Toluenesulfonyl Bromide

(a) Dictionary of Organic Compounds, 5th ed., Third Supplement Chapman and Hall New York, 1985 p 292. (b) The Merck Index An Encyclopedia of Chemicals, Drugs, and Biologicals, llthed. Budavari, S., Ed. Merck Rahway, NJ, 1989 p 1501. 

Kobayashi, T. Tanaka, Y. Ohtani,T. Kinoshita, H. Inomata, K. Kotake, H., Chem. Lett 1987, 1209. 

Alternate Name 4-methylbenzenesulfonyl bromide, tosyl bromide, TsBr. 

Solubility sparingly soluble in EI2O soluble in toluene, benzene, and methylene chloride. 

Analysis of Reagent Purity melting point a detailed structural analysis was performed using electron diffraction, MS, and 

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The activation parameters of the hydrolysis in aqueous dioxane of j -toluenesulfonyl bromide (336) pass through maxima at dioxane mole fractions of 0.01 and 0.12, which correspond to the range of stabilization of the solvent structure. 

Regio- and stereoselective toluenesulfonyl bromide-mediated radical cyclization of bis(allene) (201) in the presence of AIBN also goes ahead to give rise to the transfused 5-membered ring (202) containing vinyl sulfone and vinyl bromide as shown in eq. 3.78. 

These reactions involve lithiation of l,3-dithiole-2-thione 103 with lithium diisopropylamide (LDA) followed by reactions of the resulting carbanions with various electrophiles. Thus, the direct lithiation and subsequent bromina-tion of l,3-dithiole-2-thione 103 allowed a selective preparation of mono- and dibrominated derivatives in 80% yields. For instance, the reaction of 103 with LDA (lequiv), followed by treatment with 1,2-dibromotetrachloro-ethane, produced monobrominated derivative 104, whereas the reaction of 103 with excess of LDA (3 equiv) led to the isolation of dibrominated derivative 105 (Scheme 5) <2006T8152>. Earlier attempts at bromination of 103 using, for example,/i-toluenesulfonyl bromide <2001JMC2181> or 1,2-dibromotetrachlorethane <2001JMC1570> yielded mixtures of mono- and dibrominated derivatives in low yields (25-30%). 

Toluenesulfonyl bromide, prepared from thio-p-cresol (3 g), glacial acetic acid (15 g), and bromine (6 g), melts at 93-94° after recrystallization from a little light petroleum. 

To 4.24 g (25.8 mmol) of monosilylated diyne 30 in 110 mL of dry THF was added dropwise, under a nitrogen atmosphere, 11 mL (28 mmol) of 2.5 M H-butyUithium in hexane at — 78°C. The mixture was stirred for 30 min, then 7.12 g (30.3 mmol) of p-toluenesulfonyl bromide in 30 mL of THF was added over a 10 min period. The solution was stirred for 30 min at — 78 °C and at room temperature for 1 h. Next, 150 mL of water was added. The layers were separated, and the aqueous layer was extracted with 3 x 50 mL of pentane. The combined extracts were washed with 150 mL each of 10% aqueous sulfuric acid, saturated aqueous sodium bicarbonate, and water, dried over magnesium sulfate, and concentrated under reduced pressure. Column chromatography on silica gel with 10 1 hexane/ethyl acetate gave 4.90 g (76%) of bromoalkyne 50 as a colorless liquid that was 90% pure by GC (contaminants were not characterized). It is not advisable to purify the product by distillation due to the possibility of explosive decomposition - CAUTION [44] ... 

Free radical addition of /r-toluenesulfonyl bromide to the 1,6-diene (30) gave rise to bicyclic adduct (31) which could be reductively debrominated with B SnH. The synthesis... 

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