2-Iodoxybenzenesulfonic Acid as an Extremely Active Catalyst for the Selective Oxidation of Alcohols to Aldehydes, Ketones, Carboxylic Acids, and Enones with Oxone

Abstract

Electron-donating group-substituted 2-iodoxybenzoic acids (IBXs) such as 5-Me-IBX (1g), 5-MeO-IBX (1h), and 4,5-Me(2)-IBX (1i) were superior to IBX 1a as catalysts for the oxidation of alcohols with Oxone (a trademark of DuPont) under nonaqueous conditions, although Oxone was almost insoluble in most organic solvents. The catalytic oxidation proceeded more rapidly and cleanly in nitromethane. Furthermore, 2-iodoxybenzenesulfonic acid (IBS, 6a) was much more active than modified IBXs. Thus, we established a highly efficient and selective method for the oxidation of primary and secondary alcohols to carbonyl compounds such as aldehydes, carboxylic acids, and ketones with Oxone in nonaqueous nitromethane, acetonitrile, or ethyl acetate in the presence of 0.05-5 mol % of 6a, which was generated in situ from 2-iodobenzenesulfonic acid (7a) or its sodium salt. Cycloalkanones could be further oxidized to alpha,beta-cycloalkenones or lactones by controlling the amounts of Oxone under the same conditions as above. When Oxone was used under nonaqueous conditions, Oxone wastes could be removed by simple filtration. Based on theoretical calculations, we considered that the relatively ionic character of the intramolecular hypervalent iodine-OSO(2) bond of IBS might lower the twisting barrier of the alkoxyperiodinane intermediate 16.

Nickel‐Catalyzed Formation of a Carbon–Nitrogen Bond at the β Position of Saturated Ketones

“…[2] However, bond formation on the b-carbon atom of saturated ketones still remains unexplored. [3][4][5][6][7][8] Herein, we describe a new catalytic formation of a carbonnitrogen bond at the b position of alkyl ketones in the presence of a nickel complex.…”

“…[3] The catalytic process involves the oxidation of the a-phenylated propiophenone by using a combination of the halobenzene and the palladium catalyst, to give the corresponding a,b-unsaturated ketone through a similar pathway to that of Saegusa-Ito oxidation. [7,8] The a,b-unsaturated ketone undergoes a Mizoroki-Heck reaction to form the carbon-carbon bond at the b position. [9] We envisioned that selective bond-formation on the b-carbon atom of ethyl ketones would be achieved if the oxidation with halobenzene proceeded without a arylation.…”

Practical Azidation of 1,3‐Dicarbonyls

“…Consequently, we turned our attention to the newly developed IBX-derivative 4 (IBX-SO 3 K), which, at room temperature, is water soluble and fully lacks reactivity towards primary and secondary alcohols (Scheme 3). [28][29][30] To our delight, 3-oxoester 1 a was rapidly converted into the corresponding azide 2 a when IBX-SO 3 K and catalytic amounts of NaI were used to generate the active oxidant in situ (Table 1, entry 9). The procedure for the direct azidaScheme 1.…”

2‐Iodoxybenzoesäure – ein einfaches Oxidationsmittel mit einer Vielfalt an Anwendungsmöglichkeiten

“…Die Oxidation von Alkoholen zu den entsprechenden Carbonylverbindungen gelingt in Gegenwart von 0.05-0.5 Mol-% IBS, das in situ aus 2-Iodbenzolsulfonsäure oder dessen Natriumsalz 16 durch Oxidation mit Oxone gebildet wird (Schema 5). [45] Die von Ishihara et al entwickelte Methode kann darüber hinaus bei geeigneter Reaktionsführung die entstehenden Carbonylverbindungen weiter in die entsprechenden Enone überführen oder allylische Alkohole oxidativ umlagern. [46] Anwendungen von IBX-Derivaten in der Totalsynthese oder zur Modifizierung biologisch aktiver Naturstoffe sind bis heute rar.…”