Regioselective monobromination of aromatics via a halogen bond acceptor-donor interaction of catalytic thioamide and N-bromosuccinimide

Automated Grindstone Chemistry: A Simple and Facile Way for PEG-assisted Stoichiometry-controlled Halogenation of Phenols and Anilines Using N-Halosuccinimide

“…The century-old classical method of using hazardous and corrosive reagents X 2 (X = Br, Cl) suffers from low atom economy (<50%), formation of corrosive byproducts (e.g., HBr) [15,16], which cause serious environmental issues. To mitigate the problem, several mild and operationally safe halogenating agents have been successfully introduced to replace X 2 [17][18][19][20][21][22][23][24][25][26][27][28][29][30][31]. Among them, the use of N-halosuccinimides has turned out to be a viable alternative to X 2 because of their low-cost, ease of handling, and possible recycling of the byproduct succinimide [24][25][26][27][28][29][30][31].…”

“…To mitigate the problem, several mild and operationally safe halogenating agents have been successfully introduced to replace X 2 [17][18][19][20][21][22][23][24][25][26][27][28][29][30][31]. Among them, the use of N-halosuccinimides has turned out to be a viable alternative to X 2 because of their low-cost, ease of handling, and possible recycling of the byproduct succinimide [24][25][26][27][28][29][30][31]. In several earlier cases, the bromination with N-bromosuccinimide (NBS) was carried out in toxic polar solvents (e.g., DMF), but no iodinated or chlorinated products were obtained because of the low reactivity of NIS and NCS (Scheme 1a) [24][25][26][27].…”

Regioselective Monobromination of Phenols with KBr and ZnAl–BrO3−–Layered Double Hydroxides

“…Due to the high activity and multiple substituted sites of phenols, over-bromination frequently occurs when phenol derivatives undergo bromination [35,36]. It is usually hard to obtain mono-brominated product, as it is usually a mixture of mono-and multi-brominated substrate (Figure 1a).…”

“…Some methods use special brominating reagents or additives (Figure 1b), such as o-xylylene bis (triethyl ammonium tribromide) [35], bromotrimethylsilane and di-4-chlorophenyl-sulfoxide [37], (diacetoxyiodo)benzene and AlBr 3 [38], p-toluenesulfonic acid [39][40][41], methanol [39,42], polyvinylpolypyrrolidone-Br 2 [43], 1,3-di-n-butylimidazolium tribromide [44], ethylenebis(Nmethylimidazolium) ditribromide [45], N-benzyl-triethylenediamine tribromide [46], 1-butyl-3methylpyridiniumtribromide [47], ZrBr 4 /diazene [48], β-cyclodextrin [49] and tetrabromobenzene-1,3-disulfonylamide [50]. There are also some methods requiring a catalyst, including thioamide [36], Cu−Mn spinel oxide [51], bromoperoxidase [52], Rhenium-promoted mesoporous zirconia [53], amberlyst-15 [54], mesoporous silica supported sulfated zirconia [55], copper icons [56,57], UV-vis light irradiation [58] and ammonium acetate [59].…”

DABCO as a practical catalyst for aromatic halogenation with N-halosuccinimides

“…Alternatively, Lewis bases, with O, N, S or P centre, have also been verified to catalyse the halogenation via interaction with NXS to form the activated halonium complexes. 43–53 Recently, Jiao's group 45 discovered an efficient late-stage chlorination of complex substrates in the presence of DMSO, providing a practical method for further applications. Miura 43 also developed a novel protocol using triptycenyl sulfide to realize electrophilic aromatic halogenation of a variety of unactivated compounds.…”