Carbocations oxygen containing

A few observations of the isolation of carbocation-carbanion salt containing heteroatoms, such as oxygen and nitrogen, have been reported. Over 30 years ago LeGoff and LaCount (1963) reported the formation of a... 

An initial addition of a ruthenium-oxygen double bond to a a-C—H bond leads to an intermediate containing a carbon-ruthenium bond. This bond suffers a homolytic scission leading to a carbon radical, which is oxidized to a carbocation that provides a carbonyl group by deprotonation. 

Oxidation of Carbon Skeletons with IBX. Allylic and benzylic positions are also susceptible to oxidation by IBX. These applications are not limited to the oxidation of compounds containing a pre-existing oxygen functionality but oxidize the hydrocarbon center directly to aldehydes or ketones. These oxidations also proceed via a single-electron-transfer pathway. The oxidation of aryl methyl groups to aryl aldehydes is accomplished with 3 equiv of IBX in DMSO or DMSO/fluorobenzene mixtures at 80-90 The first two equivalents of IBX initiate the single-electron-transfer to generate a benzylic carbocation. Subsequently, the reaction with water affords the alcohol in situ and the third equivalent of IBX completes the conversion to the desired benzaldehyde (eq 13). ... 

Of the two OH groups, the one which forms the more stable carbocation is protonated preferentially. This factor takes precedence over the migratory aptitude factor. Further evidence for carbenium ion formation in the pinacol rearrangement has been obtained by oxygen-exchange experiments. Partial rearrangement of pinacol to pinacolone has been carried out in acidic solutions containing H20 (Scheme 2.27). 

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