Assembly of Spirooxindole Derivatives Containing Four Consecutive Stereocenters by Using Cascade Reactions Catalyzed by an N-Heterocyclic Carbene

Construction of Cyclopentanes Consisting of Five Stereocenters via NHC-Catalyzed Cascade Reactions of Enals with Oxindole-Dienones

Despite the widespread presence of the chiral cyclopentane motif, the asymmetric synthesis of cyclopentanes containing five stereocenters remains a formidable challenge. Here, we present an N-heterocyclic carbene (NHC)-catalyzed cascade reaction of enal and oxindole-dienone, which allows access to spiroxindole cyclopentanes featuring a complete set of chiral centers on the five-membered carbocycle. This strategy, characterized by the formation of multiple bonds and chiral centers, demonstrates a broad substrate scope, exclusive diastereoselectivity, and up to 99:1 er.

Tandem 1,6-addition/cyclopropanation/rearrangement reaction of vinylogous para-quinone methides with 3-chlorooxindoles: construction of vicinal quaternary carbon centers

A novel tandem 1,6-addition/cyclopropanation/rearrangement reaction of vinylogous para-quinone methides with 3-chlorooxindoles has been developed, providing dispirooxindole–cyclopentane–cyclohexadienones with vicinal quaternary carbon centers.

Oxidative NHC catalysis: direct activation of β sp3 carbons of saturated acid chlorides

The first activation of saturated acid chlorides by an oxidative N-heterocyclic carbene catalyst has been utilized to synthesize enantio-enriched spirooxindole lactones and δ-lactones.

N-Heterocyclic-Carbene-Catalyzed Domino Reactions via Two or More Activation Modes

Organocatalytic domino processes have become a rapidly growing area of research. N-heterocyclic carbenes (NHCs) have emerged as powerful organocatalysts for various transformations and continue to have widespread application. In the last decade, domino reactions catalyzed by NHCs have seen significant progress since the different activation modes could be successfully combined in one process. The most attractive features of these domino sequences include the readily available catalysts and substrates, the simple operational procedures, and the rapid assembly of complex molecular scaffolds with excellent levels of stereocontrol under mild reaction conditions. This review covers the advances in NHC-catalyzed domino reactions by focusing on the reaction scope, limitations, and mechanism with a close attention to the features of the reaction substrates.

N-Heterocyclic carbene-catalyzed annulation of ynals with amidines: access to 1,2,6-trisubstituted pyrimidin-4-ones

A thiazolium-catalyzed annulation of ynals and amidines has been reported to construct pyrimidin-4-ones.

NHC-catalyzed regiodivergent syntheses of difunctionalized 3-pyrazolidinones from α-bromoenal and monosubstituted hydrazine

A formal [3 + 2] annulation of α-bromoenal with monosubstituted hydrazine could give 1,5 or 2,5-difunctionalized 3-pyrazolidinone regiodivergently by tuning the structure of the N-Heterocyclic Carbene (NHC) catalyst. Moderate to high yields, mild reaction conditions, good regioselectivity and potential biological significance of the final product have made this protocol attractive for the assembly of 3-pyrazolidinone.

Diastereoselective tandem oxidation/Michael/aldol reaction: unprecedented formation of dispirocyclopentanebisoxindoles and dispiro[acenaphthylene-1,1'-cyclopentane-3',1''-acenaphthylene]-2,2''diones

An unprecedented tandem oxidation/Michael/aldol reaction is reported. The diastereoselective formation of only a single isomer of dispirocyclopentanebisoxindole and dispiro[acenaphthylene-1,1'-cyclopentane-3',1''-acenaphthylene]-2,2''dione is presented. The reaction generates two new C-C bonds and two all-carbon quaternary chiral stereocenters in a single step.

N-heterocyclic carbene-catalyzed synthesis of spirocyclopentene-oxindoles from bromoenals

Spirocyclopentene-oxindoles were synthesized in good yields with good diastereo- and enantioselectivitiesviathe N-heterocyclic carbene-catalyzed reaction of bromoenals and oxindoles.

Rapid access to bicyclic δ-lactones via carbene-catalyzed activation and cascade reaction of unsaturated carboxylic esters

The carbene-catalyzed activation of α,β-unsaturated ester initiates a well-controlled cascade process for access to iridoid-type multi-cyclic lactones with high stereo-selectivities.

Formal [3 + 3] annulation of isatin-derived 2-bromoenals with 1,3-dicarbonyl compounds enabled by Lewis acid/N-heterocyclic carbene cooperative catalysis

Several novel isatin-derived 2-bromoenals were applied for formal [3 + 3] annulation with 1,3-dicarbonyl compounds enabled by NHC/Lewis acid cooperative catalysis.

Stereoselective synthesis of spirooxindole derivatives using an organocatalyzed tandem Michael–Michael reaction

A highly efficient and stereoselective method for the synthesis of functionalized spirooxindole derivatives was realized using enamine catalysis.

Magnetic nanoparticles-supported tungstic acid (MNP-TA): an efficient magnetic recyclable catalyst for the one-pot synthesis of spirooxindoles in water

This paper reports the preparation, characterization and catalytic application of a novel, magnetically separable catalyst consisting of tungstic acid supported on silica coated magnetic nanoparticles.

Oxidative N-heterocyclic carbene catalyzed stereoselective annulation of simple aldehydes and 5-alkenyl thiazolones

A highly stereoselective annulation proceeded successfully to afford chiral thiazolo pyrones with excellent ee (up to 99%) and d.r. (up to >20 : 1). Both enantiomers can be obtained. In the presence of oxygen (O₂), the oxidant O-1 can be used in a catalytic amount (even low to 2 mol%).

N-Heterocyclic carbene-catalyzed annulation of cyclic β-enamino esters with enals: access to functionalized indolo[2,3-a]quinolizidines

A novel synthetic approach to functionalized indolo[2,3-a]quinolizidines is developed via an N-heterocyclic carbene-catalyzed annulation of cyclic β-enamino esters with enals.

NHC-catalyzed activation of α,β-unsaturated N-acyltriazoles: an easy access to dihydropyranones

Employing the NHC-catalyzed activation of α,β-unsaturated N-acyltriazoles an efficient enantioselective synthesis of dihydropyranones via a formal [3+3] cycloaddition with 1,3-dicarbonyl compounds is described.

Highly stereoselective synthesis of functionalized pyrrolo[3,2-c]quinolines via N-heterocyclic carbene catalyzed cascade sequence

An N-heterocyclic carbene-catalyzed stereoselective Michael-Mannich-lactamization cascade reaction of tosyl-protected o-amino aromatic aldimines and 2-bromoenals for the construction of functionalized pyrrolo[3,2-c]quinolines with three consecutive stereocenters was achieved in good yields with excellent diastereo- and enantioselectivities.

Cooperative N-heterocyclic carbene (NHC)–Lewis acid-mediated regioselective umpolung formal [3 + 2] annulations of alkynyl aldehydes with isatins

A novel synthesis of spirooxindoles has been developed by cooperative NHC–Lewis acid-mediated formal [3 + 2] annulations of alkynyl aldehydes with isatins.

N-heterocyclic carbene-catalyzed stereoselective cascade reaction: synthesis of functionalized tetrahydroquinolines

The first N-heterocyclic carbene-catalyzed stereoselective aza-Michael-Michael-lactonization cascade reaction of 2'-aminophenylenones and 2-bromoenals for the construction of chiral functionalized tetrahydroquinolines with three consecutive stereogenic centers has been achieved in high yields (up to 98%) with excellent diastereo- (>25:1) and enantioselectivities (up to 98.7% ee).