Durch blaues Licht induzierte Carbentransferreaktionen von Diazoalkanen

Abstract

Carbene sind wichtige reaktive Intermediate,die den Zugang zu einer Vielzahl von komplexen Molekülen ermçglichen und eine große Anwendung in der organischen Chemie und der Wirkstoffforschung besitzen.I nd er Regel wird diese Chemie durchd ie Verwendung von Übergangsmetallkatalysatoren ermçglicht. Im Folgenden beschreiben wir die Anwendung von niederenergetischem Lichtzur photochemischen Erzeugung von Carbenen ausgehend von Donor-Akzeptor-Diazoalkanen. Dieser katalysatorfreie und präparativ einfache Ansatz ermçglicht hoche ffiziente Cyclopropenierungsreaktionen von Alkinen und Umlagerungsreaktionen von Sulfiden unter milden Reaktionsbedingungen in einem diskontinuierlichen oder kontinuierlichen Prozess.

Catalyst-Free Photoinduced C–C Bond Formations

“…Koenigs and co-workers next demonstrated the use of phenyldiazoacetate 4a to cyclopropanate arylalkynes 4b under transition-metal-free and mild reaction conditions using 470-nm blue LEDs (Scheme 4 ). 29 The best solvent for this reaction was dichloromethane. Various heteroaryl- and arylacetylenes with both electron-rich and electron-poor substitution gave the corresponding cyclopropanated products in good yields.…”

[3+2]‐Cycloaddition of Catalytically Generated Pyridinium Ylide: A General Access to Indolizine Derivatives

“…With the rapid developments in synthetic photochemistry, the photochemical reaction of diazo compounds via free carbene intermediates has been re-emerged in the past years. [14,15] The early example of the formation of pyridinium ylide from diazo compounds and pyridines under photocatalysis or thermocatalysis was disclosed by Platz [16] and Surpateanu, [17] respectively. However, the only reaction with isolated cycloadduct was reported by Platz: photolysis of diazirine 1 with pyridine 2 a to produce 3 in about 30% yield via sequential formation of free carbene, pyridinium ylide, and [3 + 2]-cycloaddition with dimethylacetylenedicarboxylate (DMAD) followed by aromatization via elimination of a molecule of HCl (Scheme 4.…”

Flow photolysis of aryldiazoacetates leading to dihydrobenzofurans via intramolecular C–H insertion

“…26–34 Continuous flow photolysis of aryldiazoacetates leading to cyclopropanation have been reported. 35–37…”

“…[26][27][28][29][30][31][32][33][34] Continuous flow photolysis of aryldiazoacetates leading to cyclopropanation have been reported. [35][36][37] While photochemical reactions of α-diazocarbonyl compounds have been explored for decades, the first example of a photolytic intramolecular C-H insertion was reported by Corey and Felix in 1965 for the synthesis of methyl 6-phenylpenicillinate from an α-diazoamide. 38 Since then, the photochemical intramolecular C-H functionalisation of aryldiazoacetates 1a and 1b leading to 5,5-dimethyl-3-phenyldihydrofuran-2(3H)one 2a and 4,4-dimethyl-3-phenyloxetan-2-one 2b has been reported by Jurberg and Davies (Scheme 1).…”