Enantioselective Synthesis ofN-Phenyl-dihydropyrano[2,3-c]pyrazoles via Cascade Michael Addition/Thorpe-Ziegler Type Cyclization Catalyzed by a Chiral Squaramide

Synthesis of fully functionalised spiropyran pyrazolone skeletons via a formal [4 + 2] cascade process using β-nitro-styrene-derived MBH-alcohols

An efficient protocol was established to construct spiro pyrazolone tetrahydropyran scaffolds at ambient temperature under metal-free conditions. The reaction proceeded via formal [4 + 2] cyclisation of trans-β-nitro-styrene-derived Morita-Baylis-Hillman (MBH) alcohol with α-arylidene pyrazolone. The reaction followed an oxa-Michael/Michael cascade pathway, resulting in the formation of new C-C and C-O bonds. Organocatalytic synthesis of spiropyrazolones using quinine-derived catalyst resulted in 94% enantiomeric excess (ee) and excellent (>20 : 1) diastereoselectivity.

Efficient one-pot synthesis of arylated pyrazole-fused pyran analogs: as leads to treating diabetes and Alzheimer's disease

Background: To discover novel lead molecules against diabetes, Alzheimer's disease and oxidative stress, a library of arylated pyrazole-fused pyran derivatives, 1-20, were synthesized in a one-pot reaction. Materials & methods:¹H-NMR spectroscopic and electron ionization mass spectrometry techniques were used to characterize the synthetic hybrid molecules 1-20. Analogs were screened against four indispensable therapeutic targets, including α-amylase, α-glucosidase, acetylcholinesterase and butyrylcholinesterase enzymes. Results: Except for derivatives 17 and 18, all other compounds exhibited varying degrees of inhibitory activities against target enzymes. The kinetic studies revealed that the synthetic molecules followed a competitive-type mode of inhibition for α-amylase and acetylcholinesterase enzymes, as well as a non-competitive mode of inhibition for α-glucosidase and butyrylcholinesterase enzymes. In addition, molecular docking studies identified crucial binding interactions of ligands with the enzyme's active site. Conclusion: These molecules may serve as a potential drug candidate to cure diabetes, Alzheimer's disease and oxidative stress in the future.

Squaramide-catalysed asymmetric Friedel-Crafts alkylation of naphthol and unsaturated pyrazolones

The first method for highly efficient asymmetric Michael-type Friedel-Crafts alkylation of naphthol and unsaturated pyrazolones has been accomplished under mild reaction conditions. In the presence of the chiral squaramide catalyst, a wide range of substrates are tolerated in excellent yields (up to 99%) with reasonable enantioselectivities (up to 96% ee).

Enantioselective 1,4-Michael addition reaction of pyrazolin-5-one derivatives with 2-enoylpyridines catalyzed by Cinchona derived squaramides

The bifunctional nature of the cinchonidine squaramides has been successfully employed to catalyze the enantioselective 1,4-Michael addition reaction of pyrazolin-5-ones with 2-enoylpyridines under mild reaction conditions. Through this methodology, a broad range of optically active heterocyclic derivatives bearing both pyrazole and pyridine motifs have been synthesized in yields up to 88% and enantiomeric excess up to 96%.

Pyrazolone: a powerful synthon for asymmetric diverse derivatizations

This feature article reports recent advances in the asymmetric diverse derivatizations of the pyrazolone scaffold.

α,α-Dicyanoolefins: versatile substrates in organocatalytic asymmetric transformations

α,α-Dicyanoolefins have emerged as versatile reactants, finding use as vinylogous nucleophiles, Michael acceptors and dienophiles in a variety of organic reactions.

Asymmetric synthesis of pyrazoles and pyrazolones employing the reactivity of pyrazolin-5-one derivatives

The various catalytic asymmetric strategies employing organo- and metal-catalysts utilized pyrazolin-5-one derivatives for the synthesis of potentially bioactive enantiopure pyrazoles and pyrazolones are presented.