Oxone Oxidation of Selenides: A Mild and Efficient Method for the Preparation of Selenones

Abstract

Selenide (a) to selenoxide (b) or selenone (c) oxidation is a useful operation in organic synthesis, and a variety of reagents have been developed for this purpose. a b C Most investigations have focused on the preparation and reactivity of selenoxides,' but selenones have received little attention. Selenones have been prepared by oxidation of selenides using an excess of peroxycarboxylic acids,2 potassium permanganate,2 or hydrogen peroxide in the presence of seleninic acid.3 These methods have several disadvantages and can be applied only to selenides with limited structural features in the presence of selected solvents.Herein, we report that potassium hydrogen persulfate, commercially available as Oxone, can be used effectively for the direct conversion of selenides to selenones under very mild conditions. When selenides are treated with 3 mol equiv of Oxone in a methanolic, aqueous, buffered solution (pH 8.0-8.5) at room temperature, selenones are produced in good yield. The amount of buffered solution added in these reactions is crucial for success to selenone formation because the oxidation process involves the generation of acids, and Oxone has shown a strong pH dependence as ~x i d a n t .~ This protocol was applied to the oxidation of three classes of substrates: alkylaryl selenides, #?-methoxyalkyl selenides, and b-hydroxyalkyl selenides. The reactions can easily be monitored by TLC since selenones are more polar than selenides but less polar than selenoxide intermediates. Selenones exhibit a characteristic IR absorption at 870-970 and 912-1059 ~m -l ,~ and in 13C

Synthetic journey towards transition metal-free arylations

“…Despite the aryl-aryl biaryl compounds, researchers have moved towards organoselenium compounds because of their biological importance [93][94][95]. Often, diaryl selenide and its derivatives have shown their great antioxidative properties [96].…”

7.28 Oxidation of Sulfur, Selenium, and Tellurium

“…363 Treatment of tetraaryl-substituted selenophenes with DMDO (2 equivalents) in acetone at 0 1C leads to the clean formation of the selenophene-1,1-dioxides in good-to-high yield. 364 The isolation of the corresponding selenoxides when using 1 equivalent of DMDO was unfruitful as these compounds are labile, except in the case of benzo [b]selenophene.…”

Sulfur and Phosphorus Peroxides

“…This method was applied to prepare tricarbonyl compounds. Selenides were oxidized with Oxone in buffered methanol to the corresponding selenones in quantitative yields 169 . Webb and Levy showed that several boronic acids and boronic esters can be converted into the corresponding alcohols in excellent yields (equation 60).…”