Bromide Oxidation: A Safe Strategy for Electrophilic Brominations

Abstract

Bromination of organic substances is still an important reaction in modern synthetic chemistry. In view of the increasing demand for sustainable synthetic chemistry, oxidative bromination can play an important role to avoid the use of hazardous molecular bromine (Br 2 ). In this review, a complete overview of the chemical oxidants will be provided which have been used for the electrophilic as well as radical brominations, starting from less hazardous bromide Br(À I); e. g., HBr or a bromide salt, with a focus on the differences caused by the choice of oxidant.

Recent progress in the oxidative bromination of arenes and heteroarenes

“…There are several main routes for the bromination of arenes and heteroarenes, such as electrophilic bromination, 4 oxidative bromination, 5 transition-metal catalyzed bromination through C–H activation 6 and other ways including enzymatic bromination and bromination through a radical pathway. 7 Traditionally, electrophilic bromination has always been used for generating organic bromides.…”

In-water oxidative Suzuki coupling of arenes and arylboronic acids using H2O2 as a terminal oxidant

“…2 However, the use of pre-functionalized haloarenes is believed to be disadvantageous from the perspective of green chemistry because haloarenes are usually prepared by halogenation of arenes with hazardous and toxic halogenating reagents such as chlorine, bromine, or N -halo amides. 3 The direct use of arenes for the Suzuki reaction, oxidative coupling of arenes with arylboron reagents, has emerged as a viable alternative to the classical Suzuki–Miyaura reaction (Fig. 1).…”

Selectfluor and TBAX (Cl, Br) Mediated Oxidative Chlorination and Bromination of Olefins

“…Halogenation reactions have gained great importance since their discovery, and halides are important in organic synthesis as they are used in the synthesis of various valuable compounds. , Among the halides, chlorides and bromides attract more attention than iodides and fluorides owing to their great commercial importance . On account of chlorine gas or bromine being extremely toxic, researchers are seeking to develop new halogenation strategies. , In addition, conducting chemistry without using metals is also crucial in terms of medicinal chemistry and late-stage functionalization (LSF) of natural products and pharmaceuticals …”

“…3 On account of chlorine gas or bromine being extremely toxic, researchers are seeking to develop new halogenation strategies. 4,5 In addition, conducting chemistry without using metals is also crucial in terms of medicinal chemistry 6 and late-stage functionalization (LSF) of natural products and pharmaceuticals. 7 Selectfluor is not only a well-known, safe, easily soluble, easy-to-handle, stable solid, and reactive electrophilic fluorination reagent 8,9 but is also a robust and efficient "fluorine-free" green oxidant in organic synthesis.…”

“… 3 On account of chlorine gas or bromine being extremely toxic, researchers are seeking to develop new halogenation strategies. 4 , 5 In addition, conducting chemistry without using metals is also crucial in terms of medicinal chemistry 6 and late-stage functionalization (LSF) of natural products and pharmaceuticals. 7 …”