Regio‐ and Stereoselective Synthesis of 3‐Pyrazolylidene‐2‐oxindole Compounds by Nucleophilic Vinylic Substitution of ( E )‐3‐(Nitromethylene)indolin‐2‐one

Construction of arylthio/arylamino methylene bonds by addition-elimination of nitroolefins with aromatic thiols and amines

A highly efficient, catalyst-free, metal-free, atom economical green protocol for the synthesis of arylthio/arylamino methylene compounds by a Michael attack of arylthiols and anilines on nitroolefins derived from acenaphthaquinone and isatin has been developed. The method needs methanol as a reaction solvent and does not require any recrystallization, work-up process or column chromatography. (E)-Arylthio alkenes and (Z)-arylamino alkenes were obtained as the sole products. The results obtained from computational studies using density functional theory on ORCA program (B3LYP/def2-SVP level) are in good agreement with the data obtained from the single crystal X-ray analysis.

Enantioselective Nucleophilic Vinylic Substitution (SNV) toward 3-Alkenyl-bisoxindoles Facilitated by C6' Steric Bulk of Cinchona Alkaloid

A C6' bulky substituted quinine-catalyzed SNV reaction between 3-substituted oxindole and (E)-3-(nitromethylene)-oxindole was developed. This enantioselective C(sp3)-C(sp2) coupling furnished bisoxindole scaffolds featuring a vinyl-substituted all-carbon quaternary stereocenter with high stereoselectivities. In addition, the gram-scale synthesis and synthetic post-transformations were conducted to demonstrate the potential synthetic usefulness.

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.

Inversion kinetics of some E/Z 3-(benzylidene)-2-oxo-indoline derivatives and their in silico CDK2 docking studies

The structure-based design of some CDK2 inhibitors with a 3-(benzylidene)indolin-2-one scaffold as potential anticancer agents was realized. Target compounds were obtained as E/Z mixtures and were resolved to corresponding E- and Z-diastereomers. In silico studies using MOE 2019.01 software revealed better docking on the targeted enzyme for the Z-diastereomer compared to the E-one. A time-dependent kinetic isomerization study was carried out for the inversion of E/Z diastereomers in DMSO-d6 at room temperature, and were found to obey the first order kinetic reactions. Furthermore, a determination of the kinetic inter-conversion rate order by graphical analysis method and calculation of the rate constant and half-life of this kinetic process were carried out. For the prediction of the stability of the diastereomer(s), a good multiple regression equation was generated between the reaction rates of isomerization and some QM parameters with significant p value.

Organocatalytic enantioselective aminoalkylation of pyrazol-3-ones with aldimines generated in situ from α-amido sulfones

Herein, an efficient asymmetric aminoalkylation of pyrazolones with α-amido sulfones catalyzed by a quinine-derived squaramide in dichloromethane/aqueous media has been established. A variety of chiral amines were obtained with high yields (up to 98%) and excellent enantioselectivities (up to 99% ee). The corresponding products are transformed into optically active acetylated pyrazoles after treatment with Ac2O/Et3N, because of the instability of some adducts. The reaction tolerates a wide range of α-amido sulfones and different pyrazolones.

Asymmetric synthesis of atropisomeric pyrazole via an enantioselective reaction of azonaphthalene with pyrazolone

The first catalytic asymmetric reaction of azonaphthalene with pyrazolone has been established. A wide range of axially chiral pyrazole derivatives have been achieved in good yields (68–99%) with excellent enantioselectivities (83–98% ee) by utilizing chiral phosphoric acid as a catalyst.