Supramolecular Assemblies as Promoters of Iodohydrin Formation

Abstract

Finding alternative reaction media to replace polluting organic solvents is one aim of green chemistry. The ultimate green solvent, water, is the cheapest, non-toxic and most readily available reaction medium: three properties which make it an environmentally and economically attractive solvent. However, a fundamental problem in performing reactions in water is that many organic substrates are hydrophobic and not soluble in water. Several approaches are possible in solubilizing these compounds in aqueous media, one of which is carrying out reactions in aqueous solutions of surfactants at concentrations above their critical micellar concentration (cmc). Reactions of iodine with cyclohexene, 1-octene and styrene in water or in the presence of cationic surfactants do not give useful amounts of iodohydrins, but reactions in anionic surfactants give good yields. Iodohydrins are important functionalizable compounds and are readily prepared in the presence of sodium dodecyl sulfate (SDS) or sodium N-dodecanoyl sarcosinate (SANa). The critical conditions for these reactions were optimized with a rigorous statistical approach, the experimental design method. Use of these newly optimized reaction conditions gave high yields in short times for all of the alkenes examined. The use of anionic surfactants in water to form iodohydrins is a valid alternative to methods previously described

Efficient Iodine-Mediated Beckmann Rearrangement of Ketoximes to Amides under Mild Neutral Conditions

“…Notably, there is precedent in the literature for catalytic deoximation by iodine in water in the presence of an anionic surfactant (sodium dodecylsulfate), 26 which provides micellar solubilization as well as activation of the iodonium ion. 27 Water presumably impedes the rearrangement process by coordinating with iodine, thereby encouraging the competitive deoximation process. A reaction using 50 mol% of iodine in anhydrous refluxing acetonitrile gave excellent results in terms of the yield and reaction time (98%, 1 h), and these conditions proved to be optimal.…”

Coumarin heterocyclic derivatives: chemical synthesis and biological activity

“…In 2013, Litinas and coworkers described the synthesis of 2-methyl substituted [5,6] to its activation by SDS, 151 and its catalytic inuence could be due to the electrophilic activation of the carbonyl. 152 When the electron-rich dienophiles were changed to cyclic 1,3-diketones 196, the chromeno[3,4-b]quinoline derivatives 197 were obtained (Scheme 62).…”

“…A similar three-component transformation, followed by oxidative aromatization under auto-tandem iodine catalysis under aqueous micellar conditions (in the presence of sodium dodecyl sulfate, SDS) provides the Schiff's base reduction product 195, implying an internal hydrogen transfer process, together with a mixture of the regioisomers 193 and 194 (Scheme 61). 150 The catalytic activity of iodine was presumably linked to its activation by SDS, 151 and its catalytic inuence could be due to the electrophilic activation of the carbonyl. 152 When the electron-rich dienophiles were changed to cyclic 1,3-diketones 196, the chromeno[3,4-b]quinoline derivatives 197 were obtained (Scheme 62).…”

N-Iodosaccharin (NISac)

“…NISac reacts with electron-deficient alkenes, 11 such as a,b-unsaturated ketones, acids, esters and nitriles, in aqueous organic solvents to afford the corresponding iodohydrins [12][13][14] in good yields.…”