Metallkatalysierte desalkoxylierende C_Ar‐C‐Kreuzkupplung – Austausch aromatischer Methoxygruppen von Arylethern unter Verwendung eines funktionalisierten Nukleophils

Abstract

Der direkte Austausch aromatischer Methoxygruppen mit einem aktivierten Kohlenstoffatom würde neue Wege für gezielte und diversitätsorientierte Synthesen bahnen. Wir zeigen hier, dass solche Reaktionen in einem Schritt mit einem difunktionellen Nukleophil und einem C Ar -OMe-bindungsspaltenden Katalysator ablaufen kçnnen. Die gebildeten Produkte sind stabil, a-CH-aktiv und für diverse weitere Modifikationen geeignet.

Selective Reductive Removal of Ester and Amide Groups from Arenes and Heteroarenes through Nickel‐Catalyzed C−O and C−N Bond Activation

“…On the basis of our results [14] and previous studies, [18] we propose the following mechanism for this nickel-catalyzed reductive defunctionalization (Scheme 3): Oxidative addition of the C(acyl)ÀXbond of the aryl ester or amide to the L n Ni 0 complex A gives an acyl nickel(II) intermediate B,w hich subsequently undergoes CO migration and transmetalation with the hydrosilane to afford an aryl hydride nickel(II) intermediate C.R eductive elimination of C produces the L n Ni 0 CO species D and delivers the reduced product. Finally, extrusion of CO from D regenerates the active L n Ni 0 catalyst A.…”

“…Regarding the activation/functionalization of C À Oa nd C À Nbonds of esters and amides, [10,11] progress has been made in recent years. [10][11][12][13][14][15][16] With regard to decarbonylative transformations,the nickel-catalyzed CÀCbond formation of aryl esters was achieved. [12] Additionally,H eck-and Suzuki-type cross-coupling reactions of twisted amides through ad ecarbonylative pathway were reported, [13] as well as decarbon-ylative borylation, amination, and silylation reactions of esters and amides.…”

“…[12] Additionally,H eck-and Suzuki-type cross-coupling reactions of twisted amides through ad ecarbonylative pathway were reported, [13] as well as decarbon-ylative borylation, amination, and silylation reactions of esters and amides. [14,15] As part of our continuing efforts to develop viable protocols for the activation of inert bonds by nickel catalysis, [16] we herein describe the first nickel-catalyzed reductive defunctionalization of aryl and heteroaryl esters through ad ecarbonylative pathway.T his transformation provides av ersatile method for the late-stage removal of ester as well as amide groups from organic molecules.…”

Nickel‐Catalyzed C(Aryl)−O Bond Activation/Cross‐Coupling Reaction of Carbazoles with Methyl Grignard: Synthesis of Ellipticine

“…The crude product was purified by flash chromatography (nhexane/EtOAc = 9.8:0.2) to provide 2a (43. 7 2,6-Dimethyl-9H-carbazole (2 e): [18] By following the general procedure, am ixture of 3,6-methoxy-9H-carbazole (0.25 mmol), NiCl 2 (PCy 3 ) 2 (8.6 mg, 5mol %), PCy 3 (7.0 mg, 10 mol %), anhydrous toluene (3 mL), and methylmagnesium bromide (3 m in ether, 0.251 mL, 0.75 mmol) was stirred at 80 8Cf or 12 hu nder nitrogen. The crude product was purified by flash chromatography (nhexane/EtOAc = 9.8:0.2) to provide 2b (42.…”

“…[3] From the time of Wenkert'si nitial reporto ft he nickel-catalyzed Kumada-type cross-coupling reactions of methoxy arenesw ith ArMgX, [4] which involved the activation of an inert C(aryl)ÀOMe bond, the scope of nickel-catalyzed cross-couplings of methoxy arenes hase xpanded to aw ide range of nucleophiles, including organoboron, [5] organozinc, [6] organolithium, [7] hydride, [8] and amine compounds. [3] From the time of Wenkert'si nitial reporto ft he nickel-catalyzed Kumada-type cross-coupling reactions of methoxy arenesw ith ArMgX, [4] which involved the activation of an inert C(aryl)ÀOMe bond, the scope of nickel-catalyzed cross-couplings of methoxy arenes hase xpanded to aw ide range of nucleophiles, including organoboron, [5] organozinc, [6] organolithium, [7] hydride, [8] and amine compounds.…”