Metal-free polychloromethylation/cyclization of unactivated alkenes towards ring-fused tricyclic indolones and benzoimidazoles

Abstract

Polychloromethylative cyclization of N-alkenyl indolinones was developed under metal-free conditions to afford tricyclic pyridoindolones and pyrroloindolones in moderate to good yields. In the reaction, commercially available CHCl3 and CH2Cl2 were...

Photo‐Induced Difluoromethylation‐Cyclization of Indoles Using Tetrazole Sulfone Reagent Under Visible Light

“…[4] The cascade radical addition/cyclization of N-alkene tethered indoles has been proved as a convenient route towards the polycyclic indoles. [5] A viarety of radical species such as trichloromethyl radical (•CCl 3 ), [6] sulfonyl radical (Ts•), [7] phosphite radical(•PO(OEt) 2 ) [8] were explored to construct the pyrrolo [1,2-a]indoles under copper, [9] palladium, [10] nickel, [11] silver, [12] metal-free, [13] peroxides, [6] electrochemical synthesis [14] and photocatalysis. [8a,15] In most cases, an electron-withdrawing group at the C3 position was required.…”

Visible Light-Induced Radical Cascade Difluoromethylation/Cyclization of Unactivated Alkenes: Access to CF2H-Substituted Polycyclic Imidazoles

“…On the one hand, significant development has been made in the methods for catalyzed C–H activation and intramolecular cyclization of imidazoles with alkenes using diverse transition-metal catalysts, including [Pd], 27 [Rh], 28 [Ni], 29 and [Sc]. 30 On the other hand, a series of methods for synthesizing substituted tricyclic benzimidazole derivatives with various functional groups, such as trifluoromethyl, 31 difluoroalkyl, 32 sulfonyl, 33 perfluoroalkyl, 34 and chloromethyl, 35 have been established, involving the strategy of radical cascade addition/cyclization of olefin-containing imidazoles. Although these methods have promising prospects, there is still a necessity to develop direct, mild, and efficient methodologies to synthesize highly functionalized polycyclic imidazoles with broad substrate scopes.…”