Oxidative Breakdown of Iodoalkanes to Catalytically Active Iodine Species: A Case Study in the α‐Tosyloxylation of Ketones (original) (raw)
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The Effect of Iodine on the Peroxidation of Carbonyl Compounds
The Journal of Organic Chemistry, 2007
Peroxidation of ketones and aldehydes with iodine as a catalyst was studied. Ketones reacted with 30% aq hydrogen peroxide in the presence of 10 mol % of iodine to yield gem-dihydroperoxides in acetonitrile and hydroperoxyketals in methanol. The yield of hydroperoxidation of various cyclic ketones was 60-98%, including androstane-3,17-dione, while acyclic ketones were converted with a similar efficiency. Aromatic aldehydes were also converted to gem-dihydroperoxides with hydrogen peroxide and iodine as catalyst in acetonitrile and to hydroperoxyacetal in methanol, while the reactivity of aliphatic ones remained the same as in noncatalyzed reactions. tert-Butylhydroperoxide reacted in a similar manner, giving the corresponding perether derivatives. A study was also made of the relative kinetics of dihydroperoxidation from which the Hammet equation gave a reaction constant (F) of-2.76, indicating the strong positive charge development in the transition state and the important role of rehybridization in the conversion of hydroperoxyhemiketal to gem-dihydroperoxide. In acetonitrile, the iodine catalyst is apparently able to discriminate between the elimination of a hydroxy, methoxy, and hydroperoxy group and addition of water, methanol, and H 2 O 2 to a carbonyl group.
Advanced Synthesis & Catalysis, 2013
Hydrochloric acid activates the oxidative iodination of aromatic compounds with the iodinehydrogen peroxide system through the formation of an iodine(I) compound as the iodinating reagent. Activation with hydrochloric acid is more powerful than that with sulfuric acid. The formation of dichloroiodic(I) acid (HICl 2) with various forms of hydrogen peroxide was followed using UV spectroscopy. The HICl 2 was used as the iodinating reagent. In the preparative oxidative iodinaton of various aromatic compounds, hydrochloric acid was used in a catalytic amount and the iodine(I) reagent was formed in situ with 0.5 equiv. hydrogen peroxide and 0.5 equiv. molecular iodine. Two types of reactivity were observed in oxidative iodination with iodine(I) species catalyzed by hydrochloric acid: in the iodination of anisole 1a better yields of iodination were observed with a smaller amount of hydrochloric acid, while on the contrary 4-tert-butyltoluene 1b gave better yields of iodination upon increasing the amount of hydrochloric acid. Reactivity was further manipulated by the choice of the solvent (MeCN, trifluoroethanol, hexafluoro-2propanol).
International Academic Publishing House, 2022
Abstract: Molecular iodine is an eco-friendly, powerful catalyst and plays an important role in pharmaceutical, medicinal and organic chemistry. For a long time, molecular iodine has been hugely applied in carbohydrate chemistry. Due to the huge application of molecu-lar iodine in oxidation, cross coupling and cyclisation reactions, it has emerged as an ele-gant tool in organic synthesis. Earlier I discussed (Biswas, 2021) on iodine mediated cas-cade oxidative functionalisation, cyclisation and annulation reactions. In this review, I de-scribe the utility of iodine catalysed tandem oxidation, cross coupling, and cyclisation reac-tions in organic synthesis. Molecular iodine catalysed mild oxidative conditions yielding desired products, and oxidising techniques applied to the efficient synthesis tolerate a wide range of starting materials with aryl or alkyl replacements. These reactions were carried out as a one-pot or multi-step eco-friendly process that could be used for a wide range of drug and pharmaceutical product synthesis.
Direct α-iodination of ketones using iodine/SeO2
Tetrahedron Letters, 2000
A satisfactory yield one-pot synthesis of various α-mono iodoketones 2 was achieved by iodination under oxidative conditions of ketones 1. The monoiodination of different aliphatic or cyclic ketones (1-tetralones) showed the quite general applicability of the method.
Metal-free one-pot oxidative conversion: Molecular Iodine Mediated Oxidation Organic Reactions
International academic Publishing House, 2022
Various oxidative compounds such as aldehyde, ketone ester, and acids can be produced in large yields by an effective iodine-mediated oxidative reaction of organic molecules. Molecular iodine is a generally available and commercially extremely inexpensive substance that induces oxidative esterification. With the comparison with different Brønsted acid catalysis, molecular iodine or iodophilic activations proceed the reaction onto a deoxygenation pathway. With only a few mol% of I2, the oxidation occurs very quickly at room temperature. This approach could also be used to transport different benzil derivatives from nonactivated alkynes, such as diaryl acetylenes. Molecular iodine with several mild reagents such as aq. NH3, ∼30% aq. H2O2 and DMSO might be used to convert various one degree alcohols, particularly benzylic alcohols, into the corresponding aromatic amides in sufficiently high yields in a one-pot method. Similarly, by treating different benzylic chloride, bromide and iodide with a molecular iodine oxidation medium, the corresponding aromatic amides may be prepared in a one-pot method. The reactions in this section include transformation of several compounds into their respective oxidative products with the metal-free one-pot oxidative.