P-Bromobenzenesulfonyl chloride

Miller and Walling1 6 have shown that both bromine and sulfonyl chloride groups can be displaced during the photochemical reaction of chlorine with p-bromobenzenesulfonyl chloride and that a similar displacement of the sulfonyl group of benzenesulfonyl chloride occurs to give chlorobenzene. 

CH3OCH2CH2OTS and NaH produces the cone conformer of the tetraether in 81% yield, while with t-BuOK as the base the partial cone conformer is formed in 64% yield. Treatment of4 with p-bromobenzenesulfonyl chloride, on the other hand, yields the cone conformer with NaH but the 1,3-alternate conformer with 1-methylimidazole. ... 

It has been observed that 3-arylbenzofurans may rearrange to 2-arylbenzofurans under the conditions of cyclization <58JCS822, 77TL419>. If aryloxyalkanones of type (61) are treated with p-bromobenzenesulfonyl chloride, the corresponding vinyl esters (62) are obtained (Scheme 54). These compounds can be cyclized to 2,3-diarylbenzofurans with BF3 <72JCS(Pl)2l6>. 

A solution of 25 mg (lR,45 425, 135, 16R)-9-methoxy-13-(methoxymethoxy)-ll-oxapentacyclo[8.6.1.0 . 0 . 0 ]-heptadeca-6(17),7,9-trienone oxime (0.072 mmol), 28 mg p-bromobenzenesulfonyl chloride (0.11 mmol), 16 /xL EtsN (0.12 mmol), and a catalytic amount of DMAP in 5 mL CH2CI2 was stirred for 1 h at ambient temperature. The solvent was removed under reduced pressure, and the residue was taken up by 2 mL acetic acid. The resulting solution was stirred for 1 h and was neutralized with saturated aqueous NaHCOs. The mixture was extracted with CH2CI2, washed with saturated aqueous NaCl, dried over anhydrous Na2S04, and concentrated under reduced pressure. Chromatography of the residue on silica gel column (6 g, EtOAc/MeOH, 12 1) gave 17 mg (17 ,55,135,145, 175)-10-methoxy-14-(methoxymethoxy)-12-oxa-4-azapentacyclo[9.6.1.0 . 0 . 0 ]-octadeca-7(18),8,10-trien-3-one as a colorless oil, in a yield of 69%. [R]g = +114.2 (c 1.47, CHCI3). 

The reaction of 8-hydroxy acids with p-bromobenzenesulfonyl chloride in the presence of a tertiary amine gives /3-lactones (eq 5). Brosylate esters of oximes have been manipulated in the Beckmann rearrangement of erythromycin derivatives as an alternative to both 4-methylbenzenesulfonate esters and benzene-sulfonate esters. 

Formation of Carbodiimides. p-Bromobenzenesulfonyl chloride reacts with ureas to form carbodiimides in good yield (eq 6) ... 

A soln. of p-bromobenzenesulfonyl chloride in acetonitrile passed through the fluoride form of the strongly basic quaternary ammonium anion exchange resin AGI-XIO p-bromobenzenesulfonyl fluoride. Y 92%. - This method, which gives high yields and pure products, is best suited for small scale prepns. F. e. s. C. L. Borders, Jr., D. L. MacDonell, and J. L. Chambers, Jr., J. Org. Chem. 37, 3549 (1972). 

However, other substituted reagents were also proposed, especially for the identification of those amines which give low-melting derivatives with benzene- and / -toluenesulfonyl chloride p-bromobenzenesulfonyl chloride (83) and m-nitrobenzenesulfonyl chloride (84),... 

The preparation of /7-bromobenzenesulfonyl chloride will serve as example A freshly prepared solution of p-bromobenzenediazonium chloride [from / -bromoaniline (43 g, 0.25 mole), 36% hydrochloric acid (85 ml), and sodium nitrite (19 g, 0.275 mole, in 30 ml of water)] containing 9.5% of free hydrochloric acid is run into a 30% solution (200 ml) of sulfur dioxide in glacial acetic acid to which a concentrated aqueous solution of copper(n) chloride dihydrate (10 g) has been added. Lively evolution of nitrogen occurs and the temperature rises from 12° to 35° further rise in temperature is avoided by cooling in ice-water. The reaction is complete in 3-4 min then a three-fold amount of ice-water is added and the precipitate is collected, washed, and dried (yield 58.6 g, 92 %). After recrystallization from benzene the chloride has m.p. 76.3-76.5° and b.p. 153°/15 mm. 

Ar. thiocyanates. A soln. of / -bromobenzenesulfonyl chloride in acetonitrile added to a stirred soln. of Me3SiCN, Na2S03, and K2CO3 in the same solvent, and stirred under reflux for 10 min p-bromophenyl thiocyanate. Y 49%. F.e. inch di- and tri-subst. derivs., and 2-naphthyl and y-quinolyl thiocyanates, s. S. Kagabu et al., J. Chem. Soc. Chem. Commun. 1988, 1485-6. 

Bromobenzenesulfonyl chloride (BsCl) has been widely used to N-protect amines (eqs 1 and 2) Due to the relatively high molecular weight, p-bromobenzenesulfonyl derivatives have a higher melting point and may be more readily crystallizable than lower molecular weight derivatives. 

Related Reagents. p-Anisolesulfonyl Chloride Benzenesul-fonyl Chloride 4-Bromobenzenesulfonyl Chloride Methanesul-fonyl Chloride p-Toluenesulfonyl Chloride Trifluoromethane-sulfonyl Chloride. 

Dry Na-salt of N-chloro-p-bromobenzenesulfonyl amide added in small portions with vigorous stirring to a soln. of sulfur dichloride in benzene, and the product isolated after a few hrs. -> p-bromobenzenesulfonyliminothionyl chloride. Y 85%. F. e. s. E. S. Levchenko and A. V. Kirsanov, X. 31, 1968 (1961) C. A. 65, 27174c. 

A mixture of p-hromobenzenesulfonyl dichloramide and thionyl chloride heated 2-4 hrs. at 80-100° until Gl-evolution ceases N-thionyl-p-bromobenzene-sulfonamide (Y almost 100%) dissolved in benzene, 2,3-dimethylbutadiene added, and heated 30 min. on a steam bath 2-p-bromobenzenesulfonyl-3,6-dihydro-4,5-dimethyl-1,2-thiazine 1-oxide (Y 97%). F. e., also from N-sodio-N-chlorosulfonamides, s. E. S. Levchenko and A. V. Kirsanov, 5K. 32, 161 (1962) G. A. 57, 12365i. 

---