Cu-Catalyzed Oxidative 3-Amination of Indoles via Formation of Indolyl(aryl)iodonium Imides Using o-Substituted (Diacetoxyiodo)arene as a High-Performance Hypervalent Iodine Compound

Abstract

An oxidative 3-amination of indole derivatives using hypervalent iodine(III) and bissulfonimides, which proceeds via the formation of indolyl(aryl)iodonium imides, was developed. This reaction was followed by an indole-selective copper-catalyzed oxidative C–N coupling reaction to obtain 3-amino indole derivatives as single regioisomers. o-Alkoxy(diacetoxyiodo)arenes showed higher reactivity in the reaction than o-alkyl(diacetoxyiodo)arenes, efficiently promoting the formation of indolyl(aryl)iodonium imides in the first step.

Organophotoredox-Catalyzed Cross-Dehydrogenative Sulfonamidation of Indoles and Other Heterocycles

“…7-OBn and 7-Me functional groups were also well tolerated, producing the corresponding products 4r and 4s in yields of 63 and 82%, respectively. C3-substituted indoles also effectively underwent this transformation, which evidenced that the reaction proceeds via the direct addition of NCR rather than the intermediate formation of indolyl­(aryl)­iodinium imide . The reaction of 5-alkenylindole led to the selective monosulfonamidation product 4u in 79% yield, which indicated that the reaction condition also tolerated the alkene group on the substrate.…”

“…Again, stoichiometric amounts of hypervalent iodine reagents have also been reported to be useful for various other C–H functionalization reactions such as azidation, acetoxylation, and cyanation as well as other functional group transformations. With respect to the amination reaction, a hypervalent iodine-mediated cross-dehydrogenative amination reaction of polyaromatic amines has been reported by Ito et al The Cu-catalyzed amidation of 2,3-unsubstituted indoles with pre-synthesized indolyl(2-butoxylphenyl)iodonium bis-sulfonimides was reported to afford 3-bissulfonimido-indoles as exclusive products . The usefulness of the hypervalent iodine compounds under photoredox conditions stems from the fact that they can easily take part in the oxidative quenching of the photochemically excited photocatalyst and then undergo decompositions to afford radical intermediates that can participate in various further radical processes.…”

Copper-Catalyzed/Hypervalent Iodine-Mediated Functionalization of Unactivated Compounds

“…The process proceeded through the C-N bond formation between nucleophilic indoles and nucleophilic amides. Among different ligands, the presence of 2-butoxy group on the aryl induced high indole selectivity by a steric effect (Scheme 84) [112,113]. Moryiama group developed the synthesis of 3-bis-sulfonimido-indole derivatives using indolyl(aryl)iodonium imides.…”

Keteniminium Salts as Key Intermediates for the Efficient Synthesis of 3‐Amino‐Indoles and ‐Benzofurans

“…In the literature, the synthesis of 3‐amino‐indoles and ‐benzofurans is achieved following three main strategies. The first one is the functionalization of the naked benzoheterole through either direct amination or a nitr(os)ation/reduction sequence . The second is the generation of the heterocyclic core followed by in‐situ amination of the latter and the third is the one‐step formation of the 3‐aminobenzoheterole moiety.…”