Synthesis of 3-Haloindoles via Cascade Oxidative Cyclization/Halogenation of 2-Alkenylanilines Mediated by PIDA and LiBr/KI

Abstract

The treatment of 2-alkenylanilines with phenyliodine(III) diacetate (PIDA) and LiBr or KI in HFIP was found to afford the corresponding 3-haloindoles via cascade oxidative cyclization/halogenation encompassing oxidative C–N/C–X (X = Br, I) bond formations. A plausible mechanism involving the in situ formation of the reactive AcO-X (X = Br, I) from the reaction of PIDA and LiBr/KI was postulated.

Divergent electrosynthesis of 3-iodoindoles and indoles from 2-ethynylanilines under ambient and aqueous conditions

“…1 Particularly in synthetic chemistry, tremendous efforts have been made for the development of novel and efficient protocols for synthesizing indole derivatives, and cyclization of 2-ethynylanilines has been one of the many effective strategies. 2 Following such a design, 3-iodoindoles with potential for further cross-couplings have been accessed via oxidative iodocyclization with “I + equivalents” such as IPy 2 BF 4 , I 2 , and N -iodosuccinimide (NIS) systems (Scheme 1a); 3,4 while the formation of indoles via catalytic hydrocyclization has been achieved with various metals (Cu, Ag, Pt, Zn, etc .) and base catalysis (Scheme 1b).…”

Study of the Structure and Infrared Spectra of LiF, LiCl and LiBr Using Density Functional Theory (DFT)

“…Highly concentrated (50-60%) LiBr brines are employed as liquid desiccants [31]. Solid LiBr is often used in organic synthesis [32,33] and the catalytic conversion of waste biomass [34][35][36]. Unlike heavier halides, LiF dissolves poorly in water [37] and has rather niche applications, such as radiation-shielding materials [38], glasses for photonic applications [39] and optical materials [40].…”