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A carbene and sulfinate co‐catalyzed intermolecular Rauhut–Currier reaction between enals and nitrovinyl indoles is disclosed. The carbene catalyst activates the enal and the sulfinate co‐catalyst activates the nitrovinyl indole. Both activation processes are realized via the formation of covalent bonds between the catalysts and substrates to generate catalyst‐bound intermediates. The dual catalytic reaction affords azepino[1,2‐a]indole products with excellent stereoselectivity. Our study demonstrates the unique involvement of sulfinate as an effective nucleophilic catalyst in activating electron‐deficient alkenes for asymmetric reactions. This dual catalytic approach should also encourage future explorations of both sulfinate and carbene catalysts for new reactions. It takes two: A carbene and sulfinate co‐catalyzed intermolecular Rauhut–Currier reaction provides an efficient method to access azepino[1,2‐a]indoles with excellent stereoselectivity. The sulfinate was found to be a unique and effective nucleophilic catalyst in activating nitrovinyl indoles for the Rauhut–Currier reaction. [ABSTRACT FROM AUTHOR]

A carbene-catalyzed cascade reaction is developed for the synthesis of multi-substituted indane derivatives. The reaction involves two sequential Michael-addition steps, of which the first step is enabled by an NHC-mediated radical process. This work demonstrates the synthetic potentials of NHC-mediated single-electron-transfer processes for efficient reactions and rapid synthesis. [ABSTRACT FROM AUTHOR]

A carbene-catalyzed intermolecular C−N bond formation, which initiates a highly selective cascade reaction for the synthesis of pyrrolidine fused β-lactones, is disclosed. The nitrogen-containing bicyclic β-lactone products are obtained with good yields and excellent stereoselectivities. Synthetic transformations of the reaction products into useful functional molecules, such as amino catalysts, can be efficiently realized under mild reaction conditions. Mechanistically, this study provides insights into modulating the reactivities of heteroatoms, such as nitrogen atoms, in challenging carbene-catalyzed asymmetric carbon-heteroatom bond-forming reactions. [ABSTRACT FROM AUTHOR]

Simple and inexpensive polyhalides (CCl4 and C2Cl6) have been found to be effective and versatile oxidants in removing electrons from Breslow intermediates under N-heterocyclic carbene (NHC) catalysis. This oxidative reaction involves multiple single-electron-transfer (SET) processes and several radical intermediates. The α, β, and γ-carbon atoms of aldehydes and enals could be readily functionalized. Given the low cost of the oxidants and the broad applicability of the reactions, this study is expected to greatly enhance the feasibility of oxidative NHC catalysis for large-scale applications. Also this new SET radical process with polyhalides as single-electron oxidants will open a new avenue in the development of NHC-catalyzed radical reactions. [ABSTRACT FROM AUTHOR]

An enantioselective β-carbon amination for enals is disclosed. The nitrogen atom from a protected hydrazine with suitable electronic properties readily behaves as a nucleophile. Addition of the nitrogen nucleophile to a catalytically generated N-heterocyclic-carbene-bound α,β-unsaturated acyl azolium intermediate constructs a new carbon-nitrogen bond asymmetrically. The pyrazolidinone products from our catalytic reactions are common scaffolds in bioactive molecules, and can be easily transformed into useful compounds such as β3-amino-acid derivatives. [ABSTRACT FROM AUTHOR]

A graphical abstract of the article "Rapid Access to Bicyclic δ-Lactones via Carbene-Catalyzed Activation and Cascade Reaction of Unsaturated Carboxylic Esters" is presented.

This method allows the synthesis of β-hydroxyesters from simple enals with excellent enantioselectivities and in good yields. [ABSTRACT FROM AUTHOR]