A facile bromination of hydroxyheteroarenes

Synthesis of Gerfelin and Related Analogous Compounds

“…We adopted commercially available 4-hydroxy-6-methyl-2-pyrone as the starting material which was converted to the known bromide (15) 7) and triflate (16).…”

Preparation and Optical Properties of Novel 3-Alkoxycarbonyl Aza- and Diazacoumarins

“…of 4 was realized under the conditions described by Mase et al, [24] and the resulting bromide 16 offered an access to specifically reduced azacoumarin 17 in 45% yield. Finally, treatment of coumarin 4 with dimethylsulfate resulted in N 6 alkylation, and coumarin 18 was obtained in 89% yield.…”

Recent advances in 4-hydroxycoumarin chemistry. Part 1: Synthesis and reactions

“…N-bromosuccinmide (NBS) is generally utilized for bromination of 4-hydroxycoumarin 1 at room temperature using different catalysts such as polyethylene glycol (PEG-400) (Venkateswarlu et al, 2009), sulfonic-acidfunctionalized silica (Das et al, 2006), ammonium acetate (Das et al, 2007), anhydrous magnesium perchlorate (Zhang et al, 2007) or tetrabutylammonium bromide (TBAB) (Ganguly et al, 2005) (Scheme 98). Ammonium bromide and Oxone® (Kumar et al, 2010) or tetrabutylammomium bromide and phosphorus pentoxide (Jung and Allen, 2009;Kato et al, 2001) have also been used as another brominating agents for this reaction (Scheme 53). When the bromination of 4-hydroxycoumarin 1 is carried out using vanadium pentoxide as an effective promoters with tetrabutylammonium bromide in the presence of hydrogen peroxide, it is afforded α,α-dibromo-2-hydroxyacetophenone 184 (Bora et al, 2000) (Scheme 99).…”