Carbonyl Oxidation With Hypervalent Iodine Reagents
Carbonyl oxidation with hypervalent iodine reagents involves the functionalization of the α position of carbonyl compounds through the intermediacy of a hypervalent iodine(III) enolate species. This electrophilic intermediate may be attacked by a variety of nucleophiles or undergo rearrangement or elimination. Introduction Hypervalent iodine(III) compounds are attractive oxidizing agents because of their stability and selectivity. In the presence of enolizable carbonyl compounds, they are able to accomplish oxidative functionalization of the α position. A key iodine(III) enolate intermediate forms, which then undergoes either nucleophilic substitution (α-functionalization), elimination (dehydrogenation), or rearrangement. Common hypervalent iodine reagents used to effect these transformations include iodosylbenzene (PhIO),Schardt, B. C.; Hill, C. L. ''Inorg. Chem.'' 1983, ''22'', 1563. iodobenzene diacetate (PhI(OAc)2), Koser's reagent (PhI(OTs)OH), and (dichloroiodo)benzene (PhI ...
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Iodosylbenzene
Iodosobenzene or iodosylbenzene is an organoiodine compound with the empirical formula . This colourless solid compound is used as an oxo transfer reagent in research laboratories examining organic and coordination chemistry. Preparation and structure Iodosobenzene is prepared from iodobenzene. It is prepared by first oxidizing iodobenzene by peracetic acid. Hydrolysis of resulting diacetate affords "PhIO": : : The structure of iodosobenzene has been verified by X-ray crystallography, crystallographically. Related derivatives are also oligomeric. Its low solubility in most solvents and vibrational spectroscopy indicate that it is not molecular, but is polymeric, consisting of –I–O–I–O– chains. The related diacetate, , illustrates the ability of iodine(III) to adopt a T-shaped geometry without multiple bonds. Theoretical studies show that the bonding between the iodine and oxygen atoms in iodosobenzene represents a single dative I-O sigma bond, confirming the absence o ...
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