Gold‐katalysierte Synthese von Chinolinen aus Propargylsilylethern und Anthranilen über die Umpolung eines Goldcarben‐Kohlenstoffatoms

Abstract

Die Gold-katalysierte Kaskaden-Anellierung propargylischer Silylether mit Anthranilen verläuft sequenziell über eine Ringçffnung/1,2-H-Verschiebung/Protodesaurierung/ Mukaiyama-Aldol-Cyclisierung.Dieses Protokoll bietet einen regiospezifischen und modularen Zugang zu 2-Aminochinolinen und anderen Chinolinderivaten unter milden Bedingungen bei guter Kompatibilitätm it funktionellen Gruppen. Die Reaktionen gelingen im Gramm-Maßstab,w as den präparativen Nutzen der Methode unterstreicht. Die Vielseitigkeit der erhaltenen Molekülgerüste wurdea nhand nützlicher Folgereaktionen demonstriert.

Acyl Migration versus Epoxidation in Gold Catalysis: Facile, Switchable, and Atom‐Economic Synthesis of Acylindoles and Quinoline Derivatives

“…Either an attack at the nitrogen atom forms a-imino gold carbenes and subsequent C À H insertions gives 7-acylindoles (Scheme 1, entry 2), [9b] or this versatile reagent undergoes oxygen attack to give quinoline oxides through seven-membered ring intermediates (Scheme 1, entry 3). [9i] Inspired by previous reports, [9][10][11] we herein report the unprecedented site-selective trapping of such a-imino gold carbenes for a divergent synthesis of acylindoles or epoxides via selective acyl shifts and epoxidations (Scheme 1, entry 4).…”

“…The development of efficient synthetic methods through a-imino gold carbene intermediates has become an important tool for the construction of heterocycles. Gold-promoted nitrene transfer from nucleophilic nitrene equivalents, such as pyridine-based aza-ylides, [6] azides, [7] 2H-azirines, [8] isoxazole derivatives, [9] and sulfilimines [10] to alkynes, generates a-imino gold carbenes. These can efficiently undergo nucleophilic attack, CÀH insertion, or cyclopropanation.…”

Gold‐Catalyzed Annulations with Nucleophilic Nitrenoids Enabled by Heteroatom‐Substituted Alkynes

“…While our oxazole and imidazole forming methods are relatively unaffected by that aspect, the reactions of ynamides with other nucleophilic nitrenoids are more significantly affected, and competing pathways dominate over the (3 + 2) annulation as different substituents are introduced. [47] The unexpected βselectivity observed with alkynyl thioethers sees the metal carbene always flanked by the sulfenyl group. This provides an environment that is potentially less influenced by variations at the alkyne substituent and therefore it might provide a potentially more consistent reactivity profile across a wider reaction scope (Scheme 16).…”

Lewis Acid‐Catalyzed [4+2] Annulation between Propargylic Alcohols with Benzo[d]isoxazoles

“…achieved trifluoromethanesulfonic acid‐mediated syntheses of quinoline derivatives using ethynyl ketene‐ S, S ‐acetals with various arylamines and aldehydes as the substrates (Scheme a) . Recently, Hashmi and co‐workers disclosed an elegant protocol for the construction of 2‐aminoquinolines and other quinoline derivatives through the gold‐catalyzed cascade annulation of propargylic silyl ethers with anthranils (Scheme b) . It is worth noting that the high cost of metal reagents and complicated operations impose restrictions on the synthetic utility of such transformations.…”