Highly stereoselective organocatalytic synthesis of pyrrolidinyl spirooxindoles containing halogenated contiguous quaternary carbon stereocenters

Bromonitroalkenes as efficient intermediates in organic synthesis

Bromonitroalkenes are useful molecules in synthetic organic chemistry. They are mainly prepared from nitroalkenes via bromination reactions. In this review, the application of bromonitroalkenes as partners in the reaction with a diversity of mono- and bi-functional molecules, including aldehydes and ketones, active methylene compounds, 1,2-dicarbonyls, enamines, enols, electron-rich arenes, amidines, azomethine ylides, azirines, diazo compounds, and many others, is reviewed. By using these substrates, various biologically active scaffolds, such as heterocycles, carbocycles, spirocycles, polycyclic systems, natural products, and other useful acyclic compounds, were prepared. In addition, due to their dielectrophilic character, electrophilic and nucleophilic character, and ability to participate in cycloaddition reactions, bromonitroalkenes were efficiently applied in asymmetric cascade/domino/tandem reactions catalyzed by chiral catalysts. In this manuscript, around 55 papers are summarized and discussed during the years 2000-2023.

Recent Advances of N-2,2,2-Trifluoroethylisatin Ketimines in Organic Synthesis

The special properties of fluorine atoms and fluorine-containing groups have led to an increasing number of applications for fluorine-containing organic compounds, which are also extremely widely used in the field of new drug development. Unfortunately, naturally fluorinated organics are rare in nature, so the selective introduction of fluorine atoms or fluorine-containing groups into organic molecules is very important for pharmaceutical/synthetic chemists. N-2,2,2-trifluoroethylisatin ketimines have received the attention of many chemists since they were first developed as fluorine-containing synthons in 2015. This paper reviews the organic synthesis reactions in which trifluoroethyl isatin ketimine has been involved in recent years, focusing on the types of reactions and the stereoselectivity of products, and also provides a prospect of its application in this field.

DBU Promoted Polysubstituted Arene Formation via a Michael Addition/Cyclization/Elimination Cascade Reaction

The straightforward construction of polysubstituted arenes is essential in both synthetic chemistry and medicinal chemistry. Herein, we reported a DBU promoted Michael addition/cyclization/elimination cascade reaction between vinylogous malononitrile derivatives and chlorinated nitrostyrenes for the synthesis of polysubstituted arenes. The method features mild reaction conditions, wide substrate scope and high yield. Interestingly, preliminary study of the enantioselective version of this cascade was conducted to give chiral biaryl atropisomers with up to 40% ee through center-to-axial chirality transfer strategy.

Expeditious entry into carbocyclic and heterocyclic spirooxindoles

Spirocyclic frameworks have attracted synthetic practitioners due to their unique three-dimensional assembly, improved metabolic stability, solubility, and increased molecular complexity with regard to planar architectures. A recent surge in the number of spirocyclic oxindoles inhibiting enzymes, moderating unique protein-protein interactions, modulating receptors and transporters is testament to their prevalence. Against this background, the construction of spirocyclic frameworks containing an oxindole moiety as a torsional switch via stereoselective methods is in great demand. Herein we present a summary of the past three years in the progress of metal, organic molecule, nanostructured particle mediated, and even uncatalyzed versions of the highly diastereo- and enantioselective pathways leading to oxindole spirocycles.

Enantioselective synthesis of isoxazole-containing spirooxindole tetrahydroquinolines via squaramide-catalysed cascade reactions

A class of o-sulfonylaminostyryl isoxazole synthons were designed and demonstrated to be useful building blocks in asymmetric cascade aza-Michael/Michael reaction with 3-olefinic oxindoles. This squaramide-catalysed cascade reaction afforded structurally complex isoxazole-containing spirooxindole tetrahydroquinolines bearing three contiguous stereocenters in good to excellent yields (up to 99%) with high diastereoselectivities (up to >20 : 1 dr) and enantioselectivities (up to 88% ee). Moreover, the gram-scale synthesis and synthetic transformations were also demonstrated.

Efficient enantioselective synthesis of CF2H-containing dispiro[benzo[b]thiophene-oxindole-pyrrolidine]s via organocatalytic cycloaddition

A novel kind of CF2H-containing dispiro[benzo[b]thiophene-oxindole-pyrrolidine] has been achieved via an organocatalyzed 1,3-dipole reaction.

Synthesis of functionalized 3,2′-pyrrolidinyl spirooxindoles via domino 1,6-addition/annulation reactions of para-quinone methides and 3-chlorooxindoles

A highly efficient diastereoselective [4 + 1] cycloaddition of ortho-tosylaminophenyl-substituted p-QMs with 3-chlorooxindoles has been developed to afford 3,2′-pyrrolidinyl spirooxindoles.

Copper-catalyzed [3 + 2]-cycloaddition of α-halonitroalkenes with azomethine ylides: facile synthesis of multisubstituted pyrrolidines and pyrroles

An efficient route for the synthesis of multifunctionalized pyrrolidines based on copper-catalyzed diastereoselective [3 + 2]-cycloaddition of nitroalkenes with azomethine ylides was developed. Novel fluorinated heterocycles - β-fluoro-β-nitropyrrolidines - were accessed via this method. The products can be prepared in good to excellent yields and with high diastereoselectivity. Subsequent transformations of pyrrolidines including oxidative aromatization into fluorinated pyrrolines and medicinally attractive β-fluoro-NH-pyrroles as well as chemoselective reduction reactions were demonstrated. Application of the developed procedures for the non-fluorinated analogues was demonstrated to lead to various β-substituted pyrrole derivatives.

Enantioselective organocatalytic formal [3+2]-cycloaddition of isatin-derived ketimines with benzylidenemalononitriles and benzylidineindanones

Electron-deficient alkenes undergo organocatalysed formal [3+2]-cycloaddition with isatin-derived imines, generating complex spirocyclic products with high yield and stereoselectivity.

Stereoselective synthesis and applications of spirocyclic oxindoles

This review summaries recent synthetic developments towards spirocyclic oxindoles and applications as valuable medicinal and synthetic targets.

Recent advances in the catalytic synthesis of 3-aminooxindoles: an update

3-Substituted-3-aminooxindoles are versatile scaffolds and these motifs constitute the core structure of number of natural products and biologically active compounds.