Tosyl bromide

Table 5.12. Tosylate/Bromide Rate Ratios for Solvolysis of RX in 80% Ethanol ...

Arenesulfonyl iodide and bromide are rather unstable compounds because of low bond dissociation energies of their S02-I and S02-Br. Therefore, treatment of p-tosyl bromide (47) with alkene or allene (48) produces 1,2-adduct (49) through the addition of the formed p-tosyl radical onto the allene as shown in eq. 4.19 [52]. Here, the p-tosyl radical attacks the central sp carbon of the allene group to generate the stable allylic radical, and then it reacts with p-tosyl bromide to give 1,2-adduct (49) and a p-tosyl radical again, i.e., chain pathway. So, this is also an atom(group)-transfer reaction. 

A related radical addition/5-exo cyclization cascade involving addition of sulfonyl radicals to alkynes has been used for the diastereoselective synthesis of bicyclic p-lactams 182 from the p-lactamic enyne precursor 181 (Scheme 2.33). In this radical chain sequence, where tosyl bromide is used as source of sulfonyl radicals, the final product is a mixture of epimers (90 10) at the newly formed exocyclic chiral center. 

Scheme 5-3. Useful intermediates for the synthesis of ferrocene derivatives containing heteroatoms (a) Lithiation (generally with nBuLi) (b) mercuration with Hg(OAc)2, followed by reaction with LiCl or KCl (c) borylation with B(OnBu)3, followed by hydrolysis (d) CUCI2 (e) CuBr2 (f) compounds containing reactive bromo substituents, e.g., BrCX2 -CX2Br (X = F, Cl) or tosyl bromide (g) A-bromo succinimide (h) I2 (i) Br2.

Tosyl perchlorate. P CH CfHqSOi ClOq, Mol. wt. 254.60. The reagent is prepared in nilromethane aolullon by reaction of tosyl bromide with silver perchlorate at 0. II Is a powerful sulfonatlon reagent which reads with even the relatively inert halofaencenes to il vt lulfonos. ... 

An alternative annulation reaction results in the formation of [l.l.ljpropellane 25." - Hy-droxymethylation of Moore s hydrocarbon 24, followed by conversion to a bromo alcohol by treatment with butyllithium and tosyl bromide, then conversion into a chlorobromo compound with carbon tetrachloride/triphenylphosphane, which was dehalogenated with methyllithium, gave the [l.l.ljpropellane derivative 25. 

Metathesis of tetraarylbismuthonium halides with metal salts has often been used to exchange the halide anion for other anionic species (Section 3.3.1). For example, the reaction between tetrakis(2-methoxyphenyl)bismuthonium chloride and sodium or silver salts of formate, tosylate, bromide, iodide, tetrafluoroborate or perchlorate yields the corresponding bismuthonium compounds of the type [Ar4Bi ]Y (Ar = 2-methoxyphenyl Y = OCOH, OTs, Br, I, BFj, CIO4) [97JCS(P1)1609]. 

The phosphonium salt 175 requires similar operations but malic acid 34 is reduced to the triol 180 before selective protection 181 leaves just one alcohol for conversion to tosylate, bromide and finally protected phosphonium salt 182. 

Conversion of a Terminal Acetylene to a Bromoalkyne Using Tosyl Bromide (30 - 50, Fig. 9-14)... 

Tosylate/bromide rate ratios for solvolysis of RX in 80% ethanol... 

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

Radical Cyclization Reactions. The capable radical chain carrying character of tosyl bromide has been applied to the cyclization of several 1,6-dienes. In many examples, the products result from addition of the tosyl radical to the terminus of the less-substituted olefin, followed by S-eAU-tn gcyclization with the second olefin to deliver a five-membered ring product. In all cases, cis-stereochemistry predominates. In some cases, however, the 1,2-addition of tosyl bromide to one olefin is the observed product. The generic reaction sequence is pictured below (eq 2). 

Kang et al. reported that the radical addition of tosyl bromide (and iodide) to allenic alcohols produced the tosyl-substituted, bromo allylic alcohols or cyclic ethers (eq 9). 

Preparation of Thiolsulfonates. Fuchs and Ranasinghe demonstrated that mercaptans, in the presence of triethylamine, rapidly reacted with tosyl bromide to produce good yields of the mixed thiolsulfonates (eq 12).2 This reaction stands in stark contrast to the analogous reaction with tosyl chloride which simply yields the disulfide. 

Miscellaneous. In an interesting example of the enhanced reactivity of this reagent (in comparison with tosyl chloride), Fuchs reported the ring opening of thebaine with tosyl bromide under standard Schotten-Baumann acylation conditions (eq IS). ... 

Binnemans et al. reported that the Nd + tosylate, bromide, triflate, and sulfonylimide complexes were dissolved in l-alkyl-3-methylimidazolium ionic liquids that contain the same anion as the Nd + complexes. NIR-luminescence spectra of these Nd + salts were measured by direct excitation of the Nd + ion. And intense NIR luminescence... 

Reactions at acid centers to create 5 -2-(trimethylsilyl) ethanethiolesters are also common. Carboxylic 5-thiolesters are formed in high yield by the DCC/DMAP mediated coupling of 2-(trimethylsilyl)ethanethiol and carboxylic acids or by thiol substitution on a carboxylic acid chloride. 5 -2-(Tiimethylsilyl) ethyl p-toluenethiolsulfonate is formed by treating 2-(trimethyl-silyl)ethanethiol with tosyl bromide (eq 4). The product is a useful electrophile for carbon nucleophiles, allowing the introduction of the 2-(trimethylsilyl)ethylthio unit by an alternative mechanism. Independent of the thiol, aryl and alkyl 2-trimethylsilylethyl thioethers may be prepared by the radical addition of the appropriate arene- or aikanethiol to vinyl trimethyl-silane in a reaction comparable to that of eq l7 ... 

Of the derivatives prepared, the tosylate bromide amine and fatty-acid ester 1212 have previously been reported,... 

The light-induced reaction of tosyl bromide with the diene 25 afforded the bicyclic derivative 26. A detailed study of the configuration at the newly created chiral centre was reported. ... 

---