Stereoselective Synthesis of cis-2-Ene-1,4-diones via Aerobic Oxidation of Substituted Furans Catalyzed by ABNO/HNO₃

Abstract

We report a highly efficient and selective catalytic system, ABNO (9-azabicyclo-[3.3.1]­nonane N-oxyl)/HNO3, for the aerobic oxidation of substituted furans to cis-2-ene-1,4-diones under mild reaction conditions using oxygen as the oxidant. The catalyst system is amenable to various substituted (mon-, di-, and tri-) furans and tolerates diverse functional groups, including cyano, nitro, naphthyl, ketone, ester, heterocycle, and even formyl groups. Based on the control and 18O-labeling experiments, the possible mechanism of the oxidation is proposed.

Evaluation of Aquivion® as Recyclable Superacid Solid Catalyst in the Oxidation of Furfurylamines with Hydrogen Peroxide to 3‐Hydroxypyridines

“…Beside the starting material 2 d two other major compounds 2 x , y have proton chemical shifts in the 6–6.5 pm range indicating two other furans or the opened intermediates 6 (Scheme 1). The observed chemicals shifts are also similar to the reported but‐2‐en‐1,4‐diones prepared by oxidation of furans [47] and the formation of cyclized compounds similar to the intermediate 7 can also be postulated [48] . The ratio of 2 d – 2 x – 2 y – 9 d – 9 x was determined by 1 H NMR to be 1.3–1.0–0.5–0.6–1.0, suggesting a conversion of furan to pyridine for 2 d of approximatively 36 % with a modest 14 % conversion to the expected pyridinol 9 d .…”

The Utility of Oxoammonium Species in Organic Synthesis: Beyond Alcohol Oxidation

“…193 Recently, Zhang and Xie et al reported the aerobic oxidation of substituted furans into corresponding cis-2-ene-1,4-diones using an ABNO/HNO3 catalytic system. 194 They proposed that this transformation involves the nucleophilic addition of furans at the C2 position to form ABNO oxoammonium species.…”

Furan ring opening reaction for the synthesis of 2,5-dicarbonyl-3-ene-phosphates

“…Furan derivatives are readily available and some of them have been identified as platform molecules that can be obtained from renewable resources. [1][2][3] Due to their low aromatic properties, they serve as important building blocks in bioactive molecules, making them valuable in synthetic chemistry. [4][5][6][7] They can not only be used as masked olefins, enol ethers, 8 1,4dione, 9 and carboxylic acids, 10 but can also undergo recyclization reactions to form carbocycles and heterocyclic rings.…”