Iodides Komblum oxidation

Based upon the results of mechanism studies, a proposed mechanism containing two catalytic cycles was concluded by the authors. Firstly, benzylic radical is formed by the hydrogen abstraction of the terf-butoxy radical, which is well supported by literatures. The benzylic radical may be oxidized by iodine to give the benzylic cation with the generation of iodide ion. The interaction between iodide ion and TBHP would regenerate the terf-butoxy radical and finish the first catalytic cycle. Secondly, benzylic iodide is formed as a result of the reaction between benzylic cation and iodide ion, which is then converted into benzaldehyde by a DMSO participated Komblum oxidation. Finally, the iodide ion was oxidized back to iodine by TBHP to finish the second catalytic cycle (Scheme 4.17). Benzylic amine or alcohol may be formed from the benzylic cation. As confirmed in the control experiments, they can also lead to the nitrile product under standard condition. 

Komblum et al. had asserted that it was necessary to convert primary iodides to tosylates for the oxidation to proceed. However, Johnson and Pelter have claimed that primary iodides can be oxidized directly. They observed that ketonic substrates failed, undergoing aldol condensation under the reaction conditions, but that hydroxy-containing halides reacted normally. For substrates insoluble in DMSO such as 1-bromododecane, they found that DME worked well as a cosolvent. The most interesting example... 

One way to increase the nucleofiigacity of halides is to introduce silver ion. Komblum reported that primary unactivated chlorides, bromides and iodides could be oxidized by prior conversion to the tosyl-ate with silver tosylate, followed by reaction in DMSO (Scheme 4). ... 

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See also in sourсe #XX -- [ ]

See also in sourсe #XX -- [ ]

See also in sourсe #XX -- [ , ]

See also in sourсe #XX -- [ , ]

See also in sourсe #XX -- [ ]

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