Organocatalytic enantioselective conjugate addition of pyrazolin-5-ones to arylomethylidene malonates

Cu-Catalyzed Asymmetric Arylation of Enone Diesters with Arylboronic Acids

The Cu-catalyzed asymmetric conjugate addition of arylboronic acids to enone diesters is reported. This operationally simple and scalable reaction proceeded under mild conditions. The practical utility of this approach was demonstrated by the synthesis of structurally important γ-lactones and a cyclopentene that bear an aryl group. Mechanistic studies revealed that two different copper catalytic species work synergistically in the reaction.

Primary amine-catalyzed enantioselective 1,4-Michael addition reaction of pyrazolin-5-ones to α,β-unsaturated ketones

The enantioselective 1,4-addition reaction of pyrazolin-5-ones to α,β-unsaturated ketones catalyzed by a cinchona alkaloid-derived primary amine-Brønsted acid composite is reported. Both enantiomers of the anticipated pyrazole derivatives were obtained in good to excellent yields (up to 97%) and high enantioselectivities (up to 98.5% ee) under mild reaction conditions. In addition, this protocol was further expanded to synthesize highly enantioenriched hybrid molecules bearing biologically relevant heterocycles.

Cu-Catalyzed Asymmetric Alkenylation of Enone Diesters with Trialkenylboroxines

The Cu-catalyzed asymmetric conjugate addition of trialkenylboroxines to enone diesters is reported. This operationally simple and scalable reaction proceeded at room temperature, and a wide range of enone diesters and boroxines were tolerated under the applied reaction conditions. The practical utility of this approach was demonstrated via the formal synthesis of (+)-methylenolactocin. Mechanistic studies revealed that two different catalytic species work synergistically in the reaction.

Recent advances in the applications of pyrazolone derivatives in enantioselective synthesis

Pyrazolones and pyrazoles, featuring nitrogen-nitrogen bonds, are two of the most important classes of heterocycles, owing to their widespread occurrence in medicinal chemistry and functional materials. The last decade has witnessed a rapid increase in the construction of chiral pyrazolone and pyrazole derivatives, with the application of pyrazolone derivatives as powerful synthons. Since our last review in 2018, a large number of new achievements has emerged in this area, requiring a timely update. Thus, this review summarizes these elegant achievements based on the multiple reactive sites of different pyrazolone synthons. In addition, important mechanisms and interesting biological investigations relating to the corresponding products are also discussed.

Organocatalytic diastereo- and enantioselective conjugate addition of pyrazol-3-ones to 3-trifluoroethylidene oxindoles with a newly developed squaramide catalyst

An efficient organocatalytic conjugated addition reaction of pyrazol-3-ones with 3-trifluoroethylidene oxindoles has been developed for the synthesis of enantioenriched triflouromethylated indolin-2-ones bearing adjacent tertiary chiral centers in good yields and good to excellent diastereo- and enantioselectivities. The use of a newly developed chiral spirobiindane-derived squaramide catalyst is essential in achieving high diastereo- and enantioselectivities.

Organocatalytic diastereo- and enantioselective conjugate addition of pyrazol-3-ones to 3-trifluoroethylidene oxindoles with a newly developed squaramide catalyst has been developed.

Low catalyst loading enabled organocatalytic synthesis of chiral bis-heterocyclic frameworks containing pyrazole and isoxazole

The organocatalytic asymmetric synthesis of enantiopure bis-heterocyclic molecules containing pyrazole and isoxazole under mild reaction conditions has been reported via a low-catalyst loading Michael addition reaction of pyrazolyl nitroalkenes with 1,3-dicarbonyl derivatives. 4-Substituted pyrazole derivatives were obtained in 60-87% yields and with 82-97% ee. These pyrazolyl derivatives are further transformed into chiral bis-heterocyclic derivatives in up to 82% yields and up to 99% ee. The synthesized pyrazole and isoxazole based bis-heterocyclic derivatives are potential bio-active molecules expected to have significant applications. Additionally, the synthesis of these bis-heterocycles can efficiently be carried out in one pot without any loss of enantiopurity, which further adds to its significance.

Highly enantioselective one-pot sequential synthesis of valerolactones and pyrazolones bearing all-carbon quaternary stereocentres

Highly enantiopure and bioactive δ-valerolactones and pyrazolones, bearing α-all-carbon quaternary stereocentres, were successfully and sequentially prepared via a one-pot procedure starting from readily available, inexpensive materials, catalysed by a new chiral squaramide under mild reaction conditions. An organocatalytic Michael reaction afforded the valerolactones, while a one-pot Michael-hydrazinolysis-imidization cascade yielded the pyrazolones. This procedure is economically efficient and environmentally benign.

Design and organocatalytic synthesis of spirooxindole–cyclopentene–isoxazole hybrids as novel MDM2–p53 inhibitors

An organocatalytic 1,6-cycloaddition with exclusive α-regioselectivity to synthesize designed spirooxindole–cyclopentene–isoxazole hybrids as novel MDM2–p53 inhibitors.