l-Proline-catalysed sequential four-component “on water” protocol for the synthesis of structurally complex heterocyclic ortho-quinones

Multicomponent Dipolar Cycloaddition Strategy: Combinatorial Synthesis of Novel Spiro-Tethered Pyrazolo[3,4-b]quinoline Hybrid Heterocycles

“…Then without isolating 6 , the previously synthesized 3 { 1 } or 3 { 2 } was added and the reflux continued for another 1 h, which resulted in quantitative yields of 7 { 1–6 } or 7 { 2–5 }, respectively. The formation of 7 presumably occurred via a similar pathway as depicted by Perumal et al It is to be noted that Zheng et al reported the synthesis of 7 { 2 , 1 } in 15% yield from a two-step reaction . Later, Dzvinchuk et al synthesized 7 { 1 , 1 } in 87% yield from the reaction of 1,3-cyclohexanedione 1 , 3-methyl-1-phenyl-1 H -5-pyrazolamine 6 and 4-(dimethylamino)-benzaldehyde in boiling acetic acid for 2 h. In this reaction N , N -dimenthylaniline was obtained as a byproduct.…”

“…To the best of our knowledge these compounds have been used in the Vilsmeier–Haack formylation reaction and for the synthesis of bispyrazolo­[3,4- b :4,3- f ]­quinolines and pyrazolo­[3,4- b ]­quinoline ribofuranosides . Further, the analogous derivatives have been used to synthesize quinoxaline-fused benzo­[ h ]­isoxazolo­[5,4- b ]­quinolines and benzo­[ a ]­pyrazolo­[4′,3′:5,6]­pyrido-[2,3- c ]­phenazine . In this context, we envisaged to investigate the feasibility of pyrazolo­[3,4- b ]-quinoline derivatives as dipolarophiles in the 1,3-dipolar cycloadditions of azomethine ylides with a view to construct spiro tethered pyrazolo­[3,4- b ]­quinoline–pyrrolidine/pyrrolothiazole/indolizine–oxindole/acenaphthene hybrids.…”

Synthesis of a novel category of pseudo-peptides using an Ugi three-component reaction of levulinic acid as bifunctional substrate, amines, and amino acid-based isocyanides

“…In addition, MCRs are characterized by high yields, time efficiency, low waste production, and reduced energy consumption [1–9]. So, the design of novel MCRs with facile and green processes has fascinated considerable attention in the fields of drug discovery, organic synthesis of natural products, and materials sciences [10].…”

An efficient and environmentally sustainable domino protocol for the synthesis of structurally diverse spiroannulated pyrimidophenazines using erbium doped TiO2 nanoparticles as a recyclable and reusable heterogeneous acid catalyst

“… 1–5 Moreover, multicomponent reactions provide easy and rapid access to large libraries of drug-like scaffolds incorporating medicinally privileged heterocyclic substructures. 6,7 The nanostructured materials have attracted the attention of chemical research in view of their uses as heterogeneous catalysts in organic transformations, especially because they following the requirements of green chemistry. 8,9 In recent years, significant advances have been made in the rational design and synthesis of highly active and selective nanostructured catalysts by controlling the structure and composition of the active nanoparticles (NPs) and by manipulating the interaction between the catalytically active NP species and their support.…”