Multicomponent Reactions Using C,N-Binucleophilic Nature of Aminopyrazoles: Construction of Pyrazole-Fused Heterocycles

Synthesis of pyrazole-fused heterocycles has gained considerable attention in recent years due to their wide applications in medicinal chemistry. Aminopyrazoles are versatile building blocks for the synthesis of pyrazole-fused heterocycles by multicomponent reactions. Due to the presence of multiple reaction sites, they have fascinating chemical reactivity. Thus, they have been extensively used in multicomponent reactions for the construction of pyrazole-fused heterocycles. Although few review articles on the preparation and applications of aminopyrazoles are known in the literature, to date there is no dedicated review article on the construction of pyrazole-fused heterocycles exploring the reactivity of amino pyrazoles as C,N-binucleophiles in multicomponent reactions. Considering this, herein the multicomponent reactions for the construction of pyrazole-fused heterocycles exploring C,N-binucleophilic nature of amino pyrazoles have been reported.

Metal-free, one-pot synthesis of 2-styrylquinolines via Friedländer annulation and sp3 C–H activation using 1,3-dimethylurea and l-tartaric acid (3 : 1) as a deep eutectic solvent

Functionalized 2-styrylquinolines are prepared using DMU + l-(+)-tartaric acid as deep eutectic solvent. DFT calculations supported the experimental results on role of DES as catalyst. The absorption-emission spectra indicating that these compounds can be useful as fluorescent probes.

A novel fluorescent probe with a pyrazolo[4,3-c]quinoline core selectively recognizes c-MYC promoter G-quadruplexes

An aptamer combined with a c-MYC-selective fluorophore could work as the fluorescent core of nucleic acid mimics of fluorescent proteins to locate and image functional biomolecules in cells.

Synthesis of styryl-linked fused dihydropyridines by catalyst-free multicomponent reactions

Herein, we report a rapid catalyst-free three-component reaction of 2-hydroxy-1,4-naphthoquinone, cinnamaldehydes and 3-aminopyrazoles in ethanol medium under reflux conditions for the easy access of styryl-linked dihydropyridines fused with naphthoquinone and pyrazole moiety. A wide variety of cinnamaldehyde derivatives and 3-aminopyrazoles were found suitable for this three-component reaction. All the products were fully characterized by spectroscopic tools and by recording single crystal XRD of one of the product. Catalyst-free reaction conditions, short reaction time, good yields of the products, easy purification process, formation of three new bonds (Two C-C and one C-N) in one-pot and products having four different bioactive moieties are the notable features of this methodology.

Fluorescence sensors for detection of water based on tetraphenylethene–anthracene possessing both solvatofluorochromic properties and aggregation-induced emission (AIE) characteristics

TPE-(An-CHO)4 has been developed as an SFC (solvatofluorochromism)/AIEE (aggregation-induced emission enhancement)-based fluorescence sensor for detection of water over a wide range from low to high water content regions in solvents.

Multicomponent synthesis of styryl linked benzo[h]pyrazolo[3,4-b]quinoline-5,6(10H)-diones by liquid assisted grinding

Herein we report an interesting multicomponent reaction of α,β-unsaturated aldehydes, 2-hydroxy-1,4-naphthoquinone and 5-aminopyrazoles by liquid assisted grinding.