An Efficient and Regioselective Oxybromination of Aromatic Compounds Using Potassium Bromide and Oxone®,*

Abstract

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Development of a Multigram Synthesis of URB937, a Peripherally Restricted FAAH Inhibitor

“…The use of NaBr/Oxone in MeOH has been reported as an efficient and safe method for the bromination of electron-rich aromatic rings. 11 When this procedure was applied to our substrate, the reaction was exceedingly slow with only 46% conversion of compound 9 observed after 96 h (entry 2), most likely because of the limited solubility of 9 in MeOH.…”

Simple and Regioselective Bromination of 5,6-Disubstituted-indan-1-ones with Br2 Under Acidic and Basic Conditions

“…The molecular ion peak at m/z 350 in the mass spectrum of 6 confirmed the dibrominated nature of the product. KBr and Oxone ® (2K 2 HSO 5 ּKHSO 4 ּK 2 SO 4 ) is an oxybromination reagent used in high paraselective brominations of aromatic compounds [12]. We treated compound 1 with Oxone ® and KBr in methanol for 2 hr to obtain 4 in 46% yield (entry VII).…”

“…After 20 hrs at this temperature the reaction mixture was worked up as described for 1.9 to give 2,2-dibromoindan-1-one (12) in 67% yield. Compound 12: m.p.…”

“…Recently, bromoarenes have assumed increasing importance in organic synthesis as useful reagents for functionalization through carbon-carbon bond formation of diarenes, ethylenic, or acetylenic condensation via metal catalyzed cross coupling reactions such as the Suzuki, Negishi, and Sonogashira reactions [2]. Various reagents and reaction conditions have been developed and reported for the bromination of aromatic systems using different brominating agents, including Br 2 /SbF 3 /HF [3], NBS/H 2 SO 4 /CF 3 COOH [4], NBS/NaOH [5], NBS/ FeCl 3 [6], HBr/tert-BuOOH, HBr/H 2 O 2 , and HBr/DMSO [7], NH 4 Br/H 2 O 2 /CH 3 COOH [8], CuBr/tertBuONO [9], Br 2 /SO 2 Cl 2 over microporous catalyst [10], 3-methylimidazolium tribromide [11], NaBr/Oxone ® , KBr/Oxone ® , and KBr/H 2 O 2 /Oxone ® [12], Br 2 /tetrabutylammonium peroxydisulfate [13], quaternary ammonium tribromide [14] and quinolinium bromochromate in glacial acetic acid [15]. On the other hand, selective α-bromination of carbonyl compounds is another important transformation, as the resulting α-brominated products are also versatile synthetic intermediates.…”

Ecofriendly Oxidative Nuclear Halogenation of Aromatic Compounds Using Potassium and Ammonium Halides

“…Selective para bromination of aromatic compounds using KBr as a bromine source and Oxone ® as an oxidant was established. 21 Here a number of different aromatic compounds were subjected to bromination using this method at room temperature. The activated aromatics such as anisole, acetanilide, methoxynaphthalenes, and ortho-and meta-cresols afforded the respective para-brominated products in high yields, whereas 2-nitrophenol (less activated) gave a lower yield.…”