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An efficient organocatalyzed enantioselective hydrophosphinylation of indole-derived vinylogous imines generated in situ from sulfonyl indoles has been developed. Using quinine-derived bifunctional thiourea as the catalyst, a wide range of structurally diverse chiral 3-(1-diphenylphosphoryl-arylmethyl)indoles were obtained with good to excellent results (up to 99% yield and 99% ee). This method represents the first example of the catalytic asymmetric Michael addition of phosphine oxides to vinylogous imine intermediates.

A readily available chiral cyclohexanediamine-derived bifunctional tertiary amine-squaramide catalyst is more effective for the asymmetric dearomative 1,3-dipolar cycloaddition of 2-nitrobenzofurans and N-2,2,2-trifluoroethylisatin ketimines. A range of structurally diverse spiro-fused polyheterocyclic compounds containing oxindole, pyrrolidine, and hydrobenzofuran motifs were smoothly obtained in excellent results (up to 99% yield, >20:1 dr in all cases and up to 99% ee). This method features high efficiency, mild reaction conditions, exquisite asymmetric induction, wide functional group tolerance, great potential for scale-up synthesis, and attractive product diversification., (© 2022 Wiley Periodicals LLC.)

Quinone imines are important derivatives of quinones with a wide range of applications in organic synthesis and the pharmaceutical industry. The attack of nucleophilic reagents on quinone imines tends to lead to aromatization of the quinone skeleton, resulting in both the high reactivity and the unique reactivity of quinone imines. The extreme value of quinone imines in the construction of nitrogen- or oxygen-containing heterocycles has attracted widespread attention, and remarkable advances have been reported recently. This review provides an overview of the application of quinone imines in the synthesis of cyclic compounds via the domino annulation reaction. [ABSTRACT FROM AUTHOR]

In this research, a metal-free diastereoselective formal 1,3-dipolar cycloaddition of N-2,2,2-trifluoroethylisatin ketimines and cyclopentene-1,3-diones which can efficiently lead to the desymmetrization of cyclopentene-1,3-diones is developed. With the developed protocol, a series of tetracyclic spirooxindoles containing pyrrolidine and cyclopentane subunits can be smoothly obtained with good results (up to 99% yield and 91:9 dr). Furthermore, the methodology can be extended to trifluoromethyl-substituted iminomalonate, and the corresponding formal [3+2] cycloaddition reaction affords bicyclic heterocycles containing fused pyrrolidine and cyclopentane moieties in moderate yields with >20:1 dr. The synthetic potential of the methodology is demonstrated by the scale-up experiment and by versatile transformations of the products. [ABSTRACT FROM AUTHOR]

An efficient catalytic asymmetric coupling of vinylogous species is developed via deconjugated butenolide addition to vinylogous imines in situ generated from arylsulfonyl indoles. With quinine-derived bifunctional squaramide as the catalyst, a series of structurally diverse enantioenriched sec-alkyl-3-substituted indoles containing valuable γ,γ-disubstituted butenolide moieties and adjacent quaternary-tertiary stereocenters are obtained in synthetically viable results (up to 97% yield, 77 : 23 dr and 97% ee). [ABSTRACT FROM AUTHOR]

By taking advantage of benzylidene succinimides as a new class of 3C synthons, a highly diastereo- and enantioselective tandem Mannich reaction/transamidation has been established by reacting them with cyclic trifluoromethyl N-acyl ketimines. Using a Cinchona alkaloid-derived squaramide as the catalyst, the tandem reaction proceeded smoothly under mild conditions and afforded a range of F3C-containing chiral polycyclic dihydroquinazolinones with excellent results (up to 99% yield, all cases >20 : 1 dr, up to 99% ee). [ABSTRACT FROM AUTHOR]

A highly enantioselective aza-Friedel–Crafts reaction of structurally new ketimines with indoles and pyrrole is developed by using a chiral phosphoric acid as the catalyst. This protocol enables the first enantioselective synthesis of isoquinoline-1,3(2H,4H)-dione derivatives in good to excellent yields (up to 99% yield) and excellent enantioselectivities (up to ＞99% ee). [ABSTRACT FROM AUTHOR]

The first diastereo- and enantioselective cascade Mannich/cyclization reaction of 3-isothiocyanato oxindoles with cyclic ketimines has been successfully developed. By using chiral bifunctional organocatalysts, a range of structurally diverse chiral polycyclic spiro-thioimidazolidine-oxindoles, bearing two contiguous tetrasubstituted stereocenters, could be obtained in excellent yields (up to 99%) with good diastereo- and enantioselectivities (up to >20:1 dr and 94.5:5.5 er) under mild reaction conditions. Image 1 • The first example of catalytic asymmetric Mannich/cyclization reaction of 3-isothiocyanato oxindoles with cyclic ketimines... • An efficient method to access spiro-thioimidazolidine-oxindoles bearing two tetrasubstituted contiguous stereocenters. [ABSTRACT FROM AUTHOR]