An Organic Tridentate Ligand Stabilizing a 10-I-4 Iodinane Oxide and Related Species

Article abstract of DOI:10.1021/jo00023a022

The tridentate ligand of iodinane 7, with electronegative apical oxygens joined by five-membered rings to an electropositive equatorial carbon, strongly stabilizes pseudo-trigonal-bipyramidal (Ψ-TBP) 10-I-3 species 7, as well as 10-I-4 species such as iodinane oxide 5.Fluorination of 7 forms a pseudooctahedral (Ψ-Oc) 12-I-5 periodinane, 4, which is easily hydrolyzed to 5, or reacts with Lewis acids to form 10-I-4 fluoroperiodonium cation 8.The equatorial I⁺-O^- bond of 5 reacts with electrophiles at the oxygen .Small amounts of tetrabutylammonium hydroxide give nucleophilic addition to the iodine of 5 to form 12-I-5 intermediates (18) leading to rapid inversion of geometry at the 10-I-4 center of the iodinane oxide.Excess KOH cleaves the C-I bond of 5, forming the reduced arenediol 17.Diphenyldialkoxysulfurane 14 converts 5 to dialkoxyperiodinane 13, forming diphenyl sulfoxide.Iodine oxide 5 is a strong oxidizing agent, rapidly oxidizing HCl to Cl2, or pinacol to acetone.Oxidation of a diaryl sulfide to the sulfoxide and the sulfones occurs unselectively, but slowly, at 160 deg C with pure 5.With a catalytic amount of TFAA, selective oxidation of the diaryl sulfide to the sulfoxide by 5 is rapid at room temperature.