Arylsulfonate complexes

In the case where the arylsulfonate group is a benzene instead of a naphthalene the relaxation kinetics for guest complexation with a-CD measured by stopped-flow showed either one or two relaxation processes.185,190 When one relaxation process was observed the dependence of the observed rate constant on the concentration of CD was linear and the values for the association and dissociation rate constants were determined using Equation (3). When two relaxation processes were observed the observed rate constant for the fast process showed a linear dependence on the... 

A common method for preparing alkynyl(phenyl)iodonium tetrafluoroborates involves the reaction of iodosylbenzene in the presence of triethyloxonium tetrafluoroborate or boron trifluoride etherate with alkynyl-silanes. For example, the complex of iodosylbenzene with triethyloxonium tetrafluoroborate (362) reacts with alkynylsilanes in dichloromethane at room temperature to afford alkynyl(phenyl)iodonium tetrafluoroborates 363 in good yield [496]. A variation of this procedure employs the complex of iodosylbenzene with boron trifluoride etherate (364) followed by treatment with aqueous NaBp4 [493,497] or sodium arylsulfonates to furnish, respectively, the appropriate alkynyl(phenyl)iodonium tetrafluoroborates 363 [483,487] or organosul-fonates 365 [488,489] (Scheme2.102) [498,499],... 

One of the challenges is to extend the reaction from triflates to less reactive arylsulfonates. The palladium-catalyzed reaction of aryl mesylates results in low yields because of their slow oxidative addition to a palladium(O) complex, but they readily participate in the nickel-catalyzed cross-coupling reaction at 80°-100 °C. A nickel(O) species incorporating dppf ligand, obtained by in situ reduction of 10 mol% of NiCljCdppf) with zinc dust, is recognized as the most effective catalyst (Eq. 43). However, again the reaction needs to be optimized because a... 

C.iv.a. Hydrogenation of Sulfonates. The detachment of substituted arylsulfonates in the presence of a reducing agent such as formic acid provides a traceless cleavage. In this case it is important that the arene core is substituted with electron-withdrawing substituents to enhance the yields significantly (Scheme 45). This approach has been described (without experimental details) quite early in a patent including the possible derivatization of the intermediate o--arylpalladium-aryl complex. " ... 

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