A Selective and Practical Synthesis of Nitroolefins

Abstract

A straightforward and general synthesis of nitroolefins from nitric oxide (NO) and olefins is presented. The direct nitration of aromatic olefins, allyl compounds, and acrylic acid derivatives proceeds smoothly at room temperature with high regioselectivity and good yields. The advantages of this novel procedure compared to established nitration procedures are demonstrated.

Effective Nitration of Anilides and Acrylamides by tert‐Butyl Nitrite

“…First, TBN undergoes a thermal homolysis to liberate the alkoxyl and nitric oxide radicals. [20] In the arene nitration process, it is assumed that the initial one-electron oxidation of the anilide by copper(II) results in the formation of anilide radical A. [20] In the arene nitration process, it is assumed that the initial one-electron oxidation of the anilide by copper(II) results in the formation of anilide radical A.…”

“…On the basis of above experimental evidence and related literature, [12,[19][20][21][22] the plausible reaction mechanisms of these nitration processes are proposed in Scheme 5. First, TBN undergoes a thermal homolysis to liberate the alkoxyl and nitric oxide radicals.…”

“…[19] Then NO · is oxidized by air to afford NO 2 · . [20] In the arene nitration process, it is assumed that the initial one-electron oxidation of the anilide by copper(II) results in the formation of anilide radical A. [21] Subsequently, A undergoes a reversible transformation followed by the attack of the NO 2 radical at the ortho or para positions of the aromatic ring to generate the corresponding nitration products.…”

Oxidative Nitration of Styrenes for the Recycling of Low‐Concentrated Nitrogen Dioxide in Air

“…During optimization, it turned out that the elimination of nitric acid from the nitro nitrates 3 and 5 to yield nitrostyrenes13 as well as the retro‐aldol reaction of nitroalcohol 2 [ 48] to give benzaldehyde and nitromethane occurred as major side reactions. However, these reactions preferably occurred in protic solvents (e.g., methanol, ethanol), regardless of the presence of a buffer system such as NaH 2 PO 4 /Na 2 HPO 4 , and could then effectively be limited by the use of dry ethyl acetate.…”

“…12 Such reactions have been known for a long time, but have so far mainly been studied under protective gas atmosphere to presumably avoid multiple reaction pathways and complex kinetics. In a recent work by Beller et al.,13 the nitration of alkenes was efficiently achieved under a NO atmosphere containing catalytic amounts of O 2 (Scheme ). With NO 2 , which is present as part of an equilibrium with its dimer N 2 O 4 depending on the overall conditions,14 reactions are far more complex and the basic products obtained from alkenes can be 1,2‐dinitro compounds, nitroso nitrates, nitro nitrates as well as a number of related decomposition products 15–17.…”