Gold-catalyzed [4+3]- and [4+2]-annulations of 3-en-1-ynamides with isoxazoles via novel 6π-electrocyclizations of 3-azahepta trienyl cations

Abstract

Gold-catalysed [4+3]- and [4+2]-annulations of 3-substituted 3-en-1-ynamides with isoxazoles were achieved with Au(i) and Au(i)/Zn(ii) catalysts respectively.

Synthesis of Carbazoles and Related Heterocycles from Sulfilimines by Intramolecular C−H Aminations

“…Nitrene chemistry has a long history, possessing a distinct advantage in forging C−N bonds . In the last decade, gold‐catalyzed transformations involving nitrene transfer from nitrene equivalents to C≡C triple bonds, forming highly reactive α‐imino gold carbenes, have shown extraordinary advantages for the synthesis of heterocycles, as demonstrated by the representative work of Ye, Hashmi, Liu, and Gagosz . Nitrenes can also insert into C−H bonds to give disubstituted amines through C−N bond formations .…”

Synthese von Carbazolen und Verwandten Heterocyclen aus Sulfiliminen durch Intramolekulare C‐H‐Aminierungen

“…In der letzten Dekade haben gold‐katalysierte Transformationen mit Nitren‐Transfer aus Nitren‐Äquivalenten auf C≡C‐Dreifachbindungen, die zu hoch reaktiven α‐Imino‐Gold‐Carbenen führen, außergewöhnliche Vorteile bei der Synthese von Heterocyclen gezeigt. Diese wurde durch repräsentative Arbeiten von Ye, Hashmi, Liu, und Gagosz gezeigt . Nitrene können auch in C‐H‐Bindungen insertieren, was über C‐N‐Bindungsknüpfungen zu disubstituierten Aminen führt .…”

Iron‐Mediated Ring‐Opening and Rearrangement Cascade Synthesis of Polysubstituted Pyrroles from 4‐Alkenylisoxazoles

“…Among them, the majority of the work has been focused on transition‐metal‐catalyzed transformations of isoxazoles to N ‐heterocycles. ‐ To date, most of these transformations are noble metal catalyzed intermolecular annulations, including the annulations between isoxazoles and alkynes catalyzed by platinum and gold catalysts, forming N ‐heterocycles such as 1,3‐oxazepines and 2,5‐dihydropyridines, 4 H ‐azepines, pyrroles, quinolines, indoles, and N ‐doped polycyclic aromatic hydrocarbons . Recently, the non‐noble metal catalyst Zn(OTf) 2 ‐mediated synthesis of polysubstituted pyrroles by an intermolecular annulation of isoxazoles with ynol ethers has also been reported…”