Arylsulfonyl halides

The ability to conduct radical reactions without the use of tin reagents is important. Allylic triflones have been used to conduct allylation reactions on a range of substrates (39) as a replacement for allyltributylstannane (Scheme 28). The main limitation was that unactivated or trisubstituted triflones failed to undergo reactions. In other nontin radical methods, arenesulfonyl halides have been used as functional initiators in the CuCl/4,4 -dinonyl-2, 2 -bipyridine-catalysed living atom-transfer polymerization of styrenes, methacrylates, and acrylates.The kinetics of initiation and propagation were examined with a range of substituted arylsulfonyl halides with initiator efficiency measured at 100%. 

Preparation of arylsulfonyl 2-substituted pseudothioureas by the reaction of arylsulfonyl halides with pseudothioureas [82, 83]. 

Arylsulfonylbenzimidoyl chlorides, with aminothiazoles, 50 Arylsulfonyl halides, 98, 115 Azide, with azothiazoles, 111 to carbamate, 16 Curtius rearrangement of, 15, 16 See also Sodium azide Azido thiazoles, 113 azidothiazole-thiazolotetrazole, 113 reactions of, 113... 

Occasionally, displacements occur in the process of reacting oxoazines with phosphorous oxychloride or pentasulfide or with an arylsulfonyl halide, thionyl chloride, or sulfuryl halide. The phos-phoryloxy or sulfonyloxy intermediates (201) are now activated by virtue of the protonated ring-nitrogen plus the electron-attracting acyloxy substituent. 

Reaction with Sulfonyl Halides. Arylsulfonyl halides undergo reductive dimerization to form the corresponding disulfides (eq 35). Alkylsulfonyl halides, however, undergo this process under somewhat more vigorous conditions. Although sulfones generally do not react with TMS-I, certain cyclic sulfones are cleaved in a manner analogous to lactones. ... 

In one case arylsulfonyl halides were used to prepare biaryls. The reaction was catalyzed by a palladium complex in the presence of titanium tetraisopropoxide (Scheme 9). This procedure is convenient for the preparahon of halogen-substituted biaryls, because the homocoupling proceeds through cleavage of the C—SO2CI bond. 

The mechanism of the reaction of arylsulfonyl halides with nucleophilic reagents has been widely studied and reviewed. " The majority of kinetic and other evidence indicates that the reactions of an arylsulfonyl chloride 1 with a nucleophile (Nu") generally follow the concerted bimolecular SN2-type mechanism as depicted in Equation 7 with a linear bipyramidal transition state which is similar to the Sn2 (acyl) pathway established for acyl halides. ... 

The main evidence in support of this mechanism derives from studies of stereochemical inversions as in the reaction of a chiral sulfonate with a Grignard Reagent isotopic experiments on the hydrolysis of arylsulfonates and the rates of hydrolysis of alkyl and arylsulfonyl halides. ... 

By analogy with acyl halides, the SnI mechanism (Equation 8) should be possible for arylsulfonyl halides, provided they contain sufficiently electron-donating substitutents as in the hydrolysis of 2,4,6-trimethylbenzenesulfonyl chloride. However, this evidence has been disputed by the work of Rogne in Norway in a series of papers thus in the reaction of imidazole with substituted... 

For nucleophilic substitutions involving alkylor arylsulfonyl halides 8 possessing at least one a-hydrogen atom, a different reaction mechanism is possible as shown (Equation 10) ... 

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