-h], etc. Furthermore, this review is a concerted effort to highlight design, synthetic strategies as well as biological activities of each class of this condensed heterocycle. Structure-activity relationship studies and in silico approaches wherever reported have also been discussed. In addition, manuscript also offers scope for design, synthesis and generation of libraries of unreported classes of pyrazoloquinazolines for the biological evaluation.