Novel AMPA and kainate receptor antagonists containing the pyrazolo[1,5-c]quinazoline ring system: Synthesis and structure–activity relationships

The Practical Access to Fluoroalkylated Pyrazolo[1,5-c]quinazolines by Fluoroalkyl-Promoted [3 + 2] Cycloaddition Reaction

The efficient synthesis of fluoroalkylated pyrazolo[1,5-c]quinazolines by reactions of 3-diazoindolin-2-ones with methyl β-fluoroalkylpropionates has been achieved. This protocol affords two regioisomers of fluoroalkylated pyrazolo[1,5-c]quinazolines with excellent yields in total. The dipolarophilicity of methyl β-fluoroalkylpropionates enhanced by perfluoroalkyl groups is crucial for the high efficiency of this [3 + 2] cycloaddition reaction.

An Efficient Protocol for the Synthesis of Pyrazolo[1,5-c]quinazolines by a Staudinger–Aza-Wittig–Dehydroaromatization Sequence

The one-pot synthesis of azide-substituted dihydropyrazoles in isopropanol was performed by using chalcones, hydrazine hydrate, and an acyl chloride at 0 ℃. Subsequent Staudinger–aza-Wittig–dehydroaromatization reactions of the products with methyl(diphenyl)phosphine were also investigated for further application in the construction of pyrazolo[1,5-c]quinazolines.

Solvent and temperature effects on the tautomerization of a carbonitrile molecule: A conductor-like polarizable continuum model (CPCM) study

This research examined the effects of solvent polarity and temperature on the tautomerization of a carbonitrile molecule at CAM-B3LYP/6-311G (d,p) level of theory. The selected solvents were n-hexane, diethyl ether, pyridine, ethanol, methanol, and water. The solvent effects were examined by the self-consistent reaction field theory (SCRF) based on conductor-like polarizable continuum model (CPCM). The solvent effects were explored on the energy barrier, frontier orbitals energies, and HOMO-LUMO gap. Dependencies of thermodynamic parameters (ΔG and ΔH) on the dielectric constants of solvents were also tested. Specifically, the temperature dependencies of the thermodynamics parameters were studied within 100–1000 K range. The rate constant of the tautomerism reaction was computed from 300 to 1200 K, in the gas phase.

Regioselective Ring Expansion of 3-Ylideneoxindoles with Tosyldiazomethane (TsDAM): A Metal-Free and Greener Approach for the Synthesis of Pyrazolo-[1,5-c]quinazolines

An efficient, metal-free approach to access pyrazolo-[1,5-c]quinazolines with 3-ylideneoxindoles and tosyldiazomethane (TsDAM) under mild aqueous reaction conditions has been developed and the solvent involvement in the present reaction has also been explored for the first time. This greener approach involves 1,3-dipolar cycloaddition, regioselective ring expansion, followed by the elimination of tosyl group with aqueous base in a single operation, and the product can be isolated in high purity without column chromatographic separation. The method is also compatible with a large variety of functional groups, providing good to excellent yields in water, thus resulting in a decrease of environmental impact in the pharmaceutical industry.

Progress in Synthesis and Bioactivity Evaluation of Pyrazoloquinazolines

Background:

This paper reviews the research progress of pyrazoloquinazolines which widely used in the field of medicine and pesticide in recent years. Five types of pyrazoloquinazolines are introduced: pyrazolo [4,3-h]quinazolines, pyrazolo[1,5-c]quinazolines, pyrazolo[4,3-f]quinazolines, pyrazolo[1,5-a] quinazolines , pyrazolo[1,5-b]quinazolines, and their new progress in the synthesis methods and treatment of diseases.

Methodology:

The derivatives of pyrazoloquinazolines exhibit a wide range of pharmacological properties such as antibacterial, anticancer, antioxidants, anti-inflammatory, anti-diabetic, antiviral activities. Consequently, their syntheses have attracted significant interest. Various methodologies have been developed for the synthesis and functionalization of these class of compounds.

Conclusion:

In the present article, the relevant and recent advances in the field will be briefly covered.

Synthesis of pyrazolo[1,5-c]quinazoline derivatives through the copper-catalyzed domino reaction of o-alkenyl aromatic isocyanides with diazo compounds

Various o-alkenyl aromatic isocyanides were prepared from readily available reactants for their double annulation with diazo compounds for a one-pot synthesis of pyrazolo[1,5-c]quinazolines under mild reaction conditions.

Synthesis of Spiro[indazole-3,3'-indolin]-2'-ones via [3 + 2] Dipolar Cycloaddition of Arynes with 3-Diazoindolin-2-ones and Indazolo[2,3-c]quinazolin-6(5H)-ones by Subsequent Thermal Isomerization

An efficient protocol for facile construction of spiro[indazole-3,3'-indolin]-2'-ones was developed via [3 + 2] dipolar cycloaddition of arynes with 3-diazoindolin-2-ones under mild conditions in excellent yields. Subsequent thermal isomerization of the spiro[indazole-3,3'-indolin]-2'-ones readily afforded indazolo[2,3-c]quinazolin-6(5H)-ones.

Phosphine-catalyzed domino reactions of alkynyl ketones with sulfonylhydrazones: construction of diverse pyrazoloquinazoline derivatives

An efficient method for the synthesis of C-1 position acyl substituted pyrazoloquinazoline derivatives via a PBu₃-promoted domino process of sulfonylhydrazones and alkynyl ketones was developed.

Copper-catalyzed [3 + 2] cycloaddition reactions: synthesis of substituted pyrazolo[1,5-c]quinazolines with N-iminoquinazolinium ylides and olefins as starting materials

Pyrazolo[1,5-c]quinazoline derivatives were efficiently synthesized via cycloaddition reaction between N-iminoquinazolinium ylides and olefins in moderate to good yield.

Substrate-controlled product-selectivity in the reaction of the Bestmann–Ohira reagent with N-unprotected isatin-derived olefins

A mild and efficient reaction of the Bestmann–Ohira reagent withN-unprotected isatin-derived olefins has been developed for the selective synthesis of spiro-phosphonylpyrazoline-oxindoles and phosphonylpyrazoloquinazolinones.

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.

Progress of the synthesis of condensed pyrazole derivatives (from 2010 to mid-2013)

Condensed pyrazole derivatives are important heterocyclic compounds due to their excellent biological activities and have been widely applied in pharmaceutical and agromedical fields. In recent years, numerous condensed pyrazole derivatives have been synthesized and advanced to clinic studies with various biological activities. In this review, we summarized the reported synthesis methods of condensed pyrazole derivatives from 2010 until now. All compounds are divided into three parts according to the rings connected to pyrazole-ring, i.e. [5, 5], [5,F 6], and [5, 7]-condensed pyrazole derivatives. The biological activities and applications in pharmaceutical fields are briefly introduced to offer an orientation for the design and synthesis of condensed pyrazole derivatives with good biological activities.