Elemental Sulfur-Mediated Aromatic Halogenation

Abstract

A method for aromatic halogenation using a combination of elemental sulfur (S 8 ) and N-halosuccinimide has been developed. A catalytic quantity of elemental sulfur (S 8 ) with N-bromosuccinimide (NBS) and N-chlorosuccinimide (NCS) effectively halogenated less-reactive aromatic compounds, such as ester-, cyano-, and nitro-substituted anisole derivatives. No reaction occurred in the absence of S 8 , underscoring its crucial role in the catalytic activity. This catalytic system was also applicable to aromatic iodination with 1,3-diiodo-5,5-dimethylhydantoin.

Electrochemical C–H Mono-/Multi-Bromination Regulation of N-Sulfonylanilines on a Cost-Effective Carbon Fiber Electrode and Its Prospective Electroactive Molecule Screening

“…As a common organic building block for diverse transformations, aryl bromides are widely applied in coupling reactions , and also are usually found in natural products and bioactive compounds. , Among them, brominated anilines are of significance for clinical drugs, such as bromazepam (antianxiety), binimetinib (BRAF/MEK inhibitor), vandetanib (antithyroid cancer), and bromhexine (expectorant) (Figure a). In this regard, various synthesis methods for bromination of anilines have been developed, of which the direct bromination through specific brominating reagents or oxidants via an electrophilic aromatic substitution is the popular one and widely used. − The past decade has witnessed that the electrochemical organic synthesis has become one of the fascinating fields owing to its redox ability without using chemical oxidants. − Recently, we noted that the direct electrochemical C–H bromination of anilines could be accomplished under oxidant-free conditions from simple and available bromine sources, such as the bromine anions (NaBr, NH 4 Br, and n -Bu 4 NBr) and brominated alkanes (CH 2 Br 2 , 3-bromopropyne, and 2-bromoethan-1-ol) (Figure b). Despite these significant advances, there are some limitations: (1) the relatively expensive electrodes were required, such as Pt or RVC, and (2) the substrate scope was limited to the unique 8-aminoquinolines, , N , N- dialkylanilines, ,, N -acylated anilines, and free anilines .…”