A Predictably Selective Nitration of Olefin with Fe(NO₃)₃ and TEMPO

Abstract

Ferric nitrate with catalytic TEMPO has been identified as a useful reagent for regio- and stereoselective nitration of a wide variety of aromatic, aliphatic, and heteroaromatic olefins. This reaction provided nitroolefins in preparatively useful yields with excellent E-selectivity. Due to its mild nature and operational simplicity, the present protocol is expected to find application in synthetic setup.

Mild Nitration of Pyrazolin‐5‐ones by a Combination of Fe(NO3)3 and NaNO2: Discovery of a New Readily Available Class of Fungicides, 4‐Nitropyrazolin‐5‐ones

“…Runs 1–3 showed that Fe(NO 3 ) 3 ⋅ 9H 2 O is an effective reagent for the nitration of pyrazolin‐5‐one 1 a at 60–80 °C, but at room temperature 4‐nitropyrazolin‐5‐one 2 a was obtained in a yield of only 33 % (run 4). Apparently, an elevated temperature was necessary for the decomposition of Fe(NO 3 ) 3 ⋅ 9H 2 O and the release of the active nitrating agent NO 2 . The introduction of NaNO 2 into the reaction allowed the room‐temperature nitration of pyrazolin‐5‐one 1 a in high yields (runs 5–7).…”

“…A possible reason is the interaction of the solvents and H 2 O with NO 2 , the plausible nitrating reagent generated in situ. In the nonpolar solvent C 2 H 4 Cl 2 , which has previously been widely used in nitration reactions with Fe(NO 3 ) 3 ⋅ 9H 2 O, compound 2 a was obtained in low yield (33 %, run 11), which can be explained by the low solubility of the reagents in this solvent at room temperature. In a number of studies on Fe(NO 3 ) 3 ⋅ 9H 2 O‐mediated nitration, TEMPO proved to be an effective additive to increase the yields of nitro derivatives.…”

“…Both hydrogen‐atom abstraction and addition to double C=C bonds are typical reactions of NO 2 . For nitration reactions mediated by iron(III) nitrate, the NO 2 free radical was previously suggested to be the active nitration agent …”

Recent advances in the synthesis of nitroolefin compounds

“…32 A broader range of substrates such as aliphatic, aromatic, heteroaromatic olefins can undergo this reaction in excellent yields. 32 A broader range of substrates such as aliphatic, aromatic, heteroaromatic olefins can undergo this reaction in excellent yields.…”

Highly double selective nitration of nitrostilbenes over zeolite

“…Recently, Maiti and co-workers reported the preparation of (E)-nitroolefins from nitration of olefins using AgNO 2 /TEMPO, 7 t-BuONO/TEMPO, 8 and Fe(NO 3 ) 3 /TEMPO. 9 These methods while offering significant improvements in direct nitration of olefins have problematic issues, which include metal reagent employed, absence of recovery and reuse of the catalyst.…”