Hypervalent Iodine(III) Chemistry: Facts, Myths and Discoveries

A thesis submitted in total fulfillment of the requirements for the degree of Doctor of Philosophy to the School of Agriculture, Biomedicine and Environment, La Trobe University, Victoria, Australia.</p

A decade of lessons in the activation of ArIL2 species

Hypervalent iodine(iii) compounds of the general structure ArIL2 are widely used as oxidizing agents for a variety of applications across both organic and inorganic chemistry. Considerable work has been done on the activation of these compounds by tuning the ligands at the iodine centre. This perspective summarises the work of our and other groups on rectification of historically misidentified iodine(iii) reagents of this class, and the syntheses of activated species. Recent advances focusing on increasing the oxidative capacity of I(iii) moieties using Lewis and Brønsted acids and Lewis bases as well as the activation of halogens with I(iii) are discussed.</p

Kinetic study on the activation of PhICl₂ with Lewis bases for aromatic chlorination

A study on the kinetics of the activation of PhICl2 using catalytic chloride or pyridine in electrophilic chlorination of arenes has been carried out. The results indicate that both catalysts induce the release of Cl2 from PhICl2 and that the Cl2 is the active reagent for chlorination in these reactions.</p

Synthesis and Structural Verification of an ArI(OTf)2, NO2-Ph-I(OTf)2

PhI(OTf)2 and related ArI(OTf)2 species have been incorrectly invoked as intermediates in oxidation reactions for many years. We recently established that such compounds did not yet exist but remain an attractive target. Here we describe the synthesis, isolation, and structural characterization of NO2-PhI(OTf)2, which is resistant to decomposition and more reactive than PhI(OTf)(OAc), the species previously misidentified as PhI(OTf)2

Electrophilic activation of molecular bromine mediated by I(III)

In pursuit of a genuine bromo-λ3-iodane, it has been found that the combination of Br2 and electron deficient λ3-iodanes can result in the delivery of both bromine atoms from Br2 to a range of aryl substrates, some highly deactivated. These brominations occur rapidly in common chlorinated solvents at room temperature and can be achieved with the catalytic activation of commercially available PhI(OAc)2 and PhI(OTFA)2. para-NO2 substituted derivatives are employed to direct bromination towards more deactivated substrates. The mechanism of Br2 activation is discussed with insights being made, however it remains unclear.</p

On the potential intermediacy of PhIBr2 as a brominating agent

No description supplied </p

C-H, Si-H and C-F abstraction with an extremely electron poor I(iii) reagent

The recently discovered I(iii) reagent NO2-C6H4-I(OTf)2 is found to rapidly react with hydride sources, including HSiEt3 and relatively hydridic C-H precursors. These represent the first distinct reactions involving direct hydride abstraction by I(iii) under ambient conditions. Direct C-F abstraction is also demonstrated, as well as oxidation of cyclic alkenes to aromatic rings, all representing new reactions for I(iii) demonstrating the very high reactivity of NO2-C6H4-I(OTf)2.</p

PhI(OTf)2 Does Not Exist (Yet)

PhI(OTf) has been used for the past 30 years as a strong I(III) oxidant for organic and inorganic transformations. It has been reported to be generated in situ from the reactions of either PhI(OAc) or PhI=O with two equivalents of trimethylsilyl trifluoromethanesulfonate (TMS-OTf). In this report it is shown that neither of these reactions generate a solution with spectroscopic data consistent with PhI(OTf) , with supporting theoretical calculations, and thus this compound should not be invoked as the species acting as the oxidant for transformations that have been associated with its use.</p

PhI(OTf)2 Does Not Exist (Yet)

PhI(OTf) has been used for the past 30 years as a strong I(III) oxidant for organic and inorganic transformations. It has been reported to be generated in situ from the reactions of either PhI(OAc) or PhI=O with two equivalents of trimethylsilyl trifluoromethanesulfonate (TMS-OTf). In this report it is shown that neither of these reactions generate a solution with spectroscopic data consistent with PhI(OTf) , with supporting theoretical calculations, and thus this compound should not be invoked as the species acting as the oxidant for transformations that have been associated with its use.</p

PhICl₂ is activated by chloride ions

A study on the potential activating role of pyridine in the electrophilic chlorination of anisole by PhICl2 has led to the discovery that soluble sources of chloride ions activate PhICl2 in the reaction at catalytic loadings, greatly increasing the rate of chlorination. It is further shown that presence of chloride increases the rate of decomposition of PhICl2 into PhI and Cl2. The specific mechanism by which chloride induces electrophilic chlorination and decomposition of PhICl2 remains an open question.</p