Iodine carboxylic acids, review

Section 3.2). Catalytic application of the iodine(V) species in the oxidation of alcohols has been reviewed by Uyanik and Ishihara [10, 75]. The first examples of a catalytic application of an iodine(V) species (i.e., IBX) in the oxidation of alcohols using Oxone as a stoichiometric oxidant were independently reported by the groups of Vinod [4] in 2005 and Giannis [5] in 2006. Vinod s group employed 20-40 mol% of 2-iodobenzoic acid in a water-acetonitrile biphasic solvent system, in which primary and secondary alcohols were oxidized to carboxylic acids and ketones, respectively (Scheme 4.44) [4]. 

The synthesis of the four monocarboxylic acids of dibenzothiophene has been recorded in the previous review. However, several modified preparations have since been described. Ethyl 1-dibenzothiophene-carboxylate has been synthesized from 2-allylbenzo[6]thiophene (Section IV,B, 1) hydrolysis afforded the 1-acid (57% overall). In a similar manner, 3-methyl-1-dibenzothiophenecarboxylic acid was obtained from the appropriately substituted allyl compound. This method is now the preferred way of introducing a carbon-containing substituent into the 1-position of dibenzothiophene. 2-Dibenzothiophenecarboxylic acid has been prepared by oxidation of the corresponding aldehyde or by sodium hypoiodite oxidation of the corresponding acetyl compound. Reaction of 2-acetyldibenzothiophene with anhydrous pyridine and iodine yields the acetyl pyridinium salt (132) (92%), hydrolysis of which yields the 2-acid (85%). The same sequence has been carried out on 2-acetyldibenzothiophene 5,5-dioxide. The most efficient method of preparing the 2-acid is via carbonation of 2-lithio-... 

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