Search

(4-Triisopropylsilylphenyl)phenyliodonium tosylate, an aryliodonium salt bearing an extremely bulky, electron-donating triisopropylsilyl (TIPS) substituent in the phenyl ring, was prepared by the reaction of (4-tributyltinphenyl)triisopropylsilane with [hydroxy(tosyloxy)iodo]benzene (Koser's reagent). The TIPS-substituted aryliodonium tosylate was further converted into (4-triisopropylsilylphenyl)phenyliodonium bromide, the structure of which was established by single-crystal X-ray diffraction. Reactions of the TIPS-substituted arylodonium tosylate with bromide, azide, and thiocyanate anions predominantly afforded products of nucleophilic substitution in the electron-rich aromatic ring bearing the TIPS substituent. This unusual result is explained by the steric effect of the extraordinary bulky para-TIPS substituent on the configuration of the reaction intermediate.

New hypervalent iodine(V) oxidants are prepared by the reaction of IBX with sulfonic acids.

New powerful hypervalent iodine(V) oxidants, tosylate and mesylate derivatives of 2-iodoxybenzoic acid (IBX), were prepared by the reaction of IBX with the corresponding sulfonic acids. Single crystal X-ray crystallography of the diacetate derivative of IBX-tosylate revealed an unusual heptacoordinated iodine geometry without any significant intermolecular secondary interactions.