Synlett 2009(2): 330-331  
DOI: 10.1055/s-0028-1083571
SPOTLIGHT
© Georg Thieme Verlag Stuttgart ˙ New York

Phenyltrimethylammonium Tribromide: A Versatile Reagent in Organic Synthesis

Hong-Yan Lü*
The College of Chemistry & Material Science, Hebei Normal ­University, Shijiazhuang 050016, P. R. of China
e-Mail: hbhongyanlv@sina.com.cn;
Further Information

Publication History

Publication Date:
15 January 2009 (online)

Introduction

Phenyltrimethylammonium tribromide (PTAB) is known to be a convenient oxidizing and brominating agent. It is an orange crystal and easy to handle, with a melting point at 113-115 ˚C. [¹] It has been used for the oxidative transformation of trans-stilbene oxide to 2-phenyl-1,3-dioxane in the presence of various of 1,3-diols and a catalytic amount of SbBr3, [²] for brominating the α-position of carbonyl compounds, [³-8] α′-bromination of α,β-unsaturated ketones, [9] and for the addition of bromine to alkenes. [¹0] It was also found to be useful for the chemoselective conversion of 3-alkoxyfurans to 2-alkoxy-3(2H)-furanones, oxidative ring-opening of 3-alkoxy-2,5-diphenylfurans to cis-2-alkoxy-2-butene-1,4-diones, [¹¹] and synthesis of imidazolines, [¹²] 3-bromo-2-styrylchromones, [¹³] nitro dibromo-phenols, [¹4] pyridazines, [¹5] phytoalexin cyclobrassinin, [¹6] p-bromo­dienone calixarene derivatives, [¹7] and 2-arylthia­zino[5,6-b]indoles. [¹8]

Phenyltrimethylammonium tribromide is commercially available now. It can be readily prepared from N,N-di­methylaniline and dimethyl sulfate, followed by treatment with 48% hydrobromic acid and bromine. [¹]

Scheme 1