Dual Gold‐Catalyzed Formal Tetradehydro‐Diels–Alder Reactions for the Synthesis of Carbazoles and Indolines

Abstract

This work reports ad ual gold-catalyzed tetradehydro-Diels-Alderr eaction for the synthesis of nitrogencontaining aromatic heterocycles. Under the catalytic system (IPrAuNTf 2 /DIPEA), indolinesa nd carbazoles as well as other N-containinga romatic heterocyclesw ere prepared in high yields with good functional group tolerance. Unlike the traditional thermalt etradehydro-Diels-Alder reactions, diluted reaction concentration and radical prohibitors are not required for this protocol. Experimental data support am echanism involving gold vinylidene species, which undergoes a6 p electrocyclization, followed with 1,2-hydrogen shift.Supporting information and the ORCID identification number(s) for the author(s) of this article can be found under: https://doi.

On the Mechanism of Au‐Catalyzed Enynamide‐yne Dehydro‐Diels‐Alder Reactions: An Experimental and Computational Study

“…Gem ‐diaurated species 10 and σ,π‐digold complex 11 were also suggested to participate in the mechanism, where a dual catalyst transfer from 8 to substrate 3 is invoked. The very same transformation in the presence of (IPr)AuNTf 2 (10 mol%) and DIPEA (10 mol%) in 1,2‐dichloroethane at 80 °C was reported by Zi and co‐workers shortly after our publication [5] . The authors suggested that in the case of aryl‐substituted ynamides, a 6π electrocyclization would produce 7 from 6 .…”

“…The very same transformation in the presence of (IPr)AuNTf 2 (10 mol%) and DIPEA (10 mol%) in 1,2-dichloroethane at 80°C was reported by Zi and co-workers shortly after our publication. [5] The authors suggested that in the case of aryl-substituted ynamides, a 6π electrocyclization would produce 7 from 6. We report herein our complete experimental and computational investigations on the mechanism of this transformation.…”

Rhodium-catalysed tetradehydro-Diels–Alder reactions of enediynes via a rhodium-stabilized cyclic allene

“…For example, several recent reports have harnessed dual gold-catalysts in cycloaromatisations via TDDA reactions of enediynes. [3][4][5][6][7] In these cases the enediyne is not fully conjugated but has the alkyne and enyne units linked via a heteroatom tether leading to a diverse range of fused heterocyclic benzenoid structures of biological signicance (Scheme 1b).…”

Recent Applications of the Diels–Alder Reaction in the Synthesis of Natural Products (2017–2020)

“…Contrary to the usual standard tetradehydro-Diels-Alder reaction, Wang's adaptation proceeds without the requirements of a dilute reaction mixtures and the use of radical-trapping agents, thus making it a practical protocol. 58 Scheme 37 General approach towards the synthesis of indolines and carbazoles 146 via a dual Gold-catalyzed tetradehydro-Diels-Alder reaction, with a highlight of the crucial mechanistic steps.…”