Organocatalytic activation of isocyanides: N-heterocyclic carbene-catalyzed enaminone synthesis from ketones

Abstract

The first NHC-catalyzed C–C bond formation reaction between ketones and isocyanides was achieved via activation of the isocyanide into an imidoyl intermediate.

Silver-Catalyzed Nucleophilic Addition of β-Dicarbonyls to Isocyano Group: Facile Access to Indolin-3-ol Derivatives

“…High-resolution mass spectra (HRMS) were obtained using a microTOF II focus spectrometer (ESI). The starting materials o -acyl arylisocyanides 1a – p were prepared according to the literature. , …”

“…Additionally, the electrophilicity of isocyanides can also be activated by Lewis acid in some insertion reactions . Notably, Hong’s group recently developed novel strategies to improve the electrophilicity of isocyanides by the in situ formation of more reactive formimidate or transient imidoyl-imidazole intermediate . The formal nucleophilic addition of ketones to isocyanides was realized for the preparation of enaminones.…”

“…22 Notably, Hong's group recently developed novel strategies to improve the electrophilicity of isocyanides by the in situ formation of more reactive formimidate 23 or transient imidoyl-imidazole intermediate. 24 The formal nucleophilic addition of ketones to isocyanides was realized for the preparation of enaminones. In contrast, the silver-catalyzed reaction of β-dicarbonyls with oacyl arylisocyanides (Scheme 1d) developed by our research group also represents a direct and simple protocol for the activation of isocyanides.…”

Copper-Catalyzed Coupling of Thioamides and Donor/Acceptor-Substituted Carbenoids: Synthesis of Enamino Esters and Enaminones

“…3,7,8 Because of this importance, various methods are available for enamino ester and enaminone synthesis 2,9−19 and new methods are constantly pursued. 20−27 Exocyclic enamino esters and enaminones are generally prepared by the Eschenmoser sulfide contraction reaction (ESR) 7,28−30 or the imino ester (imidate) approach. 28,31−33 Both methods complement each other.…”

Mechanisms and Stereoselectivities of NHC‐Catalyzed [3 + 4] Cycloaddition Reaction between Isatin‐Derived Enal and N‐(ortho‐Chloromethyl)aryl Amide

“…As effective organocatalysts, N‐heterocyclic carbenes (NHCs) have a large potential for use in many synthetic strategies . In fact, NHC catalyzed carbon–carbon and carbon–heteroatom bond formation reactions have already been reported . In particular, a range of cycloaddition reactions promoted by NHC catalysts affording carbo‐ and heterocycles have also been reported, such as [2 + 2], [2 + 2 + 2], [2 + 4], [3 + n] ( n = 2, 3, 4), [4 + n] ( n = 2, 3) cycloadditions.…”